Mindmap

BIO 150

John Donnelly Science Englisch

Mind map: BIO 150

Inhalt der Mindmap

BIO 150

Biodiversity Loss
- Habitat Destruction
  - Overfishing
  - Deforestation
    - More Crop land needed to farm
      - Overpopulation of humans
        Increased food demand
- Elephants
  - Poaching
    - Ivory
      - Aphrodisiac properties
- Invasive species
Globalization
- Spread of pathogens and disease
- Spread of invasive species
Canaries in coal mines
- Amphibians are the early warning signals for humans
  - Climate change
    - Weather intensification
- Carbon monoxide alarms
  - Carbon dioxide risk for humans
    - Global Warming
      - Melting of glaciers
        much more water
        stronger hurricanes
Genetic Variation
- Alleles
  - Different variants of a gene
  - Allele Fixation
    - population only exhibits 1 allele at a particular gene in every individual
  - Allele Frequency
    - the number of time a particular allele is present in the population divided by the total number of alleles
    - 3 ways to measure genotype/allele frequencies in populations
      - 1) Observable traits
      - 2) Gel electrophoresis
      - 3) DNA sequencing
- Genotype
  - Species
    - Shared Gene pool
    - Natural populations
      - groups of organisms that breed with each other and live in the same geographic area
    - Group of individuals capable of sharing alleles with each other through reproduction that produces fertile offspring
      - Hybridization
        interbreeding between 2 varieties or species
        Hybrid Offspring are individuals produced by a cross
        can be infertile if 2 incompatible species are bred together
    - Speciation
      - formation of new and distinct species in the course of evolution
      - Evolution is as much about speciation which is the engine that generates biodiversity as it is about adaptation which is the result of natural selection
      - Species concepts
        1) Biological Species Concept (BSC)
        species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups
        Reproductive Isolation
        reason why most species can't breed with other species, caused by barriers either pre or post egg fertilization
        Pre Zygotic Factors
        occur before egg fertilization and are more common than post zygotic factors
        1) Behavioral Isolation
        the actions of one species doesn't attract sexual attention from another species
        NOT a factor in PLANTS
        2) Gametic Isolation
        incompatibility between the gametes of different individuals typically belonging to different species
        3) Mechanical Incompatibility
        structural configuration of the genitalia that prevents mating with another individual of a different species
        especially prevalent in insects
        4) Temporal Isolation
        individuals are reproductively active during different times of the year making it impossible to reproduce together
        5) Geographic / Ecological Isolation
        individuals don't live near each other and have no chance to mate OR isolation between individuals who specialize ecologically in different ways
        Post Zygotic Factors
        Genetic Incompatibility
        genetic dissimilarity between 2 organisms
        Ex) different number of chromosomes prevents 2 individuals from producing offspring together
        occur after egg fertilization
        Partially Reproductively Isolated
        populations have not yet diverged into separate species but whose genetic differences are extensive enough for the hybrid offspring they produce to have reduced fertility compared to offspring produced by crosses of individuals within each population
        Not truly different species but can't breed together
        most widely accepted definition of what a species is but doesn't apply to asexual organisms
        more useful in theory than in practice
        more useful than ESC and PSC although the other 2 both help generalize the concept of what a species is
        2) Ecological Species Concept (ESC)
        idea that there is a 1:1 correspondence between a species and its niche
        Niche is the combination of traits an organism has and the habitat in which it exits
        turns out its impossible for 2 species to coexist in the same exact niche because competition for the same resources inevitably leads to extinction of one species
        3) Phylogenetic Species Concept (PSC)
        idea that members of a species all share a common ancestry and a common fate
        PSC can be useful when thinking about asexual species but given the arbitrariness of the decisions involved in assessing whether descendants of a single ancestor warrant the term "species" limits its functional utility
        4) Morphospecies Concept
        idea that members of the same species usually look alike more than like other species
        in modern era has been extended to the molecular level, members of the same species usually have similar DNA sequences distinct from those of other species
        Cryptic Species
        organisms /species that have been traditionally considered as belonging to a single species because they look similar but turn out to belong to 2 species because of differences at the DNA sequence level
        Drawback of morphospecies concept is that members of the same species may not always look alike but instead show different phenotypes called polymorphisms
        Polymorphisms are discontinuous genetic variations causing multiple phenotypes within a single species
        members of the same species can look very different from each other but members of different species can also look very similar to each other
      - Allopatric Speciation
        speciation that results from the geographical separation of populations
        physical separation doesn't immediately cause reproductive isolation but over many generations will
      - Peripatric Speciation
        specific kind of allopatric speciation where a few individuals from a mainland population disperse to a new location remote from the original population and evolve separately
      - Sympatric Speciation
        formation of a new species from a surviving ancestral species while both continue to live in the same location
        for sympatric speciation to occur natural selection must act strongly to counteract the homogenizing effect of gene flow
    - real biological entities not just convenient way to group organisms
  - set of alleles possessed by the individual
  - Genotype Frequency
    - the number of individuals in a population with a given genotype divided by the total number of individuals in the population
- Phenotype
  - Observable traits
- Causes of genetic variation
  - Mutation
    - Somatic mutation
      - mutations in non-reproductive body cells
    - Germ line mutation
      - mutations in reproductive cells, passes on these mutations to next generation
    - Mutation classification
      - 1) Neutral
      - 2) Deleterious
      - 3) Advantageous
    - mutation is the ultimate source of all genetic variation
  - Recombination
    - Shuffles mutations into new combination to form new alleles
      - Conjugation
        process of genetic recombination that occurs between 2 organisms in addition to asexual reproduction
        asexual organisms exchange genetic material through direct contact while temporarily joined
  - Genetic Diversity
    - Asexual reproduction decreases genetic diversity
      - Mitosis
        Mitotic cell division
        mitosis and cytokinesis
        5 phases of mitosis after DNA replication
        1) Prophase
        chromosomes condense and become visible under light microscope
        2) Prometaphase
        the spindle microtubules attach to the centromeres
        3) Metaphase
        the chromosomes line up in the middle of the cell
        4) Anaphase
        the centromeres split and the chromosomes move to opposite poles
        5) Telophase
        the nuclear envelope reforms and chromosomes decondense
        Mitosis is followed by cytokinesis when 1 cell divides into 2
        In animals a contractile ring of actin pinches the cell splitting it into 2
        In plants a new cell wall called the cell plate is synthesized/made between the daughter cells
        produces genetically identical daughter cells and is the basis for asexual reproduction and development
    - Sexual reproduction increases genetic diversity
      - Meiosis
        Cell Division
        single parent cell produces 2 daughter cells
        prokaryotic cells divide by binary fission
        binary fission is the process of a cell replicating its DNA, segregates its DNA, and divides into 2 separate cells
        Eukaryotic cells divide by mitosis and cytokinesis
        DNA in eukaryotic cells is packaged as linear chromosomes rather than circular
        Humans have 23 pairs of chromosomes or 46 total chromosomes in each cell
        Homologous chromosomes are chromosomes of the same type with the same set of genes
        Each human parent contributes 1 complete set of 23 chromosomes at fertilization
        Cell Cycle Phases
        1) M Phase
        consists of mitosis and cytokinesis
        2) Interphase
        consists of G1, S, and G2 phases
        G0 phase is for cells that don't need to divide and exit the cell cycle
        During S phase chromosomes replicate forming a pair of sister chromatids held together at the centromere
        meiotic cell division produces genetically unique daughter cells and is the basis for sexual reproduction
        Sexual reproduction involves both meiosis and fertilization, both of which are very important in increasing genetic diversity
        fertilization is the fusion of haploid gametes to produce a diploid cell
        meiotic cell division reduces the number of chromosomes by half and produces haploid gametes or spores that have one copy of every chromosome
        Meiosis involves 2 successive cell divisions
        First division is reductional meaning the chromosome number is cut in half
        Second division is equational meaning the chromosome number stays the same
        Each division consist of the stages of the cell cycle
        Meiosis I
        homologous chromosomes pair and exchange genetic material at chiasmata regions crossing over
        centromeres don't split and sister chromatids don't separate
        Meiosis II
        chromosomes align in the center of the cell, centromeres split, and sister chromatids separate from each other
- Population genetics
  - Study of patterns of genetic variation in natural populations
  - Goal is to make inferences about the evolutionary process from observing patterns of genetic variation
Evolution
- Hardy Weinberg Equilibrium
  - if all conditions of equilibrium are met then it indicates evolution is not happening in that population
    - 5 conditions of Hardy Weinberg
      - 1) Sufficiently large population
      - 2) No migration
      - 3) No mutations in population
      - 4) Random mating
      - 5) No difference in survival / reproductive success
- Primary selection mechanisms of evolution
  - 1) selection
    - Natural Selection
      - results in allele frequencies changing between generations based on the allele's impact on survival and reproduction
      - Positive selection
        type of natural selection that increases the frequency of an advantageous allele
        more of a helpful gene variation
      - Fitness
        extent to which the individuals genotype is represented in the next generation
        more fit individuals are more suited to their environment and survive more and have more offspring
        Inbreeding Depression
        reduction in fitness from breeding among relatives causing homozygosity of deleterious recessive mutations
      - Negative selection
        type of natural selection that decreases frequency of a deleterious allele
        less of a gene that doesn't improve survival
      - Natural selection can be stabilizing, directional, or disruptive
        Stabilizing selection selects against extremes of a gene
        Ex) most babies are born about the same weight because it improves survival chances
        Directional selection results in shift of the mean value of a trait over time in a population
        over generations more organisms in that population tend to be a certain way
        Artificial Selection
        form of directional selection similar to natural selection except withe selection done intentionally by humans with a specific goal in mind
        Disruptive selection selects against the average expression of a gene
        Example would be all newly born babies are either 2 pounds or 12 pounds
        occurs when individuals in a population with extreme versions of a trait are the ones that survive and reproduce the most
      - Balancing Selection
        type of natural selection that acts to maintain 2 or more alleles of a gene in the population
        Heterozygote Advantage
        form of balancing slection where the heterozygote's fitness is higher than either of the homozygotes
      - Populations
        a population consists of all the individuals of a given species that live and reproduce in a particular place
        population size is the number of individuals at a particular time and place
        populations are characterized by 3 factors:
        1) size
        2) range
        population range is the total area in which a population lives
        3) density
        population density is the population size divided by its range
        population density often limits population growth because of decreasing resources
        growth of natural populations often follows a logistic growth pattern producing a S-shaped curve
        S-shaped curve is when growth is exponential at first but then tapers off as population size approaches carrying capacity of the environment
        this limit of population size is the carrying capacity (k) of the local environment
        Factors limiting population density
        1) density-dependent factors
        Ex) competition for limited resources, predation, etc.
        2) density-independent factors
        Ex) drought, fire, hurricane, etc.
        population size can be estimated by sampling and mark-recapture methods
        can increase or decrease over time
        main determinants of population size are births, deaths, immigration, and emigration
        population growth rate is the change in population size over time and commonly expressed as the per capita growth rate
        per capita growth rate is the rate of growth or decline per individual
        change in population size / time = per capita growth rate
        populations grow continuously when life cycles are not synchronized and discretely when organisms reproduce seasonally or annually
        Discrete population growth is when population size changes at one step in each generation
        Exponential growth is characterized by a constant per capita growth rate meaning the population grows proportionally to the number of current individuals
        Population age structure
        helps ecologists understand past changes and predict future changes in population size
        population age structure is the number of individuals of each age group usually shown as a histogram
        growing / younger populations are characterized by a pyramid-shaped age structure distribution with youngest age classes having more individuals than older classes
        stable populations show even distribution of all age classes
        Survivorship
        the proportion of individuals from an initial cohort that survives to each successive age or stage in the life cycle
        3 types of survivorship curves
        1) Type 1 Survivorship is when most individuals die later in life Ex) humans
        2) Type 2 survivorship is when individuals die at a consistent rate throughout the life cycle Ex) rodents
        3) Type 3 survivorship is when most individuals die at an early age Ex) fish
        r-strategists are organisms that live in unpredictable environments, produce many offspring, but invest little resources in their offspring
        K-strategists are organisms who have few offspring but invest heavily in their offspring which leads to higher survival rates
        Life history
        the life history of an organism is the evolved pattern of resource investment in each stage of a given species lifetime
        organisms often exhibit trade-offs between reproduction and other physiological functions which impacts survival probability
        Metapopulations
        multiple small, interconnected populations whose dynamics are influences by colonization and extinction
        the size of local populations (patches) and the degree of connectedness between patches determines in part whether a given patch will survive
        ecological islands can be actual islands surrounded by water OR any habitat surrounded by uninhabitable areas that organisms cant cross
    - Sexual selection
      - form of selection that promotes traits that increase an individual's access to reproductive opportunities
        2 types of sexual selection
        1) Intrasexual selection
        form of sexual selection involving interactions between individuals of 1 sex
        Ex) males competing with other males for females in their species
        2) Intersexual selection
        form of sexual selection involving interactions between males and females
        Ex) females choosing a male to mate with
  - 2) genetic drift
    - change in allele frequency due to chance between generations
  - 3) migration
    - results in gene flow
      - Gene Flow
        movement of alleles from one population to another through interbreeding between members of each population
    - consequence of migration is homogenization of populations
      - more similarities
        reduces genetic differences
        can be maladapative if the migrated individuals are well fit to their new environment
  - 4) mutation
  - 5) nonrandom mating
    - Ex) breeding cattle for higher milk production
    - Nonrandom mating alters genotype frequencies without affecting allele frequencies
- Non-Adaptive Mechanisms of Evolution
  - Genetic Drift
    - leads to changes in allele frequency and in turn evolution but NOT based on fitness improvements
    - Bottleneck effect
  - Founder Event
    - Ex) colonizing an island
    - type of genetic drift when only a few individuals establish a new population
- Phylogeny
  - the history of descent with modification and the accumulation of change over time
    - Nature displays "nested patterns of similarity among species
      - First recognized by Swedish naturalist Carolous Linnaeus
    - Darwin described this pattern as evolution
      - Evolution produces 2 distinct but related patterns both evident in nature
        1) The nested patterns of similarities found among species on present day Earth
        Homology
        similarity by common descent
        Homologous
        characters that are similar in different species because of decent from a common ancestor
        Analogous
        describes similar characters that evolved independently in different groups as a result of similar selection pressures
        result of convergent evolution
        2) Historical pattern of evolution recorded by fossils
        Fossil Record
        provides direct documentation of ancient life and offers strong complementary data to consider along with phylogeny
        Unique functions of fossils
        1) enable us to calibrate phylogenies in terms of time
        Geologic Timescale
        the series of time divisions that mark Earth's long history
        calibration of the timescale became possible with discovery of radioactive decay
        Radiometric Dating
        dating ancient materials using the decay of radio isotopes as a yardstick
        uses known rates of decay and compares how much of a substance is still left to determine how long ago it started to decay (death)
        Half Life
        the amount of time it takes for an amount of a substance to reach half of its original value
        all isotopes of elements have a unique half life which vary in duration based on molecular stability
        Isotope
        variation of an element with a different number of neutrons than the average version
        2) provide our only record of extinct species
        3) place evolutionary changes within the context of Earth's dynamic enviromental history
        Mass Extinctions
        catastrophic drops in recorded biodiversity which have occurred 5 times in the past 541 million years
        typically cause the dominant creature at the time to go extinct which provides evolutionary opportunities for survivors to become dominant
        Fossils are the remains of once-living organisms preserved through time in sedimentary rock
        2 required properties to be able to become a fossil
        1) Have a skeleton or other hard body parts that can resist decay
        2) live in an environment where being buried by sediment is likely
        2 ways that organisms who lack hard body parts can leave a fossil record
        1) trace fossils
        track or trail left by an organisms as it moves or burrows into sediments
        2) molecular fossils
        sterols, bacterial lipids, and some pigment molecules which are relatively resistant to decomposition
  - Phylogenetic trees
    - "tree of life"
    - visual representation of speciation throughout history by branching off and formation of new species and nodes
      - Nodes
        the point in phylogenetic trees where the branch splits representing the most recent common ancestor between 2 descendant species
        evolutionary relatedness is determined by following nodes from the tips to the root of the tree, the more recent the common ancestor then the more closely related those species are
      - branches of the tree can be rotated around a node without changing the evolutionary relationships of the groups
      - Monophyletic
        describes groups/taxa in which all members share a single common ancestor not shared with any other species/group of species
        identifying monophyletic groups is a major goal of phylogenetics because they include all descendants of a common ancestor and only the descendants of that common ancestor
        monophyletic groups show the evolutionary path a given group has taken since its origin
        Phylogenetic trees are constructed by comparing character states shared among different groups of organisms
        Character States
        the observed condition of a character
        Ex) presence of lungs
        Characters
        anatomical, physiological, or molecular features that make up organisms
        characters have several observed conditions
        character states in different species can be similar for 1 of 2 reasons:
        1) the character state may have been present in the common ancestor of the 2 groups and retained over time (common ancestry)
        2) the character state may have evolved independently in the 2 groups as an adaptation to similar environments (convergent evolution)
        Paraphyletic
        describes groupings that include some, but not all the descendants of a common ancestor
        the way to distinguish between mono or paraphyletic groups is if it only takes 1 cut on the tree to separate the group from the rest of the tree its monophyletic
        Synapomorphies
        shared derived characters present in some but not all members of a group
        synapomorphies are the basis of cladistic phylogenetic reconstruction
        Cladistics
        phylogenetic reconstruction on the basis of shared evolutionary changes in characters (synapomorphies)
        molecular data complement comparative morphology in reconstructing phylogenetic history
        molecular data is NOT intrinsically better than anatomical data, it's just that molecular data provides more details because there are more characters (alleles/genes) that can vary among the species
        Principle of Parsimony
        the phylogenetic tree with the least amount of evolutionary changes provides the simplest explanation of the data and is favored over more complex trees
        this is based on the assumption that evolutionary change is relatively rare/infrequent and over time most organisms stay the same
        derived character states are evolutionary innovations
        Polyphyletic
        describes groupings DON'T include the last common ancestor of all members
    - provide hypotheses of evolutionary relationships among populations or species
    - Phylogenetics is one of 2 related disciplines within systematics
      - Systematics
        the study of evolutionary relationships among organisms
        2 disciplines of systematics
        1) Phylogenetics
        goal of phylogenetics is to discover the pattern of evolutionary relatedness among groups of species or other groups by comparing anatomical and molecular features
        Sister Groups
        groups that are more closely related to each other than either of them is to any other group
        closeness of the relationship is determined by checking how recently the 2 groups shared a common ancestor
        phylogenetic trees are simply sets of sister group relationships
        2) Taxonomy
        goal of taxonomy is to recognize and name groups of individuals as species and then group closely related species into more inclusive taxonomic groups of genus and up throughout the taxonomic ranks
        Taxonomic ranks from biggest to smallest, biggest starting at #1
        1) Domain
        one of the 3 largest limbs of the tree of life
        1) Eukarya
        organisms whose cells have a nucleus enclosed by a nuclear membrane
        Eukaryotic Cells
        opposite of prokaryotic, characterized by having a nucleus with a nuclear membrane enclosing it
        internal protein scaffolding and dynamic membrane systems organize the interior of eukaryotic cells
        eukaryotic cells have dynamic cytoskeletons which require dynamic membranes that allows the cell to continue functioning even as the cell changes shape
        Endomembrane System Components
        nuclear envelope which is the membrane around the nucleus
        endoplasmic reticulum (ER)
        assembly of membranes running through the cytoplasm, the site of protein synthesis
        all membranes of the endomembrane system are interconnected either directly or by movement of vesicles
        vesicles are small transport pods that are used to send material to different places
        Golgi apparatus
        where proteins get "packaged" and sent to appropriate area
        Plasma membrane of the entire cell that surround the cytoplasm
        Provides eukaryotic organisms new movement possibilities, example is ability to consume entire molecules "endocytosis"
        energy metabolism is localized to mitochondria and chloroplasts in eukaryotic cells
        aerobic respiration happens in mitochondria and photosynthesis happens in chloroplasts
        increases sources of food because cells can now ingest larger food materials and break them down with enzymes in the cytoplasm
        Eukaryotes have multiple linear chromosomes and can begin DNA replication from many sites on each chromosome
        the ability to replicate more DNA quickly enables functions other than protein coding such as gene regulation which gives eukaryotes finer control over gene expression
        Sex in eukaryotes promotes genetic variation in 2 basic ways
        1) Meiotic cell division results in gametes that are genetically unique because each gamete has a different combination of alleles than other gametes
        2) During fertilization, new combinations of genes are brought together by the fusion of gametes
        Eukaryotes developed the abilities of aerobic respiration and photosynthesis by engulfing bacteria
        aerobic respiration came from endocytosis of proteobacteria
        photosynthesis came from endocytosis of cyanobacteria
        Endosymbiosis
        symbiosis in which one partner lives within the other
        Symbiosis is a close interaction that has evolved between species that live together
        7 super kingdoms of eukaryotes
        1) Opisthokonts
        Ex) animals /humans
        2) Amoebozoans
        Ex) plasmodial slime molds
        Coenocytic
        multiple nuclei inside bigger cells
        3) Archaeplastids
        Ex) land plants
        Plants
        Desiccation
        excessive water loss or drying out
        plants expose large surface areas to air to obtain sunlight and CO2 needed for photosynthesis
        evaporation of water from these exposed areas can lead to desiccation
        Desiccation tolerance
        suite of biochemical traits that allows cells to survive extreme dehydration by minimizing damage to membranes and macromolecules
        Land plants share many cellular features with green algae
        land plants are a monophyletic group
        monophyletic means it includes all descendants and the common ancestor of all the descendants
        embryo formation is a shared feature of all plants
        Bryophytes
        group of plants that rely on surface water for hydration
        have evolved the ability to withstand intermittent desiccation
        3 groups of bryophytes
        1) Mosses
        2) Liverworts
        3) Hornworts
        distinctive feature of bryophytes is the majority of their aboveground surfaces are permeable to water
        Cell wall made mostly of cellulose surrounds almost every cell in both pants and green algae
        cell wall is rigid/ stiff and allows for build up of turgor pressure
        Vascular plants
        pull water from the soil through their roots and transport it up the plant using bulk flow
        Vascular plants produce 4 major organ types
        1) Lycophytes
        monophyletic group of spore-dispersing vascular plants
        2) Ferns / Horsetails
        vascular plants where the gametophyte and sporophyte generations are free living and disperse by spores
        3) Gymnosperms
        seed plants whose ovules are not enclosed in a carpel
        Pine trees
        4) Angiosperms
        seed plants characterized by flowers, double fertilization, and fruits
        Major differences between vascular plants and bryophytes
        1) vascular plants use bulk flow rather than diffusion to distribute nutrients internally, bulk flow allows for plants to achieve greater size
        Steps of Bulk Flow
        1) Ventilation
        movement of an animal's respiratory medium either water or air past a specialized respiratory surface
        Respiratory Gas Exchange
        Gills are highly folded delicate structures in aquatic animals that facilitate gas exchange with the surrounding water
        Lungs are the organs for gas exchange in many terrestrial animals
        Alveoli in human lungs allow for carbon and oxygen gas exchange into and out of the blood
        Tracheae in terrestrial insects, tracheae are a system of internal tubes that branch from openings along the abdominal surface into smaller airways
        Tracheae direct oxygen to respiring tissues and direct CO2 away from respiring tissues in insects
        2) Circulation
        movement of a specialized body fluid in animals that carries oxygen, CO2, water, nutrients, and waste products though the body
        Circulatory fluid
        blood in vertebrate animals
        hemolymph in invertebrate animals
        Circulatory flow equation
        Q = P / R
        Q = rate of flow, p= pressure behind the fluid, and R = vascular resistance to flow
        2) water uptake in vascular plants primarily occurs in specialized organs that grow below ground, the roots
        3 essential nutrients in dry material of plants
        1) Carbon
        2) Oxygen
        3) Hydrogen
        Nitrogen is a very important nutrient as well and very abundant in Earth's atmosphere
        Nitrogen Fixation
        process of converting nitrogen gas or N2 into ammonia or NH3 which is a form that primary producers can use
        Root Nodule
        where nitrogen fixing bacteria live in plants
        structure formed by dividing root cells
        All vascular plants are built from the same 4 types of organs
        1) leaves
        Shoot
        the collective name for aboveground organ systems of vascular plants
        shoot includes leaves, reproductive organs, and stems
        principal site of photosynthesis in most vascular plants
        CO2 uptake results in water loss
        Transpiration
        loss of water vapor from leaves
        vascular plants can sustain high rates of transpiration because they can access water from the soil via roots
        3 major tissues of leaves
        1) sheets of epidermal cells lining the surfaces
        cell walls
        2) Mesophyll
        where photosynthesis happens
        3) Veins
        vascular conduits that connect the leaf to the rest of the plant
        2) reproductive organs
        3) stems
        4) roots
        Plant organs are constructed from only 3 types of tissue
        1) Epidermis tissue
        Epidermis is the outer layer of cells that forms the interface between the plant and the external environment
        the epidermis provides protection to the plant and some epidermal cells have special structure for enhanced uptake of water and nutrients
        Cuticle
        protective waxy substance secreted by epidermal cells that limits water loss through the leaves
        Stomata
        pores in the epidermis of a leaf that regulate the diffusion of gases between the atmosphere and the leaf interior
        allow CO2 to diffuse into the leaf for photosynthesis
        Each stoma consists of 2 guard cells surrounding a central pore
        guard cells shrink or swell to open or close the stoma
        Fungi
        heterotrophs that depend on preformed organic molecules for both carbon and energy intake
        unlike animals fungi don't have organs to breakdown and digest food so they absorb their organic molecules directly through their cell walls
        2 major problems caused by this mechanism
        1) simple molecules can diffuse readily into the cells but complex larger molecules cannot
        Diffusion and Partial Pressure
        partial pressure is simply a measure of the fractional concentration of a gas compared to other gases in that air multiplied by the total atmospheric pressure exerted by all gases
        2) fungi have no means of locomotion so they can't actively explore their environment for food
        Hyphae which are thin filaments in fungi allow fungi to explore their environment for food resources by forming networks of interconnected filaments called mycelia
        Mycelium is the singular version
        fungi transport food and signaling molecules across long distances through these complex hyphae networks called mycelia
        Septa
        walls that partially divide the cytoplasm into separate cells within fungal hyphae
        Not all fungi produce hyphae
        Yeasts are single celled fungi found in moist, nutrient rich environments
        due to where yeasts are found they don not require hyphae to search for food as they are surrounded by it
        fungi cell walls are made of chitin which is a modified polysaccharide containing nitrogen
        Fungi are principal decomposers of plant tissue
        fungi use dead organic plant material to source energy and raw materials
        2) Vascular tissue
        vascular tissue extends from the leaves to roots and allows for bulk flow movement of water and nutrients
        Vascular plants produce 2 types of vascular tissue
        1) Xylem
        water transport
        2) Phloem
        carbohydrate transport
        Phloem sap
        sugar rich solution that flows through the lumen of sieve tubes and sieve plate pores
        Sieve Tubes
        multicellular unit composed of sieve elements connected end to end, the route where phloem takes place
        Sieve Plates
        modified end wall in angiosperm phloem that has large pores and links sieve elements together
        3) Ground tissue
        all other tissue besides the epidermis and vascular tissue
        Parenchyma
        thin-walled cells that are capable of further division and differentiation
        parenchyma cells perform most of the plant's metabolic functions
        4) Stramenopiles
        Ex) Brown algae / kelp
        5) Alveolates
        Ex) Dinoflagellates
        6) Rhizarians
        7) Excavates
        Simple multicellularity is widespread among eukaryotes
        simple multicellular eukaryotes share several properties
        1) cell adhesion with nearby cells although there is little exchange between cells
        2) most cells retain full range of functions
        3) nearly every cell is in direct contact with the external environment
        simple multicellularity is most common among algae
        3 requirements of Complex Multicellularity
        1) molecular mechanisms for cell adhesion with adjacent cells
        Transmembrane proteins
        Cadherins
        Integrins
        epithelial cells secrete the matrix called basal lamina
        Epithelia are organized sheets of cells that line the inside and cover the outside of the body
        animal cell adhesion likely originated from modified versions of proteins that originally attached unicellular organisms to their environment (rock surface) or that attached pre to predator for easier predation
        2) specialized structures that allow for intercellular communication and transfer of resources
        Diffusion
        the random motion of molecules with net movement occurring from areas of higher concentration to areas of lower concentration
        diffusion is only effective for smaller organisms with high surface area to volume ratios
        Bulk Flow
        the movement of fluids over long distances through organisms due to pressure differences
        complex multicellular organisms use bulk flow and pressure gradients to transport key resources over large distances that diffusion would not be able to accomplish
        Ex) blood vessels and the heart in humans
        Gap junctions are protein channels in animals that allow for molecules to move between adjacent cells
        plants have an additional layer of protection in the cell wall but they have plasmodesmata which are thin strands of cytoplasm that connect neighboring plant cells
        plasmodesmata are lined by extension of the cell membranes and connect the endomembrane systems of adjacent cells
        3) network of genetic regulation over gene expression driving cell and tissue differentiation
        Key feature of complex multicellularity is 3D organization in space instead of time
        interior cells deep within tissue don't have the same access to resources from the external environment as surface cells
        complex multicellular organisms require mechanisms for transferring environmental signals to interior cells where genes are either activated or repressed in response
        development in complex multicellular organisms can be defined as increasing or decreasing gene expression in response to molecular signals from surrounding cells
        Selection pressures favoring multicellularity
        1) multicellularity helps organisms avoid getting eaten
        2) able to maintain position on a surface or in water better than single celled eukaryotes
        3) feeding is potentially easier with more cells able to capture food
        Costs of multicellularity
        in complex multicellular organisms with differentiated reproductive tissues, most cells don't reproduce supporting those that do
        this separation of function requires cooperation among cells but creates opportunity for cells to cheat and use nutrients only for their growth
        Example is cancer
        2) Bacteria
        single celled organisms
        bacteria lack membrane bound organelles of eukaryotic cells
        instead proteins perform cell metabolic processes in the cytoplasm
        these bacterial proteins float freely in the cytoplasm or are embedded in the cell's plasma membrane
        structural support for bacterial cells is provided by a cell wall made of peptidoglycan
        Peptidoglycan
        complex polymer of sugars and amino acids
        1 circular chromosome and no nucleus , divides using binary fission
        Plasmids
        small circular molecule of DNA carrying a small number of genes that replicate independently of the DNA in the bacterium's main circular chromosome
        not essential for the cell's survival but it may contain genes that have adaptive value under specific environmental conditions
        transcribed mRNA is immediately translated into proteins by ribosomes in bacterial cells because there is no nuclear membrane separating DNA from surrounding cytoplasm
        Cell Size
        bacterial and archaea cells are limited in size because they rely on diffusion for the delivery of nutrients
        Diffusion
        random particle motion from areas of higher molecule concentration to areas of lower molecule concentration
        Equilibrium
        net movement of particles only stops when the 2 regions achieve equal concentrations of the molecule
        diffusion continues but net movement between areas stops
        diffusion explains why bacterial cells are small because a small cell has more surface area compared to volume.
        this means that the interior parts of the cell where nutrients and other molecules are going to are closer to the surrounding environment compared to large cells
        interior parts are closer to the walls of the cell
        surface area of the cell increases proportional to the square of the radius (r^2)
        volume of the cell increases proportional to the cube of the radius (r^3)
        Horizontal Gene Transfer
        transfer of genetic material between organisms that are NOT parent/offspring
        3 mechanisms of horizontal gene transfer
        1) Conjugation
        process of direct cell to cell transfer of DNA usually in the form of a plasmid
        2) Transformation
        process of converting cells from one state to another when DNA released into the environment by cell breakdown is taken up by recipient cells
        3) Transduction
        horizontal gene transfer by means of viruses
        viruses invade bacterial cells and sometimes integrate their viral DNA into the host's bacterial DNA
        before the virus leaves the cell to infect other cells the viral DNA removes itself from the bacterial genome and is packaged in a protein capsule
        sometimes genetic material from the bacteria is incorporated into the packaged virus particle and as the virus particle infects other cells the bacterial genes are brought along and spread this way
        3) Archaea
        single celled prokaryotic organisms
        Prokaryotic
        no nucleus
        oxygen poor environments on Earth are populated by organisms that don't produce or consume oxygen but are able to cycle carbon
        These organisms share the feature of prokaryotic cell structure
        Photosynthesis
        process of transforming CO2 into organic molecules (glucose)
        Carbon Cycle
        intricately linked network of biological and physical processes that shuttles carbon among rocks, soil, oceans, air, and organisms
        Earth Cycles
        1) carbon cycle
        global imbalance between photosynthesis and respiration during summer and winter months leads to rising carbon levels in the atmosphere over the years
        records of carbon stored in air bubbles within polar ice show that global carbon levels were steady for over a 1,000 years prior to the industrial revolution
        more industrial activity without knowledge of its effects led to a boom in carbon emissions
        the ratio of different carbon isotopes in the atmosphere currently indicate that most of the carbon added during recent decades is attributable to burning fossil fuels and other human activities
        carbon levels have gone through periodic shifts over geologic time along coinciding with repeated periods of glaciation
        Short term vs long term carbon cycle
        important storage reservoirs of carbon are organisms, soil, oceans, and sedimentary rocks
        sedimentary rocks are by far the biggest carbon reservoir
        the slow leakage of organic matter from biological communities to sediments that accumulate on the seafloor link the short term and long term carbon cycles
        2) nitrogen cycle
        nitrogen in the atmosphere is fixed or converted to an organic/usable form by primary producers which enable consumption of nitrogen by organisms higher in the food chain
        primary producers include organisms such as bacteria and archaea
        closely linked to the carbon cycle
        3) phosphorus cycle
        phosphorus is mostly found in rocks and enters the food chain via weathering processes in the form of phosphate ion
        have 1 circular chromosome and no nucleus, divide by binary fission
        2) Kingdom
        group of closely related phyla
        3) Phylum
        group of closely related classes
        4) Class
        group of closely related orders
        5) Order
        group of closely related families
        6) Family
        group of closely related genera
        7) Genus
        group of closely related species
        8) Species
        Taxon
        a named taxonomic group at any rank, taxa is the plural version
        provides us with a hierarchical classification of species in groups that are more and more inclusive
        allows us to have a convenient way to communicate information about the features each group possesses

Informationen

Beschreibung: Science Mindmap am BIO 150, erstellt von John Donnelly am 28/08/2020.
Erstellt von: John Donnelly
Aufrufe: 6
Bewertung

BIO 150

Inhalt der Mindmap

Informationen

Feedback

Wie gefällt dir das neue Design?