Karteikarten
K1/2/1 Cell Biology
Karten in diesem Stapel (30)
- 1Give an overview of size ranges in biologyBiologists explore life from a microscopic to a global scale: atom - molecule - organelle - cell - tissue - organ - organ system - organism - population - community - ecosystem - biosphere
An atom is approximately 0.1nm; a cell is within the range of 1-100μm, their organelles vary in size with the nucleus (5-20μm) being the biggest - 2State the relationships between the units millimetre, micrometre and nanometremillimetre (mm); micrometre (μm); nanometre (nm)
1mm = 1000μm
1μm = 1000nm - 3Define the terms prokaroyte and eukaryoteProkaryote - a unicellular organism that lacks a membrane-bound nucleus, mitochondria, or any other membrane-bound organelle
Eukaryote - is an organism whose cells have a cell nucleus enclosing the DNA in the shape of chromosomes and other organelles enclosed within membranes - 4State the three basic principles of evolution1. Organisms find a niche to survive (e.g. plants close to the ground have larger surface area to height ratio)
2. Organisms develop from simple to complex (e.g. cells did not develop from humans)
3. The strongest offspring survives and therefore traits carried by those are passed on - 5Explain the term endosymbiosisEndosymbiosis is a type of symbiosis in which one organism lives inside the other with the two typically behaving as a single organism
It is believed to be the means by which organelles such as mitochondria and chloroplasts developed within eukaryotic cells - 6Explain the endosymbiotic theoryThe endosymbiotic theory can be divided into two aspects
1. Primary - a eukaryotic cell engulfs a prokaryotic cell, which then continues to live in the cell in a symbiotic relationship; if one dies the other still survives
2. Secondary - a eukaryotic cell engulfs anohter eukaryotic cell and the two live in a symbiotic relationship; if one dies the other also dies
The endosymbiotic theory could be used to explain the development of mitochondria and chloroplasts within eukaryotic cells, as they: are around the same size as bacteria, have their own DNA, reproduce through binary fission like bacteria, have their own double membrane and have their own different ribosomes - 7State the main differences between an animal and plant cellPlant cells have a cell wall as well as a cell membrane, while animal cells only have a plasma membrane
Plant cells have a large vacuole while animal cells have no or only a small vacuole
Plant cells have chloroplasts while animal cells do not
Plant cells only have flagella in gametes while they are more common in animal cells - 8Describe the structure, explain the functions and state the role of the chloroplastMembrane: a chloroplast has a double membrane, the inner and outer membrane
Ultrastructure: the membranes enclose the stroma (the matrix space), which contains disc-like structures called thylakoids, when thykaloids are stacked together it is called a granum (pl. grana); chloroplasts harbor the photosynthetic pigment chlorophyll
Function: the site for photosynthesis; participate in several regulatory functions of the cell; photorespiration
Role: solar plant for energy supply - 9Describe the structure, explain the functions and state the role of the nucleusMembrane: double membrane
Ultrastructure: nuclear envelope separates the nucleus from the cytoplasm; the envelope is perforated by nuclear pores and continuous with the ER; contains the nucleolus and chromatin
Function: contains most genes and houses chromosomes; the nucleolus makes ribosomal subunits; nuclear pores regulate entry and exit of materials (water, ions and small molecules pass freely through the pores, but flow of larger molecules like proteins or RNA is regulated, thus the pores help control the flow on information); site of transcription of DNA as well as the duplication of DNA before mitosis
Role: executive site of the cell - 10Describe the structure, explain the functions and state the role of the Golgi apparatusMembrane: single membrane
Ultrastructure: flattened membranous cisternae (found in large numbers in secretory cells); contains mainly proteins and material for the synthesis of the cell wall; has a cis (closer to nucleus) and trans (away from nucleus) face
Function: concentration; storage and transportation of substances produced in the ER
Role: stockroom, central post office - 11Describe the structure and state the role of the endoplasmic reticulumMembrane: single membrane
Ultrastructure: an extensive network of membranes, ER membrane separates the internal compartment of the ER, the ER lumen, from its surroundings; encloses channel-like fluid-filled spaces called cisternae; it is continuous with the nuclear envelope
Role: controlling and regulating trade, forwarding - 12Differentiate between the two different types of ER and their appearances and functionsThe ER can be split into rough and smooth ER (and transitional ER); rough ER has ribosomes on its outer surface while smooth ER does not
Smooth ER functions in metabolic processes (e.g. synthesising lipids or steroids) and it produces enzymes that detoxify drugs and poison (especially in liver cells)
Rough ER synthesises proteins which are later on secreted - 13Describe the structure, explain the functions and state the role of the ribosomeMembrane: no membrane
Ultrastructure: consists of two subunits containing r-RNA and proteins; are either bound to the surface of the ER or are free ribosomes in the cytoplasm; found in abundance in secretory cells
Function: synthesise proteins by the process of translation; site of protein synthesis
Role: production facility of produce - 14Describe the structure, explain the functions and state the role of the mitochondrionMembrane: double membrane
Ultrastructure: two membranes enclose two compartments - between the inner and outer membranes is the first compartment, the second is enclosed within the inner membrane, called the cristae; the cristae's surface area is maximised through invaginations; matrix enclosed within the cristae
Function: site of aerobic respiration; production of ATP; has its own DNA and is therefore semi-autonomous
Role: intern power plant for energy supply - 15Describe the structure, explain the functions and state the role of the lysosome, peroxisome, glyoxysomeMembrane: single membrane
Ultrastructure: vesicle-like; contains digestive enzymes; can often grow to the size of a mtichondrion
Function: break down unnecessary cell material or foreign material (e.g. pathogens); break down hydrogen peroxide
Role: recycling plant - 16Further differentiate between glyoxysomes, lysosomes, peroxisomes and plastidsGlyoxysomes - found in fat-storing tissues of plant seeds; break down fatty acids (some parts can be used in the mitochondria)
Lysosomes - contain hydrolytic enzymes that can break down many kinds of biomolecules
Peroxisomes - grow by incorporating proteins & lipids from the cytosol (cytoplasm), not directly produced by the endomembrane system; increase in number by dividing when needed, not produced by the ER/Golgi; contains catalase, the enzyme that catalyses the breakdown of H2O2 to H2O (e.g. in breakdown of alcohol or fatty acids)
Plastids: plastids are major double-membrane organelles found in the cells of plants, algae, and some other eukaryotic organisms (amongst them are chloroplasts and amyloplasts) - 17Describe the structure, explain the functions and state the role of the vacuoleMembrane: single membrane
Ultrastructure: found in plant and fungal cells as well as in some protists (for water regulation)
Function: water regulation; in plant cells - storage of substances (poison, water, irritants, pigments, proteins, minerals), turgor pressure (pressure of water that keeps the plant upright), cell growth; food vacuoles in protists to ingest food
Role: storage, warehouse - 18Name the structures present within a prokaryote and state their functionsFimbriae - surface appendages that allow a bacterium to stick to a surface
Ribosomes - site of protein synthesis
Nucleoid region - the cell's DNA, containing genes that control the cell
Flagellum - propels the cell, allows the cell to move
Capsule - sticky, jellylike protective layer outside the cell wall
Cell wall - rigid structure outside plasma membrane which surrounds, supports and protects the cell
Plasma membrane - acts as a selective barrier, allows passage of oxygen, nutrients and waste - 19State the relevance of bacteriaBacteria are prokaryotes and are very diverse - some are pathogens; some are used for digestion, protection, food production; some are nitrogen-fixing and part of the nitrogen cycle; some are destruents (break down organic material)
- 20Explain why cells are the size they arecells are generally small in size because of two main reasons - different regions of a cell can communicate with each other rapidly for the cell to function effectively;
cells have a large surface area/volume ratio for greater diffusion of substances in and of the cell
The larger surface area relative to volume of the cell ensures greater diffusion of -
nutrients into the cell, metabolic wastes from the interior to the outside of the cell, respiratory gases i.e. oxygen into the cell and carbon dioxide out of the cell; any damage to the cell can also easily be repaired - 21Name the three types of microscopy usedLight Microscopy (LM)
Transmission Electron Microscopy (TEM)
Scanning Electron Microscopy (SEM) - 22Differentiate between the three types of microscopyLM - object can be living or dead; specimen either directly examined or stained to make it more visible, vacuum not required; light beam transmitted through a slide, light refracted through glass lenses to magnify the image virtually; max. magnification up to 2,000x; image produced retains natural colour of sample, albeit at a low resolution
TEM - object must be dead and in a vacuum; mainly used to study internal ultrastructure of cells, very thin section of specimen used, stained with heavy metals; electron beam transmitted through a slide, electromagnets as lenses to bend electron paths through specimen and to focus them onto a screen to view; max. magnification up to 1,000,000x; produces monochrome 2D images of a high resolution
SEM - object must be dead and in a vacuum; especially useful for detailed study of a specimen's surface, specimen coated in thin layer of metal (e.g. gold); electron beam excites secondary electrons on specimen surface that are detected and translated into an image; max. magnification up to 100,000x; produces monochrome 3D image of a high resolution - 23State the advantages of light and electron microscopyLight microscopy advantages - fast and easy preparation; images in colour; cheap to purchase; no vacuum needed; mobile and easy to transport; specimen can be living; material is not distorted;
Electron microscopy advantages - higher resolution; ultrastructure of a cell visible (TEM); surface of a cell visible (TEM); reveals organelles that are impossible to resolve with light microscopy - 24Describe the cell wall of plantsThe cell wall is a structure that distinguishes the plant cell (present) from the animal cell (not present) and consists of cellulose
The wall protects the cell, maintains its shape, prevents excessive uptake of water and holds the plant upright against gravity
A young plant cell first secretes a thin and flexible wall, the primary cell wall; between the primary cell walls of adjacent cells is the middle lamella, which glues the cells together; when the cell stops growing and matures, either the primary cell wall is strengthened or a secondary cell wall is added - 25Describe the extracellular matrix of animalsAnimal cells lack a cell wall have instead have an extracellular matrix (ECM), consisting of glycoproteins secreted by the cell; the ECM is attached to the cytoplasmic side of the cellular membrane through integrins
By communicating with a cell through integrins, the ECM can regulate a cell's behaviour and coordinate the behaviour of cells within a tissue - 26Name and explain the different types of intercellular junctionsPlant cells:
Plasmodesmata - a channel through the plant cell wall that allows molecules and substances to move back and forth as needed; connects the chemical environment in adjacent cells
Animal cells:
Tight junctions - tight junctions seal adjacent animal cells in a narrow band to serve a barrier function, prevent leakage and hold cells together
Desmosomes - desmosomes are localised patches that hold two cells tightly together, fastening cells together into strong sheets
Gap junctions - gap junctions are intercellular channels which permit the free passage between the cells of ions and small molecules; comparable to the plasmodesmata in plant cells - 27Explain the process of cell fractionationCell fractionation is used to isolate (fractionate) cell components based on size and density
Cells are homogenised in a blender to break them up; the resulting mixture (cell homogenate) is centrifuged, leading to the fractionation of the components; a series of pellets are formed, overlaid by the remaining homogenate (supernatant); the supernatant is then poured into into another test tube and centrifuged at a different speed and duration; the process is repeated (differential centrifugation)
The higher the speed, the smaller the components of the pellet - 28List the differences between eukaryotes and prokaryotesEukaryotes // Prokaryotes
Habitat - everywhere // everywhere, including extreme habitats
Size - 10-100μm; up to metres // 0.5-2μm
Organisation - can be both uni- and multicellular // unicellular
Cell wall - cellulose (plants); chitin (fungi) // peptidoglycan
Movement - flagella // flagella & fimbriae
Cell membrane - present, phospholipid bilayer // present, bilayer, enzymes on cytoplasmic side
Nucleus - present // not present
DNA - DNA strands (linear) // circular region, nuclear region & DNA
Chromosome set - diploid // haploid
Cell division - mitosis; meiosis // nuclear fission
Plasmids - not present // present
Cytoskeleton - present // not present
Organelles - present // no organelles except ribosomes - 29Describe the endomembrane system and explain how it works together1. DNA is transcribed to RNA, which then becomes mRNA after travelling to the ribosomes before being translated to proteins
2. Proteins are synthesised at the rough ER and a vesicle containing them pinches off headed to the Golgi apparatus
3. The vesicle in the cytoplasm fuses with the Golgi apparatus in which the protein is modified by moving from one Golgi stack to the next in vesicles
4. A vesicle containing the protein buds off the Golgi apparatus and transports it towards its final destinantion (e.g. the membrane, where it is released through exocytosis) - 30State which cells have a tendency to have more of a certain organelle and whyMacrophages - these cells have many enzyme-filled lysosomes in order to break down foreign bodies
Nerve cells & muscle cells - they are very active and need a lot of energy; thus, they have large numbers of mitochondria
Pancreatic cells - these cells secrete large amounts of enzymes, which are proteins, so they would need a large number of ribosomes
Liver cells - one of the main functions of the liver cell is to detoxify products and thus they need a lot of ER
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- Biology (EI) Karteikarten am K1/2/1 Cell Biology, erstellt von Max Siegel am 22/01/2018.
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