Diversity, Classification and Variation

1. Sperm Cells
2. Egg cells
3. Haploid Number
4. Random Fertilisation
   1. Increased genetic diversity

Annotations:

• 1) Before meiosis starts, the DNA unravels and replicates so there are two copies of each chromosome, called chromatids. 2) The DNA condenses to form double-armed chromosomes, each made from two sister chromatids. The sister Chromatids are joined in the middle by a centromere. 3) Meiosis 1 (first division) chromosomes arrange themselves into homologous pairs. 4) These homologous pairs are then separated, halving the chromosome number. 5) Meiosis II (second division) the pairs of sister chromatids that make up each chromosome are separated (the centromere is divided) 6) Four haploid cells (gametes) that are genetically different from each other are produced

1. Cell Division
2. Chromatids
3. Centromere
4. Meiosis I
   1. Chromosomes arranges themselves into homologous pairs
5. Chromatids cross over during Meiosis I
6. Meiosis II
   1. Centromere divides
7. Daughter Cells

1. Cells are genetically different
2. Crossing over
3. Chromatids with different alleles
4. Independent Segregation
   1. Each homologus pair is made up of two chromosomes
      1. Maternal
      2. Paternal
   2. when the pairs are separated it's completely random which chromosome ends up in each daughter cell.
   3. Shuffling of chromosomes leads to genetic variation in any potential offspring
   4. Different combinations of maternal and paternal chromosomes

1. Errors in cell division
2. Chromosome mutations lead to inherited conditions
3. Non- disjunction
   1. Failure of the chromosome to separate properly

1. Substitution
   1. One base is substituted
2. Deletion
   1. One base is deleted

1. Not all substitution mutations will result in a change to the amino acid sequence of the protein.
2. Deletions will always lead to changes in amino acids
3. Shift in all base triplets after it

1. Ionising radiation

1. Alleles
   1. Different versions of the same gene

1. Number of different alleles of genes in a species or population
2. Genetic diversity within a population is increased
   1. Mutations in the DNA forming new alleles
   2. Different alleles being introduced into a population when individuals from another population migrate into them and reproduce
      1. Gene flow
3. Genetic bottlenecks
   1. Founder effect
      1. Initial colony is very small so the genetic diversity is low
         1. Amish
   2. Reduce genetic diversity
   3. Large number of organisms within a population die before reproducing

1. Increases advantageous alleles within a population
2. Some mutations can produce beneficial alleles that can help the organism survive
3. Differential reproductive success within a population
4. Individuals that have alles that are beneficial will be more likely to survive, reproduce and pass on their genes (including the beneficial allele)
5. Greater proportion will have the beneficial allele
6. And so they will be more likely to survive, reproduce and pass on their alleles
7. The frequency of the alle increases over generations
8. over generations this leads to evolution as the advantageous alleles become more common within the population

1. Behavioural
   1. Way the organism acts that increases its chances of survival.
2. Physiological
   1. Processes inside the organisms body that increases its chances of survival
3. Anatomical
   1. Structural features of an organism's body that increases its chances of survival

1. Indiviuals with alleles for characteristics of an extreme type are more likely to survive and reproduce.
2. Response to and environmental change
3. Antibiotic Resistance

1. Individuals with alleles for characteristics towards the middle of the range are more likely to survive and reproduce
2. Environment isn't changing
3. Reduces range of possible characteristics
4. Human birth weight

1. Evolutionary history of organisms
   1. How closely organisms are related
2. Ancestors
3. Phylogenic tree
   1. First branch is the common ancestor to all family members

1. Science of classification
2. Taxon
3. Domain
   1. Kingdom
      1. Phylum
         1. Class
            1. Order
               1. Family
                  1. Genus
                     1. Species
4. Drunk Kangaroos Punch Children On Family Game Shows
5. A species is a group of similar organisms able to reproduce to give fertile offspring

1. Nomenclature (naming system)
2. First part of an organisms name is the genus
   1. Second part is the species

1. Species specific
2. Allows species to recognise each other and prevents interbreeding
3. Can be used to classify organisms
4. Male butterflies use chemicals to attract females

1. Place where and organism lives

1. All the populations of different species in a habitat

1. The variety of species living in a small habitat

1. Variety of species on Earth

1. Species richness
   1. Number of different species in a community
2. 1. N= Total number of organisms of all species
   2. { = 'Sum of'
   3. n= Total number of organisms of one species
3. Higher the number the more diverse the area is

1. Can reduce biodiversity
2. Woodland Clearance
3. Reduces Shelter, food source and habitat
4. Hedgerow removal
5. Pesticides
6. Herbicides
7. Monoculture