Chapter 9 - Genetic Diversity Flashcards
What is a homologous pair?
One paternal and one maternal chromosome, same genes present but different alleles
What are gametes?
Haploid sex cells
What is a haploid cell?
a cell with a single set of unpaired chromosomes
What is a diploid cell?
a cell with a complete set of chromosomes
What is fertilisation?
the fusion of two gametes to form a zygote
Describe Meiosis
2 divisions to make 4 daughter cells daughter cells are genetically different makes gametes
Describe Mitosis
1 division 2 daughter cells genetically identical daughter cells for growth and repair
Define gene mutation
a change in the base sequence of DNA substitution and deletion eg) substitution and deletion
How could a mutation cause a non functioning protein?
Change to triplet during replication alters mRNA codon different anticodon —-> different amino acid changes primary structure alters hydrogen/ionic bonding in the tertiary structure
How could a mutation not result in a non functioning protein?
DNA is degenerate so a change to a base may not alter primary structure no change to bonding in tertiary structure
What is chromosome non-dysfunction?
Chromosomes don’t separate properly during either MI or MII eg) causes downs syndrome
What happens at Prophase?
chromosomes condense and become visible, nuclear membrane breaks down
What happens at Metaphase?
The homologous pairs line up, spindle forms and attaches to centromere
What happens at Anaphase?
homologous pairs pulled to poles
What happens at Telophase?
nuclei reform and the cell divides
Describe directional selection
extreme is selected for eg) antibiotic resistance
describe how directional selection may come about
change in environmental conditions individuals with extreme characteristics are more likely to survive and reproduce increasing the presence of characteristic in offspring
describe stabilising selection
mean is selected for, making normal distribution more clustered around the mean
define genetic diversity
the number of alleles of a gene in a pop
what is natural selection?
individuals that are better suited to the environment are more likely to survive and reproduce. more beneficial alleles are passed on
define evolution
change in allele frequency over time
How does evolution come about?
variation in population due to mutation selection for individuals with beneficial alleles differential reproductive success changing the allele frequency over time
what is the result of natural selection?
a species is better adapted to its environment
What are the 3 types of adaptations?
anatomical, physiological, behavioural
