Patterns of inheritance Flashcards
What’s a gene?
A sequence of bases on a DNA molecule that codes for a protein that results in a characteristic
What’s a base?
A nitrogen- containing molecule that forms part of a DNA nucleotide
What are alleles?
One or more versions of the same gene
e.g., B = brown eyes, b = blue eyes
How many alleles of each gene do plants and animals tend to have?
2 alleles of each gene (one from each parent)
What’s a locus?
The fixed position of an allele on each chromosome in a pair
What’s the genotype?
The alleles an organism has
What’s the phenotype?
The characteristics the alleles produce in an organism
(can’t always be seen e.g., metabolic rate)
What are codominant alleles?
When both alleles are expressed in a phenotype because neither one is recessive
How many alleles are there for each gene?
2
How many alleles for each gene do gametes (sex cells) have?
1
What’s monogenic inheritance?
Inheritance of a characteristic controlled by a single gene
What’s the phenotypic ratio?
The ratio of different phenotypes in the offspring
What’s the definition of a population?
A group of organisms of the same species living in a particular area
What’s a selection pressure?
Anything that affects an organisms chance of survival
What’s a gene pool?
The complete range of alleles present in a population
What’s the allele frequency?
How often an allele occurs in a population
What’s stabalising selection?
Environment is stable and individuals with alleles towards middle range more likely to survive
What’s directional selection?
Environment is changing and individuals with alleles of an extreme type are more likely to survive
What’s the difference between natural selection and genetic drift?
- Natural selection - characteristics become more common if they increase organism’s chance of survival
- Genetic drift - characteristics become more common by chance
What’s a genetic bottleneck?
An event that causes a big reduction in population size, leading to reduction in gene pool
e.e.g, disease/ habitat destruction
What’s the founder effect?
When a few organisms from a population start a new population
