Genetics & Heredity Flashcards
What is genetics?
The science of genes, heredity and variation in living organisms
What is heredity?
Passing of traits from parents to offspring
What is a trait?
A distinct variant of an observed characteristic
Why did Gregor Mendel choose to study pea plants?
pea hybrids could be produced
pure breeding pea varieties were available
peas are small plants and easy to grow
peas can self fertilise or be cross-fertilised
Define genotype
the genetic make up that determines the trait
Define phenotype
physical appearance of an organism’s trait
Define allele
Variation of a gene
Define homozygous
Pair of identical alleles for a character
Define heterozygous
Two different alleles for a character
Cystic fibrosis has an _____________ pattern of inheritance
autosomal recessive
What does Mendel’s model assume?
Each trait is controlled by a single gene
there is a clear dominant-recessive relationship between the alleles
each gene has only two alleles
(most traits and genes DO NOT satisfy these criteria)
What is polygenic inheritance?
Occurs when multiple genes are involved in controlling the phenotype of a trait. The phenotype is an accumulation of contributions by multiple genes.
The traits of polygenic inheritance show _______ variation and are referred to as __________ traits
continuous
quantitative
What is codominance?
the heterozygote shows some aspect of the phenotype of both homozygotes
What two proteins are normally expressed in the cells of the breast and other tissue, where they help repair damaged DNA?
BRCA1 and BRCA2
