Ch17 Genetics and Heredity Flashcards
DEFINE alleles.
Different forms of the same gene
DEFINE locus.
The point on a chromosome where a gene is located
DEFINE dominant and recessive
Dominant: prevents recessive gene from working
Recessive: prevented from working by the dominant gene.
DEFINE genotype
The genetic makeup of an organism
DEFINE phenotype
The physical appearance of an organism. Genotype + environment = phenotype.
What are the rules for genetic crosses?
- Write a KEY
- Determine GENOTYPES OF PARENTS
- Provide GAMETES from parents
- DO CROSS using gametes
- state PHENOTYPE(S) of offspring.
DEFINE incomplete dominance
When neither allele is dominant or recessive with respect to each other. (Heterozygous leads to new trait)
Who was the father of genetics?
Gregor Mendel
Why did he use pea plants?
They’re fast growing, easy to raise, have several visible characteristics with 2 values.
How did Mendel cross the plants?
Manually assisting fertilisation - transferring pollen to carpel manually.
DEFINE: State Mendel’s 2 laws.
- Law of Segregation: traits are controlled by a pair of factors that separate at gamete formation
- Law of Independent Assortment: either of a pair of alleles can randomly combine with any one of another pair.
What’s the ratio for a dihybrid cross of 2 heterozygous parents?
9:3:3:1
DEFINE sex-linked
Gene is present on X chromosome.
DEFINE linkage
Genes are located on the same chromosome and do not show independent assortment.
Give examples of sex-linked traits.
Colour blindness, haemophilia
