Genetics 1 Flashcards
What are mendel’s two laws?
1) Law of segregation: A parent gives one allele for a gene (consists of a pair of alleles) to each gamete (egg or sperm) they produce.
- occurs in anaphase 1 (separating)
2) law of independent assortment: During gamete formation different pairs of alleles in a gene segregate independently of each other.
- In other words the inheritance of one allele a gamete receives has no affect on the inheritance of the other.
- occurs in metaphase 1 (lining up)
- occurs in anaphase 1 (separating)
What is genotype and phenotype?
- Genotype: Genetic makeup of an organism
- Phenotype: Observable traits in an organism
1) what is homozygous alleles?
2) what is heterozygous allele?
(Genotypes)
1) homozygous alleles: the same alleles
Ex:
- homozygous recessive: aa
- homozygous dominant: AA
2) heterozygous alleles: Different alleles; one dominant and one recessive
Ex:
-Aa
What are other forms of inheritance that are non-Mendelian?
DESCRIPTION: A homozygous dominant allele (AA) expresses a red flower, a homozygous recessive allele (aa) expresses a white flower
- Codominance: both alleles are expressed in a heterozygous individual.
Ex: if a flower has the gene Aa, the flower will show patches of red and white.
- Incomplete dominance: a dominant allele does not completely mask the recessive allele, so colours blend.
Ex: If the flower has an allele that is Aa the flower I’ll be pink.
What is polygenic inheritance?
It’s when more than one gene determines a character.
Ex: skin colour, eye colour, hair
What is pleiotropy?
It’s when a single gene has Multiple phenotypic effects.
Ex: one mouse has fur and another does not.
Give an example on how the environment can influence gene action?
Skin tones could also be enhanced by usage of suntan lotions
What is monohybrid cross?
- it is used to study the dominance of genes
- the law of segregation is explained by this cross
- the phenotypic ratio is 3:1
- the genotypic ratio is 1:2:1
What is a dihybrid cross?
- it is used to study offspring assortment
- the law of independent assortment is explained by this cross
- the phenotypic ration is 9:3:3:1
- the genotypic ratio is 1:2:2:4:1:2:1:2:1 (not important)