Genetics 1 Flashcards

1
Q

What are mendel’s two laws?

A

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)
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2
Q

What is genotype and phenotype?

A
  • Genotype: Genetic makeup of an organism

- Phenotype: Observable traits in an organism

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3
Q

1) what is homozygous alleles?
2) what is heterozygous allele?

(Genotypes)

A

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

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4
Q

What are other forms of inheritance that are non-Mendelian?

A

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.

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5
Q

What is polygenic inheritance?

A

It’s when more than one gene determines a character.

Ex: skin colour, eye colour, hair

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6
Q

What is pleiotropy?

A

It’s when a single gene has Multiple phenotypic effects.

Ex: one mouse has fur and another does not.

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7
Q

Give an example on how the environment can influence gene action?

A

Skin tones could also be enhanced by usage of suntan lotions

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8
Q

What is monohybrid cross?

A
  • 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
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9
Q

What is a dihybrid cross?

A
  • 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)
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