Chapter 17 - Inherited Change Flashcards

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1
Q

Genotype def.

A

The genetic constitution of an organism

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2
Q

Phenotype def.

A

The expression of the genes and its interaction with the environment

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3
Q

Homozygous def.

A

A pair of chromosomes carrying the same the same alleles for a single gene

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4
Q

Heterozygous def.

A

A lair of homologous chromosomes carrying two different alleles for a single gene

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5
Q

Recessive allele def.

A

An allele only expressed if no dominant allele is present

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6
Q

Dominant allele def.

A

An allele that will always be expressed in the phenotype

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7
Q

Codominant def.

A

Both alleles are equally dominant and expressed in the phenotype

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8
Q

Multiple alleles def.

A

More than two alleles for a single gene

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9
Q

Sex linkage def.

A

A gene who’s locus is in the X chromosome

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10
Q

Autosomal linkage def.

A

Genes that are located on the same chromosome

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11
Q

Epistasis def.

A

When one gene masks or modifies the expression of a different gene on a different locus

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12
Q

Monohybrid def.

A

Genetic inheritance cross if characteristics determined by one gene

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13
Q

Dihybrid def.

A

Genetic inheritance cross for a characteristic determined by two genes

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14
Q

Why do the actual phenotype observations differ from the predicted phenotypic ratios from tue dihybrid cross

A
  • Gamete fusion
  • Small sample sizes can lead to skewed ratios whilst larger samples minimise these random effects
  • crossing over can change the allele combinations by separating the linked genes
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15
Q

How many alleles of a specific gene can an individual hold

A

2

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16
Q

Suggest one reason why the expected phenotype ratio may differ from the actual ratio

A
  • crossing over during meiosis’s as a new combination of gametes will produce
17
Q

What are the effects of crossing over on autosomal linkage

A
  • Crossing over seperates linked genes.
  • fewer recombinant offspring tend to be produced (offspring that have a different combination of alleles from their parents due to crossing over) so less genetic variation being introduced from crossing over when genes are linked.
  • The probability of linked genes being separated during crossing over is inversely proportional to how close they are on a chromosome i.e., the closer the genes, the more likely they will be inherited together.
18
Q

What is a hypostatic gene

A

The gene whose expression is blocked by another gene

19
Q

What is an epistatic gene

A

The gene whose allele affects the expression of the hypostatic gene

20
Q

Two types of epistatic interactions and what occurs during them

A
  • recessive epistasis - occurs when the epistatic gene must be homozygous recessive to block the expression of the hypostatic gene
  • dominant epistasis - Occurs when the epistatic gene is dominant and actively modifies or blocks the expression of the hypostatic gene.
21
Q

Two types of epistatic interactions and what occurs during them

A
  • recessive epistasis - occurs when the epistatic gene must be homozygous recessive to block the expression of the hypostatic gene
  • dominant epistasis - Occurs when the epistatic gene is dominant and actively modifies or blocks the expression of the hypostatic gene.
22
Q

Know how to do chi squared

A