Inheritance Flashcards

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1
Q

Di-hybrid cross

A

Inheritance of two different characteristics controlled by two different genes

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2
Q

Co-dominance

A

Both alleles in a heterozygous organisms are expressed in the phenotype

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3
Q

Define an allele

A

One of the different forms of a gene

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4
Q

Dominant

A

The allele of a heterozygous organism that is expressed in the phenotype
Only one copy needed

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5
Q

Recessive

A

In a heterozygous state the allele is NOT expressed, only expressed if homozygous recessive.

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6
Q

Define a gene

A

A base sequence of DNA that codes for the amino acid sequence of a polypeptide or a functional RNA molecule

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7
Q

Define phenotype

A

The expression of an organism’s genetic constitution and its interaction with the environment.

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8
Q

Autosomal linkage

A

Two Genes carried on the same autosome- non-sex chromosome

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9
Q

What is the effect of genes being closer together on the same autosome?

A

The closer together the more closely linked they are
Less likely to be split up in meiosis, crossing over
Therefore higher proportion of gametes and offspring will have parents geno/phenotypes

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10
Q

Epistasis

A

The interaction of non-linked genes when one affects/ masks the expression of another

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11
Q

What is a Chi-squared test?

A

Statistical test used to find out wether there is a significant difference between observed and expected results.

Or difference is due to chance- sampling effects

Used on categoric data, frequencies

Null hypothesis, alternative hypothesis
Is Chi value > critical value at p=0.05
Then Reject Ho

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12
Q

Sex linkage

A

Genes which have a locus on a sex chromosome

Most often x linked

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13
Q

Males

A

XY

So recessive X-linked genes will expressed even if only one copy present

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14
Q

Females

A

XX

So recessive X-linked genes will only be expressed if the organism is homozygous recessive

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15
Q

Multiple alleles

A

More than two alleles (versions) of the same gene

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16
Q

Why are observed results not similar to predicted?

A

Small sample size- high influence of chance
Fertilisation of gametes is a random process
Lethal genotypes
linked genes

17
Q

Why is a chi-squared test used?

A

To determine the probability; [Accept: Likelihood]

Of the results being due to chance; [Accept: Coincidence]

18
Q

Effect of autosomal linkage

A

They will stay together during independent segregation
Assume no crossing over
All linked genes will stay together during meiosis
So linked genes are passed onto gametes and the offspring together
Higher proportion of offspring will have parents
Geno/phenotype

19
Q

Evidence of autosomal linkage

A

when a di-hydrid cross results in production of offspring/ gametes which are predominately 2 genotypes

identify which alleles are linked- which are the 2 most common gametes?

production of most gametes- therefore most offspring produced like to have the geno/pheno types of parents- inherited together

20
Q

What dose the Hardy-Weinberg Principle predict?

A

predicts allele frequencies will not change in a population from one generation to the next

21
Q

Conditions for the Hardy-Weinberg Principle

A
mating is random
no death 
no immigration 
large population
no natural selection
22
Q

Hardy equation to predict allele frequencies

A

p+q=1

where p is freq of domination, q is freq of recessive

23
Q

Hardy equation to predict geno and phone type frequencies

A

p^2 +2pq+ q^2=1

p^2 homozygous dominat

q^2 homozygous ressecive

2pq hetrozygous