Topic 10.2 - Inheritance

Question 1

Segregation

Answer 1

Separation of the two alleles of a gene

Not always independent - linked genes will not segregate independently unless very far away on the chromosome.

Question 2

Linked genes

Answer 2

Gene loci are said to be linked if on the same chromosome.

Autosomal linkage - genes that are linked on an autosomal gene
Allosomal (sex) linkage - genes that are linked on an allosomal (sex) gene

Question 3

Dihybrid crossing

Answer 3

(page 446 biobook)

Only works for unlinked genes

Question 4

Continuous variation

Answer 4

Polygenic traits show continuous variation. These additive genes impact each other to affect the phenotype

Shows a normal distribution

(? check below ?)
More unlinked genes with more co-dominant alleles, a wider normal distribution - more phenotypic variants.

Less unlinked genes with less co-dominant alleles, leads to a narrower normal distribution.

Question 5

Exceptions to Mendel’s rule of hybrid crossing

Answer 5

1) Linked genes (alleles may not separate independently)
2) Sex Linkage (X chromosome gene may cause only one allele - ie for males. ie haemophilia, colourblindness)
3) Mutations

Question 6

Recombinant

Answer 6

Different allele combinations to both parents.

Question 7

Environmental influence

Answer 7

Skin colour due to polygenic inheritance, but also to the sun.

Question 8

Chi-squared tests

Answer 8

(page 453 - 454 biobook)
Mrs Gradley’s topic 10.2 powerpoints

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Table of exp freq vs observed (exp is found by doing expected ratio x total amount)

Equation is sigma (observed - exp)/exp

If found value is < given value at a certain signif level, accept Ho and there is no evidence that traits are linked