Back to AI Flashcard MakerAnatomy and Physiology /LGS A-Level OCR Biology - Unit 6 - Patterns of Inheritance Part 2

LGS A-Level OCR Biology - Unit 6 - Patterns of Inheritance Part 2

Anatomy and Physiology20 CardsCreated about 1 month ago

This deck Epistatic alleles may produce repressor proteins or transcription factors that bind to the promoter of another gene, blocking transcription or enzyme function.

What may prevent linked genes from being inherited together

If they’re separated by chiasmata

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Key Terms

Term
Definition

What may prevent linked genes from being inherited together

If they’re separated by chiasmata

W/ crossing over in autosomal linkage

Genotypic and phenotypic ratios are variable

Parental types > cross-over type

Proportion depends on how often cross overs ocurred be...

Recombinant offspring

Offspring w/ a diff combination of alleles to either parent

Closer genes are located on a chromosome …

Less likely to be separated during crossing over –> fewer recombinant offspring

Recombination frequency

Measure of amont of crossing over occured in meoisis - indicating level of linkage

Also used to map genes loci ; 1% = distance of 1 map unit ...

Calculating recombinant frequency

No of recombinant offspring/ total no. of offspring

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TermDefinition

What may prevent linked genes from being inherited together

If they’re separated by chiasmata

W/ crossing over in autosomal linkage

Genotypic and phenotypic ratios are variable

Parental types > cross-over type

Proportion depends on how often cross overs ocurred between two loci

Recombinant offspring

Offspring w/ a diff combination of alleles to either parent

Closer genes are located on a chromosome …

Less likely to be separated during crossing over –> fewer recombinant offspring

Recombination frequency

Measure of amont of crossing over occured in meoisis - indicating level of linkage

Also used to map genes loci ; 1% = distance of 1 map unit on chromosome

Calculating recombinant frequency

No of recombinant offspring/ total no. of offspring

50% recombination frequency

No linkage, separate chromosomes

<50% recombination frequency

Gene linkage and IA has been hindered

Signifies autosomal linkage

Linked genes are inherited together

Crossing over produces few recombinant offspring

Homozygous

Has identical alleles on both chromosome

H0 in chi squared

There is no sig. difference between expected and observed values

Degrees of freedom in chi squared

No. of categories - 1

Epistasis

Interaction of genes at diff loci

Genes masking the expression of other genes (not alleles)

Gene regulaion is a example w. reg . genes controlling structural genes

When can epistasis be seen

Multistep reactions

Hypostatic

Gene affected by another gene

| Cause the phenotype

Epistatic gene

Gene that affects the expression of another gene; can happen as a result of dominant or recessive alleles

Epistatic alleles

Another pair of alleles found at diff loci

Antagonistic epistasis

Dominant and recessive epistasis

Dominant epistasis

If there are ANY dominant alleles present in the epistatic alleles, masks expression of hypostatic alleles

Phenotypic ratio in a heterozygous dihybid cross w/ dominant epistasis

12:3:1

Recessive epistasis

Occurs when a pair of homozygous recessive alleles at one gene locus masks the expression of the hypostatic allele at a 2nd locus