CB12 Genome Mapping

Question 1

Describe the exceptions to mendel’s rule

Answer 1

Mendel’s 2nd law: independent assortment

Exceptions:
- probability of all combinations not equal
- resulting phenotypic combinations are not as expected

Question 2

Explain the epistatic inheritance

Answer 2

The effect of a gene is dependent on another gene

Question 3

Summarise the nature & role of genetic maps

Answer 3

• Show the order & relative distance between genes in chromosomes

Question 4

Explain how linkage occurs

Answer 4

• Genes affecting traits are physically close, and tend to be inherited together
• some allelic combinations are more frequent than expected because they are inherited together

Question 5

Calculate genetic distance between two loci from numbers of recombinant & parental progeny

Answer 5

Recombination frequency = no. of recombinant gametes/no. of total gametes x 100

Back cross= no. of recombinant progeny /no. of total progeny x 100

Question 6

What is the purpose of linkage maps

Answer 6

• Linkage maps reflect the order of genes & markers based on recombination
• linkage maps require heterozygosity in parents and use genes &/ genetic markers
• help to inform the inheritance of important traits
• allow you to locate key genes close to markers

Question 7

Name DNA markers

Answer 7

• Microsatellites
• single nucleotide polymorphisms (SNPs)

Question 8

What is the purpose of a physical map

Answer 8

-Physical maps show the complete DNA sequence with genes & other DNA regions
- describes the whole genome
- distance measured in base pairs