Week 10 - Molecular Markers

Question 1

What are Molecular markers?

Answer 1

A measurable attribute in the DNA that is exhibiting Mendelian inheritance

Question 2

10 Characteristics of an ideal marker

Answer 2

Polymorphic - variable between individuals
Discriminating - allows differentiation between related individuals
Multi-allelic - has several alleles at a single locus
Co-dominant - a heterozygote displays characteristics intermediate between its homozygous parents
Non-epistatic - genotype can be determined regardless of the genotype
Independent of the environment- fixed regardless of the environment during development
Neutral- no selective advantage of any allele or combination of alleles
Uniformly distributed - spread throughout the entire genome
Reproducible - across time and place of analysis
Economical - cost effective and able to be handled at high-throughput rates

Question 3

Morphological Markers

Answer 3

Poor level of polymophism 
Affected by environment 
Dominant
Not always neutral 
May be epistatic

Question 4

Biochemical Markers

Answer 4

Few loci
Not neutral
Not evenly distributed
Can be expensive

Question 5

Molecular Markers

Answer 5

Thousands available 
Evenly distirbuted
Independent of environment
Cheap and able to be automated
Co-dominant
Highly polymorphic

Question 6

Applications of Molecular Markers

Answer 6

Estimate genetic relationships

• Parentage
• Geographic locations
• Forensics
• Gene detection

Question 7

Molecular Markers can distinguish between…

Answer 7

Homology
- descent from a common ancestor
Analogy
- convergence from different ancestors

Question 8

Minisatellites

Answer 8

Repeating DNA
< 5kb pairs motif length 7-50 bp
Polymorphic
Repeats too long for PCR

Question 9

Microsatellites

Answer 9

< 300 bp motif length 2-6 bp
Highly polymorphic (informative)
Amenable to PCR analysis

Question 10

Single Nucleotide Polymorphisms

Answer 10

A change in a single base
Usually bi-allelic
Arise by spontaneous mutation
Occur in non-coding regions

Question 11

Continuous and Discontinuous genetic variation

Answer 11

Continuous - controlled by multiple genes e.g. height

Discontinuous - controlled by one or very few genes e.g. coat colour

Question 12

Application of Genetic Variation

Answer 12

Forensics
Evolutionary relationships
Health 
Production 
Biotechnology

Question 13

Genetic Drift

Answer 13

The change in allele frequencies in a population from generation to generation that occurs due to chance events

Question 14

Changes in the Chromosome

Answer 14

In the:
Structure
- deletions
- duplications
- inversions
- recombination
Number
- extra and missing chromosomes in human can lead to complications

Question 15

Effects of Point Mutations on Proteins

Answer 15

Mutations in these regions affect protein
- coding regions
- non-coding
- regulatory
- intergenic regions
Outcomes
- incorrect protein
- no protein 
- incorrect splicing and sorting

Question 16

Hardy Weinberg Principle

Answer 16

Allele frequencies remain constant over succeeding generations provided that:

• members mate randomly
• selection is unbiased
• mutation doesnt change frequencies or mutation doesnt occur and change frequencies

Question 17

Sickle Cell Anaemia

Answer 17

Caused by mutations in B-globin gene
Harder to carry O in blood
Caused by a single nucleotide polymorphism
Changes adenine to thymine which results in glutamic acid being substituted for valine