DNA markers

Question 1

What are molecular markers?

Answer 1

A measurable attribute in DNA - exhibit Mendelian inheritance

Question 2

What characteristics make a good marker? (10)

Everyday M-A & Pa Rested, IE. (they) Used N-E C-D During Naps

Answer 2

1. Polymorphic: variable b/w indiv.
2. Discrimination: allow differentiation b/w related indiv.
3. Multi-allelic: several alleles @ single locus
4. Co-dominant: heterozygote express intermediate phenot. to homozygous parents
5. Non-epistatic: Genotype not influenced by another genot. @ another loci
6. Independent of enviro.: is fixed & won’t change due to e.g. temp.
7. Neutral: no selective advantage
8. Uniformly distributed: spread through whole genome
9. Reproducible:
10. Economical: cost effective

Question 3

Distinguish between analogy and homology

Answer 3

• Analogy: Convergence from different ancestors- may look alike but markers show species come from diff. population= diff. ancestors (old world vs. new world)
• Homology: Decent from common ancestor

Question 4

What can genetic markers be used for? explain

Answer 4

Gene identification: Can find a target gene’s association w/ a marker. By having a dense-coverage of markers on a genome then linking the target gene to the marker that’s the closest to it.

Question 5

What’s Minisatellites?

Answer 5

aka Variable Number Tandem Repeats (VNTR)

• Repeating DNA (seq.) that’s 7-50bp long
• Polymorphic

Question 6

Types of markers

Answer 6

• Interspersed repeats: Short & Long interspersed nuclear elements (SINES & LINES)
• Tandem repeats: Minisatellites, Microsatellites
• Single nucleotide polymorphisms (SNPs)

Question 7

What’s microsatellites aka VNTRs, short tandem repeats (STR), simple seq. repeats (SSR)?

Answer 7

• Repeating DNA (seq.) that’s 2-6bp long: named di- to hexanucleotide
• marker length ≤ 300bp
• highly polymorphic (informative= lots of diff. b/w indiv.)

Question 8

What’s SNP

Answer 8

Single nucleotide polymorphisms

- spontaneous point mutation (1x base changed) occur in non-coding regions

Question 9

Distinguish between STRs which contain di,tri,tetra,penta,hexa repeats.

Answer 9

an STR will contain 2/3/4/5/6 nucleotide per repeat. It is named (prefix)nucleotide e.g. 2= dinucleotide (ACAC= 2 base in 2 repeats)

Question 10

What application is SNP & STR used for?

Answer 10

• SNP: detect mutation in a single base

- STR: DNA fingerprinting? (e.g. for parentage)

Question 11

In DNA fingerprinting, What technique can you use when DNA pieces are too long for PCR?

Answer 11

Southern blotting used for minisatellites (VNTR)

Question 12

Which marker is used for forensics & ID testing?

Answer 12

microsatellites (VNTR, STR, SSR)

Question 13

What is a genome map?

Answer 13

a map of the chromosome w/ identifiable markers

Question 14

What’s SINEs & LINEs?

Answer 14

SINE: non-coding transposable elements- 100-700 bp long
LINE: Endogenous retrotransposable elements- 1000bp long

Question 15

Which marker is used for the basis of DNA fingerprinting?

Answer 15

minisatellites

Question 16

microsatellites are _ _ that are _ bp long

Answer 16

dinucleotide repeats

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