DNA 2 - MT2 - Part 1

Question 1

Polymorphism

Answer 1

Is an inherited character from which different traits are present in a population

Question 2

What are 3 examples of polymorphisms?

Answer 2

1. Mouse fur colour
2. Human eye colour
3. Human blood type

Question 3

Where is DNA polymorphism located?

Answer 3

On a specific chromosome that has appreciable variation in a population

Question 4

What are genes and the expression of genes in an organism basic to? (2)

Answer 4

1. Morphology

2. Functioning of the organism

Question 5

What can DNA sequence be irrelevant in determining?

Answer 5

The organisms observable properties

Question 6

What do many polymorphisms have nothing to do with?

Answer 6

Determining the characteristics of the organism that carry from one individual to another

Question 7

What are 3 types of DNA polymorphism?

Answer 7

1. SNP
2. VNTRs
3. STR

Question 8

SNP

Answer 8

Single nucleotide polymorphism

Question 9

Single nucleotide polymorphism

Answer 9

Is a site where different base pairs are found in different individuals
- the sight might be part of a gene or might be outside the gene sequences

Question 10

VNTRs

Answer 10

Variable number of tandem repeats

Question 11

STR

Answer 11

Short tandem repeats

Question 12

What are VNTR regions?

Answer 12

Sites in the genome where a short DNA sequence (15-100bps long) is repeated over a distance of 1000-20,000 bp

Question 13

What are STR regions?

Answer 13

Is similar to VNTR region, except that the repeated sequence is 2-9bp long and is repeated 7-40 times

• its a lot shorter
• the repeat number is polymorphic but the flanking sequence are not

Question 14

What does each STR region have? (2)

Answer 14

1. An unique name

2. Chromosome location

Question 15

What do no 2 people have the same of?

Answer 15

Chromosome repeats

- expect maybe identical twins

Question 16

What are 6 sources of DNA?

Answer 16

1. Blood
2. Semen
3. Hair
4. Bits of tissue
5. Saliva
6. bones

Question 17

When should you use VNTR loci?

Answer 17

When there is a lot of source tissue and a lot of DNA is available

• DNA needs to be largely intact
• not used very much anymore

Question 18

Southern blot

Answer 18

Is a method used in molecular biology for detection of a specific DNA sequence in DNA samples

Question 19

What is souther blot a combination of? (2)

Answer 19

1. Electrophoresis
2. Hybridization

• combines transfer of electrophoresis separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization

Question 20

What are the 6 steps in southern blotting?

Answer 20

1. DNA digestion
2. Gel electrophoresis
3. Blotting
4. Probe labeling
5. Hybridization and washing
6. Detection

Question 21

What can restriction enzymes do?

Answer 21

They can cut DNA at specific sequences

• different restriction enzymes recognize and cut different sequences
• wanted the ability to move genes around

Question 22

When do you use STR loci?

Answer 22

When a small amount of DNA is available
- the procedure involves PCR amplification of the STR region, using flanking sequences as primers and direct detection of the amplified DNA on a gel

Question 23

What does 1 peak in the STR loci mean?

Answer 23

Homozygous

Question 24

What does 2 peaks in the STR loci mean?

Answer 24

Heterozygous

Question 25

How can you calculate the probability of a DNA match between 2 unrelated people?

Answer 25

Hardy Weinberg equilibrium equation

Question 26

What does the Hardy Weinberg equilibrium equation describe?

Answer 26

What happens in one generation (with no natural selection, immigration or reproduction, etc)
- the frequencies of the genotypes in progeny can be calculated by the frequencies of the alleles in the parents generation

Question 27

What 5 things can go wrong with DNA evidence?

Answer 27

1. The DNA might be too degraded to use
2. DNA from someone who is not at the crime scene
3. Contaminating DNA might have been accidentally introduced during testing
   - PCR is very sensitive
4. DNA evidence might have been planted or fabricated to fame someone who was innocent or avert suspicion from someone who is guilty
5. Two of more experts might draw different conclusions from the same evidence

Question 28

What enzyme digests DNA? (2)

Answer 28

1. Nucleases
   - as long as the cells have not been dried out
   - they are naturally occurring enzymes
   - no recognition sequence
2. Micro-organisms

Question 29

What is a very good source for DNA? (2)

Answer 29

1. Dried blood
   - it wont degrade very fast and can last a long time
2. Neanderthal toe bone

Question 30

What sequences can only be amplified?

Answer 30

Intact sequences