Topic 7 Modern Genetics

Question 1

What is the definition of genome?

Answer 1

All of the genetic information in an organism

Question 2

What is in vitro PCR used for?

Answer 2

Replicate copies of DNA outside body
Eg DNA profiling, COVID19 testing,

Question 3

What are the steps of PCR?

Answer 3

1. Separate DNA strand - heat to 95C, breaking H bonds exposing bases
2. Annealing - cool to 55C, primers added
3. Elongation - heat to 72C, DNA polymerase replicates DNA using complementary base pairing
4. REPEAT to get more samples

Question 4

What are the 3 raw materials used in PCR?

Answer 4

• DNA primer
• free DNA nucleotide
• DNA strand
• Taq polymerase

Question 5

What needs to happen before PCR?

Answer 5

Purify dna (break up cells, filter and suspend)

Question 6

Why is DNA polymerase from human sources not suitable for PCR use in machine? (2)

Answer 6

• human enzymes can’t work at high temps
• will denature

Question 7

Why can’t xylem be used in PCR and DNA profiling?(2)

Answer 7

• dead, made of dead material
• so no dna present

Question 8

What nucleotide do we use for gene sequencing?

Answer 8

Terminator bases or dideoxyribose molecules
They lack -OH on carbon 3
So it stops(terminates) the extension during PCR

Question 9

How to identify the terminator bases?

Answer 9

Add radioactive markers

Question 10

What does PCR stand for?

Answer 10

polymerase chain reaction

Question 11

Describe how a DNA profile can be produced from a small sample of DNA. (6 marks)

Answer 11

• use PCR
• to multiple copies of DNA
• use restriction endonucleases to produce DNA fragments
• gel electrophoresis
• load DNA onto gel (agarose)
• electric current applied
• use florescent tag

Question 12

Describe how small samples of DNA can be amplified. (4 marks)

Answer 12

• use PCR
• add Taq polymerase
• and primer and free nucleotides
• heat to 95C, cool to 55C, heat to 72C
• repeat several cycles to make several copies

Question 13

How to DNA sequence?

Answer 13

• PCR steps
• but with terminator nucleotides labelled with fluorescent dye
• DNA polymerase incorporates labelled dideoxynucleotides randomly during replication
• gel electrophoresis
• detect fluorescent dye

Question 14

What is the human genome?

Answer 14

all the genes of the human species

Question 15

How are DNA profiles compared? (3 marks)

Answer 15

compare
- total number of bands
- position of bands
- size/width of bands

Question 16

What are exons and introns?

Answer 16

exons are the gene, coded region/expressed
introns are the non-coded region

Question 17

What is the role of restriction endonuclease? (1 mark)

Answer 17

cut DNA to produce short sections of DNA

Question 18

Describe the process of PCR. (3 marks)

Answer 18

• use primers / nucleotides
• heat to 95C to separate strands
• cool to 55C to bind primers
• heat to 72C with Taq polymerase
• repeat to obtain multiple copies

Question 19

What is proteomics used for?

Answer 19

To study proteins (including enzymes)

Question 20

How to distinguish between species?

Answer 20

Gel electrophoresis