Gene Technology & Applications

Question 1

What breaks the hydrogen bonds in DNA during replication?

Answer 1

The DNA strands separate as hydrogen bonds are broken.

Question 2

What acts as the template in replication?

Answer 2

The parent strand is the template (semi-conservative replication).

Question 3

How do new nucleotides pair up?

Answer 3

Via complementary base pairing (A with T, C with G).

Question 4

What enzyme joins new nucleotides?

Answer 4

DNA polymerase.

Question 5

What bonds does DNA polymerase form?

Answer 5

Phosphodiester bonds.

Question 6

In which direction does DNA polymerase work?

Answer 6

5’ to 3’ direction.

Question 7

What is the result of semi-conservative replication?

Answer 7

Each new DNA has one old strand and one new strand.

Question 8

What is a plasmid?

Answer 8

Circular DNA separate from the main bacterial DNA.

Question 9

What does a plasmid contain?

Answer 9

Only a few genes.

Question 10

What is a vector in genetic engineering?

Answer 10

A carrier of DNA/gene into a cell or organism.

Question 11

Why is mRNA called a polymer?

Answer 11

It’s made of many nucleotides (monomers).

Question 12

Why does a restriction enzyme cut human DNA many times?

Answer 12

The recognition site appears many times in human DNA.

Question 13

Why does it cut the plasmid only once?

Answer 13

The recognition site appears only once in the plasmid.

Question 14

How is a target gene inserted into a plasmid?

Answer 14

Use restriction enzymes (sticky ends) and DNA ligase.

Question 15

What is added alongside the target gene?

Answer 15

A marker gene (e.g., antibiotic resistance).

Question 16

How are modified plasmids detected in bacteria?

Answer 16

Use replica plating to grow colonies and test for marker gene expression.

Question 17

What is the role of restriction enzymes?

Answer 17

Cut plasmid to produce sticky ends.

Question 18

What is the role of ligase?

Answer 18

Joins DNA and plasmid at sticky ends.

Question 19

How do genetically modified bacteria produce insulin?

Answer 19

Grown in fermenters under ideal conditions.

Question 20

What happens to the insulin produced?

Answer 20

It accumulates and is extracted for commercial use.

Question 21

How are STRs removed from DNA?

Answer 21

Using restriction enzymes at specific base sequences.

Question 22

What is a DNA probe?

Answer 22

A short single strand of DNA complementary to a gene/allele.

Question 23

What is the purpose of labelled DNA probes?

Answer 23

Screen for heritable conditions, drug responses, and health risks.

Question 24

Name three techniques to compare DNA.

Answer 24

PCR, DNA fingerprinting, gel electrophoresis.

Question 25

What happens first in PCR?

Answer 25

Heat DNA to 95°C to break hydrogen bonds and separate strands.

Question 26

What happens after cooling?

Answer 26

Primers bind to the DNA strands.

Question 27

What is added next?

Answer 27

DNA polymerase and nucleotides.

Question 28

What happens after primer binding?

Answer 28

DNA polymerase synthesizes new strands.

Question 29

How is PCR amplified?

Answer 29

The cycle is repeated many times.

Question 30

Why is the DNA heated to 95°C?

Answer 30

To break weak hydrogen bonds and separate strands.

Question 31

Why are primers added?

Answer 31

They bind to the start of the gene and prevent strand re-annealing.

Question 32

Why might PCR stop?

Answer 32

Primers or nucleotides run out, or DNA polymerase denatures.

Question 33

How is DNA cut for analysis?

Answer 33

Restriction enzymes cut at specific base sequences.

Question 34

How is DNA separated by size?

Answer 34

Gel electrophoresis: smaller fragments move further.

Question 35

Why are base-pairs a suitable unit for DNA length?

Answer 35

Each base-pair is the same length; DNA has constant width.

Question 36

What are introns?

Answer 36

Non-coding sections of a gene.

Question 37

Where are VNTRs found?

Answer 37

In intergenic regions between adjacent genes.