DNA, RNA and biotechnology

Question 1

What is the force between the Phosphate groups in DNA and RNA?

Answer 1

Electrostatic replusion

Question 2

What is the bonding between pentose sugar and nitrogenous base?

Answer 2

N-glycosidic bond

Question 3

What is the bonding between nitrogenous bases in DNA?

Answer 3

Hydrogen bonding

Question 4

What is the forces between nitrogenous bases in DNA and RNA?

Answer 4

Van der Waals (London forces)

Question 5

What does a DNA nucleotide consist of?

Answer 5

Phosphate - Sugar - Base

Question 6

What does a DNA nucloside consist of?

Answer 6

Sugar - Base

Question 7

What configuration are nucleosides in?

Answer 7

β configuration

Question 8

How many hydrogen bond are between Adenine and Thymine?

Answer 8

2 hydrogen bonds

Question 9

How many hydrogen bonds are between cytosine and guanine?

Answer 9

3 hydrogen bonds

Question 10

What is Palindrome?

Answer 10

The top strand read forwards is the same as the bottom strand read backward

Question 11

What is the hairpin structure?

Answer 11

Single palindromic DNA strand

Question 12

What is the cruciform structure?

Answer 12

Double palindromic DNA strand

Question 13

What is the secondary structure of DNA?

Answer 13

Double helix

Question 14

How is tertiary structure formed in DNA?

Answer 14

Chromosomal DNA forms a closed circle, twisting into a supercoiled DNA

Question 15

What else can supercoiled DNA occur in?

Answer 15

Plasmids

Question 16

What is the process of DNA folding?

Answer 16

1) DNA helix wraps around a histone protein twice - forming a nucleosome

2) Further packed into loops creating chromatin fibre

3) CHromatin fibre folded into loops to form chromosome

Question 17

What are sister chromatids?

Answer 17

Exact copies created prior to cell divison

Question 18

What is mRNA?

Answer 18

RNA carrying code for producing proteins

Question 19

What is the function of mRNA (Messenger RNA)?

Answer 19

1) DNA is unzipped and a single chain of pre-mRNA is made
2) Pre-mRNA is processed into mRNA (removing non coding sequence)
3) mRNA sequence is read 3 bases at a time to determine the order of amino acids in the protein chain

Question 20

What is tRNA?

Answer 20

Transfer RNA that transfers a specific amino acid to the ribosome

Question 21

What is the function of tRNA?

Answer 21

One end of tRNA binds to a specific amino acid and the othr end binds to a specific codon

Question 22

What is denaturation?

Answer 22

Separation of double stranded DNA into coiled single strands

Question 23

What is the characteristic melting curve for each DNA strand dependent on?

Answer 23

Nucleotide sequence

Question 24

What can be done under controlled pH?

Answer 24

Estimating base composition

Question 25

What is the purpose of Polymrase chain reaction (PCR)?

Answer 25

Amplify targeted regions of DNA

Question 26

What is the process of using PCR?

Answer 26

1. DNA heated to 90 °C → denatures 2. Cool to 60 °C → allows primersto bind to complimentary DNA sequence 3. Heat to 72 °C → allows Taq polymerase to extend the primers → synthesise complimentary DNA strand (You will now have 2 identical copies of DNA. ) 4. Repeat

Question 27

What is the purpose of Gel electrophoresis?

Answer 27

Identify DNA fragments based on size and shape

Question 28

What is important about te gel in gel electrophoresis?

Answer 28

Contains microscopic holes of different sizes

Question 29

What is the function of Gel electrophoresis?

Answer 29

Fragments are drawn through the gel via electrical current (DNA is negatively charged so moves towards positive anode) - Fragments are viewed under UV to compare fragments to known length

Question 30

What happns if the fragment is short in Gel electrophoresis?

Answer 30

Travels faster along the gel

Question 31

What is short tandem DNA repeats?

Answer 31

4 base pairs repeated many times

Question 32

What is DNA profiling?

Answer 32

Specific positions on the chromosomes (loci) where the number of repeats is highly variable between individuals

Question 33

What do PCR primers do?

Answer 33

Select chromosomes (loci) where short tandem repeats of interest lie for amplification by PCR

Question 34

What is the process of Sanger DNA sequencing?

Answer 34

Primer binds to template strand (strand to be sequenced) • dNTPs available to extend primer strand, complementary to template • ddNTPs compete with dNTPs • Binding of a ddNTP stops further synthesis

Question 35

What are Nucleases?

Answer 35

Enzymes that catalyse the hydrolysis of phosphodiester bonds to break apart DNA

Question 36

What are Restriction endonucleases?

Answer 36

Breaks apart DNA sequnces at specific sites to produce DNA fragments

Question 37

What is the process of DNA cloning?

Answer 37

1. Plasmid is cleaved by a restriction endonuclease 2. DNA fragment of interest cleaved from eukaryotic chromosome by a restriction endonuclease 3. DNA fragment of interest added to plasmid by DNA ligase to form recombinant vector 4. Recombinant vector inserted into bacterium 5. Bacterial growth → cloning of recombinant DNA