Nuclei acids

Question 1

What is dna made up of

Answer 1

2 polynucleotide chains which twist to form a double helix

Question 1

Describe a dna nucleotide

Answer 1

Question 2

How are the components of dna joined

Answer 2

As a result of a condensation reaction

Question 3

How are nucleotides joined together

Answer 3

Through condensation reaction between deoxyribose of 1 mono nucleotide and phosphate group of next by a phosphodiester bond

Question 4

What are the base pairs on DNA?

Answer 4

Adenine pairs with thymine
Guanine pairs with cytosine

Question 5

What is key information from the mark scheme about DNA and RNA

Answer 5

DNA and RNA are polymers of nucleotides

Question 6

What do histones do

Answer 6

Organise and condense DNA tightly so it fits into nucleus

Question 7

What does DNA stand for

Answer 7

Deoxyribonucleic acid

Question 8

What does RNA stand for

Answer 8

Ribonucleic acid

Question 9

What are the bases in RNA?

Answer 9

Adenine to uracil
Cytosine to guanine

Question 10

Is RNA single or double stranded

Answer 10

Single

Question 11

Is it a short or long, polynucleotide chain

Answer 11

Relatively short

Question 12

Who worked out structure of DNA

Answer 12

Watson and Crick

Question 13

What is phosphodiester made of

Answer 13

2 ester bonds and a phosphate group

Question 14

How is DNA adapted to carry out its function

Answer 14

Large molecule- carries lots of genetic material

Question 15

Why have many scientists doubted dna carried genetic code

Answer 15

Because of its simplicity

Question 16

How is dna adapted to carry out function (2 strands..)

Answer 16

2 strands joined by hydrogen bonds allow to separate during dna replication

Question 17

How is DNA adapted to carry out its functions( base pairing)

Answer 17

Base pairing- dna can replicate and transfer information mRNA

Question 18

How id DNA adapted to carry out it’s function(generations)

Answer 18

Can pass genetic information from generation to generation without signifant change. Mutations are repaired

Question 19

How do you package DNA

Answer 19

DNA wrapped around histones, which are protein beads to form a structure called a nucleosome. Chain of nucleosome is called chromatin. chromatin is woundup to form a single chromosome.

Question 20

What is the function of R.N. A

Answer 20

to transfer genetic code found in DNA to ribosomes

Question 21

What is each DNA polynucleotide strands said to have

Answer 21

A 3’ end and a 5’ end

Question 22

What does three end and a five end do

Answer 22

They run in opposite directions they are antiparallel

Question 23

Are ribosomes bigger in eukaryotic cells or prokaryotic cells

Answer 23

Eukaryotic (80S)

Question 24

Are ribosomes surrounded by membranes

Answer 24

No

Question 25

What is the purpose of semiconservative replication?

Answer 25

Before cell divides, it needs to copy DNA within so that to new daughter cells will both receive for copies of parental DNA

Question 26

Why is it called semiconservative replication?

Answer 26

In each new DNA molecule one DNA strand is from original DNA molecule and one is new

Question 27

Why is it important to retain one original DNA strand?

Answer 27

It insures genetic continuity between generations of cells

Question 28

What does semiconservative replication need?

Answer 28

Free Nucleotides Both strands of DNA to act as a template, enzyme DNA polymerase, DNA helicase and a source of chemical energy

Question 29

Describe semiconservative replication

Answer 29

Enzyme DNA Heli case breaks hydrogen bonds between complimentary base pairs Double helix, then unwinds Each exposed polynucleotide strands then acts as a template to which complimentary three nucleotides bind by specific base pairing Nucleotides joined in a condensation reaction by enzyme DNA polymerise to adjacent ones

Question 30

What were the three possible ways, scientist, believed DNA could replicate

Answer 30

Fragmented, semi, conservative or conservative

Question 31

Who was Watson and Criks theory proved by

Answer 31

Meselson and Stahl

Question 32

How did Meselson and Stahl prove it was semi conservative replication

Answer 32

Heavy 15 and culture bacteria was spun in centrifuge. DNA containing heavy nitrogen settled in a bottom of tube. This was added to only lighter 14 and nitrogen it was left long enough for one round of DNA replication, then centrifuged

Question 33

What would Meselson and Stahl findings have been if it was conservative replication

Answer 33

The original DNA, which was the only heavy nitrogen what is settle at the bottom and the new DNA, which was only lighter nitrogen would be at the top

Question 34

What did the test tube show to prove it was semiconservative replication

Answer 34

DNA containing mixture of light and heavy nitrogen settled in middle of test tube