Nucleic Acids

Question 1

What does DNA stand for

Answer 1

Deoxyribosenucleic acid

Question 2

Describe the structure of a nucleotide

Answer 2

Pentose sugar (deoxyribose in DNA)

A phosphate group attached to the sugar

A nitrogenous base (A,T,C or G)

Question 3

What is the difference between ATP and a RNA nucleotide

Answer 3

ATP has become phophorylated (gained 2 extra phosphates)

Question 4

What term describes the direction the 2 DNA strands run in

Answer 4

Antiparallel

Question 5

What is the name of the covalent bond between the pentose sugar and the phosphate

Answer 5

Phosphodiester bond

Question 6

What is a purine and what are the 2 examples

Answer 6

A purine is a nitrogenous base with 2 rings

Adenine and Guanine

Question 7

What is a pyramidine and what are the 2 examples

Answer 7

A pyramidine is a nitrogenous base with only 1 ring

Thymine and Cytosine

Question 8

How many hydrogen bonds form between A and T

Answer 8

2

Question 9

How many hydrogen bonds form between C and G

Answer 9

3

Question 10

What is the name of the shape of a DNA molecule

Answer 10

Double Helix

Question 11

How is DNA stored in Eukaryotes

Answer 11

The majority is stored in the nucleus

wrapped around protiens called histones to form chromosomes

there is a loop of DNA without a histone in mitochondria and chloroplasts

Question 12

How is DNA stored in Prokaryotes

Answer 12

DNA is in a loop within the Cytoplasm (no nucleus)

DNA is described as naked as it has no histone

Question 13

What stage of the cell cycle does DNA replication take place

Answer 13

Interphase

S

Question 14

What is the name of the enzyme that catalyses the ‘unzipping’ process

Answer 14

DNA Helicase

Question 15

What enzyme catalyses the unwinding process

Answer 15

Gyrase

Question 16

What is the name of the type of replication DNA performes

Answer 16

Semi-conservative Replication

Question 17

What is Semi-conservative Replication

Answer 17

DNA replication where 1 strand in the new molecule is from the origional molecule and 1 strand is newly formed

Question 18

What is the name for a different variation of a gene

Answer 18

an Allele

Question 19

What are the 5 structural differences between RNA and DNA

Answer 19

Sugar is different (Ribose in RNA)

Uracil replaces Thymine

Single stranded

Shorter chain

3 forms of RNA (mRNA, tRNA and rRNA)

Question 20

What specifically does DNA code for

Answer 20

the Amino acid sequence (primary structure)

Question 21

Why is it importand that the amino acid sequence (primary structure) is correct

Answer 21

because then it allows the chain to flod and be held in its tertiary structure giving it its specific 3D shape

Having a specific 3D shape is vital to a protiens function

Question 22

What process allows the genetic code to be able to be moved out the nucleus, and what molecule does this form

Answer 22

Transcription

forms mRNA

Question 23

Describe the process of Transcription

Answer 23

Gyrase and DNA helicase unwind and unzip the DNA

Hydrogen bonds break between bases

RNA polymerase catalyses the formation of tempory hydrogen bonds between RNA nucleotides and the DNA bases

The RNA strand is now complementary to the ‘template strand’

mRNA moves out the nucleus and joins a ribosome

Question 24

Where are tRNA molecules made

Answer 24

the Nucleolus

Question 25

What is the name of the 3 bases at the top of the loop on a tRNA molecule

Answer 25

the Anticodon

Question 26

What joins to the 3 bases at the straight tip of a tRNA molecule

Answer 26

Amino acid

Question 27

What causes the ribosome to stop moving along the mRNA chain

Answer 27

the Stop Codon

Question 28

What happens to the mRNA chain after translation

Answer 28

it breaks down into free nucleotides again