DNA + RNA

Question 1

What does DNA & RNA stand for?

Answer 1

Deoxyribonucleic acid

Ribonucleic acid

Question 2

What is the structure of DNA and RNA?

How many strands in each?

Answer 2

Deoxyribose sugar, phosphate group, base (A,T,C,G)
Double helix

Ribose sugar, phosphate group, base (A,U,C,G)
Single stranded

Question 3

What are the functions of DNA and RNA?

Answer 3

DNA= stores genetic info
RNA= transfers genetic info

Question 4

What are 3 bases called in DNA & RNA?

Answer 4

Triplet code

Codon

Question 5

Where can DNA be found?

How is it arranged? (Coiled?)

Answer 5

Nucleus and mitochondria

DNA coils around proteins (histones) and forms nucleosomes, then supercoils, then chromosomes

Question 6

What is DNA replication called? And why is it called that?

Answer 6

Semi conservative replication

Retains one strand of original DNA

Question 7

Which enzymes are involved in DNA replication?

Answer 7

Topoisomerase
DNA helicase
DNA polymerase
DNA ligase

Question 8

What does topoisomerase do?

Answer 8

Unwinds the supercoil

Question 9

What does DNA helicase do?

Answer 9

Separates DNA strands by breaking H bonds between bases, exposing nucleotides

Question 10

What happens after DNA helicase?

Answer 10

Free nucleotides bind to complimentary exposed template bases on DNA strands

Question 11

What does SSB stand for and what does it do?

Answer 11

Single strand binding protein

Bind to exposed bases, keeps two strands apart whilst synthesis of new DNA occurs, prevent annealing to other strand

Question 12

*What does DNA polymerase do?

Prime ends=‘

Answer 12

Reads 3’ to 5’ and synthesises DNA on daughter strand 5’ to 3’
Forms phosphodiester bonds between free nucleotides

Question 13

Why is DNA synthesised 5’ to 3’?

Answer 13

Runs antiparallel

Question 14

What does DNA ligase do?

Answer 14

Join short DNA pieces (Okazaki fragments) together into one continuous strand

Question 15

Where does transcription occur?

What initiates it? What enzymes and what do they do?

Answer 15

Nucleus
Topoisomerase- unwinds supercoil and double helix
DNA helicase- separates DNA strands by breaking H bonds and exposing nucleotides
SSB- coat DNA to prevent reannealing

Question 16

What happens In transcription after SSBs are attached?

Answer 16

Free mRNA nucleotides bind to complimentary bases on template strand of DNA, initiated by TATA box sequence (promoter region)
AUG = start codon methionine
RNA polymerase goes from 5’ to 3’ from Promoter to stop codon
Pre mRNA released

Question 17

What happens after transcription?
Where does it occur?
Where does it exit?

Answer 17

Splicing
Pre mRNA removes introns (non coding parts of DNA) to leave just exons
Now translatable

Nucleus

Nuclear pore

Question 18

Where does translation occur?

Answer 18

Cytoplasm

Question 19

What are the 3 types of RNA?

Answer 19

mRNA
rRNA
tRNA

Question 20

What does tRNA carry and have on it?

mRNA

Answer 20

Amino acids

Binds to mRNA codon with complimentary anticodon (temp H bonds)

Question 21

What happens in translation?

Answer 21

Ribosome moves along mRNA, once ‘read’, tRNA detaches and leaves AA behind, another tRNA arrives
Adjacent AA form peptide bonds
Polypeptide chain released at mRNA stop codon
Sent to Golgi apparatus for modification