Diploma Prep: DNA

Question 1

What is the structure of DNA?

Answer 1

double helix, ATCG, dioxyribose, phosphorus

Question 2

How are nucleosomes formed?

Answer 2

winding DNA around histones

Question 3

What did Franklin contribute to discovering the structure of DNA?

Answer 3

x-ray crystallography

Question 4

What did Watson and Crick contribute to discovering the structure of DNA?

Answer 4

discovered the double helix

Question 5

What is the role of helicase in dna replication?

Answer 5

unwinds two strands

Question 6

What is the role of single stranded binding proteins in dna replication?

Answer 6

stabilizes dna to keep it open

Question 7

What is the role of rna primase in dna replication?

Answer 7

builds short sections of rna primer, provides attachment site for dna polymerase 3

Question 8

What is the role of dna polymerase 3 in dna replication?

Answer 8

attaches to rna primer and adds complimentary nucleotides

Question 9

What is the role of dna polymerase 1 in dna replication?

Answer 9

replaces rna primers with base pairs

Question 10

What is the role of dna ligase in dna replication?

Answer 10

glues fragments together

Question 11

What is gel electrophoresis, how is it performed and what is it used for?

Answer 11

dna is put with restriction enzymes and put in a gel medium with a current, dna is - and so the smallest pieces of dna move the fastest, used in parental testing and forensics

Question 12

What are the steps in dna recombination?

Answer 12

1. isolate gene (w restriction enzymes)
2. restriction enzyme cuts plasmid - cant cut on binding site or inside antibacterial resistance code
3. grow bacteria on agar with antibiotic

Question 13

What are the differences between dna and rna?

Answer 13

rna is single stranded, rna uses uracil instead of thymine, rna uses ribose

Question 14

What are the steps of rna transcription and what do they do?

Answer 14

1. initiation (rna polymerase opens double helix and reads 3’ strand)
2. elongation (rna nucleotides are placed)
3. termination (mRNA falls off when it hits the terminator

Question 15

What happens to rna after transcription?

Answer 15

methyl cap is added, poly-a tail is added, non-coding rna is taken out (introns)

Question 16

What are the steps of rna translation and what do they do?

Answer 16

1. initiation (mrna associates with rsu, aug is at p site, trna with met a.a aligns with anticodon, held together by h bonding)
2. elongation (trna enters with the next codon, old trna moves to e site, single trna goes to a site)
3. termination (stop codon signals end of a.a., a.a. is released and ribosome falls apart)

Question 17

What does polysome mean?

Answer 17

when translation is occuring at various places along the mrna

Question 18

what is a codon?

Answer 18

3 nucleotides that code for an a.a.

Question 19

what is an anticodon?

Answer 19

3 nucleotides forming a unit of genetic code

Question 20

what are the e p and a sites?

Answer 20

sites on ribosome for trna during translation

Question 21

what is trna?

Answer 21

small rnas that carry amino acids to the ribosome

Question 22

what is mrna?

Answer 22

messanger rna, carries rna from nucleus to ribsome

Question 23

what is a start codon?

Answer 23

first codon of mrna, codes for met

Question 24

what is a stop codon?

Answer 24

trna stops adding a.a. and chain is released