DNA & RNA

Question 1

DNA

Answer 1

• basis for heredity

- ability to self-replicate

Question 2

central dogma

Answer 2

DNA->RNA->proteins

Question 3

DNA structure

Answer 3

• basic unit: nucleotide

- nucleotide: sugar bonded to a phosphate group and a nitrogenous base

Question 4

2 types of nitrogenous bases

Answer 4

• purines: adenine and guanine, 2-ring base

- pyrimidines: cytosine and thymine, 1-ring base

Question 5

antiparallel arrangement

Answer 5

5’ end pointing up and the other strand has the 3’ end pointing up

Question 6

Watson-Crick DNA model

Answer 6

• DNA is a double-strand helix with the sugar-phosphate chains on the outside and nitrogenous bases H-bonded on the inside
• T forms 2 H bonds w A
• G forms 3 H bonds w C

Question 7

topoisomerase

Answer 7

-uncoils the DNA strands in order to replicate

Question 8

DNA helicase

Answer 8

-breaks the H bonds b/w nitrogenous bases of each nucleotide

Question 9

replication fork

Answer 9

opening in the DNA molecule created by DNA helicase

Question 10

semiconservative replication

Answer 10

-original DNA strand separates and acts as a template for complementary base pairing, containing one strand from parent and a new strand

Question 11

DNA polymerase

Answer 11

• reads parent strand and creates a complementary strand
• reads 3’->5’
• leading strand (synthesized by DNA pol) and lagging strand

Question 12

Okazaki fragments

Answer 12

-short fragments of DNA which are synthesized discontinuously and later linked together by DNA ligase to create the lagging strand

Question 13

genetic code

Answer 13

• A, T, C, and G
• in RNA T is replaced with U
• codons (triplets)

Question 14

redundancy

Answer 14

most AA have more than one codon coding for them

Question 15

RNA structure

Answer 15

-ribose sugar, uracil instead of thymine, and it is single stranded

Question 16

mRNA

Answer 16

-carries complement of DNA sequence from nucleus to the ribosome for protein synthesis

Question 17

tRNA

Answer 17

-brings AA coded for in the mRNA sequence to the ribosome (anticodon)

Question 18

rRNA

Answer 18

-structural component of ribosomes, helps translate mRNA to protein

Question 19

transcription

Answer 19

• info coded in the sequence of DNA is transcribe in mRNA that leaves the nucleus
• RNA pol binds to DNA at the promoter region, ten factors help RNA pol bind to DNA and initiate txn
• RNA pol (reads 3’->5’) adds comp nucleotides

Question 20

introns

Answer 20

-extra sequence of nucleotides, spliced out by splisosome

Question 21

exons

Answer 21

-nucleotides necessary to make the protein

Question 22

guanine cap and poly-A tail

Answer 22

provide protection of RNA from enzyme degradation

Question 23

translation

Answer 23

• mRNA codons are translated into a sequence of AA

- occurs in cytoplasm

Question 24

4 stages of translation

Answer 24

1. initiation
2. elongation
3. translocation
4. termination

Question 25

initiation

Answer 25

ribosome scans the mRNA until it binds to a start codon

Question 26

elongation

Answer 26

- H bonds form b/w the mRNA codon in the A site and its comp anticodon - peptide bond is formed b/w AA attached to tRNA in the A site and the AA attached to the tRNA in the P site

Question 27

translocation

Answer 27

- ribosome advances 3 nucleotides along the mRNA in the 5'->3' - tRNA in P site is expelled and the peptidyl-tRNA in the A site moves to the P site

Question 28

termination

Answer 28

-stop codons arrives in the A site

Question 29

A site

Answer 29

-aminoacyl-tRNA site, binds to the incoming tRNA

Question 30

P site

Answer 30

-peptidyl-tRNA site, transferred from A then contributes it AA to the polypeptide chain

Question 31

E site

Answer 31

-tRNA is released