Chapter 4

Question 1

DNA characteristics

Answer 1

1) able to store info that pertains to development, structure and metabolic activities of a cell or organism
2) stable so division is possible

Question 2

Who discovered DNA

Answer 2

James Watson and Francis Crick

Question 3

nucleotide composition

Answer 3

phosphoric acid (phosphate), pentose sugar, nitrogen containing base

Question 4

purine

Answer 4

Adenine and guanine, double ring

Question 5

pyrimidine

Answer 5

thymine and cytosine

Question 6

what kind of bonds hold the bases together

Answer 6

hydrogen

Question 7

How many hydrogen bonds do adenine and thymine have

Answer 7

2

Question 8

How many hydrogen bonds do cytosine and guanine have

Answer 8

3

Question 9

what is antiparallel

Answer 9

dna strands are oriented in opposite directions

Question 10

What does DNA polymerase do?

Answer 10

carries out replication by using each original strand to form a complimentary new strand

Question 11

What are the steps of DNA replication?

Answer 11

1. helices unwinds the DNA by braking H-bonds
2. new complimentary DNA nucleotides join
3. the leading strand follows the enzyme, the lagging strand results in fragments
4. DNA ligase connects Okazaki fragments

Question 12

what is gene expression?

Answer 12

using a gene sequence to synthesize a protein

Question 13

Where does transcription occur?

Answer 13

in the nucleus

Question 14

Where does translation occur?

Answer 14

in the cytoplasm in the ribosome

Question 15

What is transcription?

Answer 15

gene is a template for RNA production

Question 16

what is a promoter

Answer 16

region of DNA that contains a special sequence of nucleotides

Question 17

introns

Answer 17

segments of DNA that are NOT the gene

Question 18

exons

Answer 18

segments of DNA that have genetic material

Question 19

How does RNA modify genes?

Answer 19

RNA adds a cap (guanine) to one end and a poly A-tail (adenosine) to the other end, then the introns are removed and the exons remain

Question 20

What is translation?

Answer 20

gene expression leads to protein synthesis

Question 21

What is a codon?

Answer 21

3 nucleotides

Question 22

What is degenerate

Answer 22

some proteins can be code for more than one codon, helps prevent mutation

Question 23

tRNA

Answer 23

a single stranded polynucleotide, has anticodons that are complimentary to mRNA

Question 24

what is the wobble effect?

Answer 24

for the same tRNAs, the 3rd nucleotide may vary

Question 25

Where is rRNA produced?

Answer 25

in the nucleolus, then joins with proteins manufactured in the cytoplasm to form 2 ribosomal subunits

Question 26

What are the 3 steps of translation?

Answer 26

initiation, elongation, termination

Question 27

initiation

Answer 27

initiation factor proteins are required to assemble the small ribosomal subunit to start protein synthesis

Question 28

What are the 3 binding sites for the tRNAS

Answer 28

P(peptide)
A(amino acid)
E(exit)

Question 29

What are the steps in elongation?

Answer 29

1. tRNA with a peptide is already @ the peptide site, the next on his already moving to the A site
2. Once the next tRNA is in place @ the A site, the peptide chain transfers to the P site

Question 30

gene expression summary

Answer 30

1. DNA in nucleus serves as a template for mRNA
2. mRNA is processed before leaving the nucleus
3. mRNA moves into cytoplasm and becomes associated with ribosomes
4. tRNAs with anticodons carry amino acids to mRNA
5. anticodon-codon complimentary base pairing occurs
6. polypeptide synthesis takes place one amino acid at a time

Question 31

what are transposons?

Answer 31

specific DNA sequences that can move between chromosomes, can alter genes

Question 32

sickle cell mutation

Answer 32

caused by a point mutation that subs valine instead of glutamic acid

Question 33

recombinant DNA

Answer 33

2+ different sources of DNA

Question 34

vector

Answer 34

piece of DNA that can be manipulated so foreign DNA can be added