chapter seventeen part one

Question 1

telomeres

Answer 1

special nucleotide sequences that have multiple repetitions of 1 short nucleotide sequence
- at end of linear DNA

Question 2

what is aging associated with?

Answer 2

the loss/shortening of telomeres

Question 3

what are telomeres regenerated with?

Answer 3

telomerase

Question 4

where is telomerase active?

Answer 4

embryonic development/gametes, single-celled eukaryotes, some cancers
- not active in somatic cells

Question 5

why do single-celled eukaryotes need telomerase?

Answer 5

their species can’t continue without it

Question 6

Beadle/Tatum experiment/study

Answer 6

• Neurospora crossa - haploid species
• studied protein-coding genes for nutritional activity
• X-rayed to cause mutations, looked for mutants among survivors
• supported one gene-one enzyme theory

Question 7

gene expression

Answer 7

process by which DNA directs synthesis of proteins or RNAs

Question 8

what does reverse transcription use?

Answer 8

reverse transcriptase
- how retroviruses like HIV spread

Question 9

language for DNA and RNA

Answer 9

nucleotides

Question 10

language for proteins

Answer 10

amino acids

Question 11

where does transcription and translation occur in prokaryotes?

Answer 11

tcr: cytosol
tsl: cytosol

Question 12

where does transcription and translation occur in eukaryotes?

Answer 12

tcr: nucleus
tsl: cytosol

Question 13

1 gene to 1 protein/enzyme/polypeptide hypothesis

Answer 13

better: RNA molecule
- gene can code for set of polypeptides or RNA molecules

Question 14

2 steps of protein synthesis/gene expression

Answer 14

transcription and translation

Question 15

transcription

Answer 15

synthesis of RNA from DNA

Question 16

steps of RNA synthesis in transcription

Answer 16

1. RNA polymerase cuts open DNA at promoter
2. DNA read from 3’ to 5’, RNA assembled from 5’ to 3’
3. stops at termination sequence
4. RNA breaks free, DNA reseals

Question 17

RNA polymerase

Answer 17

• pries 2 DNA strands apart
• joins RNA nucleotides complementary to DNA
• 10-20 DNA nucleotides exposed at once

Question 18

what are sometimes needed to initiate transcription?

Answer 18

transcription factors

Question 19

transcription initiation complex

Answer 19

transcription factors and RNA polymerase

Question 20

promoter

Answer 20

TATA box

Question 21

what is required in transcription that is also required in DNA synthesis?

Answer 21

template, nucleotides, RNA polymerase that starts de novo (helices activity), ssDNA binding proteins

Question 22

what is not required in transcription that is required in DNA synthesis?

Answer 22

ligase, topoisomerase, sliding clamp protein

Question 23

how many strands of DNA are transcribed

Answer 23

1

Question 24

3 types of RNA

Answer 24

mRNA, tRNA, rRNA

Question 25

mRNA

Answer 25

• dictates A.A. sequence (protein recipe/blueprint)
• carries genetic message from dNA to protein-synthesizing machines

Question 26

tRNA

Answer 26

• transfers A.A. to ribosome for assembly
• A.A. on one end of structure, other end is nucleotide triplet complementary to codon on mRNA

Question 27

rRNA

Answer 27

• combines w/ proteins to make ribosome workbench for translation
• transcribed in nucleolus

Question 28

mRNA processing

Answer 28

• both end of primary pre-mRNA transcript altered, interior parts cut out/spliced
• eukaryotic only

Question 29

5’ cap

Answer 29

• added to 5’ end after transcription of first 20-40 nucleotides
• contains methylated guanine

Question 30

poly-A tail

Answer 30

• enzyme adds 50-250 more adenine nucleotides to 3’ end after RNA transcribed

Question 31

introns

Answer 31

intervening sequences, cut out/removed by spliceosome
- noncoding

Question 32

exons

Answer 32

spliced together to form mRNA by spliceosome
- eventually expressed

Question 33

purpose of 5’ cap and poly-A tail

Answer 33

1. facilitate export of mature mRNA from nucleus
2. protect mRNA from degradation from enzymes
3. helps ribosomes attach to 5’ end of mRNA once it reaches cytoplasm