Week 6_Gene expression

Question 1

what is the central dogma of info flow in biological systems?

Answer 1

DNA

–> transcription by RNA polymerases

–> RNA

–> translation by ribosomes

–> protein

Question 2

what does the DNA do?

Answer 2

stores information

Question 3

what does RNA do?

Answer 3

carries that information into the cytoplasm

Question 4

what do ribosomes do?

Answer 4

translate the information into proteins

Question 5

describe the updated central dogma with retroviruses

Answer 5

retroviruses (use RNA as their genetic material)

–> viral infection of a cell (viral enzyme: reverse transcriptase)

–> viral DNA genes

–> cellular enzymes: transcribe and translate

–> viral proteins: new virus is produced (ex. HIV virus)

Question 6

describe the updated central dogma without retroviruses

Answer 6

RNA

–> reverse transcription

–> DNA

–> transcription

–> RNA

–> translation

–> protein

Question 7

reverse transcriptase is very ___

Answer 7

error prone

Question 8

reverse transcriptase is very error prone:

causes retroviruses to…

can quickly become…

Answer 8

causes retroviruses to mutate a lot

can quickly become drug resistant (hard to treat)

Question 9

does every gene code for a protein?

Answer 9

no;

some are protein coding genes (PCG)

some are non-protein coding genes (nPCG)

Question 10

how does a PCG code for proteins?

Answer 10

PCG is transcribed into a messenger RNA (mRNA)

mRNAs are translated into proteins

Question 11

how does an nPCG not code for any proteins?

Answer 11

nPCG is transcribed into a non-coding RNA which is not translated into a protein (but still has a function)

Question 12

what are examples of non-coding RNA that nPCGs become?

Answer 12

transferRNAs

ribosomal RNAs

microRNAs

Question 13

describe the anatomy of a gene

Answer 13

promoter region

coding region

termination sequence

Question 14

what is the promoter region?

Answer 14

site where RNA polymerase binds

Question 15

what is the coding region?

Answer 15

contains the DNA sequence that will be transcribed by RNA polymerase

Question 16

what is the termination sequence?

Answer 16

where transcription ends

Question 17

which two regions in a DNA sequence is not transcribed?

Answer 17

promoter and termination regions

Question 18

what is the difference between RNA and DNA?

Answer 18

RNA is single stranded

DNA is double stranded

Question 19

the 4 RNA nucleotides are…

Answer 19

C, G, A, U

Question 20

the 4 DNA nucleotides are…

Answer 20

C, G, A, T

Question 21

what are the complementary base pairing rules for RNA nucleotides?

Answer 21

G = C

A = U

Question 22

what are the complementary base pairing rules for DNA nucleotides?

Answer 22

G = C

A = T

Question 23

in transcription, RNA polymerases synthesize an RNA strand (transcript) that is ___ to a DNA strand

Answer 23

complementary

Question 24

describe how the template strand produces the coding strand:

Answer 24

(1) RNA polymerase binds to the gene, unwinds the DNA strands

(2) RNA polymerase reads the template strand of the gene

(3) the RNA sequence is complementary to template strand sequence

Question 25

what are the phases of transcription?

Answer 25

initiation

elongation

termination

Question 26

what is initiation?

Answer 26

RNA polymerase attaches to the promoter region of the gene

separates the coding and template strands

Question 27

what is elongation?

Answer 27

RNA polymerase transcribes (reads) the template strand to generate the RNA transcript

Question 28

what is termination?

Answer 28

RNA polymerase reaches the termination sequence

• detaches from the DNA
• releases the RNA transcript

Question 29

describe what is different about transcription in prokaryotes vs in eukaryotes

Answer 29

different RNA polymerase enzymes

different details of process

different events immediately after transcription