Gene Expression - Basic Mechanisms in Transcription

Question 1

What do genes encode?

Answer 1

proteins

Question 2

What do proteins dictate?

Answer 2

cell function

Question 3

Do all cells have the same genetic material?

Answer 3

yes

Question 4

What can determine cell differentiation and identity/function?

Answer 4

differential gene expression regulated by the combination of different transcription factors in that cell

Question 5

What gene types do red blood cells have?

Answer 5

housekeeping and haemoglobin

Question 6

What gene types do muscle cells have?

Answer 6

housekeeping and myosin

Question 7

What gene types do pancreatic cells have?

Answer 7

housekeeping and insulin

Question 8

What is the initiation of transcription of a gene?

Answer 8

the primary control point for gene expression, usually at the very beginning of the protein production process

Question 9

Cells have distinct sets of transcription regulators;…

Answer 9

some of these regulators work to increase transcription, whereas others prevent or suppress it, such that only a fraction of the genes in a cell are expressed at any one time.

Question 10

In prokaryotes, what are regulatory proteins often controlled by?

Answer 10

nutrient availability

Question 11

Why is nutrient availability a benefit for regulatory proteins in prokaryotes?

Answer 11

allows organisms such as bacteria to rapidly adjust their transcription patterns in response to environmental conditions

Question 12

What two steps are in gene expression to form a polypeptide?

Answer 12

1. transcription
2. translation

Question 13

What does transcription produce?

Answer 13

RNA complementary to one strand of DNA

Question 14

What does translation convert?

Answer 14

converts RNA sequence to amino acid sequence of a polypeptide

Question 15

5 ways RNA differs from DNA

Answer 15

1. usually one polynucleotide strand
2. the sugar is ribose
3. bases in RNA can pair with a single strand of DNA
4. single strand RNA can fold into complex shapes by internal base pairing
5. contains uracil instead of lycine

Question 16

snRNA:

Answer 16

• small nuclear RNA
• involved in RNA processing(splicing)

Question 17

miRNA:

Answer 17

• micro RNA
• inhibits translation

Question 18

tRNA:

Answer 18

• transfer RNA
• adapter between amino acids and mRNA sequence

Question 19

mRNA:

Answer 19

• messenger RNA
• protein-coding sequence of a gene

Question 20

rRNA:

Answer 20

• ribosomal RNA
• structural and catalytic component of the ribosome

Question 21

Which way is RNA synthesised?

Answer 21

5’ –> 3’

Question 22

Formation of the linkage between nucleotides always occurs by adding what to what?

Answer 22

the 5’-phosphate end of the new nucleotide to the 3’-OH end of the nucleic acid

Question 23

3 transcription components

Answer 23

1. nucleoside triphosphates as substrates
2. an RNA polymerase enzyme
3. a DNA template for base pairings

Question 24

Parts of a gene:

Answer 24

• promoter
• transcription initiation site
• RNA coding sequence
• terminator
• transcription termination site

Question 25

What does RNA polymerize?

Answer 25

synthesis of RNA, complementary to a DNA template strand

Question 26

RNA polymerases are processive:...

Answer 26

a single enzyme-template binding results in polymerization of hundreds of RNA bases

Question 27

Do RNA polymerases need primers?

Answer 27

no

Question 28

Do RNA polymerases need to proofread?

Answer 28

no

Question 29

3 steps of transcription:

Answer 29

1. initiation 2. elongation 3. termination

Question 30

Initiation: Sigma factors and transcription factors are proteins that do what?

Answer 30

they bind to the promoter DNA sequences, recruit DNA polymerase to the promoter, and help determine which gens are expressed at particular times

Question 31

Initiation: What do promoters do?

Answer 31

direct the enzyme where to start and which strand of DNA to transcribe

Question 32

At which stage of transcription does unwinding of DNA occur?

Answer 32

initiation

Question 33

What is the initiation site?

Answer 33

where transcription begins (promoters have these)

Question 34

Elongation: How many base pairs at a time does RNA polymerase unwind DNA?

Answer 34

about 10 base pairs at a time

Question 35

Elongation: Which direction is DNA unwound?

Answer 35

3' --> 5'

Question 36

Elongation: Is the transcript parallel or antiparallel to the DNA template strand?

Answer 36

antiparallel

Question 37

Elongation: Do RNA polymerases proofread and/or correct mistakes?

Answer 37

no and no

Question 38

Elongation: What do RNA polymerases use as substrates?

Answer 38

nucleoside triphosphates(NTPs)

Question 39

Elongation: How many phosphate groups are removed from each substrate molecule?

Answer 39

two

Question 40

What is termination specified by?

Answer 40

a specific DNA sequence

Question 41

Termination: What two things may happen?

Answer 41

1. the transcript forms a loop and falls away from the DNA 2. a protein binds to the transcript and causes it to detach from the DNA