lectrue 13

Question 1

Genetic information directs

Answer 1

the synthesis of protein (and RNA) products

Question 2

Transcription

Answer 2

the process of synthesizing RNA from a DNA template

Question 3

Translation

Answer 3

the process of synthesizing protein from an RNA template

Question 4

DNA

Answer 4

-bases include A, T, G and C
-linear polymer
-usually double stranded (ds)

Question 5

RNA

Answer 5

-contains a 2’ hydroxyl group
-RNA contains a ribose sugar instead of a deoxyribose sugar
-RNA uses uracil instead of thymine. Uracil forms a base pair with adenine

Question 6

Transcription produces an RNA transcript that is

Answer 6

complementary to the template stand except it uses uracil in place of thymine

Question 7

Sense strand

Answer 7

coding strand

Question 8

template strand

Answer 8

noncoding strand

Question 9

Gene expression includes

Answer 9

the process of transcription and/or translation (because translation will not always occur)

Question 10

Several RNA polymerases can be

Answer 10

working on the same gene at the same time

Question 11

RNA can form — that allow for the ability to adopt a variety of shapes/do diff functions

Answer 11

nonconventional base-pair interactions

Question 12

Transcription and DNA replication similarities

Answer 12

• DNA needs to be unwound
• one DNA strand acts as a template
• NTPs (instead of dNTPs for DNA replication) are added one at a time in a 5’ to 3’ manner

Question 13

Transcription in bacteria (4 steps)

Answer 13

1. RNA polymerase binds to promoter (upstream of the transcription start site)
2. double helix is opened, transcription begins using template strand
3. transcription stops when the terminator (stop site) is reached
4. RNA and RNA polymerase dissociate from the DNA

Question 14

The promoter has conserved sequences at the — regions

Answer 14

-10 and -35

Question 15

What are the -10 and -35 regions bound by?

Answer 15

the sigma factor (a subunit of the RNA polymerase)

Question 16

the sigma factor

Answer 16

is important for recognizing where to begin transcription

binds to the -10 and -35 regions in only one direction
(so polymerase can only bind in one orientation)

Question 17

Eukaryotic transcription differences when compared to bacterial transcription (5)

Answer 17

1. has more RNA polymerases
2. needs general transcription factors
3. has a more elaborate control mechanism
4. takes DNA packing into account
5. has mRNA

Question 18

general transcription factors help to

Answer 18

position the RNA polymerase, separate the DNA and initiate transcription

Question 19

Transcription in euk (sequence of events/general transcription factors)
TFIID, TFIIH, CTD

Answer 19

-TFIID binds to the TATA box found in the promoter
-TFIIH (general transcription factor) contains a kinase domain that phosphorylates the C terminal domain (CTD), allows the RNA polymerase to clear the promoter
-then transcription is complete, the CTD is dephosphorylated

Question 20

TATA box

Answer 20

binding of the TATA binding protein (subunit of TFIID) to the TATA box causes a change in DNA structure that helps other general transcription factors assemble

Question 21

chromatin must be — to allow access by —

Answer 21

modified
the transcription factors
(eukaryotic DNA is packed in nucleosomes)

Question 22

eukaryotic mRNA undergoes processing before being exported

Answer 22

• addition of a 5’ cap (capping)
• polyadenylation
• splicing of introns

Question 23

processed RNA is exported from the — to the —

Answer 23

nucleus to the cytoplasm

Question 24

what does the addition of the 5’ cap do? (RNA capping)

Answer 24

increases the stability of the mRNA and helps w its export to the cytoplasm

Question 25

polyadenylation

Answer 25

adds a series of repeating adenine nucleotides to the 3’ end of the molecule

increases stability of the mRNA and helps w export

Question 26

splicing

Answer 26

in euk immature mRNA, introns (noncoding) sequences interrupt exons (coding) sequences of genes

–> splicing= removing introns before translation occurs

Question 27

what carries out splicing?

Answer 27

small nuclear ribonucleoproteins (snRNPs) which contain both RNA and protein

snRNPs work together to form the spliceosome

Question 28

export of mRNA– what proteins does it need to bind to?

Answer 28

poly-A-binding proteins, a cap-binding complex and proteins that bind to mRNAs that have been appropriately spliced

Question 29

3 steps of splicing

Answer 29

1. branch point adenine attacks the 5’ splicing site and cuts the sugar phosphate backbone of the RNA
2. the 5’ end of the intron becomes covalently linked to the 2’ OH group of the ribose of the A to form a branched structure.
   3’ OH end of the exon sequence reactions w the start of the next exon sequence
3. two exons join together to form a continuous coding sequence.
   Introns are released in the form of a “lariat structure” which is further degredated

Question 30

export of mRNA
- mediated by?
- bound to?

Answer 30

mediated by the nuclear pore complex
bound to specific proteins (the poly-A-binding proteins, a cap-binding complex and proteins that bind to mRNAs that have been appropriately spliced)

Question 31

how is mRNA degraded?

Answer 31

degraded in the cytosol by nucleases (ribonucleases)

it is affected by the 3’ untranslated region of the mRNA which is between the end of the coding region and the poly-A-tail