Lecture 9

Question 1

How do cells from a single, fertilized egg become different from each other?

Answer 1

The proteins produced in each type of cell are different

Question 2

true/false: Human cells contain ~22,000 genes, but only a fraction of them may be
expressed in any one cell

Answer 2

true!

Question 3

true/false: Some genes are expressed in all cells all the time

Answer 3

true! (These so-called
housekeeping genes are responsible for the routine metabolic functions
(e.g. respiration) common to all cells)

Question 4

what are the key steps in the expression of a protein-coding gene?

Answer 4

transcription
processing
transportation
translation
protein folding + modification

Question 5

________: RNA polymerase II transcribes a
complementary RNA sequence from the DNA template,
resulting in a single-stranded pre-mRNA molecule

Answer 5

Transcription

Question 6

________: The pre-mRNA transcript undergoes
processing to make a finalized messenger RNA strand

Answer 6

Processing

Question 7

_________: The mRNA complexes with a ribosome, and its information is translated into an ordered polymer of
amino acids

Answer 7

Translation

Question 8

___________ – eukaryotic RNA polymerase for mRNA synthesis

Answer 8

RNA polymerase II

Question 9

________:
1. Unwinds the DNA strands
2. Reads the DNA template strand in a 3’ to 5’ direction
3. Catalyzes the polymerization of ribonucleotides in a 5’ to 3’ direction
(adds the next base 5’ phosphate to the 3’ hydroxyl of the previous base)
4. Uses ATP, GTP, CTP, and UTP as substrate

Answer 9

RNA polymerase II

Question 10

transcription initiates at the ________

Answer 10

core promoter

Question 11

The ________ is just ‘upstream’ of the transcriptional start site and is where RNA pol II binds prior to initiating
transcription.

Answer 11

core promoter

Question 12

RNA pol II requires the help of ____________ to recognize the part of the promoter and form a pre-initiation complex (PIC)

Answer 12

general transcription factors (GTFs)

Question 13

A critical portion of the eukaryotic promoter lies 24-32 bases upstream from the initiation site, and contains the _________

Answer 13

TATA box

Question 14

The preinitiation complex assembly starts with the
binding of the _____________ to the promoter

Answer 14

TATA-binding protein (TBP)

Question 15

TATA-binding protein is a subunit of the ______ and when it binds to the
promoter causes a conformation change in DNA

Answer 15

TFIID, transcription factor II D

Question 16

The three general transcription factors bound to the promoter allows the binding of RNA polymerase II with its _____

Answer 16

TFIIF, transcription factor II F

Question 17

The spacing of the TATA box and the other GTS means
that RNApol II is positioned right at the ___________

Answer 17

transcriptional start site

Question 18

As long as ______ remains bound to the promoter,
additional RNA polymerases may be able to attach for
additional rounds of transcription. So multiple mRNAs can be made from a gene at once… amplification!

Answer 18

TFIID, transcription factor II D

Question 19

true/false: Many molecules of RNA polymerase can simultaneously
transcribe the same gene

Answer 19

true!

Question 20

true/false: Modifications capping and polyadenylation increase the stability of a eukaryotic mRNA molecule

Answer 20

true!

Question 21

___________ structure:
- “inverted” guanine nucleotide added
(5’ to 5’ bond)
- Methyl group is added to G.
Functions of the ________:
- Stabilizes the 5’ end, protecting it from
exonucleases
- Aids in transport out of the nucleus
- Helps to start the translation process

Answer 21

5’ guanine cap

Question 22

where do we splice introns?

Answer 22

Highly conserved, recognizable sequence regions
called the splice-sites

Question 23

splice sites conform to a __________

Answer 23

Consensus sequence: same for almost all genes

Question 24

true/false: Splicing is done by a number of protein/RNA molecules

Answer 24

true

Question 25

small nuclear RNAs (snRNAs) bind to proteins (the U proteins) to form _______ - pronounced “snurps”, these do splicing!

Answer 25

snRNPs

Question 26

the complex of snRNA and proteins is called a _______

Answer 26

spliceosome

Question 27

Spliceosome is formed in _____, as that's where transcription takes place

Answer 27

nucleus

Question 28

what does polyadenylation consist of? (two events)

Answer 28

cleavage and addition of Poly A tail

Question 29

________: an enzyme that cuts the growing mRNA chain at a particular sequence of nucleotides, which separates the mRNA from the transcribing RNA polymerase II

Answer 29

Cleavage

Question 30

__________: A special type of RNA polymerase adds 50–250 adenosine (A) residues to the end of the cleaved mRNA.

Answer 30

Addition of Poly A tail

Question 31

what are the functions of the Poly A tail?

Answer 31

Increases the stability of a eukaryotic mRNA molecule Facilitate its export from the nucleus to the cytosol

Question 32

when is transcription terminated?

Answer 32

after polyadenylation, the polymerase dissociates from the DNA template

Question 33

Processed mRNAs are exported out of the nucleus by a specialized set of __________, which recognize different parts of a mature mRNA molecule.

Answer 33

RNA-binding proteins

Question 34

what are the main differences between prokaryotes and eukaryotic mRNA production?

Answer 34

The 5' end of an mRNA molecule is produced by the initiation of transcription by RNA polymerase The 3' end is produced by the termination of transcription Translation and transcription occur in the same compartment Translation of a prokaryotic mRNA begins before its synthesis has been completed