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Cell Bio > Lecture 9 > Flashcards

Lecture 9 Flashcards

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Biology 101 flashcards
1
Q

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

A

The proteins produced in each type of cell are different

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2
Q

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

A

true!

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3
Q

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

A

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

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4
Q

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

A

transcription
processing
transportation
translation
protein folding + modification

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5
Q

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

A

Transcription

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6
Q

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

A

Processing

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7
Q

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

A

Translation

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8
Q

___________ – eukaryotic RNA polymerase for mRNA synthesis

A

RNA polymerase II

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9
Q

________:
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

A

RNA polymerase II

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10
Q

transcription initiates at the ________

A

core promoter

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11
Q

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

A

core promoter

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12
Q

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

A

general transcription factors (GTFs)

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13
Q

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

A

TATA box

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14
Q

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

A

TATA-binding protein (TBP)

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15
Q

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

A

TFIID, transcription factor II D

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16
Q

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

A

TFIIF, transcription factor II F

17
Q

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

A

transcriptional start site

18
Q

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!

A

TFIID, transcription factor II D

19
Q

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

A

true!

20
Q

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

A

true!

21
Q

___________ 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

A

5’ guanine cap

22
Q

where do we splice introns?

A

Highly conserved, recognizable sequence regions
called the splice-sites

23
Q

splice sites conform to a __________

A

Consensus sequence: same for almost all genes

24
Q

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

A

true

25
Q

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

A

snRNPs

26
Q

the complex of snRNA and proteins is called a _______

A

spliceosome

27
Q

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

A

nucleus

28
Q

what does polyadenylation consist of? (two events)

A

cleavage and addition of Poly A tail

29
Q

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

A

Cleavage

30
Q

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

A

Addition of Poly A tail

31
Q

what are the functions of the Poly A tail?

A

Increases the stability of a eukaryotic mRNA
molecule

Facilitate its export from the nucleus to the
cytosol

32
Q

when is transcription terminated?

A

after polyadenylation, the polymerase dissociates from the DNA template

33
Q

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

A

RNA-binding proteins

34
Q

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

A

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

Cell Bio (11 decks)

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