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Cell Bio > Lecture 11 > Flashcards

Lecture 11 Flashcards

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Biology 101 flashcards
1
Q

true/false: Multiple ribosomes
simultaneously translate
same mRNA

A

true! the advantage to this is that is boosts efficiency!

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2
Q

true/false: Many common antibiotics were
first isolated from fungi

A

true

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3
Q

why were many common antibiotics first isolated from fungi?

A

fungi and humans are both eukaryotes, and fungi naturally produce antibiotics to kill or inhibit the growth of bacteria, because it limits their competition in the natural environment

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4
Q

Proteins fold into the correct three-dimensional
shape either spontaneously or with the help of
_________

A

chaperone proteins

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5
Q

true/false: Newly synthesized proteins require post-
translational modifications to become fully functional

A

true

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6
Q

newly synthesized proteins are covalently modified using which two methods?

A

phosphorylation (adding phosphate group) and glycosylation (adding glucose)

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7
Q

Some proteins bind or associate with small molecule ________ or other protein subunits

A

co-factors

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8
Q

________ are enzymes that degrade proteins

A

Proteases

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9
Q

what do proteases do?

A

They hydrolyze the peptide bonds between amino acids (can repurpose amino acids for making new proteins)

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10
Q

why do we need to degrade proteins?

A

The lifetime of proteins must be kept short.

Damaged or misfolded proteins must be recognized and removed

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11
Q

where are proteins broken down in eukaryotic cells?

A

in proteasomes

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12
Q

Why is it good to house proteases inside the proteosome cylinder?

A

It keeps the protease activity confined to the proteosome

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13
Q

what is the central cylinder of a proteosome cylinder made of?

A

proteases

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14
Q

How are proteins directed to the proteasome
for degradation?

A

Covalent attachment of a small protein
called ubiquitin

Specialized enzymes tag those proteins
with a short chain of ubiquitin molecules

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15
Q

is it possible that life began as RNA?

A

yes, ribosome are ribozymes

the theory means that RNA stored both genetic information and catalyzed the chemical reactions in primitive cells, DNA took over after but never fully took control because RNA is still used for many biological functions

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16
Q

How do cells become different from each other?

A

The proteins produced in each type of cell are different

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17
Q

true/false: Every somatic cell nucleus of an organism contains the complete
genome established in the
fertilized egg

A

true

18
Q

________ level: if and how often a gene is transcribed

A

Transcription level

19
Q

________ level: different messenger RNAs made from a given gene
(alternative splicing)

A

Processing level

20
Q

________: selective mRNAs are able to enter the cytoplasm

A

RNA transport

21
Q

_______ level: how much of the mRNA is made into protein (and mRNA
lifetime)

A

Translational level

22
Q

____________ level: Protein lifetime and activity

A

Post-translational level

23
Q

General transcription factors (GTFs) recognize a part
of the promoter and recruit RNA pol II to form a ______________

A

pre-
initiation complex (PIC)

24
Q

Transcription depends on _________
(enhancer or silencer) on the DNA

A

regulatory sites

25
Q

true false: enhancer/silencer regulatory sequences work on their own

A

false, they need to be recognized by proteins called transcription factors

26
Q

true/false: transcription
factors can be activators or repressors

A

true

27
Q

____________ are DNA-binding proteins that
regulate transcription

A

Transcription factors

28
Q

what two domains do Transcription factors have?

A

they have a DNA-binding domain

they have an activation domain (a binding site for other
proteins)

29
Q

true/false: Binding a transcription factor to a regulatory DNA sequence acts as the switch to control transcription

A

true

30
Q

true/false: The DNA between the regulatory
sequence and the promoter loops out- brings the transcription factor into close proximity to the promoter

A

true

31
Q

how do we close the loop between the regulatory sequence/promoter to the transcription factor?

A

Mediator proteins serve as
adaptors to close the loop

32
Q

_________ attracts and positions the general transcription factors and RNA polymerase at the promoter, forming a transcription initiation
complex

A

mediator proteins closing the loop

33
Q

why are general transcription factors(GTFs) and RNA
polymerase unable to assemble on a promoter
that is packaged in nucleosomes

A

the DNA is wound tightly around the histone, they can’t access the sequence to initiate transcription

34
Q

true/false: transcription factors bound to their regulatory
sequences also play a role in remodeling chromatin
structure and changing promoter accessibility by
attracting chromatin-modifying proteins

A

true

35
Q

___________ attaches of acetyl groups
to selected lysines in the histone tail - enhance the
efficiency of transcription initiation

A

Histone acetyltransferases

36
Q

___________ removes the acetyl groups from
histone tail - decreases the efficiency of transcription
initiation

A

Histone deacetylases

37
Q

How does a transcription factor avoid improperly influencing neighboring gene
transcription when bound to the control region of one gene?

A

Chromosomal DNA of plants and animals is arranged in a series of
loops- prevents enhancers from affecting neighboring genes

38
Q

___________ – groups of transcription
factors work together to determine the
expression of a single gene

A

Combinatorial control

39
Q

in combinatorial control, what are transcription factors involved in assembling?

A

Mediators

Chromatin-remodeling complexes

Histone modifying enzymes

General transcription factors and RNA polymerase

40
Q

Do combinations of transcription factors switch genes on and off?

A

Although they work as a committee, a single transcription factor can
play a key role in switching a particular gene(or multiple genes) on or off

  • one of them has the “final” say!

Cell Bio (11 decks)

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