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BMS 100 > The Central Dogma > Flashcards

The Central Dogma Flashcards

1
Q

_____ is the main key enzyme for
transcription

A

RNA polymerase

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2
Q

RNA polymerase moves along the DNA, unwinding the DNA helix
just ahead of the active site for polymerization. Catalyzes a new ________ on the newly-forming strand of RNA

A

phosphodiester bond

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3
Q

RNA polymerase works in a ___ to ____ direction

A

5’ to 3’ direction

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4
Q

Which of the following bonds contribute to the stability of the DNA helix?

A

B) H-bonds

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5
Q

what do the following compose?
- 147 base pairs wrapped around a histone core
- Octamer of H2A, H2B, H3 and H4
- H1 linker protein

A

Nucleosomes

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6
Q

Chromatin: complex of DNA + tightly bound protein. heterochromatin is ____ while Euchromatin is ____

A

packed, dispersed

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7
Q

coding sequence of a gene

A

exon

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8
Q

noncoding sequences of a gene § Removed via splicing after transcription

A

intron

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9
Q

____ of the human genome does not encode protein

A

98.5%

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10
Q

What is the name of the non-coding sequence removed during splicing?

A

Intron

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11
Q

___ always occurs in a double-stranded helix. While ___ is single-stranded. RNA can therefore fold up into various shapes

A

DNA, RNA

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12
Q

Some sequences of DNA are transcribed into RNA then do not get translated into proteins. What are these called?

A

non-coding RNA

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13
Q

_____ serves as enzymatic, structural, and regulatory components of a wide variety of processes in the cell

A

Non-coding RNA

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14
Q

Small nuclear RNA (snRNA) functions in the ______

A

spliceosome

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15
Q

_____ are needed for the basic structure of the ribosome complex. Involved in catalysis of the peptide bond between amino acids

A

ribosomal RNA

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16
Q

_______ are needed in translation to carry the correct amino acid to the growing polypeptide chain. tRNA folds into a unique cloverleaf shape.

A

Transfer RNA (tRNA)

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17
Q

____ Regulate gene expression via post-transcriptional silencing
Block/prevent translation of specific mRNAs & promote their degradation

A

miRNA (micro RNA):

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18
Q

_____ Reduce gene expression
Direct degradation of specific mRNA

A

siRNA (Small interfering RNA)

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19
Q

____ Regulate gene expression
Can increase or decrease transcription

A

lncRNA (long non-coding RNA):

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20
Q

Which of the following RNA molecules are involved in gene regulation

A

siRNA, miRNA, lncRNA

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21
Q

_______ moves along the DNA, unwinding the DNA helix just ahead of the active site for polymerization. Catalyzes a new phosphodiester bond on the newly-forming strand of RNA

A

RNA polymerase

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22
Q

RNA polymerase makes mistakes at a rate of 1 for every 10^4 nucleotides. DNA polymerase makes mistakes at a rate of 1 in every 10^7 nucleotides. What is the significance of this?

A

DNA in a cell is constant - if there is a change in the DNA, then it affects the proteins that are being synthesized. While a change in the mRNA only affects that synthesis ONCE

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23
Q

Transcription can be divided into 4 stages:

A

Initiation, elongation, processing and termination

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24
Q

Transcription initiation factors help RNA polymerase recognize where to start.

A

Transcription initiation factors

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25
Q

what is a general transcription factor?

A

TFII

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26
Q

TFII recognizes and binds a consensus sequence in the promoter region. What is an example?

A

The TATA box

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27
Q

TATA box is located ____ nucleotides
upstream from the transcription start site.

A

~25

28
Q

_____ is the specific TFII
that binds the TATA box. Other transcription factors join. Then _____ joins.

A

TFIID. RNA Polymerase II

29
Q

Transcriptional activator proteins bind upstream sequences of DNA called ____. They ____ the rate of transcription by attracting the RNA polymerase II enzyme.

A

enhancers, increase

30
Q

What might happen if there was a mutation in an enhancer sequence of DNA?

A

We may not be able to enhance our protein synthesis rate - which may affect the activation our of mRNA formation

31
Q

Once RNA Polymerase
begins transcribing DNA, most of the general transcription factors (TFII) are _____

A

released

32
Q

Various _______ are needed to help reduce the likelihood that RNA polymerase dissociates from DNA before it reaches the end of a gene.

A

elongation factor

33
Q

________ help the RNA polymerase navigate the chromatin structure

A

Chromatin remodeling complexes

34
Q

_______ partially disassemble &
reassemble nucleosomes as an RNA Polymerase passes through

A

Histone chaperones

35
Q

In Eukaryotes DNA ______ removes this super-helical tension by breaking ______ bonds.

A

topoisomerase, phosphodiester

36
Q

pre-mRNA has to go through ______ in order to be called mRNA

A

processing

37
Q

A modified _______ nucleotide is added to the 5’ end of the transcribed premRNA. This occurs early, once ~25 nucleotides of RNA have been transcribed

A

guanine

38
Q

This 5’ cap facilitates _____ of the mRNA into the nucleus and is involved in translation

A

export

39
Q

Splicing is performed by ______

A

spliceosomes

40
Q

Splicing allows the same gene to produce a variety of different ______

A

proteins

41
Q

Once cleaved, _____ A nucleotides are added to the mRNA

A

~200

42
Q

Poly A tails protects the mRNA from ______ and facilitates export from
the nucleus

A

degradation

43
Q

How is Prokaryotic transcription different?

A
  1. no process is required (no 5’ cap, splicing, or poly-A tail
  2. no export from the nucleus (thus, translation can happen right away)
  3. mRNA transcript is polycistronic (codes for more than one protein on a single mRNA)
44
Q

There are ___ possible combinations of of 3
nucleotides but only __ amino acids

A

64, 20

45
Q

The Shine-Dalgarno

A

enables initiation of protein synthesis by aligning the ribosome with the start codon in prokaryotes

46
Q

special punctuation in eurokaytoes

A

AUG

47
Q

aminoacyl-tRNA synthetase

A

catalyzes the attachment of correct amino acid to tRNA

48
Q

Protein synthesis is performed in the

A

ribosome

49
Q

The ribosome complex is composed of
various ribosomal proteins and ribosomal
RNA (rRNA). and what two subunits?

A

small subunit and large subunit

50
Q
  1. tRNA caries the amino acid meth
  2. met-tRNA is loaded into the small ribosomal subunit at the P site with initiation factors
  3. small ribosome binds to 5’ end of mRNA (5’ cap helps with recognition)
  4. small ribosome moves along and scans for AUG (ATP hydrolysis is required)
  5. Initiation factors dissociate & the large ribosome subunit assembles to complete the ribosome complex
A

initiation of translation

51
Q

Newly charged tRNA binds to the A site of the ribosome complex

A

tRNA binding of elongation

52
Q
  • The carboxyl end of the polypeptide chain is released from the tRNA at the P site & joins the amino acid linked to the tRNA at the A site
  • This new peptide bond is catalyzed by peptidyl transferase enzyme contained within the large ribosomal subunit
A

peptide bond formation of elongation

53
Q

Large ribosomal subunit moves relative to the mRNA held by the small subunit
- Two tRNAs are shifted to the
E and P sites

A

Translocation of large subunit of elongation

54
Q
  • Small subunit shifts by 3 nucleotides
  • tRNA in the E site is ejected
A

Translocation of small subunit of elongation

55
Q

Elongation proceeds efficiently and
accurately with the help of ______

A

elongation factors (EFs)
These elongation factors enter and leave the
ribosome during each cycle & are coupled with GTP hydrolysis

56
Q

A ___ codon marks the end of the translation. These include ___, ___, and ___. Not recognized by a tRNA & does not specify an amino acid

A

STOP. UAA, UAG, UGA
Release factors bind to ribosomes with a stop codon in the A site

57
Q

Peptidyl transferase catalyzes the addition of a _____ molecular rather than ____. This frees the carboxyl end and releases the polypeptide

A

water, amino acid

58
Q

In prokaryotes: The synthesis of proteins occurs
on _____.

A

polysomes
Multiple initiations take place on each mRNA molecule being translation

59
Q

Once fully translated, what happens next?

A

Protein is folded into a specific 3-D shape

60
Q

Proper folding is important since the structure of a protein dictates its _____

A

function!

61
Q

blocks binding of aminoacyl-tRNA to the A side of the ribsome

A

tetracycline

62
Q

prevents the transition from translation initiation to chain elongation and also causes miscoding

A

streptomycin

63
Q

blocks the peptidyl transferase reaction on ribosomes

A

chloramphenicol

64
Q

binds in the exit channel of the ribosome and thereby inhibits elongation of the peptide chain

A

erythromycin

65
Q

blocks initiation of the RNA chains by binding to RNA polymerase (prevents RNA synthesis)

A

rifamycin

66
Q
A

BMS 100 (37 decks)

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