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Cells and Molecular biology > Transcription > Flashcards

Flashcards in Transcription Deck (56):
1

What is Transcription

DNA is copied into RNA by the enzyme RNA polymerase

2


Reverse transcriptase

make DNA from RNA template

3

Most eukaryotic genes contain noncoding sequences among the

coding regions

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alternative splicing

Coding sequences can be read in various combinations, each coding for a unique polypeptide chain;

5

Three characteristics of the Genetic Code?

Degenerate, Non-overlapping and Unambiguous -

6

Who provided the triplet nature of the code?

Francis Crick & Sydney Brenner (1961)

7

Open reading frame (ORF) can cause?

Frameshift mutations

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a way of dividing the sequence of nucleotides in a nucleic acid (DNA or RNA) molecule into a set of consecutive, non-overlapping triplets.

Reading frame

9

amino acids/ stop signals are called

codons

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Open reading frame (ORF) contains?

no stop codons

11

Causes Garbled words due to changes in reading frame

Due to Frameshift mutation

12

Transcription of mRNA from DNA does same thing but uses

uracil (U) in place of thymine

13

Transcription of mRNA from DNA uses what four stages

Binding, Initiation, Elongation and Termination

14

Sigma factors promotes

binding of RNA polymerase to specific DNA sequences called promoters

15

RNA polymerase in bacterial cells ONLY has

single kind of RNA polymerase and a lot of α and β subunits and sigma factor

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RNA synthesis takes place when the DNA is

unwound

17

RNA polymerase catalyzes the formation of a

phosphodiester bond between the NTPs

18

Is transcription in Prokaryotes or Eukaryotes more complex?

Eukaryotes

19

Uses 3 different RNA polymerases

Transcription in Eukaryotes

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a deadly toxin produced by the mushroom, Amanita phalloides an inhibitor of RNA polymerase

α-aminitin

21

Small nuclear ribonucleic acid (snRNA) AKA

U-RNA, all RNA molecules that are found within the nucleus of eukaryotic cells.

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processing of pre-mRNA in the nucleus

U-RNA

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a small non-coding RNA molecule

Functions in transcriptional and post-transcriptional regulation of gene expression

 miRNA

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What are the three classes promotors of Eukaryotes

RNA polymerase I
RNA polymerase II
RNA polymerase III

25

Consists of core promoter and upstream control element
RNA polymerase binds to the core promoter

RNA polymerase I

26

Which RNA Polymerase uses At least 4 DNA sequences are involved

RNA polymerases II

27

Used to make mRNA in RNA polymerase II

BRE, TATA box, Inr and DPE

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Common upstream control elements

CAAT and GC box

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upstream control elements:

Those within 100–200 nucleotides of the startpoint are called

proximal control elements

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upstream control elements:
Those farther away from 100–200 nucleotides of the startpoint

enhancer elements

31

Entirely downstream of the startpoint - for transcribing tRNA and 5S-rRNA

RNA Polymerase III

32

Required to bind to its promoter and initiate RNA synthesis

General Transcription Factor

33

What plays a crucial role in binding stage of eukaryotic transcription

protein-protein interactions

34

General transcription factors in binding RNA polymerase II to DNA:

what binds to what

1. TFIID first binds to TATA box in the DNA sequence
2. Preinitiation complex binds to promoter region
3. General transcription factor TFIIH

35

possesses both helicase activity, that unwinds DNA, and a protein kinase activity that catalyzes the phosphorylation of RNA polymerase II

General transcription factor TFIIH

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changes the shape of RNA polymerase II, so it can initiate RNA synthesis at the startpoint

Phosphorylation

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Helicase activity

unwind the DNA, so that RNA polymerase molecule can begin to move

38

Ability to recognize and bind to DNA promoter sequences is conferred by one of its subunits

TFIID

39

If there is a DNA damage, RNA polymerase becomes

stalled temporarily during DNA excision repair

40

RNA polymerase I: Termination signals

Terminated by a protein factor that recognizes an 18-nt termination signal in the growing RNA chain


41

RNA polymerase II: Termination signals

Termination signals include a short run of U’s and no proteins are required for their recognition

42

RNA polymerase II: Termination signals

mRNAs are cleaved at a specific site, a cleavage site, before transcription is actually terminated

The cleavage site is10-35 nts downstream from a special AAUAAA sequence in the growing RNA chain

43

Newly produced RNA molecule

primary transcript

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all chemical modifications necessary to generate a final protein product from the primary transcript

RNA processing

45

RNA processing uses what three RNA's

rRNA, tRNA and mRNA

46

most abundant and most stable RNA in cells and In eukaryotes, cytoplasmic ribosomes contain four types?

rRNA

47

The Presence of three different rRNA genes within a single transcription unit ensures what?

Theres RNAs in equal amounts

48

The nontranscribed spacers

separate transcript units within each cluster

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transcribed spacers


The DNA sequences that code for the three rRNA

50

remove the transcribed spacers and release the mature rRNAs

Cleavage reactions

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i) Removal of leader sequence at the 5’ end
ii) Replacement of two nucleotides at the 3’ end by the sequence CCA
iii) Chemical modification of certain bases
iv) Excision of an intron

tRNA gene into mature tRNA (clover structure)

52

Which RNA does not require processing before translated?

Bacteria RNA
transcription and translation occur simultaneously

53

In what Eukaryotes or Prokaryotes is Transcription and translation are separated, both time and space

Eukaryotes

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Transcription takes place in

the nucleus

55

Translation takes place in

in cytoplasm

56

What are the three processes of mRNA

1. Capping
2. poly (A) tail
3. Splicing