Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/40

Click to flip

40 Cards in this Set

  • Front
  • Back
Review; what is TRANSCRIPTION?
The process of copying DNA into mRNA.
What is TRANSLATION?
The process of making protein products out of the mRNA.
What type of RNA gets translated? What types don't?
mRNA gets Translated.
tRNA, sRNA, and rRNA don't.
What is the central feature to remember about Transcription?
It is highly SELECTIVE - some sequences are transcribed, but not ALL.
How is it that Transcription is so selective?
Very specific signals embedded in DNA tell where and when to start and stop transcription.
List the 3 major types of RNA, state its % and complexity:
mRNA - 5% most complex
tRNA - 15%
rRNA - 80% least complex
How do most RNA molecules exist in the cell?
As single strands - not a double helix like DNA.
Where are rRNA molecules found?
In RIBOSOMES
What are Ribosomes?
Complex structures - sites of protein synthesis.
What are the 3 size species of rRNA in proks?
-23S
-16S
-5S
What are the 4 rRNA size species in the eukaryotic cytosol?
28S
18S
5.8S
5S
What is S?
the Svedburg unit; relates mw and shape of the rRNA.
Which type of RNA is smallest?
tRNA.
How many residues are commonly in tRNA?
74-95
What are 2 unique qualities of tRNA?
-They have unusual bases
-Have extnsive intrachain base-pairing.
How many tRNA molecules are there?
At least one specific type for each of 20 amino acids.
Which end of a tRNA molecule carries:
-The amino acid?
-The binding code for mRNA?
3' end - amino acid

Anticodon loop - anticodon
What is the Major Function of mRNA?
Carrying genetic information from the nuclear DNA to the cytosol for protein synthesis.
What characteristics make eukaryotic mRNA unique from Prokaryotic?
-5'-5' CAP - 7methylguanosine

-3' PolyA Tail
What is a PROMOTER REGION?
A sequence (at the beginning of a DNA sequence for transcriptn) that is recognized by RNA Pol
What is a Termination Region?
Similar to the promotor region but tells RNA Polymerase to stop transcription.
In what direction is RNA sequenced during transcription?
5' -> 3'
What are the subunits in the Core enzyme RNA Polymerase?
2 alpha
1 Beta
1 Beta'
1 w (omega)
What makes up the holoenzyme RNA Polymerase?
The Core subunits + Sigma
What is the function of the sigma subunit in RNA Pol?
Confers specificity for recognizing various promotor regions of DNA.
What is the function of the core portion of RNA Pol?
Polymerization of the RNA.
What TYPE of an enzyme is RNA polymerase?
a Zinc Metalloenzyme - requires Zn2+.
What is rho (p) factor?
A termination factor in E. coli that signals transcription to stop.
What are the 3 main Phases of transcription in E. coli?
1. Initiation
2. Elongation
3. Termination
What is a Promotor site again?
The sequence where RNA Pol binds to start transcription.
What is the Operator site?
A site near the Promotor, but it has binding sites for activation or repression of the gene.
What component of RNA Pol is responsible for binding the Promotor site again?
Sigma.
How many genes intended for translation are usually in the DNA being transcribed in bacteria?
Many - polycystronic.
What is an Operon?
The combined name for the Promotor, Operator, and Structural genes in bacteria.
What is the Pribnow box, really?
The name for the Standard promotor found in bacterial genes.
Where is the Pribnow box located?
-10 nucleotides from the start of transcription.
What is the Pribnow box sequence?
TATAAT
What key info should be remembered re: bacterial promotor regions?
Consenses sequences are highly conserved - the promotors are very similar, but not identical allowing varied gene expression.
Are all consenses sequences (promotors) recognized by the same sigma factor?
No; there are different sigma factors for different operators.
What other sequence is an important promotor in prokaryotes?
-35