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7 From DNA to Protein
Terms in this set (73)
How many types of RNA? What are they? Explain them.
Do all genes encode protein? Explain
Know the terms contemplate strand, template straw, coding strand, and noncoding strand. Describe them.
What are the similarities between RNA synthesis and DNA replication?
1. Carried out by several enzymes including a polymerase
2. Produces a linear polymer of nulcleotides connect by phosphodiester bond
3. synthesis is 5'-3'
4. Uses 4 distinct nucleotides
5. Energy comes from nucleotide triphosphate.
How does RNA synthesis differ from DNA replication?
1. No primer is needed
2. Only one template strand.
3. RNA is immediately unwound from DNA, restoring the helix.
3. Only the gene is copied.
5. Numerous copies are made at a time.
What is a promoter? What are its two functions?
How does RNA polymerase know where to start and where to stop?
What is a TATA box?
What is transcriptional difference between he promoter and the terminator?
What is a significant benefit of RNA not being double stranded?
It can take up multiple conformations and functionalities.
What enzyme carries out the transcription process? IN what direction?
T/F RNA polymerase holds onto DNA for a moment after being translated.
Why can multiple copies of RNA be made from a single strand of DNA simultaneously?
Cuz the RNA transcript is released as its being made so a new one can take its place.
T/F RNA polymerase does not need a primer to start synthesing.
WHY OR WHY NOT??
B/c likely evolved because tran- scription need not be as accurate as DNA replication; unlike DNA, RNA is not used as the permanent storage form of genetic information in cells, so mistakes in RNA transcripts have relatively minor consequences for a cell.
Can eukaryotes put multiple genes onto one mRNA? Whabout prokaryotes?
What is rRNA?
Translates genes into proteins, ribosomal RNA
What is tRNA?
These select and hold amino acids onto a ribosome to incorporate them into a protein.
What is miRNA?
They regulate gene expression.
How does polymerase know where to start copying DNA?
It attaches to the DNA weakly, slides down it until hits a promoter and starts copying the dna downstream starting at the "transcription site" until it hits a terminator.
Is the terminator sequence transcribe into RNA?
How does RNA polymerase know which strand of DNA to use?
What fuels RNA polymerase?
Does RNA polymerase copy the entire DNA sequence?
NO, only the "coding region" of the DNA.
How does a promoter indicate in which direction the RNA polymerase should go?
the sequence is asymmetrical
T/F The promoter does not enable control
What is a transcription site?
Sequence next to the promoter where transcription begins.
What is the stop site?
Where transcription ends.
T/F Sigma factors are unique to prokaryotes.
What does it do?
It actually recognizes the promoter.
RNA polymerase and an associated sigma factor SLIDE along the DNA until binding a promoter.
T/F The terminator functions in the RNA
TRUMP APPROVED MAGA
Can genes exist anywhere in the DNA molecule and run in opposite directions? Can genes run on opposite directions on the same strand of DNA?
NO. Genes only run 3'-5'
T/F Bacteria use a different enzyme from eukaryotes to synthesize RNA
FAKE NEWS CNN
Bacteria and eukaryotes both use RNA pol
T/F Eukaryotic mRNA can leave if most of the processing is complete
ALLLLLLLL the process needs to be completed
T/F RNA processing happens after it is synthesized
happens as it is being synthesized
What are the three types of processing that mRNA undergoes?
What is 5' capping? What takes place? When does it happen?
The 5' end of the RNA is bonded to the 5' end of a methyl guanasine by triphosphate bridge between them.
This capping occurs after RNA polymerase II has produced about 25 nucleotides of RNA, long before it has completed transcribing the whole gene
What is 3' polyadenylation? What takes place? How long is it?
The 3' end is cut at some location then hundreds of adenines are placed at the end of the tail
What function does 3' capping have?
identification of the transcript as an mRNA
What is the purpose of 5' capping and 3' adenylation?
They provide stability
What is splicing? What enzyme carries it out?
Splicing is the removal of introns from RNA and is carried out by snRNA
What is a snRNP?
RNA molecules, called small nuclear RNAs (snRNAs), are packaged with additional proteins to form small nuclear ribonucleo- proteins
What is spliceosome? What is its function?
It is the large complex of snRNP and proteins which acts as the macromolecular machinery in charge of splicing.
It is able to detect sequences that make the intron-exon junction.
There are three sequences needed to remove an intron?
How does a spliceosome recognize introns?
snRNA recognizes introns by complimentary base pairing.
What is the mechanism for splicing?
U1 and U2 bind at the 5' and 3' end of the intron sequence, the 5' is cut and bound to the 2' of an adenine in the middle off the intron. The 3' end of the intron is cut and the 3' and 5' ends of the exon are ligated together as the intron lariat is released.
Can a single gene encode several different proteins? Why or why not?
Splicing out exons can produce several different mRNAS from a single gene, therefore many proteins can be made from 1 gene.
What is alternative splicing?
The transcripts of many eukaryotic genes can be spliced in differ- ent ways, each of which can produce a distinct protein
What is the benefit of introns?
They allow for alternative splicing
They push evolution forward
What is a codon?
A triple sequence of nucleotides
How many possible codons?
An mRNA contains THREE potential reading frames.What determines the CORRECT frame?
A SPECIFIC SEQUENCE is used to start all proteins: AUG (Met,M)
Amino acids are specified by a __________________of nucleotides, without stop codons.
What is an open reading frame?
Open reading frame (ORF) is the part of a reading frame that has the potential to be translated. An ORF is a continuous stretch of codons that contain a start codon (usually AUG) and a stop codon (usually UAA, UAG or UGA).
What is the start
Does the entire mRNA get translated into protein?
no, only the sections between the start and stop codon.
What sequence of tRNA recognizes the codon?
What does the conformation of a tRNA look like?
What does it mean when a tRNA is charged?
It is bound to an amino acid via a high energy bond
Is there thousands of tRNA?
No, we have 48 tRNA
If we have 48 tRNA and 64 possible codons, how is this possible?
Some tRNA recognize more than one codon by wobble base pairing at the 3rd codon position
How is an amino acid bound to tRNA? What is significant about this in terms of energy?
A synthetase uses ATP to create a big henergy bond between the amino acid's carboxyl end to the tRNA. This high energy bond drives protein synthesis?
Where does the energy for protein synthesis come from?
It comes from the high energy bond between the amino acid and the tRNA.
What carries out protein synthesis?
What are the two subunits of a ribosome? How many proteins and ribosomes in each?
Small subunit 3 RNA 49 PROTEINS
large subunit 1 RNA AND 33 PROTEINS
Where is the ribosome built?
Each subunit is built in the nucleus
Where is the mRNA bound in the ribosome?
What is initiator tRNA?
It is the tRNA which recognizes AUG and carries methionine. It associates with the small subunitt first and together they slide down the mRNA until they reach AUG, once there, the large subunit associates and translation begins.
Is the initiator of translation the same and eukaryotes and prokaryote?
What recognizes the stop codons?/
A release factor
T/F As soon as one ribosome release an mRNA another will snatch it
What part of the tRNA is the amino acid attached to?
What are the 3 sequences that signal an intron?
The 5' splice junction - GURAGU
The branch point- something with A
The 3' splice junction - YNCAG
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