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53 Cards in this Set

  • Front
  • Back
Ribonucleic acid
A type of nucleic acid consisting of nucleotide monomers with a ribose sugar and a nitrogenous base adenine (A), cytosine (C), guanine (G) and uracil (U)
Is usually single stranded; functions in protein syntheis and as the genome of some viruses.
Is the production of an RNA molecule base on the nucleotide sequences of a single stranded DNA template.
Production of a polypeptide based on a sequence of a single stranded RNA molecule.
RNA is made by______?
What is the function of tRNA?
-An adaptor molecule between an mRNA molecule and a ribosome
-carries the amino acid to the ribosome.
What is the function of mRNA?
- transcript for gene's protein building instructions.
- encodes a sequence of amino acids.
WHat is the function of rRNA?
-part of the ribosome structure.
What is the function of snRNA in eukaryotes?
-small nuclear
-adding of mRNA before translation.
What is the function of miRNA in eukaryotes?
-regulation of expression of mRNA.
Where does transcription and translation occur in eukaryotes?
The nuclear envelope seperates transcription and translation. Transcription occurs in the nucleus, and mRNA is dispatched to the cytoplasm, where translation occurs. But before it leaves the nucleus, eukaryotic RNA transcripts are modified in various ways to produce the final, functional mRNA. ie, pre-mRNA to mRNA.
Where does transcription and translation occur in prokaryotes?
-They lack a nuclei, their DNA is not segregated from the ribosome and the other protein-synthesizing equipment.
What three features distiguish RNA and DNA?
RNA-single standed,has an OH on the 2' carbon, and constains a U base.
DNA- double stranded, and contains a T bases, and does not contain a OH on the 2' carbon.
Translation RNA processing
Modification of RNA before it leaves the nucleus, a process unique to eukaryotes.
- RNA transcript is modified in various ways to produce the final, functional mRNA.
Primary transcript
Is the initial RNA transcipt.
What type of RNA's are never translated?
tRNA, rRNA, snRNA, and miRNA
Template strand
FOr each gene, only one of the two DNA strands is transcribes.
It provides the template for ordering the sequence of nucleotides in the RNA transcript.
Which of the two DNA strands is used for transcription?
When the DNA strand is transcribed, the base triplet ACC in the DNA providesa template for UGG in the mRNA molecule.
Amino Acid
An organic molecule processing both carboxyl and amnio group. Amino acids serve as a monomers of proteins.
A 3-D biological polymer constructed from a set of 20 different monomers called amono acids
A polymer (chain) m=of many amino acids linked togetherby a peptide bond.
Triplet code
The genetic instructions for a polypeptide chain are written in the DNA as a series of three-nucleotide words.
-They code for an amino acid.
-there are 64 possible codes.
-3 nucleotide encode 1 amino acid.
Reading frame
Our ability to extract the intended message from written lauguage depends on reading the symbols in the correct sequence and grouping.
How does RNA polymerase differ from DNA polymerase? In which ways are they similar?
RNA polymerase- synthesizes RNA. It recognizes a promoter region at the begining of a length of DNA that is transcribed. It make a complementary RNA copy of the DNA template.
-RNA is synthesized in the 5' to 3' end.
DNA polymerase- has 3' to 5' and 3' to 5'exonuclease.
- It synthesizes in th3 5' to 3' direction onto a primer.
-They are only similar in the direction of synthesis.
RNA polymerase
Pries the two DNA strands apart anf hooks together the RNA nucleotide asnthey base-pair along the DNA template
Double stranded, region specific DNA sequence.
- promoter sequence is not transcribed.
At which end (5' or 3') of the template does transcription occur?
The RNA polymerase can only add nucleotides in the 3' to 5' end of the growing polymer.
Which end (5' or 3') of the RNA molecule is made first?
The RNA molecule elongates in its 5' to 3' directions.
Amino terminus
5' end
Carboxyl terminus
3' end
up stream
the nucleotide where RNA synthesis acutually begins and extends several nucleotides before the promoter
Down stream
After promoter
TATA box
A crucial promoter DNA sequence (5'TATAAA 3')that forms the initiation complex. Once the polymerase is firmly attached to the promoter DNA, the two strands unwind there, and the enzyme starts transcribing the template.
-consensus sequence
CAAT box
-5' CAAT 3'
Upstream from the transcription start site is often found a second consensus sequence
GC box
5'GGGCGG 3' many promoters conain this box because these DNA sequnce are on the same molecule of DNA as the genes baing transcribed
This is an RNA sequence
FUcnctions as the actual termination signal
What type of DNA sequence are included in prokaryotic and eukaryotic promoter?
prokaryotic (pribnow box)-5'TATAAT 3'or '5TTGACA 3'
eukaryotic (TATA, CAAT, and GC box)5'TATAAA 3',5' CAAT 3'and 5'GGGCGG 3'.
Where are these sequences located in relation to the trascription site?
The Pribnoe box is usually found centered about 25 nucleotides upstream of the initial base of the transcription start sitefor the mRNA molecule.
- Hogness box is between seventy and eighty nucleotides upstream from the transcriptionstart site is often found a second consnesus sequence.
What types of RNAs are transcribed by the 3 eukaryotic RNA polymerse?
RNA pol II- some ssRNA responsible for transcription of mRNA or synthesizes precursors for mRNA's

RNA pol I-most rRNA is required for assistance from basal transcription factor. and synthesizes precursors oftRNA and someother small RNA's in the nucleoplasm.
-Pol III produces the precursors of tRNA and some small RNA's in the nucleoplasm. (same snRNA)
They speed up expression or when it needs to be transcribed.
Due all eukaryotes genes have enhancers?
Enhancers binds to proteins that are activators and cause a conformational change. They are only present when expression is required.
bind repressor proteins. They are present when a gene should not be expressed . Eukaryotic cells regulate expression of a gene.
What is the termination factor in transcription in eukaryotes ?
formation of a hairpin loop. It destablizes RNA polymerase and DNA falls off.
Hairpin loop
Synthesis of RNA sequence within two fold symetry.
-base pairing within the RNA.
causes termination
Rho dependent termination
Rho recognizes a signal. Rho binds to recognition signal and uses ATP hydolysis to propel towards RNA polymerase.
-slows down RNA polymerase
-Breaks H-bonds between template and newly made RNA. This causes termination.
Sigma factor
Diferent types of sigme factors are expressed for different types of envriomental conditions.
- in eukaryotes initiation of transcription of protein coding gene requires a complex of RNA polymerase and the sigma factor protein binding to the promoter. Once transcription begins, the sigma factor dissociates.
Transcription factors
Initiation of transcripton of a gene in RNA requires a basal transcription factor.
TFIID binds to TATA box
TFIIB binds to TFIID
RNA polymerase binds to complex slightly down stream.
- Other transcription factors join for seperation of double stranded DNA.
-Most transcription factors are removed after initiation
Prokaryotes modifications
-In pokaryotes translation and transcription can be coupled.
-translation of an mRNA can begin before transcription of that mRNA is complete.
-THey both happen in the cytoplasm.
- RNA's don't require modification before translation.
Eukaryotes modification
-RNA is transported from nucleas to cytoplasm.
-RNA requires modification after trascription.
5' capping
-addition of a modified nucleotide to 5' end.
- it facilitates 5' binding
-7methylguanosine (methylated nucleotide)
Poly A tail
Polyadenylation added in a chain of a nucleotide
- stabelizes mRNA in the cytoplasm. (increase poly A tail lasts longer in cytoplasm)
-protect mRNA
-at the 3' end of an mRNA a consensus sequence synthesized AAUAA give a signal for the poly A tail.
-Found 35 nucleotides in the 5' of a poly A site, where poly A tail starts.
-A complex of proteins binds to poly A signal.
-Cleaves any NRA after (3' of) the poly A sites.
Before three modifications in eukaryotes
After three modifications in eukaryotes