Dr. Howe Study Guide # 4

Front 1

RNA

Back 1

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.

Front 2

Transcription

Back 2

Is the production of an RNA molecule base on the nucleotide sequences of a single stranded DNA template.

Front 3

Translation

Back 3

Production of a polypeptide based on a sequence of a single stranded RNA molecule.

Front 4

RNA is made by______?

Back 4

transcription

Front 5

What is the function of tRNA?

Back 5

-transfer
-An adaptor molecule between an mRNA molecule and a ribosome
-carries the amino acid to the ribosome.

Front 6

What is the function of mRNA?

Back 6

-messenger
- transcript for gene's protein building instructions.
- encodes a sequence of amino acids.

Front 7

WHat is the function of rRNA?

Back 7

-ribosomal
-part of the ribosome structure.

Front 8

What is the function of snRNA in eukaryotes?

Back 8

-small nuclear
-adding of mRNA before translation.

Front 9

What is the function of miRNA in eukaryotes?

Back 9

-regulation of expression of mRNA.

Front 10

Where does transcription and translation occur in eukaryotes?

Back 10

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.

Front 11

Where does transcription and translation occur in prokaryotes?

Back 11

-They lack a nuclei, their DNA is not segregated from the ribosome and the other protein-synthesizing equipment.

Front 12

What three features distiguish RNA and DNA?

Back 12

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.

Front 13

Translation RNA processing

Back 13

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.

Front 14

Primary transcript

Back 14

Is the initial RNA transcipt.

Front 15

What type of RNA's are never translated?

Back 15

tRNA, rRNA, snRNA, and miRNA

Front 16

Template strand

Back 16

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.

Front 17

Which of the two DNA strands is used for transcription?

Back 17

When the DNA strand is transcribed, the base triplet ACC in the DNA providesa template for UGG in the mRNA molecule.

Front 18

Amino Acid

Back 18

An organic molecule processing both carboxyl and amnio group. Amino acids serve as a monomers of proteins.

Front 19

Protein

Back 19

A 3-D biological polymer constructed from a set of 20 different monomers called amono acids

Front 20

polypeptide

Back 20

A polymer (chain) m=of many amino acids linked togetherby a peptide bond.

Front 21

Triplet code

Back 21

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.

Front 22

Codon

Back 22

-3 nucleotide encode 1 amino acid.

Front 23

Reading frame

Back 23

Our ability to extract the intended message from written lauguage depends on reading the symbols in the correct sequence and grouping.

Front 24

How does RNA polymerase differ from DNA polymerase? In which ways are they similar?

Back 24

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.

Front 25

RNA polymerase

Back 25

Pries the two DNA strands apart anf hooks together the RNA nucleotide asnthey base-pair along the DNA template

Front 26

Promoter

Back 26

Double stranded, region specific DNA sequence.
- promoter sequence is not transcribed.
-5'UTR

Front 27

At which end (5' or 3') of the template does transcription occur?

Back 27

The RNA polymerase can only add nucleotides in the 3' to 5' end of the growing polymer.

Front 28

Which end (5' or 3') of the RNA molecule is made first?

Back 28

The RNA molecule elongates in its 5' to 3' directions.

Front 29

Amino terminus

Back 29

5' end

Front 30

Carboxyl terminus

Back 30

3' end

Front 31

up stream

Back 31

the nucleotide where RNA synthesis acutually begins and extends several nucleotides before the promoter

Front 32

Down stream

Back 32

After promoter

Front 33

TATA box

Back 33

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

Front 34

CAAT box

Back 34

-5' CAAT 3'
Upstream from the transcription start site is often found a second consensus sequence

Front 35

GC box

Back 35

5'GGGCGG 3' many promoters conain this box because these DNA sequnce are on the same molecule of DNA as the genes baing transcribed

Front 36

terminator

Back 36

This is an RNA sequence
FUcnctions as the actual termination signal

Front 37

What type of DNA sequence are included in prokaryotic and eukaryotic promoter?

Back 37

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'.

Front 38

Where are these sequences located in relation to the trascription site?

Back 38

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.

Front 39

What types of RNAs are transcribed by the 3 eukaryotic RNA polymerse?

Back 39

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)

Front 40

enhancer

Back 40

They speed up expression or when it needs to be transcribed.

Front 41

Due all eukaryotes genes have enhancers?

Back 41

Enhancers binds to proteins that are activators and cause a conformational change. They are only present when expression is required.

Front 42

silencers

Back 42

bind repressor proteins. They are present when a gene should not be expressed . Eukaryotic cells regulate expression of a gene.

Front 43

What is the termination factor in transcription in eukaryotes ?

Back 43

formation of a hairpin loop. It destablizes RNA polymerase and DNA falls off.

Front 44

Hairpin loop

Back 44

Synthesis of RNA sequence within two fold symetry.
-base pairing within the RNA.
causes termination

Front 45

Rho dependent termination

Back 45

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.

Front 46

Sigma factor

Back 46

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.

Front 47

Transcription factors

Back 47

Initiation of transcripton of a gene in RNA requires a basal transcription factor.
RNA pol II (TF IIX)
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

Front 48

Prokaryotes modifications

Back 48

-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.

Front 49

Eukaryotes modification

Back 49

-RNA is transported from nucleas to cytoplasm.
-RNA requires modification after trascription.

Front 50

5' capping

Back 50

-addition of a modified nucleotide to 5' end.
- it facilitates 5' binding
-7methylguanosine (methylated nucleotide)

Front 51

Poly A tail

Back 51

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.

Front 52

Pre-mRNA

Back 52

Before three modifications in eukaryotes

Front 53

Mature-mRNA

Back 53

After three modifications in eukaryotes