RNA Translation Flashcards by Reginald Richter

What makes Aminoacyl-tRNA synthetase a special enzyme

2nd Enzyme to have its own editing function. !st is DNA polymerase

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Ribosyme

RNA melecules that have enzyme activity

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How many nucleotides code for 1 amino acids

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How many combinations of nucleotides triplets are there

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How many of the total triplet combination of nucleotides are stop codons

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How many sense codons are there

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Other name of stop codons

non sense codon

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How many nucleotides are in a codon

3 nucleotides

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What are the three nucleotides that make up the antisense codon

Uracil and Purine nucleotide

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Which combination of Uracil and Purine nucleotides is not considered a stop codon

UGG(Tryptophan)

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Which amino acids have only 1 codon that codes for it

Methionine and tryptophan

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What provides the framework for the second statement of
the Central Dogma (RNA specifies Protein).

Translation

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What do we need for protein synthesis?

1) Ribosome
2) Aminoacyl-tRNAs
3) mRNA
4) Soluble protein factors

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Wgich soluble protein factors have GTPase activity

IF-2
EF-Tu and EF-G
RF-3

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Why do some soluble protein factors have GTPase activity

In translation, they act as GTP fueled
motors to drive the process of protein
synthesis forward.

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Usually Eukaryotic mRNA are polycistronic

False theyre monocistronic

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‘What does it mean for Eukaryotic mRNA to be monocistronic

It means it codes for only 1 polypeptide

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What is the start codon in Eukaryotic mRNA

AUG

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What are some of the covalently modify nucleotides present in tRNA

Pseudouridine
Dihydrouridine

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The first two nucleotide can vary without affecting the amino acids. true or false?

False, the first two nucleotides must always be constant, else would lead to mutation

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Which position nucleotide in a codon can vary without affect the amino acid

The 3rd nucleotide

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Give three characteristics of the Genetic Code:

its a ribonucleotide “triplets”.
its “degenerate
its “universal”.

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What does it mean for genetic code to be degenrate

Most amino acids are specified by more than 1 codon

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What does it mean for genetic code to be universal
And whats its exception

It codes for the same amino acids in every organism
The only exceptionis in mitochondria

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Types of mutations: -

point mutation, Silent mutation mis sense mutations, nonsense mutations, read through mutations Insertion or deletion mutations, Splicing mutation Chromosomal Abnormalities

Which amino acids have 6 genetic codes that specifies them

Agenine leucine Serine

What are the two parts of

Small Subunit Large Subunit 30s 50s together 70s

Which tRNAs identify the first codon for methionine both in Eukaryotes and Prokaryotes

fMet-tRNA for bacteria And Met-tRNA i for Eukaryotes

Initiatiation occurs at what part of the ribosome

Small subunit

The peptidyl transferase reaction occurs in what subunit of the ribosome

50S subunit(Large subunit)

What specific species of the 50s Subunit cata;yzes the peptidyl transferase reaction

The 23s species

What are the 3 Ribosome binding sites

A site for Aminoacyl-tRNA p for peptidyl-tRNA E for exit

Movement of ribosome one codon at a time

Translocation

Aminoacyl-tRNA binding to A site

Elongation factor TU

Translocation

Elongation factor G in prokaryotes

All tNRA have what at the 3' end

CCA

About 20% of the bases in trna are covalently modified

Aminoacyl-tRNA synthas

Adds the correct amino acid to the correct tRNA

How is the anino acid attached tp trna

3' and 2'

Which position is prefered by the ribosome

3'end

Two purposes of tRNA aminoacylation (tRNA “charging")

: 1) Provides the amino acid with the necessary “adaptor” 2) Activates the carboxyl group for peptide bond formation There

The ribosome is a ribozyme

Terminates protein synthesis

puromycin

Peptidyl transferase reaction is in the large subunit

What locates the start codon methionine sometimes in prokaryotes

fMet-tRNA

What locates the start codon methionine in eukaryotes

Met-tRNA

# In Prokaryotes Shine-Dalgarno sequence

Rich in purine nucleic acids, Forms complementary base pair with the 3' end of 16S base pair to help identify the start and also holds the mRNA in place

Kozak Sequence

CCAUGG complementary CCAUGG

Palindromic sequence

A dna squence which is equal to their complementary base pair

Why are prokaryotes mRNA polycistronic

Because of the Shine-Dalgarno sequence

# In Prokaryotes what is also known as the dissociating factor

Initiation factor 3

# In Prokaryotes What does IF 3 do

Seperates the small subunit

What role does IF-2 play in translation

It binds to the fmet-tRNA and positions it at the p-site

Where does IF-1 bind during initiation in Translation

At the A site

WHat causes the release of the initiation factors from the small sub unit of the ribosome

The gtpase of IF-2, converting GTP from GDP releasing the factor

WHat is the order of binding by the initiation factors

IF 3 then IF 1 then IF2

# In Prokaryotes What is the function of EF tu

binds aminoacyl tRNA to the A site

# In Prokaryotes What is the function of EFts

replaces GDP with GTP on EFtu

# In Prokaryotes What is the function of EF-G

Promotes translocation by GTPase

# In Prokaryotes What is the Most abundant protein in bacteria

EF Tu

What are the equivalents of the elongation factors in prokaryotes in Eukaryotes

eEF1a- EFTu eEF1b-EFts eEF2- EF-g

Eukaryotic Translation initiation

1) Binding of the mRNA cap by the 40S subunit+initiation factors 2) Scanning of the mRNA to search for AUG 3) Binding of the 60S subunit

Name one way by which gene expression is regulated during translation

By the binding of the 4E-BP( Binding Protein) which is a competitive inhibitor | Phosphorylation causes the release of the 4E-BP

phosphorylation of eIF2

translation regulation, Phosphorylation blocks eIF 2B catalyzed release of GDP

40S subunit binds cap with eIF complex and then scans the mRNA until it finds the 1st AUG. Requires:

➤met-tRNA Met ➤ helicases (to unwind 2º structure in mRNA) ➤ ATP

How many releasing factors are present in Eukaryotes

In Eukaryotes theres only one releasing factor that identifies all the stop codons

3 termination codons

UAG recognized by RF 1 (36 kD) UAA UGA recognized by RF 2 (38 kD )

RF 3 releases bound RF 1 or 2; (46 kD) requires GTP

Translation immediately follows transcription in eukaryotes, Why?

Because theres no need to pre process the mRNA by splicing and capping

RNA Translation Flashcards

(70 cards)