BIO 325 Lecture 3: Amino Acid

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amethystkangaroo179

29 May 2018

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Amino Acid

• Triplet codon represents each amino acid

• 20 amino acids encoded for by 4 nucleotides

• Must be at least triplet combinations that code for amino acids

Codons and Code

• Codons consist of a triplet codon each of which specifies an amino acid

o Code shows 5’ to 3’ dietio

• Codons are nonoverlapping

• Code includes 3 stop codons that terminate translation

o UAA, UAG, UGA

o There are 64 total possible codons. Of these, the codon AUG/ATG is recognized

by a ribosome as the initiator codon

• Code is degenerate

• Fixed starting point establishes a reading frame

o AUG ethioie – an initiation codon that specifies reading frame

• 5’ to 3’ dietio of RNA oespods with N teius to C teius of polpeptide

• Mutations modify message encoded in sequence

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Related Questions

QUESTION 1

Each triplet codon encodes for a unique amino acid

True

False

QUESTION 2

The codon and anticodon are always antiparallel to each other when base-paired.

True

False

QUESTION 3

Which one of these is not a stop codon:

	(a)	UAA
	(b)	UAG
		(c) UAC
		(d) UGA

QUESTION 4

In Prokaryotic translation which of the following occurs:

		a) the 50S ribosome joins with the 60S initiation complex to allow for initiation
		b) The AUG is identified by being 20 nucleotides downstream of the shine-dalgarno sequence
		c) GTP is hydrolyzed as initiation factors are released
		d) A 45S initiation complex is formed by numerous factors, including mRNA

QUESTION 5

The extended polypeptide chain occurs in the E site in the ribosome

True

False

coffeeswan749

Fill in the blank. Elongation during translation does NOT involve ____________.

Question 16 options:

	the translation of codons according to the genetic code
	the formation of bonds catalyzed by the ribosome
	complementary base pairing between RNA molecules
	amino acids being linked together in a polypeptide
	reading the DNA template 3' to 5'

For a given gene, what establishes the reading frame for translation?

Question 17 options:

	the location of the enhancer relative to the gene
	the first three nucleotides at the 5' end of the mRNA
	the first three nucleotides at the 3' end of the mRNA
	the start codon in the mRNA
	the location of the promoter relative to the gene

Which of the following is the LEAST likely direct consequence of a substitution mutation?

Question 18 options:

	changing the length of a protein coded for by a gene
	changing one amino acid in a protein
	creating a stop codon
	eliminating a start codon
	changing the length of the DNA molecule containing a gene

Suppose that the pre-mRNA transcript from a eukaryotic gene is 30,000 nucleotides long, and the gene codes for a sequence of 300 amino acids. What is the best explanation for the relationship between these numbers?

Question 19 options:

	only the first 900 nucleotides of the pre-mRNA transcript are translated
	it takes 100 nucleotides to specify a single amino acid
	300 of the nucleotides in the transcript are important, and the rest are "junk"
	only the last 900 nucleotides of the pre-mRNA transcript are translated
	large portions of pre-mRNA transcripts are cut out during RNA processing

Suppose an individual is born into a population with a novel mutation. Is the new mutation an evolutionary change, and why?

Question 20 options:

	no, because it is not a big enough change to count
	yes, because new mutations are always adaptive
	yes, because the appearance of a new genetic variant is a genetic change in a population
	no, because not enough individuals have the mutation for it to matter
	no, because most mutations are not adaptive

Match the following:

1	Region which lies upstream of thetranslation start site contains the Shine Dalgarno sequence
2	Sequence added to the 3' end of thepre-mRNA which affects mRNA stability
3	Establishes the reading frame andspecifies the first amino acid of the protein chain
4	DNA sequence that the transcriptionapparatus recognizes and binds to initiate transcription
5	Expressed sequences of DNA that arenot removed during alternative splicing
6	Signals the end of translation andthe protein molecule
7	Group of three nucleotides that codefor an amino acid
8	Site begins the coding region of thegene and is located 25-30 nucleotides downstream of the TATAbox
9	Non-coding sequences of DNA thatintervene within coding regions of a gene
	10 Ribosome binding site ineukaryotes; functions in the initiation of translation and mRNAstability
11	A sequence which lies downstream ofthe coding region of the gene; determines the location of the 3'cleavage site in the pre-mRNA molecule
12	Sequence of nucleotides at the 3' endof the mRNA that is not translated into protein; affects thetranslation and stability of the mRNA molecule

A.	5' untranslated region
B.	AAUAAA consensus sequence
C.	Promoter
D.	Transcription start site
E.	3' untranslated region
F.	Introns
G.	Initiation codon (AUG)
H.	Poly(A) tail
I.	5' cap
J.	Termination codon (UAA, UGA, UAG)
K.	Exons
L.	Sense codon

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BIO 325 Lecture 3: Amino Acid

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