MCB 150 Lecture 16: Week 4 - Topic 3

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azurebutterfly65

7 Dec 2017

School

University of Illinois

Department

Molecular and Cell Biology

Course

MCB 150

Professor

B Mehrtens

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Document Summary

Topic 3: the genetic code and components of translation. Nucleotide sequence (acgu) of mrna information for making protein. Must take more than one nucleotide to specify an amino acid. 4 possibilities at first position, 4 at second (= 42 = 16) 4 x 4 x 4 = 43 = 64. 3 nucleotides per amino acid is the minimum number to account for the 20 amino acids we already know about. Codons nucleotides in groups of three triplet. One codon 3 bases one amino acid. Nirenberg: synthesize an artificial mrna of 60 uracils. Feed this to protein synthesizing machinery in vitro. Get a polypeptide made up of 20 phenylalanines. Genetic code is triplet (60 bases = 20 aa, or 3:1) Related experiments uncovered what each of the 64 codons specified. 3 specify the end of the protein (stop codons) Most amino acids can be specified by multiple codons. Degenerate/redundent genetic code (but not ambiguous!) ambiguous a codon codes for more than.

Related Questions

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

Which of the following is NOT a direct consequence of the fact that DNA polymerase can only build onto the end of an existing nucleic acid?

Question 6 options:

	DNA replication requires primers
	Bits of DNA are lost from the ends of your chromosomes in each successive round of replication
	RNA is involved in DNA replication
	The enzyme "primase" is needed for DNA replication
	There are multiple origins of replication on each eukaryotic chromosome

How does a nucleotide sequence code for a protein in nearly all living organisms?

Question 7 options:

	a sequence of 3 nucleotides can code for one of 64 different amino acids
	a sequence of 2 nucleotides can code for one of 64 different amino acids
	a sequence of 2 nucleotides can code for one of 20 different amino acids
	a sequence of 3 nucleotides can code for one of 20 different amino acids
	a sequence of 3 nucleotides can code for 3 different amino acids

Fill in the blanks. To make one strand of DNA, _________ monomers are linked together in a chain, forming a polymer we call a(n) ________ .

Question 8 options:

	nitrogenous bases, hydrogen bond
	nucleotide, nucleic acid
	amino acid, nucleic acid
	nucleotide, nitrogenous base
	amino acid, protein

Which of the following was NOT part of the ideas that Darwin used in his book On the Origin of Species?

Question 9 options:

	organisms vary in characteristics that affect survival and reproduction
	variation in traits is often heritable
	descent with modification explains life's unity and life's diversity
	organisms inherit characteristics from their parents that the parents acquired in their own lifetimes
	natural selection is a cause of adaptive evolution

Here is a hypothetical mRNA sequence:

5' G G A U G C U A G U A U G A 3'

What is the amino acid sequence encoded by this mRNA?

Question 10 options:

	Met-Ile-Val
	Asp-Ala-Ser-Met
	Met-Leu-Val
	Ser-Met-Ile-Val
	Gly-Cys

QUESTION 1. Choose the true statement about prokaryotic and eukaryotic DNA replication.

A.Eukaryotic DNA replication involves less protein factors than does prokaryotic DNA replication.

B. Prokaryotic DNA polymerases replicate DNA 5' to 3', while eukaryotic DNA polymerases replicate DNA 3' to 5'.

C. Eukaryotic DNA replication begins at multiple origins of replication, while prokaryotic DNA replication begins at a single origin of replication.

D. Prokaryotic genomes take longer to replicate than eukaryotic genomes.

QUESTION 2. Bacterial cells use DNA replication to:

A. make back-up copies of their genome in case of a mutation.

B. manifest multiple phenotypes at once.

C. copy their genetic material prior to binary fission.

D. build functional proteins.

QUESTION 3. Choose the true statement about the genetic code.

A. A cell's mRNA code is read four nucleotides at a time to specify a single amino acid.

B. The genetic code encodes 64 amino acids, one for each of the 64 corresponding codons.

C. The genetic code is redundant, with multiple codons specifying a single amino acid.

D. The genetic code varies widely among organisms, with each having a different set of codons for a corresponding amino acid.

QUESTION 4. Of the following enzymes, which are correctly matched with their function? To be marked correct, you'll need to select all correctly matched statements, as there may be more than one correct answer.

A. Helicase, relieves torsion stress as DNA unwinds

B. Ligase, covalently bonds adjacent Okazaki fragments

C. Primase, removes RNA primers

D. DNA polymerase III, builds most of the DNA on the leading and lagging strand

QUESTION 5. Which of the following contributes to DNA replication accuracy? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer.

A. The capacity to proofread improves DNA replication accuracy.

B. A slow rate of DNA replication contributes to accuracy.

C. The use of primase improves DNA replication accuracy.

D. DNA replication accuracy is improved thanks to complementary base pairing rules.

MCB 150 Lecture 16: Week 4 - Topic 3

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