Biochemistry 2280A Lecture Notes - Start Codon, Streptomycin, Frameshift Mutation

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7 Dec 2012

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A one-letter code with a, g, u, c would provide: 4 codons. A two-letter code would provide: 4 x 4 = 16 codons. A three-letter code would provide: 4 x 4 x4 = 64 codons. As there are 20 amino acids, a 3-letter code (64 codons) is sufficient. Commaless, no gaps (gaps were removed by splicing) 61 codons for 20 amino acids therefore redundant. Redundancy some codons specify the same amino acid: occurs at the 3rd position of the codon (wobble) 3 stop codons: uaa, uag, uga. More common amino acids (found in proteins) have more codons: met aug, trp ugg. Related amino acids have similar codons: asp: gac, gau, glu: gag, gaa, gln: cag, caa. Missense mutation single base mutation which results in a single amino acid change. Nonsense mutation a nonsense mutation results in premature termination of the protein trna (transfer): Vehicle that bring amino acids to the growing polypeptide chain.

Related Questions

The sequence of a template strand is ACTTTGGAAAAC. If the given template strand was transcribed to produce mRNA and the mRNA was translated to produce a peptide, what would be the amino acid sequence of the resulting peptide? Assume that translation of the mRNA begins with the first codon (i.e., assume that a start codon is not required to begin translation). Also, assume that if a stop codon is encountered prior to reaching the end of the mRNA, translation stops and does not resume, in which case you should enter the sequence of amino acid(s) incorporated into the peptide prior to encountering the stop codon. Use the Genetic Code to help you, and enter your answer using the one-letter code of amino acids.

The sequence of a coding strand is AATATTCGAAGG. If the strand that is opposite to the above-given coding strand (i.e., the template strand) was transcribed to produce mRNA and the mRNA was translated to produce a peptide, what would be the amino acid sequence of the resulting peptide? Assume that translation of the mRNA begins with the first codon (i.e., assume that a start codon is not required to begin translation). Also, assume that if a stop codon is encountered prior to reaching the end of the mRNA, translation stops and does not resume, in which case you should enter the sequence of amino acid(s) incorporated into the peptide prior to encountering the stop codon. Use the Genetic Code to help you, and enter your answer using the one-letter code of amino acids.

Question 9

Codominance is a form of inheritance in which two different allelesfor a gene are both expressed, and neither allele is dominant overthe other. One example of codominance is fur color in cattle; thealleles for red fur and white fur are codominant. If a homozygousred cow and a homozygous white bull mate, what would you expect tofind in their offspring?.912.l.16.2>

They will all have white fur.

Their fur will be a mixture of red and white hairs.

Their fur will be a lighter shade of red.

They will all have red fur.

Question 10

If a tRNA molecule has an anticodon which reads AUG, what will itmatch up with and what amino acid is it carrying?
.912.l.16.5>

	U		C		A		G
	UUU	Phenylalanine	UCU	Serine	UAU	Tyrosine	UGU	Cysteine	U
U	UUC	Phenylalanine	UCC	Serine	UAC	Tyrosine	UGC	Cysteine	C
	UUA	Leucine	UCA	Serine	UAA	Stop	UGA	Stop	A
	UUG	Leucine	UCG	Serine	UAG	Stop	UGG	Tryptophan	G
	CUU	Leucine	CCU	Proline	CAU	Hisitidine	CGU	Arginine	U
C	CUC	Leucine	CCC	Proline	CAC	Hisitidine	CGC	Arginine	C
	CUA	Leucine	CCA	Proline	CAA	Glutamine	CGA	Arginine	A
	CUG	Leucine	CCG	Proline	CAG	Glutamine	CGG	Arginine	G
	AUU	Isoleucine	ACU	Threonine	AAU	Asparagine	AGU	Serine	U
A	AUC	Isoleucine	ACC	Threonine	AAC	Asparagine	AGC	Serine	C
	AUA	Isoleucine	ACA	Threonine	AAA	Lysine	AGA	Arginine	A
	AUG	Methionine/Start	ACG	Threonine	AAG	Lysine	AGG	Arginine	G
	GUU	Valine	GCU	Alanine	GAU	Aspartate	GGU	Glycine	U
G	GUC	Valine	GCC	Alanine	GAC	Aspartate	GGC	Glycine	C
	GUA	Valine	GCA	Alanine	GAA	Glutamate	GGA	Glycine	A
	GUG	Valine	GCG	Alanine	GAG	Glutamate	GGG	Glycine	G

It is carrying arginine and will match with a CGU codon on themRNA.

It is carrying methionine and will match with a TAC codon on theDNA.

It is carrying methionine and will match with a UAC codon on themRNA.

It is carrying tyrosine and will match with a UAC codon on themRNA.

Question 11

While the DNA in a human skin cell was being replicated, a singlebase was miscopied. What will be the most likely result of this forthe cell in which it happened?.912.l.16.3>

All the proteins the cell creates from the miscopied strand willdo different jobs than the old ones.

If the new sequence codes for the same amino acid as theoriginal cell, it will function normally.

Both new DNA strands will end up together in a new cell, and theinaccurate one will be discarded.

Any miscopied DNA will be replaced with an accurate DNA copyonce the cell divides.

Question 12

A ferret's haploid number of chromosomes is 20. How would thenumber of chromosomes in the ferret's body cells compare to thenumber of chromosomes in its gametes?.912.l.16.17>

Its body cells would have 20 chromosomes, and its gametes wouldhave 40 chromosomes.

Its body cells and gametes would both have 40 chromosomes.

Its body cells and gametes would both have 20 chromosomes.

Its body cells would have 40 chromosomes, and its gametes wouldhave 20 chromosomes.

Question 13

A body cell is in the longest stage of its life cycle. The cellgrows, synthesizing proteins and increasing in size. Eventually,the cell will grow too large to carry out normal activities. Whichof the following is the best conclusion you can make about the lifecycle of this cell?.912.l.16.14>

The cell is close to the end of its life cycle, and a chemicalsignal will initiate cell death.

The cell is ready to undergo mitosis, and a chemical signal willsend the cell to prophase.

The cell is in the G1 phase of interphase, and a chemical signalwill send the cell to the S phase.

The cell is in the S phase of interphase, and a chemical signalwill move the cell to the G2 phase.

Question 14

While mRNA strands are being created a sequence is sometimesmiscopied. What is the best possible outcome for the cell shouldthis take place?.912.l.16.5>

The miscopied sequence codes for the same amino acids as theoriginal sequence.

The new sequence creates a protein that serves a differentfunction from the original.

The ribosomes will correct the mistake before the tRNA matchesan amino acid to it.

The mRNA will only be used to create non-critical proteins forthe cell.

Question 15

Over the last several decades, the scientific community hasgathered a large amount of information regarding genetics andgenetic variation. What are two main sources that lead toincreased genetic variation?.912.l.15.15>

Selective breeding

Gamete mutations

Recombination

Genetic drift

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Biochemistry 2280A Lecture Notes - Start Codon, Streptomycin, Frameshift Mutation

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