BIS 101 Lecture 10: Lecture 10

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burgundywombat446

16 Dec 2017

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4 4 4 = 64 codons 21 total (well, for proteins, and depending on the species) Some aa have multiple codons ex: a c a. Not one trna per aa and not one trna per codon. How do we know that there can"t be 64 trnas: wobble pairing = pairing of the trna anticodon with the mrna codon proceeds from the 5" end of the codon. Once the first two positions are paired, exact base pairing of the third position is less critical. A c a a c g this is the codon: stop codons have no trna at all. By default, you can never have all 64 codons being used. otherwise, translation would never stop. Aug stop promoter shine trxn sequence dalgarno termination. Transcribed mrna is bigger than translated mrna. The process of controlling which, whether, how, when, to what extend genes in a cell"s dna are expressed:

Related Questions

A single base substitution in the anticodon loop of one of thetRNAs for glutamic acid (tRNAglu) can hypothetically generate amutant tRNA that is able to suppress translational termination bycausing insertion of a glutamic acid residue at certain terminationcodons. Such mutant tRNAs are in fact encountered in nature and arereferred to as suppressor tRNAs. Assume that there are two tRNAgenes for glutamic acid (so that this hypothetical mutation wouldnot be lethal) and that one of these tRNAs acquires a single basemutation in its anticodon loop. Assume also that this tRNA has a Uresidue at the wobble position (and can therefore base pair withboth Glu codons) and that the mutation does NOT occur at thiswobble position.

A) What is the nucleotide sequence of the wildtype anticodon oftRNAglu (5â?3â polarity) and what is the mutant sequence that wouldhave the properties described above?

Wt sequence:

Mutant sequence:

B) At which stop codons would the mutant tRNAglu be able tosuppress translational termination? (assume that G-U base pairingis possible at the wobble position)

C) Mutations of the sort described above are rarely encountered innature, due in part to the existence of a key step in the chain ofevents that helps ensure translational fidelity. What is this stepand how might it prevent suppressor tRNAs from being able toincorporate amino acids at stop codons?

ochrehedgehog380

If one is testing a goodness of fit to a 9:3:3:1 ratio, how many degrees of freedom would be associated with the Chi-square?

not enough information to determine

Which of the following choices does not describe a type of posttranslational modification of proteins?

The amino terminal methionine may be removed.

Glycoproteins are produced by the attachment of phosphates to newly synthesized proteins.

Precursor proteins are cleaved and trimmed by protease enzymes to produce a functional protein.

Molecular chaperones help proteins fold correctly.

Amino acids in the amino terminal of the protein can be acetylated.

A eukaryotic DNA sequence that affects transcription at distant promoters is called a(n)

long distance promotor

regulator

operon

enhancer

DNA methylation may be a significant mode of genetic regulation in eukaryotes. Meythylation refers to

altering RNA polymerase activity by adding methyl-groups

changes in DNA-DNA hydrogen bonding

altering translation activity via methylated tRNAs

adding methyl groups to certain cytosines in DNA

If a nucleotide lacks a 3â-OH group, what will happen?

itâs transformed into RNA

another nucleotide can bond at the 3â site during replication

replication will halt

no effect

Which of the following describe posttranscriptional modifications commonly seen in mRNA of eukaryotes?

5â capping, 3â-poly-A tail addition, splicing

3â capping, 5â poly-A tail addition, splicing

heteroduplex formation

5â capping, 3âpolyA tail addition, removal of exons

In birds, females are the heterogametic sex. This means that

females have chromosomes in pairs.

emales produce eggs.

females determine the gender of their offspring.

males have two identical sex chromosomes (ZZ)

An anticodon on a tRNA has the sequence 5'âGCAâ3'. What would be the effect on translation if the G in the anticodon were mutated to a U?

The anticodon could pair to the serine codon 5'âUCAâ3', and a cysteine would be incorporated at all points where a serine should have been incorporated.

The anticodon could pair to the threonine codon 5'âACUâ3', and a threonine would be incorporated at all points where a cysteine should have been incorporated.

The anticodon could pair to the serine codon 5'âAGUâ3', and a serine would be incorporated at all points where a cysteine should have been incorporated.

The anticodon could pair to the stop codon 5'âUGAâ3', and instead of stopping translation, a cysteine would be incorporated and translation could continue.

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

salmonlouse680

BIS 101 Lecture 10: Lecture 10

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