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Biochemistry 2280A Chapter Notes - Chapter 8: Lac Operon, Tyrosine Aminotransferase, Gene Expression

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School
Western University
Department
Biochemistry
Course
Biochemistry 2280A
Professor
Derek Mc Lachlin

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Document Summary

Cell differentiation is achieved by gene expression not by losing genes or gaining genes. Gene expression: process by which cells selectively direct the synthesis of the many thousands of proteins and rnas encoded in their genome. Different cell types of a multicellular organism contain the same dna: No altering of dna genome even to specialized: all cells have the same genome. Different cell types produce different sets of proteins: Using mass spectroscopy (which works better than electrophoresis) saw different protein in different tissues. Housekeeping proteins: proteins for chromosomes, rna polymerases, dna repair enzymes, ribosomal proteins, enzymes involved in glycolysis and other basic metabolic processes, and many of the proteins that form the cytoskeleton. We can also catalogue rna to see protein. Estimates of human cell estimate around 5000-15000 protein coding genes expressed in a total of 21000. A cell can change the expression of its genes in response to external signals: Will insert into the major groove of the.

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Related Questions

1. Which cellular processes occur as a consequence of differential control of gene expression in eukaryotic cells?

a) Cell Differentiation

b) Differential Translation

c) Differential Polymerization

d) Differential DNA Replication

e) Differential tRNA Degradation

2) Multicellular organisms are comprised of a variety of cells with different morphologies and different functions. Which is the underlying mechanism that leads to the generation of diverse cell in one organism?

a) The expression of all genes in all cell types.

b) The duplication of the genome in certain cell types.

c) The elimination of specific group of genes from different cell types.

d) The differential expression of particular sets of genes required for a particular cellular phenotype

e) All of the above

3) Which of these statements defines paracrine cell signaling?

a)

A messenger molecule released into the blood stream to bind to a receptor on a cell far away from the release site.

b)

A messenger molecule released by a cell into the extracellular space that binds to receptors on the surface of the same cell.

c)

A messenger molecules released by a cell into the extracellular space that travels short distances to bind to a receptor in a nearby cell.

d)

A messenger molecule release by a tissue into the lumen of an organ that diffuse to bind to receptors far away from the release site.

e)

All of the above.

4) Which effect has the binding of the ligand to a G-protein coupled receptor on intracellular G-protein?

a)

ATP is hydrolyzed, activating phosphorylation

b)

GTP is exchanged for GDP on the G protein, inactivating the G protein

c)

GDP is exchanged for GTP on the G protein, activating the G protein

d)

GMP is released from the G-protein, inactivating the receptor

e)

None of the above

Expression vectors inprokaryotes do not make functional eukaryotic gene products inbacteria very well because

Answer Not sure which one ?!

· the codon sequence for prokaryotes is differentthan the codon sequence in eukaryotes

· there are no disulfide bridges formed in proteinsnormally made in prokaryotes

· prokaryotic expression vectors cannot translateeukarytic sequences

· eukaryotic genes have introns, and prokaryotesdon't

· eukaryotic genes have exons and prokaryotesdon't


I create a knockout mouseusing the agouti/black fur system \. When I cross the agoutioffspring of the originally engineered mouse, I find a ratio of 2agouti mice to 1 black furred mouse. What is the bestexplanation?

Answer not sure which one?!

· The gene knocked out was recessive.

· The gene knocked out was dominant.

· The gene knocked out was a lethalgene.

· The knockput was integrated into a random spot,and did not knockput the original gene.

A restriction enzyme cuts DNAand leaves the following end

xxCTGCA
xxG

Which of the following could be the sequence of the correspondingend of the other end of the cut DNA?

Answer

· xxG
xxCTGCA

· xxC
xxGTGCA

· xxCCGAT
xxG

· xxGGCTA
xxC


An SNP always occurs dueto

Answer

· a one base-pair change.

· a three base-pair change.

· a single restriction site change.

· a single amino acid change.

· None of these.


I PCR out a mutated gene in apatient with Lisenbee chorea (the inability to dance in acoordinated fashion) and I compare it to another patient with thatsame disease phenotype. One subject had a mutation on chromosome 4,and the other subject couldn't rock it because of a mutation onchromosome 5. This is an exampe of

Answer

· pleitropy

· locus heterogeneity

· allelic heterogeneity

· dominant negative mutation

· penetrance

In his experiments, Mendelnoted that when two traits are involved in a genetic cross, theyare inherited independently of each other. Though Mendel didn'tknow about chromosomes, this still holds true (mostly)because

Answer

· genes on the same chromosome are often mixedthrough meiotic crossover during the formation ofgametes.

· variant alleles of the same gene do not interferewith the phenotypic expression of the gentoype in different geneticloci.

· most higher organisms are diploid, making only twoalleles available for every genetic locus, and there is a 50/50chance of geting either allele from a single parent.

· expression of phenotypes can vary from thegenotypes because of encironmantal influences.

· chromosomes often recombine

Anticipation is caused by amutation that increases in expressivity over subsequentgenerations.

Answer

· True

· False

Question 44

I have a genotype that shouldproduce a specific phenotype, but some of the individuals with thegenotype do not demonstrate any evidence of the phenotype. I wouldconsider this an example of

Answer

· allelic heterogeneity.

· locus heterogeneity.

· penetrance.

· expressitivity.

· sheer luck.

Question

Which of the following doesnot occur during the PCR reactions?

Answer

· Changes in the reaction temperature by athermocycler

· Denaturation at high temperatures

· Synthesis of oligonucleotide primers

· Extension of primers by DNA polymerase

· Annealing of oligonucleotide primers

Question

DNA markers, or variantnon-coding regions of DNA, are DNA polymorphisms that are usefulfor genetic mapping.

Answer

· True

· False

A mosaic is an organismwith

Answer

· multiple genotypes within one organism

· multiple alleles within one genotype

· more than one color of fur

· transgenes added to the zygote beforedevelopement

· a wt phenotype but a mutated genotype

Question

Genotype causesphenotype.

Answer

· No, gentoype just influences phenotype.

· Yes, genotype is the DNA sequence that createsphenotype.

Question

A true genetic chimera can becreated by

Answer

· mutating a gene early on in the development of anorganism resulting in different alleles being present in theadult

· multiple fertilized eggs or zygotes fusing to formone embryo

· adding a transgene to the genome of an organismduring fetal development only

· adding cells of a different species to an adultorganism

· adding a transgene to the genome of an animal atany stage in development

Question

The ABO blood group can bestbe explained by the concept of _______.

Answer

· dominant traits

· recessive traits

· allelic heterogeneity

· locus heterogeneity

· vampirism

If a loss of functionmutation creates a dominant phenotype, it may be becauseof

Answer

· haploinsufficiency

· penetrance

· expressivity

· allelic heterogeneity

· locus heterogeneity

Please select the best matchfor each.

Answer

· PCR: Technique used to generatecopies of a DNA fragment

· Southern blot : Screeningprocedure used to assay DNA fragments

· RFLPs : DNA fragments generatedby restriction enzymes that vary in length betweenindividuals

· Northern blot : Screeningprocedure used to assay mRNA fragments

· Electrophoresis Movement ofmacromolecules in an electrical field

Answer

A.

Screening procedure used toassay DNA fragments

B.

Movement ofmacromolecules in an electrical field

C.

Screening procedure used toassay mRNA fragments

D.

DNA fragments generated byrestriction enzymes that vary in length betweenindividuals

E.

Technique used to generatecopies of a DNA fragment

A gene mutates, and theprotein produced has a novel way of interacting with the cell, andcreates a new phenotype because of this new functionality. This iscalled

Answer

· pleitropy

· locus heterogeneity

· allelic heterogeneity

· dominant negative mutation

· gain of function dominant mutation

Question 62

Mutations in the somaticchromosomes may be inherited by the next generation.

Answer

· True

· False


A degenerate PCR primer withmany variant sequences must be used to make multiple copies of agene

Answer

· if only the protein sequence of the gene productis known to construct the primers

· if the DNA you are using is cDNA to constructthe primers

· if the DNA you are using is genomic DNA to becopied

· if the DNA you are trying to copy iscDNA

· if the vector is prokaryotic and the transformedcell is eukarytotic

Question

Please select the best matchfor each term.

Answer

· Restriction enzyme


· PCR C

· Plasmid

· YAC A

· Dideoxynucleotide

Answer

A.

Endonuclease isolated frombacteria

B.

Eukaryotic cloningvector

C.

Method for amplification ofDNA sequences

D.

Small circular fragment ofDNA

E.

Molecule used in DNAsequencing

Question

A couple goes on MauryPovitch, and the results are in: you are not the father. But noother man impregnated the female (granted, unlikely for a MauryPovitch guest, but work with me here) and he must be the father.DNA analysis claims otherwise, though the child definitely wasmom's (poor thing). What may be going on here?

Answer

· the child is parthenogenic because the motheractually impregnated herself like a shark, and the child's DNA isall mom's

· the child had a mutation that changed the genethat is used to trace paternity

· the child is a mosaic because he is actually a setof twins fused early during fetal development, and therefore camefrom 2 eggs and 2 sperm

· the dad may have germ-line mosaicism, meaning thatthe genotype of his sperm is different from his somaticgenotype

· mitochondrial DNA only comes from mom, so there isno way to tell whobthe baby's father is




13. The arms of a human and the wing of a bat are _________________ structures, composed of the same bones that have been modified for different functions.

a. analogous
b. vestigial
c. homologous
d. convergent

14. Xeroderma pigmentosum is an autosomal recessive genetic disorder. People who are homozygous for the disease-causing allele have skin that is damaged by exposure to ultraviolet radiation; this can lead to skin cancer at an early age. The mutation that causes this disorder is in a gene that functions:

a. to repair DNA by excising (removing) nucleotides damaged by UV light.
b. in lysosomes, to break down lipids that otherwise accumulate in the nervous system.
c. to produce the UV blocking pigment melanin in the skin cells
d. in red blood cells to carry oxygen to the skin.

15. The Amish are a religious sect descended from a small group of colonists who came to the United States over 200 years ago. Their religious beliefs have kept them isolated from society. The Amish have a much higher than average incidence of both polydactyly (extra fingers and toes) and dwarfism in their communities. This is most likely explained by:

a. inheritance of acquired characters.
b. the founder effect.
c. disruptive selection.
d. natural selection.

16. In the structure of DNA that Watson and Crick proposed, the sides of the "ladder" of the DNA molecule are always the same distance apart, making the molecule a constant width. This occurs because when the bases hydrogen bond to form the rungs of the "ladder", a:

a. purine always pairs with a pyrimidine.
b. purine always pairs with a purine.
c. pyrimidine always pairs with a pyrmidine.
d. The structure of the double helix is not determined by how the bases pair.

17. The RNA transcript of DNA that travels to the cytoplasm, carrying the instructions to make a protein, is called:

a. rRNA.
b. tRNA.
c. mRNA.
d. RNA polymerase.

18. When DNA is replicated, the error rate is approximately one error for every 10,000 nucleotides copied. However, that error rate is reduced to only 1 error for every 1 billion nucleotides. The DNA sequence is "corrected" by:

a. repeating S phase to see if the error rate is lower the second time around.
b. enzymes that proofread the DNA and repair errors.
c. messenger RNA during the process of transcription.
d. Any errors made during DNA replication cannot be corrected. If errors are detected after S phase, the cell is destroyed.

19. Mendel's principle of segregation says that:

a. when gametes are formed, each gamete receives only one allele for a particular gene.
b. some genes are dominant to others.
c. a testcross must be used to determine the genotype of an organism with a dominant phenotype.
d. all of the above

20. Tay-Sachs disease is lethal before reproductive age, but the allele persists in Louisiana French Canadians because:

a. it is a dominant allele.
b. new mutations causing this disease are common in that population.
c. it is not expressed in the phenotype of heterozygous individuals.
d. the disease is contagious and can be transmitted by nonheritable means.

21. Physical features that are similar in organisms which are not closely related to each other are most likely a result of ____________. A good example of this is the similarities seen between some marsupial and placental mammals.

a. natural selection.
b. adaptation to similar environments
c. convergent evolution
d. All of the above phrases can be used to correctly fill this blank.

22. In humans, which of the following sex chromosome compliments could be found in males?

a. XY
b. XX
c. Y

23. The proteins that are associated with eukaryotic chromosomes:

a. help to package the DNA within the nucleus.
b. are involved in gene expression, through binding with the DNA.
c. may be replicating or transcribing the DNA.
d. All of these are true of proteins that are associated with eukaryotic chromosomes.

24. A sequence of DNA nucleotides that contains the information to produce a single protein is a(n):

a. codon.
b. gene.
c. polypeptide.
d. anticodon.