GENETICS EXAM 3 UH LIN/DAANE

1.) In bacterial inducible gene regulation, a small molecule inducer binds to a repressor and...

A) prevents it from binding to DNA.

B) helps it bind to DNA.

C) inhibits gene transcription.

D) prevents RNA polymerase from binding to the promoter.

E) increases its binding to cAMP.

A) prevents it from binding to DNA.

2.) Which of the following is NOT a mechanism of gene regulation in bacteria?

A) Regulatory proteins can bind to DNA and decrease transcription.

B) Proteins or RNAs can bind to mRNA and prevent translation.

C) Modifications of their protein products can alter their functions.

D) Regulatory proteins can bind to DNA and increase transcription.

E) 5' capping of RNA can regulate their stability and translation.

E) 5' capping of RNA can regulate their stability and translation.

3.) *For a repressible gene in bacteria, the binding of a small molecule corepressor to a repressor...

A) prevents it from binding to DNA.

B) helps it bind to DNA.

C) inhibits gene transcription.

D) prevents RNA polymerase from binding to the promoter.

E) two of the above

E) two of the above

4.) What type of molecule is the lac repressor?

A) DNA

B) RNA

C) Protein

D) Sugar

E) Lipid

C) Protein

5.) What type of molecule is the lac operator?

A) DNA

B) RNA

C) Protein

D) Sugar

E) Lipid

A) DNA

6.) Which small molecule functions as the inducer which binds the lac repressor in the regulation of the lac operon?

A) cAMP.

B) GTP

C) ATP

D) Galactose

E) Allolactose

E) Allolactose

7.) How does glucose play a role in regulating the lac operon?

A) High glucose increases intracellular cAMP levels and activates CAP.

B) High glucose decreases intracellular cAMP levels and activates CAP.

C) Low glucose increases intracellular cAMP levels and activates CAP.

D) Low glucose decreases intracellular cAMP levels and activates CAP.

E) None of the above.

C) Low glucose increases intracellular cAMP levels and activates CAP.

8.) Under which of the following conditions will the lac operon have the highest expression?

A) Glucose present, lactose absent

B) Glucose present, lactose present

C) Glucose absent, lactose absent

D) Glucose absent, lactose present

E) None of the above

D) Glucose absent, lactose present

9.) In multicellular eukaryotic organisms, what distinguishes one cell type from another (example: skin vs. liver cells)?

A) The genotype of parents

B) The phenotype of parents

C) Extranuclear DNA

D) Differences in gene regulation, including which genes are expressed or not expressed

E) Which X chromosome is inactivated

D) Differences in gene regulation, including which genes are expressed or not expressed

10.) Which of the following is NOT a mechanism of gene regulation in eukaryotes?

A) Regulatory proteins can bind to DNA and decrease transcription.

B) 5' capping of RNA can regulate their stability and translation.

C) Modifications of their protein products can alter their functions.

D) Regulatory proteins can bind to DNA and increase transcription.

E) All of the above are gene regulation mechanisms in eukaryotes.

E) All of the above are gene regulation mechanisms in eukaryotes.

11.) Please select the correct matches of regulatory proteins and their corresponding regulatory elements/sequences in eukaryotes:

A) Activators - Silencers

B) Activators - Enhancers

C) Repressors - Silencers

D) Repressors - Enhancers

E) Two of the above are correct

E) Two of the above are correct

12.) What is the role of the Mediator protein in eukaryotic gene regulation?

A) It mediates the binding of the spliceosome.

B) It mediates the interaction between transcription factors bound to regulatory sequences and the general transcription factors and RNA polymerase in the promoter region.

C) It mediates the synthesis of RNA in 5' to 3' direction.

D) It mediates the binding of mRNA to the ribosome to initiate translation by placing the initiator tRNA in the P site with the start codon.

E) None of the above

B) It mediates the interaction between transcription factors bound to regulatory sequences and the general transcription factors and RNA polymerase in the promoter region.

13.) Regulation of glucocorticoid receptor and its transcriptional activity by the steroid glucocorticoid hormone is an example of which type of transcription factor regulatory mechanisms in eukaryotes?

A) Small molecule effectors

B) Protein-protein interactions

C) Covalent modification

D) Negative feedback

E) Attenuation

A) Small molecule effectors

14.) Chromatin remodeling in eukaryotes can result in what type of changes to the chromatin?

A) Change in the position of nucleosomes

B) Eviction of histone octamers

C) Change in the histone composition of nucleosomes

D) Makes the DNA more or less amenable to transcription

E) All of the above

E) All of the above

15.) The histone code refers to...

A) how specific histones code for codons.

B) combinations of different histone modifications and their consequences on chromatin structure.

C) the code that determines which histone is expressed.

D) the order in which histones are assembled to form nucleosomes.

E) None of the above

B) combinations of different histone modifications and their consequences on chromatin structure.

16.) Acetylated histones are associated with which effect on gene transcription?

A) Increase in transcription

B) Decrease in transcription

C) Increase in transcription termination

D) Decrease in transcription termination

E) Increase in splicing

A) Increase in transcription

17.) Transcripts are categorized as non-coding RNAs based on which of the following characteristics?

A) They do not code for proteins but rather function as RNAs.

B) They are not encoded by a DNA sequence, hence the name.

C) They use a different genetic code and codons than mRNAs.

D) They interfere with the interaction between codons and tRNA anticodons.

E) All of the above.

A) They do not code for proteins but rather function as RNAs.

18.) Non-coding RNAs can carry out their functions by interacting with which of the following types of molecules?

A) DNA

B) RNA

C) Protein

D) Small molecule/chemical compound

E) All of the above.

E) All of the above.

19.) Which of the listed examples below demonstrates that RNA can function as an enzyme?

A) Group I and II self-splicing introns

B) Ribosomal RNA catalyzing the formation of peptide bonds during protein synthesis

C) Cutting of target DNA sequence by CRISPR RNA

D) 3' to 5' exonuclease activity of RNA polymerase

E) Two of the above

E) Two of the above

20.) According to the RNA World theory on the origin of the molecular components and mechanisms of life, ...

A) RNA contained genetic information and catalyzed chemical reactions in protobionts.

B) RNA was the only molecule when the first cells formed.

C) RNA was the earliest molecule found on the planet.

D) First proteins were made with RNA nucleotides instead of amino acids.

E) RNA was the energy source used by protobionts.

A) RNA contained genetic information and catalyzed chemical reactions in protobionts.

21.) What is the natural function of the CRISPR-Cas system in bacteria?

A) Regulate mRNA stability

B) Defend against bacteriophage infection

C) Induce the expression of genes involved in sugar metabolism

D) Limit DNA damage and activate repair

E) Activate transcription of non-coding RNAs

B) Defend against bacteriophage infection

22.) Which part of the CRISPR locus in the bacterial chromosome contains the "collected" bacteriophage sequences?

A) Repeats

B) Spacers

C) Cas1

D) tracr

E) Cas9

B) Spacers

23.) CRISPR-Cas technology is used in genetic engineering and biotechnology for which specific purposes?

A) Edit gene sequences

B) Inactivate genes

C) Prevent homologous recombination

D) Improve existing drugs

E) Two of the above

E) Two of the above

24.) What is the function of the Cas9 protein in the CRISPR-Cas system?

A) Cut the CRISPR RNA

B) Cut the TRACR RNA

C) Cut the target DNA

D) Bind mediator proteins to enhance transcription

E) Stabilize RNA polymerase binding to promoters

C) Cut the target DNA

25.) Mutations can have both positive and negative consequences for gene function and the evolution of organisms. True or False?

A) True

B) False

A) True

26.) It is possible for mutations to have no effect on the amino acid sequences of resulting proteins. These are known as nonsense mutations. True or False?

A) True

B) False

B) False

27.) (HAS AN IMAGE) The wild-type mRNA has the following sequence at the beginning of the coding region (the codons are shown, including the start codon):

AUG GCC GGA CUU UUU GCC

Which of the following is the resulting amino acid sequence if an A is inserted between the first and the second codons (use the Genetic Code table included in the exam)?

A) Met, Ala, Gly, Leu, Phe, Ala

B) Met, Ser, Arg, Thr, Phe, Cys

C) Met, Gly, Ala, Phe, Cys, Pro

D) Met, Thr, Ala, Gly, Leu, Lys

E) Can't determine using the information given.

B) Met, Ser, Arg, Thr, Phe, Cys

28.) (HAS AN IMAGE) An important enzymatic protein isolated from Drosophila melanogaster was shown to have the following initial sequence of amino acids:

Wildtype: Lys - Ser - Pro - Trp - His - . . . . . .

Following exposure to x-rays, a series of mutant flies developed, each of which lacked normal activity for this enzyme. One of the mutant enzymes was isolated and displayed the following amino acid sequence:

Mutant: Lys - Arg - Pro - Trp - His - . . . . . .

What is the likely mutation which led to the observed amino acid sequence for the mutant (use the Genetic Code table included in the exam)?

A) Transition of the third base in the second codon.

B) Transversion of the third base in the second codon.

C) Insertion of the third base in the second codon.

D) Deletion of the third base in the second codon.

E) Methylation of the third base in the second codon.

B) Transversion of the third base in the second codon.

29.) Which type of mutation is the most likely to give rise to a new allele for a gene?

A) Silent

B) Nonsense

C) Frameshift

D) Missense

E) Common sense

D) Missense

30.) What is a possible consequence of mutation within the enhancer region of a eukaryotic gene if the activator protein is no longer able to bind?

A) There is a decrease in transcription.

B) There is an increase in transcription.

C) A different amino acid will be added to the resulting protein.

D) A codon for an amino acid in the gene will be converted into a stop codon.

E) The reading frame will be shifted in the resulting mRNA during translation.

A) There is a decrease in transcription.

31.) For organisms which use photolyase to repair thymine dimers, what is the source of energy used to break the bonds which form the dimers?

A) Light

B) ATP

C) GTP

D) cAMP

E) Allolactose

A) Light

32.) Alkylation of DNA can affect DNA replication and transcription. How do cells repair such damages?

A) These damages cannot be repaired and the cell dies.

B) These damages are also repaired by photolyase.

C) These damages can be directly reversed by alkyltransferase enzymes which remove the alkyl group.

D) Nothing is done to repair this type of damage. Alkylated DNA has no effect on replication or transcription.

E) Nothing is done to repair this type of damage since they help give rise to new genetic variation and alleles, and this is actually beneficial to the cell.

C) These damages can be directly reversed by alkyltransferase enzymes which remove the alkyl group.

33.) Biotechnology using the knowledge and tools of molecular genetics have resulted in genetically modified organisms which make products that benefit mankind. The creation and use of GMOs can be problematic or controversial because of...

A) safety concerns.

B) the difficulties in creating GMOs.

C) negative public perceptions.

D) the poor performance of GMOs in delivering the promised products.

E) Two of the above

E) Two of the above

34.) Recombinant bacteria have been engineered to produce human insulin. Which of the following is the strategy used to do so?

A) The A and B chains of insulin are expressed separately in bacteria and then purified and combined to allow proper folding and formation of disulfide bonds to form active insulin.

B) Bacteria are injected with human insulin, which they then copy and mass produce.

C) Special nutrients (sugars) are used to culture the bacteria, and they naturally produce insulin to counteract the increase in sugar levels.

D) Bacteria are fused with human pancreatic β cells which produce insulin. This will allow the recombinant bacteria to produce insulin, like the β cells.

E) Nice try Dr. Lin. Bacteria can't make human proteins.

A) The A and B chains of insulin are expressed separately in bacteria and then purified and combined to allow proper folding and formation of disulfide bonds to form active insulin.

35.) What would be required to express a human protein-coding gene, such as the one that codes for erythropoietin, in bacteria?

A) A bacterial promoter

B) A bacterial terminator

C) Addition of the Shine-Delgarno sequence to the beginning of the gene

D) Removal of intronic sequences

E) All of the above

E) All of the above

36.) A transgenic animal, by definition, has been engineered to...

A) express a gene from another species.

B) convert one gene to another.

C) increase transcription of its genes.

D) decrease transcription of its genes.

E) be immune to infection by bacteriophages.

A) express a gene from another species.

37.) In reproductive cloning of animals, what is transferred from the donor animal to the enucleated egg?

A) The nucleus of its sperm

B) The nucleus from its egg

C) The nucleus from a diploid cell

D) The mitochondria from a diploid cell

E) The X chromosome from a diploid cell

C) The nucleus from a diploid cell

38.) What is the advantage of using nuclei of blood cells collected from the umbilical cord of a baby versus those from adult skin cells for reproductive cloning?

A) Telomeres are longer in cord blood cells.

B) Telomeres are shorter in cord blood cells.

C) The histones are acetylated in cord blood cells.

D) The histones are deacetylated in cord blood cells.

E) None. There is no advantage to using nuclei from one cell type as compared to others.

A) Telomeres are longer in cord blood cells.