Bio 285 exam 2 questions

The tryptophan operator _______. A: is an allosteric protein B: binds to tryptophan repressor when repressor is bound to tryptophan C: is required for production of mRNA encoded by tryptophan operon D: is important for production for tryptophan repressor

B: Binds to tryptophan repressor when repressor is bound to tryptophan

Distinct characteristics of different cell types in a multicellular organism are produced mainly by the differential regulation of the: A: replication of specific genes B: transcription of genes transcribed by RNA polymerase 2 C: transcription of housekeeping genes D: translation of mRNA E: packing of DNA into nucleosomes in some cells and not others

B: transcription of genes transcribed by RNA polymerase 2

Distinct characteristics of different cell types are produced mainly by differential regulation of: A: replication of specific genes B: transcription of genes transcribed by RNA polymerase 2 C: transcription of housekeeping genes D: translation of mRNA E: packing of DNA into nucleosomes in some cells and not others

B: transcription on genes transcribed by RNA polymerase 2

Which of the following molecules is thought to have arisen first during evolution? A: protein B: DNA C: RNA D: all came to be at the same time

C: RNA

Which is least likely to arise from a point mutation in a regulatory region of a gene? A: changes the time in organism's life during which protein is expressed B: eliminates production of protein in a specific cell type C: changes the subcellular localization of a protein D: increases the level of protein production in cell

C: a mutation that changes the subcellular localization of a protein

RNA in cells differs from DNA in that: A: it contains uracil, which pairs to cytosine B: it's single-stranded and can't form base pairs C: it's single-stranded and can fold up into variety of structures D: nucleotides are linked together in a different way E: ribose contains fewer O atoms than deoxyribose

C: it's single-stranded and can fold up into a variety of structures

Sigma subunit of bacterial RNA polymerase: A: contains catalytic activity of polymerase B: remains part of the polymerase throughout transcription C: recognizes promoter sites in DNA D: recognizes transcription termination sites in DNA

C: recognizes promoter sites in DNA

Which is main reason a eukaryotic gene can respond to greater variety of regulatory signals than prokaryotic gene? A: eukaryotes have 3 types of RNA polymerase B: eukaryotic RNA polymerases require general transcription factors C: transcription of eukaryotic gene can be influenced by proteins that bind far from promoter D: prokaryotic genes are packaged into nucleosomes E: protein-coding regions of eukaryotic genes are longer than prokaryotic genes

C: transcription of eukaryotic gene can be influenced by proteins that bind far from promoter

Which molecule can be used as a probe that will hybridize this DNA sequence: 5'GATTGCAT3' A: 5-GATTGCAT-3 B: 5-TACGTTAG-3 C: 5-CTAACGTA-3 D: 5-ATGCAATC-3

D: 5-ATGCAATC-3

Which is NOT a general mechanism cells use for stable patterns of gene expression as they divide? A: Positive feedback loops B: Faithful propagation of condensed chromatin structures as cells divide C: Inheritance of DNA methylation patterns when cells divide D: Proper segregation of housekeeping proteins when cells divide

D: Proper segregation of housekeeping proteins when cells divide

DNA can be introduced into bacteria by a mechanism called ______. A: transcription B: ligation C: replication D: transformation

D: transformation

Gene repressor proteins can reduce the efficiency of transcription initiation by attracting histone ____

Deacetylases

When a molecule complementary to an miRNA is found, it is then targeted for ______.

Destruction

RNAi is triggered by the presence of foreign ____ molecules, which are digested by the ____ enzyme into shorter fragments approximately 23 nucleotide pairs in length.

Double-stranded RNA, dicer

During transcription in ____ cells, transcriptional regulators that bind to DNA thousands of nucleotides away from a gene's promoter can affect a gene's transcription

Eukaryotic

T or F: All amino acids are specified by more than one codon

False

T or F: All codons specify an amino acid

False

T or F: All codons specify more than one amino acid

False

T or F: Because the two strands of DNA are complementary, mRNA of a given gene can be synthesized using either strand as template

False

T or F: Immediately after DNA replication, each daughter helix contains one methylated DNA strand, which corresponds to the newly synthesized strand

False

T or F: The genetic code is different in prokaryotes and eukaryotes

False

T or F: all mRNAs fold into particular 3D structures that are required for their translation

False

T or F: The Ey transcription factor must bind to the promoter of every eye-specific gene in the fly

False; Ey turns on the transcription of other transcriptional regulators; it's the combined action of the genes directly regulated by Ey and the genes regulated by the regulators that Ey turns on that form the eye

T or F: Introns and transposons tend to slow evolution of new genes

False; Introns and transposons can act as sites where recombinational crossovers occur. Transposons can also catalyze genetic rearrangements. Rearrangements occurring within these sequences are less likely to be detrimental than those occurring elsewhere in genome. In general, only short intron sequences required for splicing are important to intron function; alterations in sequences outside splicing sites may have no consequences for intron function and thus won't be subject to purifying selection

T or F: All highly conserved stretches of DNA in the genome are transcribed into RNA

False; Many highly conserved stretches of DNA aren't transcribed but instead contain information critical for regulating where and when genes are expressed

T or F: Because gene duplication can occur when crossover events occur, genes are always duplicated onto homologous chromosomes

False; Regions of homology between non homologous chromosomes will cause gene duplications onto a different chromosome (as well as chromosome rearrangements)

T or F: most genes in vertebrates are unique, and only a few genes are members of multi gene family

False; a large proportion of the genes in vertebrates (and many other species) are members of multi gene families

T or F: horizontal transfer is very rare and thus has had little influence on the genomes of bacteria

False; by some estimates, 20% of genomic DNA in some bacterial species arose by horizontal gene transfer

T or F: Ribosomes are large RNA structures composed solely of rRNA

False; composed of 2/3 rRNA and 1/3 protein

T or F: Restriction nucleases recognize specific sequences on single-stranded DNA

False; double-stranded DNA

T or F: In southern blotting, single-stranded DNA is separated by electrophoresis

False; double-stranded DNA is loaded onto the agarose gel. The DNA becomes denatured (and thus single-stranded) as it gets transferred by the alkali solution from the gel to the sheet

T or F: To meet a challenge or develop a new function, evolution essentially builds from first principles, designing from scratch, to find the best possible solution

False; evolution can work only by tinkering with the tools and materials on hand, not by starting from scratch to make completely new genes or pathways. New functions arise from ancestral functions by gradual mutational change, thus may not represent the best solution to a problem.

T or F: A ribosome binds one tRNA at a time

False; it can bind 2 at a time, one at P site and one at A site

T or F: nearly every instance of DNA duplication leads to a new functional gene

False; many duplications are subsequently lost or become pseudogenes, and only a few evolve into new genes

T or F: a mutation that arises in a mothers somatic cell often causes a disease in her daughter

False; only mutations in gametes are passed on to progeny

T or F: Ribosomes are synthesized entirely in the cytoplasm

False; ribosomes are synthesized in the nucleolus

T or F: A ribosome consists of two equally sized subunits

False; ribosomes have a smaller and larger subunit

T or F: The Lac repressor binds when lactose is present in cell

False; the Lac repressor binds when lactose is not present in the cell

T or F: miRNAs are produced from rRNAs

False; they are produced from DNA

Sometimes, many contiguous genes can become transcriptionally inactive as a result of chromatin remodeling, like the ____ found in interphase chromosomes

Heterochromatin

The ____ is a complex of proteins that links distantly bound transcription regulators with the proteins bound closer to transcriptional start site.

Mediator

MicroRNAs are noncoding RNAs that are incorporated into a protein complex called ____, which searches the ____ in the cytoplasm for sequence complementary to that of the miRNA.

RISC, mRNA

T or F: A homolog of Ey is found in vertebrates; this homolog is also used during eye development

True

T or F: A labeled DNA probe binds to the DNA by hybridization

True

T or F: A new RNA molecule can begin to be synthesized from a gene before previous RNA molecules synthesis is complete

True

T or F: Appropriate inheritance of DNA methylation patterns involves maintenance methyltransferase

True

T or F: DNA methylation involves a covalent modification of cytosine bases

True

T or F: Duplicated genes can diverge in both their regulatory regions and their coding regions

True

T or F: Even when CAP activator is bound to DNA, if no lactose is present, the Lac operon won't be transcribed

True

T or F: Expression of Ey in cells that normally form legs in the fly will lead to formation of an eye in the middle of the legs

True

T or F: Methylation of DNA attracts proteins that block gene expression

True

T or F: Not all duplicated genes will become functional members of gene families

True

T or F: One miRNA can regulate the expression of many genes

True

T or F: Positive feedback loops ensure that Ey expression remains switch on in the developing eye

True

T or F: Some bacteria use restriction nucleases as protection from foreign DNA

True

T or F: Some restriction nucleases cut in a staggered fashion, leaving short single-stranded regions of DNA at the ends of the cut molecule

True

T or F: Southern blotting involves the transfer of DNA molecules from gel onto nitrocellulose or nylon paper

True

T or F: The CAP activator can only bind DNA when it's bound to cAMP

True

T or F: The DNA that is separated on a gel in southern blotting is not labeled

True

T or F: The Lac operon only produces RNA when lactose is present and glucose is absent

True

T or F: The genetic code is redundant

True

T or F: Whole genome duplication can contribute to formation of gene families

True

T or F: a reproducible set of DNA fragments are produced every time a restriction nuclease digests a known piece of DNA

True

T or F: miRNAs are transcribed in nucleus from genomic DNA

True

T or F: Proteins required for growth, metabolism, and cell division are more highly conserved than those involve in development and in response to environment

True; All organisms need to perform similar basic set of fundamental functions. Proteins involved in these are shared by descent, and their evolution is constrained. Different species and cells are likely to require different developmental paths and to encounter different environmental challenges, so proteins involved in these processes will be more variable

T or F: miRNAs are made by RNA polymerase

True; it is usually RNA polymerase 2

T or F: Most mutations and genome alterations have neutral consequences

True; most genomic changes don't alter amino acid sequence of proteins or the regulatory proteins of genes. Even some mutations that cause minor alterations have little effect on protein function.

T or F: a pseudogene is very similar to a functional gene but cannot be expressed because of mutations

True; pseudogenes look very similar to normal genes but cannot produce a full-length protein, as a result of one or more disabling mutations

T or F: rRNA contains the catalytic activity that joins amino acids together

True; rRNA catalyzes the peptidyl transferase reaction that takes place on the ribosome (attaches adjacent amino acids)

T or F: To find functionally important regions of genome, it's more useful to compare species whose last common ancestor lived 100 million years ago rather than 5 million years ago

True; species that diverged recently have many identical stretches of DNA sequence by chance, whereas sequence similarity between species that diverged long ago is probably due to functional constraints. Sequences that are necessary to preserve the function of the gene won't be able to undergo changes and thus are more likely to be similar between species that diverged long ago

During gel electrophoresis, DNA fragments ________. A: travel through a matrix containing a microscopic network of pores B: migrate toward a negatively charged electrode C: can be visualized without stains or labels D: are separated on basis of their sequence

A: travel through a matrix containing a microscopic network of pores

Transcriptional activators can interact with histone _____, which alter chromatin by modifying lysine's in the tail of histone proteins to allow greater accessibility to underlying DNA

Acetylases