Exam 2 BE 359

Splice sites in pre-mRNA are marked by two universally conserved sequences located

at the ends of introns.

The ability of DNA to denature is important for which process?

DNA synthesis

nucleic acid hybridization experiments

RNA synthesis

All of the above

All of the above

A mobile genetic sequence that is transcribed to RNA and then reverse transcribed to DNA during transposition

Retrotransposon

microRNAs play a key role in which of the following?

translational repression

Viral rna degradation

Rna interference

All of the above

All of the above

A repeated sequence at the end of a chromatid that protects the chromosome from enzymatic degradation

Telomere

There are four basic molecular processes in a cell, three of which lead to the production of protein. Which of the following shows the correct order?

transcription, RNA processing, translation

Splicing joins

Two exons sequences

In biology the central dogma refers to:

DNA to RNA to protein.

Blood samples were retrieved from a crime scene, and three suspects were arrested on suspicion of committing the crime. Which of the following techniques is likely to be used to identify the suspect(s) responsible for crime?

DNA fingerprinting and polymerase chain reaction

In DNA, which of the following base pairing normally occurs between two strands of DNA?

T to A

Which of the following is a functional element of a plasmid?

Original of replication

drug-resistance gene

polylinker sequence

All of the above

All of the above

The base in the wobble position of a codon

is the 3´ (third) base.

Short micro RNAs (miRNAs)

Are involved in regulation of gene expression

Which of the following series of steps does the polymerase chain reaction follow in order to amplify DNA in a test tube?

DNA denaturation, primer annealing, primer elongation

Which of the following structures interacts with ribosomes?

tRNA

mRNA

rRNA

All of the above

All of the above

In birds, a gene encoding a Ca²⁺-activated K⁺ channel is expressed in auditory hair cells as multiple mRNAs, which encode for proteins that open at different Ca²⁺ concentrations. The Ca²⁺ concentration at which the channel opens allows these cells to respond to different sound frequencies. Which one of the following would explain the appearance of the various isoforms of this particular channel?

Alternative splicing

Why does CRISPRi target Cas9 to the promoter?

to interfere with transcription initiation

Which process involves two transesterification reactions?

Splicing

Which of the following are removed from mRNAs during processing?

noncoding sequences

A cell with a lac operon in the following conditions yields:

+lactose/+glucose

Lac repressor releases and transcription occurs slowly

A polylinker increases the versatility of a DNA plasmid because it contains:

a DNA recognition sequences for several different restriction enzymes

Fully processed messenger RNA with 5′ cap, introns removed by RNA splicing, and a poly(A) tail.

mRNA

~22 bases long, that base-pair extensively, but not completely, with mRNAs, especially over bases 2 to 7 at the 5′ end (the “seed” sequence). This pairing inhibits translation of the target mRNA and targets it for degradation

miRNA

An mRNA precursor containing introns and not cleaved at the poIy(A) site.

pre-mRNA

~22 bases long, that are each perfectly complementary to a sequence in an mRNA. Together with associated proteins, siRNAs cause cleavage of the target RNA, leading to its rapid degradation.

siRNA

Five small nuclear RNAs that function in the removal of introns from pre-mRNAs by RNA splicing, plus two small nuclear RNAs that substitute for the first two at rare introns.

snRNA

These RNAs base-pair with complementary regions of the pre-rRNA molecule, directing cleavage of the RNA chain and modification of bases during maturation of the rRNAs.

snoRNA

This type of RNA functions in the removal of introns from pre-RNAs.

snRNA (small nuclear RNA)

In which of these polymers are the monomers added one at a time?

DNA

rRNA

Protein

All of the above

All of the above

The process by which genes cloned into specialized eukaryotic vectors are introduced into cultured animal cells for transient expression analysis is called:

Transfection

The branch-point A residue involved in lariat formation is part of the

Intron

The most common arrangement of protein-coding genes in bacteria are those where the genes encoding proteins that work together are arranged in a contiguous array of DNA called:

Operon

Nucleotide bases within a single strand of DNA are held together by which of the following bonds?

Phosphodiester

Mobile DNA elements likely contributed to the evolution of higher organisms by the

generation of gene families by gene duplication.

creation of new genes by exon shuffling.

formation of more complex regulatory regions.

All of the above

All of the above

A cell with a lac operon in the following conditions yields:

+lactose/-glucose

Lac repressor releases and transcription occurs quickly

One common difference between meiosis and mitosis is that in meiosis, the end result is:

four cells each having one chromosome.

Which of the following is NOT a functional element required for any eukaryotic chromosome to replicate and segregate correctly?

Kinetochore

All the following statements about complex transcription units are true except:

They are common in bacteria

DNA replication begins at sequences called

Origins

A cell with a lac operon in the following conditions yields:

-lactose/+glucose

Lac repressor binds to operator and blocks transcription

Which of the following is NOT a stage of protein synthesis in either prokaryotes or eukaryotes?

Transcription

All the following statements are true about a nucleosome except:

It is the “string” of the “beads-on-a-string” appearance.

Okazaki fragments are small fragments of DNA that eventually are ligated to form which of the following strands of DNA?

Lagging

Which of the following statement(s) is (are) true of a eukaryotic chromosome?

It is a linear structure.

It consists of a single DNA molecule.

It can contain greater than a billion base pairs of DNA.

all of the above

All of the above

Viruses that use the lytic cycle of growth proceed through five general stages. Which one of the following shows the correct order of three of these stages?

replication, assembly, release

The first stage of protein translation occurs when Met-tRNA_i^Met base pairs with the mRNA being translated in the ribosomal

P-site

Cellular protein synthesis proceeds in which direction?

amino to carboxyl terminus

The export of mRNAs outside the nucleus requires several proteins that are post-translationally modified by:

ubiquitination.