Deck 4: Molecular Biology

Question 1

Which of the following statements is TRUE concerning mRNA?

A)mRNA has a very short half-life.
B)mRNA has complex secondary structure.
C)mRNA is catalytic.
D)mRNA is the product of translation.

Answer 1

A

Question 2

AT-rich DNA will denature/melt

A)at a higher temperature than GC-rich DNA.
B)at a lower temperature than GC-rich DNA.
C)usually at the same temperature as GC-rich DNA,with some minor variations.
D)in accordance with the animal or plant from which it was taken.

Answer 2

B

Question 3

The template for RNA polymerase is ________,and the new RNA chain is ________ to the template.

A)an independent RNA segment / parallel and identical
B)DNA / antiparallel and complementary
C)an independent RNA segment / antiparallel and complementary
D)DNA / parallel and identical

Answer 3

B

Question 4

An example of correct nucleotide pairing is

A)T and U.
B)G and U.
C)A and T.
D)C and U.

Question 5

Supercoiling is important for DNA structure,because

A)it holds together the antiparallel strands of DNA in the double helix.
B)it provides energy for transcription.
C)it condenses the DNA so that it can fit inside the cell.
D)it prevents RNA from pairing with DNA in the double helix.

Question 6

Stop codons are also called ________ codons.

A)nonsense
B)release factor
C)degeneracy
D)conversion

Question 7

Transfer RNA molecules

A)function to transfer ribonucleotides to RNA polymerase during transcription.
B)function to transfer the correct amino acids to the ribosome during translation.
C)contain codons that bind to ribosomes during translation.
D)are only present in the nucleus or eukaryotes.

Question 8

DNA replication always proceeds in only one direction because the ________ of the incoming nucleotide is attached to the free ________ of the growing DNA strand.

A)5'-phosphate / 3'-hydroxyl
B)3'-phosphate / 5'-hydroxyl
C)5'-deoxyribose / 3'-base
D)3'-base / 5'-deoxyribose

Question 9

Many pharmaceutical drugs specifically inhibit transcription in Bacteria but not Archaea or Eukarya.Why would drugs that inhibit transcription only affect Bacteria and not Archaea even though they are both prokaryotes?

A)Archaea and Eukarya have very similar ribosomes that are different than bacterial ribosomes.
B)Bacteria lack a nucleus.
C)Archaea lack operons.
D)Archaea and Eukarya have very similar RNA polymerases that are different than bacterial RNA polymerases.

Question 10

The precursor of each new nucleotide in a strand of DNA is a

A)deoxynucleoside 5'-diphosphate.
B)deoxynucleoside 3'-diphosphate.
C)deoxynucleoside 5'-triphosphate.
D)deoxynucleoside 3'-triphosphate.

Question 11

In the process of transcription,promoters are specific sequences of ________ that are recognized by ________.

A)DNA / DNA polymerase
B)RNA / DNA polymerase
C)DNA / sigma factors
D)RNA / ribosomes

Question 12

Genes that encoded for polymerases,gyrases,ribosomal proteins,and other proteins essential to replication,transcription,and translation are present on

A)chromosomes.
B)plasmids.
C)chromosomes and plasmids.
D)neither chromosomes nor plasmids.

Question 13

The Tat system is involved in

A)protein synthesis.
B)transcriptional initiation.
C)protein folding.
D)protein secretion.

Question 14

In all cells,genes are composed of

A)nucleic acids.
B)mRNA.
C)proteins.
D)chaperones.

Question 15

Which statement is TRUE regarding protein synthesis?

A)Ribosomal proteins catalyze peptide bond formation in the growing polypeptide chain.
B)The 23S rRNA catalyzes peptide bond formation in the growing polypeptide chain.
C)Transfer RNAs catalyze peptide bond formation in the growing polypeptide chain.
D)Messenger RNA catalyzes peptide bond formation in the growing polypeptide chain.

Question 16

The functional unit of genetic information is the

A)nucleotide.
B)gene.
C)chromosome.
D)protein.

Question 17

tRNA is released from the ribosome at the ________ site.

A)P
B)A
C)R
D)E

Question 18

How are plasmids different than chromosomes?

A)Plasmids are always small,linear pieces of DNA.
B)Plasmids are composed of single-stranded DNA.
C)Plasmids contain genes that are NOT essential for cellular growth and replication.
D)Plasmids carry unimportant genes that are of little significance for the ecology and metabolism of an organism.

Question 19

Which of the following is formed on the lagging strand during DNA synthesis?

A)DNA secondary structures
B)Okazaki fragments
C)RNA polymerase
D)replisomes

Question 20

DNA-binding proteins interact predominantly within which portion of a double-stranded DNA helix?

A)major groove
B)minor groove
C)3' end
D)supercoil

Question 21

The codon on the ________ matches with the anticodon on the ________ to direct the addition of the correct amino acid to the growing polypeptide chain.

A)mRNA / tRNA
B)tRNA / mRNA
C)DNA / mRNA
D)tRNA / rRNA

Question 22

Which of the following is NOT correct regarding DNA and RNA synthesis?

A)The overall direction of chain growth is from the 5' to 3' end.
B)Both processes require an RNA primer to begin.
C)The template strand is antiparallel to the newly synthesized strand.
D)DNA is the template for both DNA and RNA synthesis.

Question 23

The structure and function of a protein are determined by its ________ sequence.

A)nucleotide
B)amino acid
C)ribonucleotide
D)translocation

Question 24

Transcription of chaperonins is greatly accelerated when a cell is stressed by

A)excessive osmotic pressure.
B)extremes in pH value.
C)lack of oxygen.
D)excessive heat.

Question 25

Termination of RNA synthesis is ultimately determined by

A)exhaustion of RNA polymerase activity.
B)special protein factors.
C)terminases.
D)specific nucleotide sequences on the template strand.

Question 26

DNA replication is started with a(n)________,which,in most cases,in vivo is a short stretch of ________.

A)promoter / DNA
B)mRNA / RNA
C)primer / RNA
D)ribosome-binding sequence / DNA

Question 27

Transposable elements are

A)segments of DNA that move from one site to another.
B)transcribed genes.
C)segments of RNA that are involved in transposing DNA into proteins.
D)proteins that aid in the secretion of enzymes out of the cell.

Question 28

In all cells a gene encodes for

A)a protein (via mRNA).
B)a tRNA.
C)an rRNA.
D)a protein,tRNA,or rRNA depending on the specific gene.

Question 29

In Bacteria,a chromosome can be distinguished from a plasmid,because a chromosome is a genetic element that

A)is circular.
B)is linear.
C)encodes for essential functional genes.
D)replicates via a bidirectional fork.

Question 30

An operon is a useful genetic element,because it

A)encourages the binding of RNA polymerase.
B)allows coordinated expression of multiple related genes in prokaryotes.
C)translates DNA sequence into amino acid sequence.
D)encourages the binding of ribosomes in the correct location.

Question 31

The function of RNA polymerase is to

A)catalyze the formation of phosphodiester bonds between deoxyribonucleotids.
B)catalyze the formation of phosphodiester bonds between ribonucleotides.
C)cleave mRNA to remove introns.
D)activate tRNAs.

Question 32

The flow of biological information begins with

A)DNA replication.
B)RNA transcription.
C)mRNA translation.
D)transcriptional regulation.

Question 33

DNA participates in protein synthesis through

A)cyclic messengers.
B)direct pairing with amino acids.
C)an RNA intermediate.
D)protein folding.

Question 34

The function of the DNA polymerase is to catalyze

A)the addition of deoxynucleotides.
B)the formation of RNA primers.
C)the addition of ribonucleotides.
D)hydrogen bonding between complementary base pairs.

Question 35

The two strands of the DNA double helix are held together by

A)5' to 3' attraction.
B)hydrogen bonds between nucleotide bases.
C)codons.
D)peptide bonds between nucleotide bases.

Question 36

In complementary base pairing of DNA,adenine pairs with ________ (or ________ in RNA)and cytosine always pairs with ________.

A)guanine / uracil / thymine
B)uracil / thymine / guanine
C)thymine / guanine / uracil
D)thymine / uracil / guanine

Question 37

Polycistronic transcription units are common in

A)Archaea.
B)Bacteria.
C)Eukarya.
D)both Archaea and Bacteria.

Question 38

Which of the following is an example of one codon?

A)CATT
B)GCCATT
C)CAG
D)CCGUAA

Question 39

Plasmids often encode for proteins

A)involved in translation.
B)required for cellular growth.
C)that confer resistance to antibiotics.
D)involved in DNA replication.

Question 40

GTP provides energy for

A)transcription.
B)translation.
C)DNA replication.
D)protein folding.

Question 41

In nature,the predominant form of DNA is supercoiled in a negative direction.

Question 42

DNA replication is bidirectional in prokaryotes with circular chromosomes.

Question 43

Inverted repeats are common features of transcription termination sequences in all three domains of life.

Question 44

Proteins known as chaperones are found only in Bacteria.

Question 45

Transcription in eukaryotes occurs in the

A)RNA polymerase.
B)endoplasmic reticulum.
C)cytoplasm.
D)nucleus.

Question 46

rRNA has an enzymatic role in all stages of protein synthesis.

Question 47

A triplet of bases on an mRNA molecule is known as a(n)

A)amino acid.
B)anticodon.
C)codon.
D)ribosome-binding sequence.

Question 48

During DNA replication Okazaki fragments are linked together by________,an enzyme that creates phosphodiester bonds between nicked fragments of DNA.

A)exopolymerase
B)DNA gyrase
C)topoisomerase
D)DNA ligase

Question 49

Aminoacyl-tRNA synthetase catalyzes the reaction between the appropriate amino acid and ATP to form an activated amino acid: amino acid + ATP ↔ aminoacyl-AMP + P-P.

Question 50

Each adenine-thymine base pair has ________ hydrogen bonds,while each guanine-cytosine base pair has ________ hydrogen bonds.

A)two / one
B)two / three
C)four / three
D)three / two

Question 51

The formation of new DNA does NOT require energy.

Question 52

You experimentally change the DNA sequence directly upstream of a start codon of an operon in E.coli to investigate the function of this region of DNA.Analysis reveals that after the change the same amount of mRNA is made from the operon,but there are very few proteins made from the operon.What is the most likely function of the DNA sequence that you changed?

A)The DNA sequence likely functions as a ribosome-binding site.
B)The DNA sequence likely functions as a promoter.
C)The DNA sequence likely functions as a termination sequence.
D)The DNA sequence likely functions as in transcriptional regulation.

Question 53

Genes found on plasmids DO NOT impact metabolism or cellular structures.

Question 54

You are studying a protein in Salmonella typhimurium that you believe is a toxin.Whenever you attempt to purify the protein from lysed cell cultures,you get two forms of the protein.One form is smaller than the other and is missing 15 amino acids from the N-terminus compared to the larger form.This leads you to hypothesize that

A)there are two termination sites in the mRNA.
B)the protein requires chaperonins to fold properly.
C)the protein is secreted and folds outside of the cell.
D)you need to re-do the experiment because there should only be one form.

Question 55

Most prokaryotic genomes are double-stranded circular DNA.

Question 56

RNA acts at both the genetic and the functional levels.

Question 57

The genetic material in a virus is technically called a plasmid.

Question 58

RNA is incapable of forming secondary structure.

Question 59

In DNA replication there are leading and lagging strands,because

A)DNA replication is conservative and a completely new DNA molecule must be made.
B)DNA replication is semiconservative and each strand is copied simultaneously in opposite directions.
C)the strands of DNA are parallel and are copied in the same direction simultaneously.
D)one strand of DNA is copied faster than the other.

Question 60

In ________ several ribosomes can simultaneously translate a single mRNA molecule in a complex called a(n)________.

A)prokaryotes / polysome
B)eukaryotes / polysome
C)prokaryotes / initiation complex
D)eukaryotes / splicing complex

Question 61

Discuss how the initiation of DNA synthesis occurs in bacteria using the terms origin of replication,replication fork,and theta structures.

Question 62

You are trying to design a protein that will be expressed in Escherichia coli and secreted outside of the cell for purification and use as a pharmaceutical.E.coli is a gram-negative cell and the protein folds after it has exited the cell.Which secretion system would work best for this project? Support your answer with evidence based on the properties of E.coli,the protein,and the secretion system.

Question 63

DNA replication involves the synthesis of an RNA primer on one strand of the DNA.

Question 64

Explain the difference between transcription and translation and how the processes differ in bacteria and eukaryotes.

Question 65

Speculate on why it can be problematic to copy and express genes from Bacteria into Eukarya.

Question 66

Explain the function of the helicases and why they are necessary.

Question 67

Explain the process of RNA transcription using the terms upstream,Pribnow box,and consensus sequence.

Question 68

Explain the difference between an intrinsic terminator and a Rho-dependent termination site.

Question 69

Is the following statement TRUE or FALSE? Explain why you think so.
"Proteins are the only biomolecules capable of catalyzing bond formation."

Question 70

Explain the concept of semiconservative replication and how simultaneous copying of both strands of DNA is accomplished in prokaryotic cells.

Question 71

You isolate a piece of DNA from a microorganism you cultivated from your teeth.The piece of DNA is 94 kbp is size and is circular.You sequence it and discover that it contains genes for capsule formation,pili,and antibiotic resistance,as well as an origin of replication.What is this piece of DNA and how is it related to the other genetic elements found in prokaryotic cells?

Question 72

Explain the role of sigma factors in RNA synthesis in Bacteria.

Question 73

Some essential genes and DNA sequences in cells DO NOT encode for proteins but are still essential for cellular growth and replication.Give two examples of a gene or sequence of which this is true and explain why it is essential for growth or replication.

Question 74

Describe protein synthesis in terms of initiation,elongation,and termination/release.

Question 75

Throughout the living world,the genetic code is generally universal; however,there are slight variations.

Question 76

Speculate why the half-life of mRNA is short,while the half-lives of rRNA and tRNA are long.

Question 77

Explain how Escherichia coli can grow with a doubling time of 20 minutes when chromosome replication takes 40 minutes.

Question 78

What is the basic flow of genetic information in all cellular life? Include in your answer a diagram that illustrates the relationships between the basic components and steps in the flow of genetic information.

Question 79

How is an open reading frame (ORF)identified and used to determine the sequence of amino acids in the gene it encodes for?

Question 80

The following is the sequence of bases in the sense strand of a DNA segment and contains the beginning of a gene.
DNA 3' A T A T T A C C A G G C A T G G A C C C C C G G G 5'
Based on this sequence,write the sequence of the anti-sense DNA strand and the mRNA.Label the 5' and 3' ends in your predicted sequences.The start codon in this organism is AUG.Indicate where the start codon is in your sequence.Why is the start codon important? Why does there have to be a specific start codon?