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EBIO 1210 Exam 4: Viruses, DNA Replication, and Gene Expression, Exams of Biology

University of Colorado Boulder (CU Boulder)Biology

A comprehensive set of multiple-choice questions and answers covering key concepts in biology, specifically focusing on viruses, dna replication, and gene expression. it's ideal for students preparing for an exam in ebio 1210, offering a valuable review of fundamental biological processes such as viral characteristics, dna structure and replication mechanisms, and the central dogma of molecular biology. The questions delve into the intricacies of these topics, promoting a deeper understanding of the subject matter.

Typology: Exams

2024/2025

Available from 04/20/2025

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EBIO 1210 EXAM 4 QUESTIONS WITH CORRECT ANSWERS
1) What are the defining characteristics of viruses? -- Answer ✔✔ - Particles that
infect cells
- Nucleic acids with protein coats
- Obligate intracellular parasites
- Most have a well-defined host range
- Viruses are NOT considered to be living things.
2) What advantage can a virus gain by having an "envelope" derived from the host?
A) The virus can use the envelope to help in translation of its mRNA
B) The virus can use the envelope to hide from the host's immune system
C) The virus can use the envelope to make its own cells
D) The virus can use the envelope to send itself through the mail to new hosts
E) All of the above -- Answer ✔✔ B. The virus hides from the immune system
**Cannot be C because viruses don't have cells
3) How does a virus do its business? -- Answer ✔✔ 1. Virus enters the cell
2. Cell manufactures viral proteins and copies of virus's genome
3. Virus makes use of the host enzymes, ribosomes, tRNA, amino acids, ATP, etc.
4. Assembly of new viruses
5. New virus particles break out of the cell
4) Two key variables used to classify viruses that infect animals: -- Answer ✔✔ 1.
DNA or RNA?
2. Single or double stranded?
5) How do viruses make you sick? -- Answer ✔✔ 1. Damage or kill cells (with
enzymes)
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Download EBIO 1210 Exam 4: Viruses, DNA Replication, and Gene Expression and more Exams Biology in PDF only on Docsity!

EBIO 1210 EXAM 4 QUESTIONS WITH CORRECT ANSWERS

  1. What are the defining characteristics of viruses? -- Answer ✔✔ - Particles that infect cells
  • Nucleic acids with protein coats
  • Obligate intracellular parasites
  • Most have a well-defined host range
  • Viruses are NOT considered to be living things.
  1. What advantage can a virus gain by having an "envelope" derived from the host? A) The virus can use the envelope to help in translation of its mRNA B) The virus can use the envelope to hide from the host's immune system C) The virus can use the envelope to make its own cells D) The virus can use the envelope to send itself through the mail to new hosts E) All of the above -- Answer ✔✔ B. The virus hides from the immune system **Cannot be C because viruses don't have cells
  2. How does a virus do its business? -- Answer ✔✔ 1. Virus enters the cell
  1. Cell manufactures viral proteins and copies of virus's genome
  2. Virus makes use of the host enzymes, ribosomes, tRNA, amino acids, ATP, etc.
  3. Assembly of new viruses
  4. New virus particles break out of the cell
  1. Two key variables used to classify viruses that infect animals: -- Answer ✔✔ 1. DNA or RNA?
  1. Single or double stranded?
  1. How do viruses make you sick? -- Answer ✔✔ 1. Damage or kill cells (with enzymes)
  1. Cause infected cells to produce toxins
  2. Envelope proteins that are toxic ****However, most symptoms & damage come from your own immune system!!! Apoptosis, inflammation, etc.
  1. Why can't we take antibiotics to successfully cure ourselves of viral infections? A) Viruses evolve resistance too quickly B) Viruses use our own cellular machinery C) Viruses are smarter than bacteria D) Viruses get inside our cells E) Viruses replicate too quickly -- Answer ✔✔ B. Viruses use our own cellular machinery
  2. Why are vaccines effective in preventing viral illnesses? A) Vaccines are just like antibiotics B) Vaccines teach your immune system how to recognize specific viruses C) Vaccines make it impossible for a virus to enter your body D) Vaccines change your cells so that no virus can enter them E) Vaccines add "virus-fighting" genes to your genome -- Answer ✔✔ B. Vaccines teach your immune system how to recognize specific viruses
  3. Why don't all influenza A viruses readily jump back and forth between humans, birds, pigs, dogs, etc.? -- Answer ✔✔ Most viruses are host specific; specializing to infect one species can make a virus unable to infect another
  4. How do different viruses get mixed up? -- Answer ✔✔ Reassortment: possible when multiple virus types infect the same individual host and get into the same cell.... think "viral sex"
  5. What are vaccines? -- Answer ✔✔ Derivatives of pathogenic microbes that stimulate the immune system to mount defenses against the actual microbe
  6. A nucleotide consists of: -- Answer ✔✔ 1. A nitrogenous base
  1. A sugar
  2. A phosphate group
  • Adjacent nucleotides are linked phosphate to 3' carbon atom--- This forms the backbone
  • Antiparallel arrangement allows proper base pairing
  1. During what phase does DNA replication occur? -- Answer ✔✔ S Phase of Interphase
  2. How is DNA replicated? -- Answer ✔✔ Each strand can serve as a template for a new strand containing exactly the same information.... essential for heredity!
  3. In DNA replication, what happens to the original, "parent" DNA molecule (parent molecule = the double-stranded DNA molecule present before replication starts)? a) its two strands stay together, and the copy of the parent molecule consists of two newly synthesized daughter strands b) the original molecule serves as a template which is eventually destroyed once two new daughter molecules are synthesized c) the two strands in the original molecule separate, with each serving as a template for a newly synthesized strand d) none of the above e) all of the above -- Answer ✔✔ C. The two strands in the original molecule separate with each serving as a template for a newly synthesized strand
  4. When a new strand of DNA is being synthesized, what determines its sequence? a) the sequence of the template strand b) the rules of complementary base pairing c) hydrogen bonding d) all of the above -- Answer ✔✔ D. All of the above
  5. Based upon the semiconservative model, which is true about the DNA molecules contained by sister chromatids present in G2 phase? A) Only one sister chromatid contains a newly synthesized DNA molecule; the other sister chromatid has the original DNA molecule. B) Each sister chromatid has a double-stranded DNA molecule C) Each sister chromatid has a strand of DNA from the original DNA molecule paired with a newly synthesized strand

D) A and B E) B and C -- Answer ✔✔ E. B and C

  1. According to the Watson and Crick "semi-conservative" model, how does DNA replicate? -- Answer ✔✔ 1. Separation of parental strands into templates
  1. Formation of new strands complementary to template strands Base principle base pairing with a template strand
  1. DNA polymerase needs 2 things to be able to start: -- Answer ✔✔ 1. Primase
  1. RNA Primer
  1. What is the function of DNA polymerase? -- Answer ✔✔ 1. Match the right monomers with the template
  1. Catalyze formation of new sugar-phosphate bonds
  2. Add 50 (eukaryotes) to 500 (bacteria) bases per second!
  1. DNA polymerase "reads" the parental template from ___' to ___' -- Answer ✔✔ Reads form 3' to 5'
  2. DNA polymerase synthesizes the new strand by building onto the 3' end of the primer.... It builds the new strand ____' to _____' -- Answer ✔✔ Builds the new strand 5' to 3'
  3. Which of the following lists steps involved in DA replication in the correct order? A) Open double helix---> Build RNA primer ---> Add DNA to 3' end of RNA primer ---> Replace RNA primers with DNA B) Open double helix---> Build DNA primer---> Add DNA to 5' end of DNA primer C) Open double helix---> Build RNA primer---> Add RNA to 3' end of RNA primer -- Answer ✔✔ A.
  1. Open double helix
  2. Build RNA primer
  3. Add DNA to 3' end of RNA primer
  4. Replace RNA primers with DNA
  1. Genes located on the same chromosome that tend to be inherited together are called.... -- Answer ✔✔ Linked genes
  2. What is the advantage of doing a test cross vs. an F1xF1 cross? -- Answer ✔✔ We know the patterns of heredity We can isolate what is actually going on
  3. What is the mechanism for recombining alleles? -- Answer ✔✔ Crossing over in Meiosis I
  4. Genetic map of a chromosome based on recombination frequencies -- Answer ✔✔ Linkage Map
  5. One map unit = ____% recombination frequency -- Answer ✔✔ 1%
  6. Independent assortment does NOT (always) apply to genes on the same chromosome. Why not? A) Allele combinations on a chromosome can never be broken up B) A combination of alleles on one chromosome is less likely to be broken up than a combination of alleles from multiple chromosomes C) Non-homologous chromosomes pair up during meiosis D) Meiosis makes it impossible to create non-parental combinations of alleles in gametes. -- Answer ✔✔ B. A combination of alleles on one chromosome is less likely to be broken up than a combination of alleles from multiple chromosomes
  7. Why would some genes be inherited neither completely together nor completely independently? -- Answer ✔✔ Recombination of linked genes
  8. Suppose we are investigating two characters (e.g., body color and wing type) in a study of heredity. If the ratio in the offspring of parental types : recombinant types is intermediate between the predictions of dependent assortment and independent assortment, then we should conclude that: A) meiosis has been disrupted in the parents used to produce the observed offspring

B) the parents used to produce the offspring have cancer C) Mendel's law of segregation has been violated D) This outcome should never happen because Mendel's law of independent assortment holds for any two genes we consider E) The genes responsible for the phenotypes we are observing are "linked," i.e., located near each other on the same chromosome -- Answer ✔✔ E. The genes responsible for the phenotypes we are observing are "linked," i.e., located near each other on the same chromosome

  1. How can information about recombination frequencies be used to make a genetic map? -- Answer ✔✔ Assume that genes that are farther apart will show higher recombination frequencies
  2. A genetic map of chromosomes based on recombination frequencies -- Answer ✔✔ Linkage map
  3. What is the formula for recombination frequency? -- Answer ✔✔ (# of recombinants/ total # of Offspring) x 100
  4. In experiments with two fruit fly characters like those we just learned about, suppose that the raJo of the two parental types and the two recombinant types was 1:1:1:1. What would the recombination frequency be? A) 25% B) 50% C) 75% D) 100% E) not enough information given -- Answer ✔✔ B. 50%
  5. What can explain a recombination frequency of 50%? -- Answer ✔✔ Genes that are far apart on the same chromosome behave as if they are unlinked
  6. Can multiple crossover events PER chromosome occur? -- Answer ✔✔ Yes. And these can affect observed recombination frequencies.
  7. What is a nucleic acid? -- Answer ✔✔ A polymer made of nucleotide monomers.

Initiation:

  1. Figure out where to start reading DNA
  2. Actually begin making mRNA
  1. HOW???? We need a signal... -- Answer ✔✔ Promoter= the "start here" signal
  2. What does RNA Polymerase do during transcription? -- Answer ✔✔ Untwists DNA, makes RNA
  3. Summary of elongation in transcription: -- Answer ✔✔ 1. RNA polymerase untwists and separates 10-20 base pairs of DNA at a time
  1. This opens space for RNA nucleotides to come into the site of mRNA synthesis- ---> base pairing of RNA nucleotides with the DNA template
  2. RNA polymerase catalyzes the addition of correct nucleotides onto the 3' end of the RNA molecule
  3. RNA polymerase moves along, the new RNA molecule peels away from the DNA, and the helix re-twists
  1. Before RNA transcripts leave the nucleus, they are modified in what way? -- Answer ✔✔ 1. Alteration of ends
  1. Cutting out some of the middle (RNA splicing) This offers the cell a way of controlling when and where protein is produced
  1. Why do introns exist? -- Answer ✔✔ - Alternative splicing---> alternative mRNA---

multiple proteins from a single DNA sequence

  • The possibility of "exon shuffling" may facilitate evolutionary change
  1. What are the nucleotides in RNA? -- Answer ✔✔ Adenine, Uracil (replaces thymine), Guanine, and Cytosine
  2. What is a codon? -- Answer ✔✔ A sequence of 3 nucleotides = specification of amino acid. Each triplet is called a codon
  3. Codons are read in what direction? -- Answer ✔✔ 5' to 3'
  1. When we say "codon," we are referring implicitly to what? -- Answer ✔✔ the RNA triplets
  2. What are the major players in translation? -- Answer ✔✔ - mRNA
  • Amino acids
  • Ribosome (the physical site for translation to happen)
  • tRNA- bring amino acids to the site of translation
  1. What does the ribosome do during translation? -- Answer ✔✔ - Facilitates the coupling of mRNA codons with tRNA anticodons
  • Provides a physical site for translation in which all the participating molecules find their proper spatial arrangement
  • Catalyzes formation of peptide bonds
  1. RNA molecules can: A) be information carriers B) catalyze chemical reactions C) be carriers of the building blocks for proteins D) have complex 3-D structure E) all of the above -- Answer ✔✔ E. All of the Above
  • mRNA is the info carrier
  • Ribosomes catalyze reactions
  • tRNA are carriers
  • Both ribosomes and tRNA have complex 3D structure
  1. Match the RNA molecule with its function:
  1. The RNA transcript produced initially during transcription
  2. Forms the structure of the ribosome
  3. Brings amino acids to the ribosome
  4. The processed RNA transcript molecule that will actually be translated. -- Answer ✔✔ 1. Pre-mRNA
  5. rRNA
  6. tRNA
  1. How do we know what "reading frame" to use/ Where to start translating the mRNA and how to break it into codons? -- Answer ✔✔ Some kind of "start" signal in the mRNA sequence.... The first codon (AUG) establishes the start point and the reading frame
  2. Which of the following types of cells in your body has a gene for eye color? A) Eye cells only B) Toe cells C) Gametes only D) Brain cells E) All of the above -- Answer ✔✔ E. All cells are pretty much the same!
  3. What would need to happen in order for a healthy adult human to make more insulin? A) "Turn on" expression of the insulin gene in cells in the pancreas B) Activate pancreatic stem cells to differentiate to make more pancreatic cells C) "Turn on" the human insulin operon -- Answer ✔✔ A. "Turn on" expression of the insulin gene in cells in the pancreas ** Can't be C because only bacteria have operons
  4. Given what you know about eukaryotic gene regulation: To turn on expression of the insulin gene in pancreatic cells, what would be needed? A) A signal directly from the brain to each cell in the pancreas B) The sight, smell, and taste of a donut C) The right combination of transcription factors to promote expression of the insulin gene D) A mutation in the insulin gene -- Answer ✔✔ C. The right combination of transcription factors to promote expression of the insulin gene
  5. How does "Coordinate Control" (accomplishing multiple parts of regulation in concert) differ in Bacteria vs. Eukaryotes? -- Answer ✔✔ 1. Bacteria
  • Genes organized on Operons.... one promoter for multiple genes
  • Repressor and activator proteins that can inhibit or promote gene expression
  1. Eukaryotes
    • No operons
    • "Turn on" one Transcription factor.... promote the expression of multiple genes
  1. What would happen in a person that had a mutation which prevented the synthesis of the PDX-1 transcription factor? A) Too much insulin, low blood sugar B) Defective form of insulin C) Normal blood sugar regulation D) High blood sugar -- Answer ✔✔ D. No PDX- 1 ---> No insulin---> high blood sugar
  2. What are the steps in the Development Process? -- Answer ✔✔ 1. Determination- cell committed to its fate
  1. Differentiation- cell specialization in structure & function; production of tissue- specific proteins
  2. Morphogenesis- tissues, organs, and organism take shape
  1. How do you get the right tissues/organs in the right places? -- Answer ✔✔ Pattern Formation: Setting up the body plan
  • Pattern formation= development of spatial organization of tissues & organs
  • Positional information = molecular cues that tell a cell its location
  1. What are the two complementary mechanisms of pattern formation? -- Answer ✔✔ 1. Cytoplasmic Determinants
  • Before fertilization, when eggs are made
  • Maternally derived
  • Seeds of differential gene expression
  1. Inductive Signals
  • Once there are multiple cells
  • Substance from outside a cell (e.g. signal from nearby cell) influences cell's gene expression

C) Lack a 3'=OH group preventing additional nucleotides from being added D) Cause the breakdown of the template strand -- Answer ✔✔ C. Lack a 3'=OH group preventing additional nucleotides from being added

  1. How is evolution defined? -- Answer ✔✔ Change over time in a populations genetic makeup Descent with modification
  2. Evolution refers to both patterns and processes. How do they differ? -- Answer ✔✔ 1. Patterns
  • Observations of the natural world
  • Factual descriptions of change
  1. Processes
  • Mechanisms that produce a pattern
  1. How do hypotheses, theories, and facts differ? -- Answer ✔✔ 1. Hypothesis: a testable, falsifiable explanation for a phenomenon of interest
  1. Theory: A framework of internally consistent ideas used for generating hypotheses
  2. Fact: A piece of information about circumstances that exist or events that have occurred; an actual occurrence
  1. Evolution is a... A) Fact B) Theory C) Hypothesis -- Answer ✔✔ FACT!!!
  • Modern forms are not present in the early fossil record
  • Novel flu viruses arise
  • Populations of many species have gone extinct in our lifetimes
  1. Evolution refers to both patterns and processes. Is natural selection a pattern on a process? -- Answer ✔✔ A process.... Natural selection is one of multiple possible mechanisms that produce a pattern
  1. What best describes the relationship between evolution and natural selection? -- Answer ✔✔ Evolution refers to patterns and processes of descent with modification Natural selection is a mechanism that can produce the processes of evolution
  2. Darwin developed two main ideas: -- Answer ✔✔ 1. Descent with modification explains life's unity & diversity
  1. Natural selection is a cause of adaptive evolution
  1. How does natural selection work? -- Answer ✔✔ 1. Offspring are overly abundant
  1. .... Yet many populations remain stable in size
  2. Resources (food, mates) are limited.... only a subset of all individuals will survive & reproduce
  3. No two individuals are alike
  4. Variation is heritable.... individuals that happen to have traits conferring survival and reproductive advantage will tend to leave more offspring... such favorable traits will tend to increase in frequency in a population over time
  1. Which of the following is NOT a part of the theory of natural selection? A) More offspring are born than can survive and reproduce B) Resources essential for survival and reproduction are limited C) Heritable, phenotypic variation D) Offspring inherit characteristics from their parents that the parents acquire during their lifetimes E) New traits that are more adaptive than old traits can replace the old traits in a population -- Answer ✔✔ D. Acquired traits are not inherited
  2. What does natural selection most generally favor? A) having many offspring B) being large C) long life D) traits that benefit the species as a whole E) cooperative behavior -- Answer ✔✔ A. Having many offspring