bio exam 2
A possible sequence of nucleotides in the template strand of DNA that would code for a portion of a polypeptide with the amino acid sequence Phe-Ile would be
3' AAA-TAA 5'
What anticodon would have been found on the tRNA that had amino acid X attached to it?
3' CUU 5'
5' UCUGAUGGGCUUU.. Which of the following sequences in the coding strand of the DNA could code for the amino acid sequence Phe-Pro-Lys-Gly-Phe-Pro?
5' TTT-CCC-AAA-GGG-TTT-CCC
The sequence below is part of the template strand of a gene. The first nucleotide shown is at position -10 of the gene. Nucleotides +21 through +23 encode the start codon and are in bold and underlined. -10 taccgccaac gagtcttgag taccgccgca tacacatgcg acgcaggagc atttgccgtcThe first 10 nucleotides of the primary transcript of this genes will be __
5'-CUCAGAACUC-3'
How might a single base substitution in the sequence of a gene affect the amino acid sequence of a protein encoded by the gene?
A single amino acid could change
Which of the following is a part of a DNA molecule?
All of the above
Which of the following accurately describes how the presence of an antibiotic causes evolution in a bacterial population?
Antibiotics cause antibiotic resistant bacteria to have higher fitness than antibiotic sensitive bacteria.
Mutations arise......
As the DNA is being replicated
You have a friend helping you study for the exam. They tell you the four statements below. Which one is FALSE?
Bacteria mutate to become resistant to antibiotics only when antibiotics are present in the environment
If having one or more antibiotic resistance genes in the bacterium Staphylococcus aureus reduces fitness in environments that lack of antibiotics, what is predicted to happen to bacterial populations in environments that lack antibiotics?
Bacteria with the antibiotic resistance genes would be outcompeted and replaced by bacteria that do not have the genes.
The first amino acid to have been encoded by this mRNA would have been:
CAC
Cheetahs are the fastest land animal, causing some people to proclaim that they have a perfect body design for running. How would an evolutionary biologist refer to the body design of cheetahs?
Cheetah bodies have adaptations for running fast but do not represent perfection.
Which of the following would you expect to find in a mature mRNA?
Codons
The PitX1 gene in some populations of stickleback fish is expressed during development in three different cell types, leading to development of the jaw, the pituitary and pelvic spines. What causes expression of this gene in three different cell types?
Each of three switches is bound by a different switch activator in each cell type.
Artificial selection cannot be considered a mechanism of evolution because it does not change allele frequencies.
False
The DNA molecules in eye cells contain which of the following?
Genes that encode eye color and skin color, and switches that control both eye color and skin color
Which amino acid is connected to the amino group of the amino acid labeled O?
His
Secondary structure is caused by which of the following?
Hydrogen bonding between groups along the backbone.
Which of the following is a similarity between DNA and RNA?
In both, nucleotides are connected by phosphodiester bonds
Which of the following is transcribed? The 5' cap The poly(A) tail The promoter Switches introns
Introns
A protein called hepatoglobin is synthesized by human liver cells but not by human skin cells. Which of the following explains this fact?
Liver cells have the activator for the hepatoglobin gene switch but skin cells do not.
How do the chromosomes from a bird and the chromosomes from a whale differ?
Many of the genes are different between the two species
5' UCUGAUGGGCUUU.. Beginning with the start codon, which amino acids, in order, are coded for by this section of mRNA?
Met, Gly, Phe,
In the above sequence, nucleotide +4 changes from a "A" to an "C". What change occurs to the encoded protein because of this mutation?
No change would occur to the encoded protein.
Which type of mutation results in a shorter peptide chain?
Nonsense
Which of the following contains information that determines the amino acid sequence of the protein encoded by this gene?
Nucleotides in exons
Within the eukaryotic cell, transcription occurs in the __________ and RNA splicing occurs in the _____.
Nucleus; nucleus
Gene duplication events have been important for the evolution of new traits because
One copy of the gene can undergo mutation and eventually adopt a new function
RNA polymerase
Synthesizes a nucleic acid that is complementary to the template strand
Consider a gene Or12c that produces the protein or12c. The gene has two switches: a tail switch, which allows expression in the tail fin, and a pectoral switch, which allows expression in the pectoral fin. Each switch is bound by a unique activator. Suppose there was a mutation in the gene that produced the tail switch activator protein. What would be there result?
The Or12c protein would not be produced in the tail
Two populations of butterflies of the same species differ in their wing patterns: one population has a black spot on the wings, and the other population does not have the black spot. The black spot is encoded by the paintbrush gene, which is expressed in the wings in the form of the black dot, and also in the abdomen as black body coloration. A "wing switch" controls expression in the wings and an "abdomen switch" controls expression in the abdomen. The DNA sequence of the paintbrush gene was determined in butterflies from both populations and was found to be exactly the same. Which of the following could explain why?
The butterflies without the spot have a mutation in the gene encoding the wing switch activator
Many different types of protein molecules are made within cells. If two cells in a single individual animal contain different proteins, then...
The cells contain the same genes, promoters and gene switches but different switch activators.
Which of the following is TRUE about translation in eukaryotes?
The first amino acid added during translation of all mRNAs is the same
Finch beak size is a heritable trait. Large beaks is an adaption to large hard seeds. Small beaks is an adaption to small soft seeds. Which of the following describes how natural selection could cause a finch population to change from mostly large beaked birds to mostly small beaked birds after a climate change event?
The food source changed from large hard seeds to small soft seeds, so finches with smaller beaks produced more offspring than finches with large beaks.
Snakes are limbless reptiles. Which of the following most logically explains the relationship of snakes to limbed reptiles?
There must have been some environment in which being legless was an advantage, and snakes evolved from limbed reptiles in this environment.
Which process is described by the Central Dogma?
Which process is described by the Central Dogma?
A doctor is trying to identify the mutant gene that causes her patient to be colorblind. To do this she takes a swab of the patient's cheek cells to send off for DNA sequencing. Did she sample the correct cells?
Yes, because both cells have the same genes
Transcription will occur from right to left in the diagram above. Which DNA strand is the coding strand?
Z
Proteins in human eye cells can detect three wavelengths (colors) of light: short (blue), long (red) and medium (green). All three proteins are very similar in primary structure. We have ancestors whose eyes only have two proteins, one for blue light and one for red light. Which of the following is the best hypothesis for the mutation that resulted in the ability to detect three wavelengths of light?
a duplication of the gene producing red-detecting protein, followed by mutation in the duplicated gene
Transcription ends _____________. Translation ends_____________
after the poly(A) signal; at a stop codon
Suppose an individual is born with a slightly different nucleotide sequence in their PGC gene. This different gene sequence can be expected to be found in...
all cells in their body.
A mutation in a gene switch could:
change the amount of protein expressed
Amino acids with ______ side chains are typically located in the interior of globular proteins whereas amino acids with ______ side chains are typically located on the surface of globular proteins.
hydrophobic; hydrophilic
Fill in the blank. ______ are part of the primary transcript but never leave the nucleus.
introns
The population of medium ground finches on the island of Daphne Major shows variation in beak size. After a drought, the average beak size of the offspring of surviving finishes increased. Beak size in medium ground finches ____.
is controlled by genes that produce variable phenotypes in the population.
A _____ is a copy of genetic information that can be found in the cytoplasm of eukaryotic cells.
mRNA
A mutation changes a gene such that a UGG codon is changed to a UGA codon. Which type of mutation is this?
nonsense
within the cell, you would expect to find RNA polymerase in the ____________ . Enzymes involved with splicing would be found in the ____________.
nucleus; nucleus
Two different polypeptide chains would differ in their __________
secondary structures teritiary structures functions chemcial properties
The change in the nucleotide sequence of the PGC gene caused a change in the amino acid sequence that was produced after translation. The altered pepsinogen molecule likely has a different ______ compared to the original pepsinogen molecule.
shape function secondary structured tertiary structure
How might a single base change (substitution) in the sequence of an exon affect the protein encoded by the gene?
single amino acid could change The length of the polypeptide could change It is possible that the change would have no effect on the protein
The _______________ of a polypeptide is determined by its _____________
structure, amino acid sequence
Which part(s) of different amino acids is/are different?
the R group
If a mutation was within a coding sequence of a gene, it could lead to...
the creation of a different allele of the gene. the synthesis of a different type of protein a change in the phenotype of the organism.
Which of the following have the exact same genes but different alleles of those genes?
two different individuals of the same species
Consider a gene called M that is expressed in the heart muscles and the stomach muscles of mice. Some mice inherit weak hearts and die young because the M gene is not expressed in heart muscles. Further investigation shows that the M gene is expressed in the stomach muscles of these mice. Which of the following is a possible reason for the heart condition of these mice?
A mutation in the gene that encodes the activator for the M gene heart switch
A frog is born with a nonsense mutation in a gene that affects its ability to vocalize. It's offspring all inherit this mutation. What was the source of this mutation?
A mutation in the germline cells of one of the frog's parents
Which of the following mutations would prevent expression of PitX1 gene in all cells?
A mutation that prevents RNA polymerase from binding to d.
The gene sonic hedgehog is expressed in both the developing limb and the developing facial bones, with switches controlling this expression. Which mutation would prevent sonic hedgehog from being expressed anywhere in the body?
A mutation that prevents RNA polymerase from binding to the promoter.
Suppose there is a mutation in a DNA sequence causing a change in where a gene is expressed. Which of the following is true?
A new switch was created due to the mutation An existing switch was inactivated due the mutation
A patient with his first case of tuberculosis arrives at the emergency room of a hospital and is examined by a physician who prescribes the antibiotic, rifampin. The patient takes the antibiotic for three days, the infection diminishes, and the patient throws the remaining rifampin away. A week later the patient is sick again, goes to a different emergency room, doesn't tell the physician about his previous infection, and is prescribed rifampin again. The patient takes the antibiotic for three days, the antibiotic is ineffective at treating the infection, and he dies. Which of the following is a reasonable explanation for why rifampin was initially effective at treating the infection but subsequently became ineffective?
A random mutation in the surviving bacteria caused resistance to rifampin, which spread in the presence of rifampin
Given the DNA template strand shown in the figure above, which of the following bases would you find in the resulting mRNA strand and where would the strand be synthesized in eukaryotes?
AAAAA; nucleus
Only 1% of the bacteria in a population are resistant to the antibiotic rifampicin. Which of the following environments would cause the % of rifampicin resistant bacteria to increase over time?
An environment with rifampicin but not any other antibiotics.
A farmer finds that a few of the potato plants in his field are resistant to potato beetles. He uses the seeds from those plants to seed the next year's crop. The next year's crop has mostly beetle-resistant plants. Which of the following statements is true?
Evolution has occurred in the potato field.
A tRNA with its anticodon is shown at right. The anticodon is written 3' to 5'. Which amino acid is attached to this tRNA? CGA
GCU=ALA
Which of the following is made out of DNA nucleotides (i.e., is part of a DNA molecule)?
Gene switch
Which of the following statements regarding mutations is true?
Mutations are responsible for the creation of new alleles of genes.
Which of the following statements regarding mutation is TRUE
Mutations can occur but not alter protein structure Mutations are the only way new alleles can be produced Mutations can arise during DNA replication
In order for new functions to arise, what must happen after gene duplication events?
Mutations must occur in one copy of the gene or in its regulatory region
Which of the following statements regarding mutation is FALSE?
Mutations that result in new phenotypes are always found in exons
Which of the following is a TRUE statement with regard to evolution?
Natural selection can lead to a change the genetic characteristics of a population
Olfactory (smell) receptors are a family of over 900 proteins in the nasal passage, each slightly different, but sharing most of the same structure. Each different variation detects a different chemical structure, which combine to allow us to sense thousands of different odors. What is the most likely source of the 900 slightly different proteins?
One gene that made a single olfactory protein was miscopied in DNA replication, allowing for gene duplication, then the different copies independently mutated.
Pepsinogen is a protein encoded by the PGC gene. Pepsinogen is found in the human stomach to aid digestion, but is not found in other cell types. Which of the following would you NOT expect to find in human skin cells?
PGC switch activators
Which of the following statements is correct?
Populations—not individuals—change when natural selection occurs.
In a study of red deer in one European forest, researchers found that frequency of alleles of certain genes change in the population as climate changed. They proposed that this is a result of natural selection imposed by climate change. Which of the following must be true for evolution by natural selection in such a case?
Reproductive success varies according to genetic make up. There is genetic variation in the red deer population. Variation among individuals is heritable.
The primary structure of a protein refers to the.......
Sequence of amino acids in a polypeptide
The gene sonic hedgehog is expressed in both the developing limb and the developing facial bones, with switches controlling this expression. What would happen if the switch for limb expression was deleted?
Shh would be expressed only in the jaw.
Tapeworm species tend to have simple morphologies (body forms). Which of the following statements best explains this observation?
Simple morphologies convey some reproductive advantage in most tapeworms.
Which of the following is a TRUE statement?
Small genetic changes can result in large phenotypic changes
A child has an ear infection and is treated with an appropriate antibiotic. A week after being cleared of infection by the doctor, the child develops another ear infection. Which of the following is the best explanation for this scenario?
Some bacteria in the initial bacterial population were resistant to the antibiotic, survived the antibiotic treatment, and caused a second infection.
How might an evolutionary biologist explain why a species of birds has evolved a larger beak size?
Some members of the ancestral population had larger beaks than others. If larger beak size was advantageous, they would be more likely to survive and reproduce. As such, large beaked birds increased in frequency relative to small beaked birds.
A population of dark mice live in a wooded region close to a sandy white beach. White mice are born due to mutations in a gene required for dark fur. Most of the mice are dark but some are white. If white mice mate, they produce white offspring. The climate changes, causing the forest to die off and the beach to expand. Which of the following is expected to occur to the mouse population over time after the forest dies off?
The frequency of white mice in the population will increase.
An individual has a mutation in the gene that encodes a switch activator protein. The mutation prevents the activator protein from binding to the switch that controls the expression of the lactase gene. What will the ultimate outcome of this mutation be?
The lactase gene will not be transcribed so the mRNA will not be translated
MC1R is a gene that codes for a protein that controls fur color. All of the mice in a forest population have the MC1R allele that causes fur color to be dark. A heritable mutation in MC1R occurs that creates an allele that causes a light-colored mouse to be born. Which of the following statements about this MC1R mutation is true?
The mutation was random.
Which of the following is an accurate statement concerning a population of bacteria in the absence of antibiotics?
The percentage of antibiotic resistant bacteria in the population is unlikely to increase.
Which of the following will be the most different?
The proteins in a skin cell and a brain cell of the same human.
Which of the following about switch activators is TRUE?
They are proteins that bind to DNA sequences
For most multicellular organisms, how can the cells of a single organism have different shapes and actions?
They express different genes
If the DNA sequence that acts as the template for transcription reads 3' TTT 5', the amino acid it encodes will be:
They express different genes
Which of the following is FALSE about translation in eukaryotes?
Translation ends at the very end of an mRNA
The amino acid located at the carboxyl (C) end of the above peptide chain is the last amino acid found in this peptide. It is encoded by the codon UCC. Which of the following codons could occur after this codon in the mRNA?
UGA or not enough info
The _____ of a polypeptide determines the _____ of the protein, which determines the _____ of the protein.
amino acid sequence; structure; function
Which of the following populations will undergo evolution?
population of cats on a breeder's farm. The cats vary in body size, a heritable trait, and only the slimmest cats are allowed to breed A population of fish in a lake. The fish vary in body size, a heritable trait, and fishermen catch and kill only the largest individuals (they release smaller individuals back into the lake). A population of birds in a forest. The birds vary in where they build nests, which is a heritable trait, and birds that build nests in the highest parts of trees produce the most offspring.
A mutation changes a gene such that a CUG codon is changed to a UUG codon. Which type of mutation is this?
silent
What type of mutation never has an effect on fitness?
silent
Which type of mutation doesn't change the amino acid sequence of the polypeptide?
silent
