Study guide week 11 exam

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is

3' UCA 5'

DNA has sequences of

4 nucleotide bases that form a code that is "read" by the cell to produce specific proteins.

Dominant alleles

A dominant allele masks the presence of a recessive allele in determining the trait expressed.

Which of the following statements about vestigial structures is accurate?

A vestigial structure in species A can be homologous to a functional structure in species B.

**Animal cloning may result in premature death of the clones due to which of the following?

Abnormal gene regulation due to variant methylation

Which of the following statements is accurate with regard to a population in Hardy-Weinberg equilibrium?

Allele frequencies should not change from one generation to the next.

Traits are controlled by

Alleles, which are different versions of a gene. Each individual inherits 2 alleles for each gene, one from each parent. These alleles can either be dominant or recessive.

Recessive allele

An allele that is masked when a dominant allele is present and only affects the trait if both alleles are recessive

In which of the following situations would genetic drift most likely occur?

Chance events cause allele frequencies to fluctuate unpredictably.

Transcription

DNA is copied into mRNA in the cells nucleus. RNA polymerase unwind the DNA and assemble the complementary mRNA strand based on the DNA template. The mRNA leaves the nucleus and goes to the cytoplasm.

**Much of the human genome does not code for proteins. Which of the following types of DNA are found in these regions of the genome?

DNA that is transcribed into several kinds of small RNAs with biological function

Which of the following statements best describes Darwin's theory of evolution by natural selection?

Darwin's theory emphasized that populations vary and change over time.

Which statement about the beak size of finches on the island of Daphne Major during prolonged droughts is accurate?

Each birds survival was strongly influenced by the depth and strength of its beak as the drought persisted.

Which of the following best explains why a neuron and a pancreatic cell isolated from the same individual contain different sets of proteins?

Each cell type contains different regulatory proteins and, therefore, they express different proteins.

Which of the following statements correctly describes one of the main differences between embryonic stem cells and adult stem cells?

Embryonic stem cells can give rise to all cell types in the organism, and adult stem cells cannot.

Translation

In the cytoplasm, ribosomes read the mRNA sequence and translate it into a chain of amino acids, which are the building blocks of proteins. This sequence of amino acids folds into a specific shape to perform a wide range of tasks in the cell.

Which of the following statements correctly describes a ribozyme?

It is an RNA with catalytic activity.

Under which condition do high levels of transcription of structural genes occur in an inducible operon?

It starts when the pathway's substrate is present.

Which of the following descriptions correctly identifies a main structural difference between viruses with envelopes and viruses without envelopes?

Only viruses with envelopes have their contents enclosed by a layer containing lipids

Which of the following process occurs as part of transcription?

RNA is synthesized

In eukaryotes, there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a protein?

RNA polymerase II

Which of the following about RNA processing is correct?

Ribozymes may function in RNA splicing

Which of the following statements correctly describes a characteristic of genetically engineered food plants?

The alterations can be made in a somatic cell then grown into a whole plant with new traits

Which of the following statements describes a technical barrier to using gene therapy in humans?

The expression of transferred genes may not be appropriately controlled.

gene expression

The process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs.

The host range of a virus is determined by wheather

The proteins on virus surface can bind with proteins on the host sirface

DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Instead, DDT is largely useless against many insects. Which of these would have prevented this evolution of DDT resistance in insect pests?

The use of DDT should have been interspersed with the use of other pesticides that have a different mode of action.

Starting from the wild mustard Brassica oleracea, plant breeders have created the strains known as Brussels sprouts, broccoli, kale, and cabbage. Which of the following statements is correct with regard to the wild mustard?

There is enough heritable variation in the wild mustard to permit these different varieties.

Viruses can carry out which of the following processes?

They can use the host cell machinery to make copies of viral genomes and viral proteins.

Which of the following statements best supports the argument that viruses are nonliving?

They do not carry out metabolic processes.

Which of the following describes the role typical proto-oncogenes have when they are expressed in cells that are not cancerous?

They stimulate normal cell growth and division.

Gene expression occurs through two main processes:

Transcription and translation.

Which of the following statements correctly describes vaccines and how they help prevent viral infection?

Vaccines are inactive versions of a virus that stimulate an immune reaction in a person.

A single base substitution mutation is likely to have a less harmful effect when the base change results in which of the following?

a codon that specifies the same amino acid as the original codon

Which of the following statements best describes the characteristics of siRNA?

a double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA

Which of the following types of mutation would convert a proto-oncogene into an oncogene?

a mutation that greatly increases the amount of the proto-oncogene protein

The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. What is the result of this type of mutation?

a polypeptide missing an amino acid

If a mutation alters a maternal effect gene in a female Drosophila zygote, which of the following is most likely to occur?

all of her offspring will show the mutant phenotype, regardless of their genotype

Assays analyzing transcriptional control of gene expression focus on which of the following characteristics?

amount of the mRNA generated

Imagine a human population with an extremely low frequency of sickle cell alleles. Which of the following changes is most likely in the human population 15 generations after introducing a mosquito population that carries the malaria parasite?

an increase in the sickle cell allele

Accuracy in translation of mRNA into the primary structure of a polypeptide depends on specificity in the

attachment of amino acids to tRNAs

Which of the following best explains the inability of bacteria to correctly express the protein products of plasmid containing an unmodified mammalian gene?

bacteria cannot remove eukaryotic introns

Which of the following is the best definition of evolution in the smallest scale?

change in allele frequencies in a population over time

Which of the following conclusions is consistent with the fact that plants can be cloned from somatic cells?

differentiated cells retain all the genes of the zygote

Which of the following processes best describes the cause of a bottleneck effect?

drastic decrease in the size of the population

Which of the following observations helped Darwin agree with Lyell that Earth was more than a few thousand years old?

experiencing an earthquake and seeing fossils of ocean organisms high in the Andes

Which of the following processes can be effective in preventing the onset of viral infection in humans?

getting vaccinated to certain viruses

Which of the following statements is most consistent with data obtained from the fossil record?

older strata carry fossils that differ greatly from living organisms

Which of the following outcomes could be achieved using RNAi methodology?

reduction in protein produced from a gene of interest

Which of the following molecules is a protein produced by a regulatory gene?

repressor

Which of the following enzymes is required to make complementary DNA (cDNA) from RNA?

reverse transcriptase

Which of the following conditions would most likely cause allele frequencies to change by chance?

small populations

Most Swiss starlings (birds) produce four to five eggs in each clutch. Starlings producing more or less eggs have reduced fitness. Which of the following terms best describes this situation?

stabilizing selection

In eukaryotes, which of the following is the first step in translation?

the small subunit of the ribosome recognizes and attaches near the 5' cap of mRNA

Which of the following characteristics best support using yeast cells instead of bacterial cells to express mammalian proteins via cloning?

they are eukaryotic cells

Transcription in eukaryotes requires which of the following in addition to RNA polymerase?

transcription factors