BIO101T Wk 4 – Exam #4: Genetics Unit

Humans have two sex chromosomes that are named based on their shape. Males have (a) _____ and females have (a) _____.

• two X chromosomes; two Y chromosomes
• X and Y chromosome; two X chromosomes
• two Y chromosomes; two X chromosomes
• two X chromosomes; X and Y chromosome

During gene therapy, bone marrow stem cells are removed from the individual. What must happen to those cells before they are injected back into the individual?

• The cells are treated with high doses of radiation to destroy any faulty genes. Then, viruses act as vectors to replace those faulty genes with normal ones.
• The DNA of the stem cells is removed completely and replaced with a new genome that carries the normal gene.
• The mRNA of the stem cells is completely removed and used to create new normal genes that are then injected into the nucleus of the stem cells.
• Viruses act as vectors to carry the normal gene into the genome of the stem cells.

Select all of the following statements that describe the structure of a molecule of DNA.
Check All That Apply

• twisted double helix twisted double helix
• single-stranded single-stranded
• contains the nitrogenous bases, adenine, thymine, cytosine, and guanine contains the nitrogenous bases, adenine, thymine, cytosine, and guanine
• contains deoxyribose sugar contains deoxyribose sugar
• contains the nitrogenous bases adenine, uracil, cytosine, and guanine

Which of the following best describes the overall goal of transcription?

• To edit the mRNA strand and make it ready to leave the nucleus.
• To create a mRNA copy of a segment of DNA to take outside the nucleus.
• To retrieve amino acids and bring them to the ribosome for assembly into a polypeptide.
• To unpackage and unwind DNA so that enzymes can access the individual genes.

True or False: Gene therapy has been used for years to treat or cure sickle-cell disease.

• False
• True

DNA replication is considered to be _____ because the end product consists of one old strand and one newly synthesized strand.

• semiconservative
• relaxed
• dispersive
• conservative
• stringent

Describe the movement of oxygen and carbon dioxide during gas exchange.

• Oxygen diffuses out of the lungs into red blood cells and carbon dioxide diffuses out of red blood cells and into the lungs.
• Oxygen diffuses out of the lungs into red blood cells and carbon dioxide diffuses out of red blood cells into the kidney nephrons.
• Carbon dioxide diffuses out of the lungs into red blood cells and oxygen diffuses out of red blood cells and into the lungs.

RNA polymerase has several jobs during the transcription process. Which of the following is not a job that it performs?

• RNA polymerase binds to the promoter region to start transcription.
• RNA polymerase makes a complementary mRNA strand by adding RNA nucleotides.
• RNA polymerase edits the mRNA strand by removing some sections and splicing together remaining sections.
• RNA polymerase unwraps small segments of DNA to expose the template strand to be transcribed.

Which of the following best describes how the environment may play a role in the expression of our genes.

• The environment is not able to alter genes or their physical expressions. Genotypes and phenotypes are both completely independent of environmental changes, unless in the form of mutations.
• All genes are directly influenced by the environment, even if only in minor ways, so the environment will always alter phenotype for all genes.
• Some phenotypes, including skin color, can be influenced by the environment. The genotype still determines some aspect of skin color, but the interaction with the environment, in the form of sun exposure, can cause variations in the resulting phenotype.
• The environment can alter an individual’s appearance, but because these changes are temporary and unable to be inherited, they have no impact on the genotype or the expression of that genotype.

Variations in genes are called _____. Examples of these variations include eye color. There are blue eyes, green eyes, brown eyes, and several combinations of these.

• traits
• homeologues
• polymorphisms
• alleles

The pedigree shown displays the occurrence of an inherited disease. For an individual in the fourth generation with two heterozygous parents, what is the likelihood that they will be impacted by the disease?

• 75%
• 25%
• 0%
• 50%

If the codon is CCA, what is the anticodon and what amino acid will be inserted?
rev: 11_15_2019_QC_CS-190800

• ACC, threonine
• UGG, tryptophan
• GGT, glycine
• GGU, proline
• CCA, proline

Which of the following is the main difference between in vivo and ex vivo gene therapy?

• Ex vivo gene therapy uses donor cells from other healthy individuals, where in vivo gene therapy uses an individual’s own cells.
• Ex vivo gene therapy uses an individual’s own cells, where in vivo gene therapy uses donor cells from other healthy individuals.
• Ex vivo gene therapy occurs outside the body and in vivo gene therapy occurs inside the body.
• Ex vivo gene therapy occurs inside the body and in vivo gene therapy occurs outside the body.

Which of the following traits are considered to be inheritable?

• bleached hair
• calluses on fingers
• eye color
• the ability to speak Spanish

Familial hypercholesterolemia is a disease that is incompletely dominant. This means that

• multiple alleles exist for this trait, so multiple phenotypes are possible. In the case of familial hypercholesterolemia, heterozygotes can have a range of cholesterol levels depending on which combination of alleles exists.
• the dominant allele completely masks the recessive allele, so the dominant phenotype is displayed. In the case of familial hypercholesterolemia, heterozygotes will have extremely high levels of cholesterol, identical to those seen in homozygous dominant individuals.
• the dominant allele is equally dominant with a second (or third) dominant allele, so both phenotypes are displayed. In the case of familial hypercholesterolemia, heterozygotes have moderately higher levels of cholesterol compared to normal.
• the dominant allele does not fully mask the recessive allele, so an intermediate phenotype is displayed. In the case of familial hypercholesterolemia, heterozygotes have moderately higher levels of cholesterol compared to normal.

What is the role of the enzyme ligase in DNA replication?

• It seals any breaks in the sugar-phosphate backbone.
• It unzips the double-stranded DNA.
• It matches new bases to the old strand by complementary base-pairing.
• It breaks the hydrogen bonds that hold the two strands of the DNA together.
• It folds the DNA into a coiled structure.

Which of the following is the most effective means of treating or even curing sickle-cell disease?

• Blood transfusions
• Bone marrow transplants
• Gene therapy
• Antibiotics

True or False: Sickle-cell disease is a recessive disease. This means that two individuals without the disease cannot have a child with the disease. Only parents with the disease can pass it on.

• True
• False.

Sickle-cell disease causes hemoglobin proteins to become altered. What direct effect does this have on red blood cells?

• Red blood cells swell up, allowing fewer to flow through tiny capillaries and reducing blood flow.
• Red blood cells become sickle-shaped, clumping up and blocking blood flow in capillaries.
• Red blood cells shrivel up, causing too many of them to flow through capillaries at once, increasing blood pressure.
• Red blood cells become sickle-shaped, resulting in them carrying increased oxygen to body cells. Hyperoxia results.

During translation, a polypeptide chain is created using a RNA template. Which of the following components is responsible for bringing amino acids to the growing polypeptide chain?

• tRNA
• mRNA
• rRNA
• ribosomes
• RNA polymerase

A single mutation causes sickle-cell disease. Which of the following statements best describes how this occurs?

• The addition of several nucleotides cause the start codon to shift down several places. This causes RNA polymerase to bind in the incorrect spot so that several extra amino acids are included in the polypeptide chain during translation. This results in a hemoglobin protein that is incorrectly formed, resulting in sickle-shaped red blood cells that cannot function as intended.
• Three nucleotide mutations cause normal glutamine amino acids to be replaced with valine amino acids. This causes excess hemoglobin proteins to be synthesized, causing red blood cells to swell to the point of bursting, resulting in burst cells that have a sickle-shape.
• The removal of several nucleotides cause the start codon to shift down several places. This causes RNA polymerase to bind in the incorrect spot so that several amino acids are left out of the polypeptide chain during translation. This results in a hemoglobin protein that is incorrectly formed, resulting in sickle-shaped red blood cells that cannot function as intended.
• A single nucleotide mutation causes a normal glutamine amino acid to be replaced with a valine amino acid. This causes the resulting hemoglobin protein to form incorrectly, resulting in sickle-shaped red blood cells that cannot function as intended.

Some traits are multiple-allele traits, meaning there are more than simply one recessive and one dominant allele possible. Which of the following is not an example of a multiple-allele trait?

• blood grouping, which is controlled by the interaction of three different alleles
• cystic fibrosis, which is controlled by more than 300 different alleles
• sickle-cell disease
• All of these answer choices are correct.

CRISPR may work to treat sickle-cell disease by

• targeting and attacking red blood cells that carry faulty hemoglobin molecules, so that new normal red blood cells may take their place.
• targeting faulty portions of the hemoglobin gene within the genome of cells and removing and replacing those portions with normal sequences of nucleotides.
• targeting and attacking faulty hemoglobin molecules within red blood cells, so that new normal molecules may take their places.
• targeting the mRNA produced during the expression of the hemoglobin protein, removing and replacing faulty portions with correct sequences.

Sickle-cell disease is a recessive genetic disease. This means

• only one copy of the recessive allele must be present in order for the disease to be expressed.
• the environment can alter the expression of recessive genes, meaning any combination of alleles can cause the disease if the right environmental conditions are encountered.
• at least one copy of each recessive allele must be present for each gene involved in sickle-cell disease in order for the disease to be expressed.
• two copies of the recessive allele must be present in order for the disease to be expressed.

Which of the following best describes the sequence of DNA compaction, beginning with least compacted to most compacted?

• chromosomes, nucleosomes, DNA strand
• nucleosomes, DNA strand, chromosomes
• DNA strand, nucleosomes, chromosomes
• DNA strand, chromosomes, nucleosomes

Sickle-cell disease results in malformed hemoglobin molecules. Which cell type contains millions of hemoglobin molecules per cell?

• red blood cells
• white blood cells
• neurons
• osteoblasts

Segments of DNA that contain instructions for making either proteins or RNA molecules that regulate proteins are called _____.

• chromatin
• traits
• expressed factors
• genes

Sickle-cell disease results in misshapen red blood cells. What impact does this have on their ability to carry gases in the bloodstream.

• It reduces their ability to carry oxygen, resulting in anemia.
• It increases their ability to carry oxygen, resulting in anemia.
• It makes no difference in the ability of red blood cells to carry gases in the bloodstream.

Sickle-cell disease is a disorder that is caused by…

• a collection of genetic mutations and environmental factors.
• a collection of mutations that span several different genes.
• a collection of mutations on a single gene.
• a single mutation on a single gene.

For the following pedigree, what does the green circle in the fourth generation represent?

• male with the disease
• female without the disease
• male without the disease
• female with the disease

Which of the following is not an accurate statement describing the contributions of researchers to the structure of DNA.

• Watson and Crick used the work of previous researchers, including Chargaff and Franklin to determine the overall structure of DNA with sugar and phosphate components making up the strands with the nitrogenous bases in the interior.
• Erwin Chargaff determined that the percent of adenine was equal to the percent of thymine and the percent of guanine was equal to the percent of cytosine.
• Rosalind Franklin used X-ray crystallography to determine that DNA was a double helix in shape.
• Alfred Hershey and Martha Chase injected viruses into mice to determine that the inheritable material was DNA and not protein.

What is the name of the enzyme that fits new complementary DNA nucleotides into the new strand?

• DNA helicase
• DNA polymerase
• DNA telomerase
• DNA ligase

Mendel’s experiments led him to the conclusion that individuals have two factors for each trait that separate during gamete formation, resulting in gametes with one factor for each trait. In addition, fertilization results in a new individual with two factors for each trait again. He referred to this as the _____.

• law of pedigrees
• law of segregation
• factorial law
• law of independent assortment

During prophase I of meiosis, genetic information is exchanged between two homologous chromosomes, resulting in new combinations of alleles. This process is called _____.
rev: 10_30_2019_QC_CS-188538

• spermatogenesis
• crossing-over
• oogenesis
• homology
• shuffling

Erwin Chargaff’s research determined the composition of the nitrogen bases within a strand of DNA. His work determined that

• the percent of adenine is equal to the percent of thymine and the percent of cytosine is equal to the percent of guanine.
• the concentrations of adenine, thymine, guanine, and cytosine are all equal.
• the percent of adenine is equal to the percent of guanine and the percent of cytosine is equal to the percent of thymine.
• the concentration of adenine is twice the concentration of thymine and the concentration of cytosine is twice the concentration of guanine.

In humans, male gametes are called _____, while female gametes are called _____.

• sperm; eggs
• pollen; eggs
• eggs; sperm
• eggs; pollen

Several different researchers all contributed to the study of the structure of DNA. For each of the following researchers, match their contribution.
1. Frederick Griffith
2. Oswald Avery
3. Erwin Chargaff
4. Rosalind Franklin
Match each of the options above to the items below.

• DNA is a repeating helical structure.
• The percent of adenine is equal to the percent of thymine and the percent of guanine is equal to the percent of cytosine.
• There is a transforming factor that exists and can change bacteria’s characteristics.
• Transformation of bacteria did not occur with the addition of Dnase enzyme, suggesting DNA is the genetic material.

Duplicated chromosomes result in two sister chromatids that are held together by a centromere. Which of the following statements best describes the location of genes along these sister chromatids?

• Sister chromatids have identical genes, but different alleles. These are located in the same location on each sister chromatid.
• Sister chromatids have identical alleles but are located in different locations along each sister chromatid because of crossing-over during meiosis.
• Sister chromatids have identical alleles that are located in the same place along each sister chromatid.
• Sister chromatids have identical genes, but different alleles. Additionally, they are located in different locations along each sister chromatid because of crossing-over during meiosis.

Two parents with Type A and Type B blood have a child with Type AB blood. How is this possible?

• This is not possible. The child cannot be their biological child.
• Type A blood is incompletely dominant to Type B blood. This means that individuals with alleles for both Type A and Type B will express a blended intermediate between these two blood types.
• Type A blood is co-recessive with Type B blood, so as long as there is not a dominant blood type present, both recessive alleles will be expressed equally.
• Type A blood is codominant with Type B blood, so both alleles are expressed equally.

Which of the following statements best describes the structure of a hemoglobin molecule?

• Hemoglobin is comprised of three globin molecules and one heme group per hemoglobin molecule.
• Hemoglobin is comprised of two globin molecules, both with their own heme group that binds to and carries oxygen.
• Hemoglobin is comprised of four globin molecules, each of which contain millions of heme groups.
• Hemoglobin is comprised of four globin molecules, each with their own heme group that binds to and carries oxygen.

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