Genetics Final Exam Questions and Answers: BIOD 210 (2024/2025), Exams of Genetics

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BIOD 210 Genetics Final Exam Questions and

Answers (2024 / 2025) (Verified Answers)

What cellular structures are involved in the synthesis of the majority of a cell's proteins? - ANSWER Rough endoplasmic reticulum and ribosomes What type of chromosome has a centromere located very close to, but not on, the end of the chromosome? - ANSWER Acrocentric What stage is characterized by cells that are not actively dividing (i.e. proliferating)? - ANSWER G0 phase How are the chromosomes organized during mitosis metaphase? - ANSWER Sister chromatids align along the equatorial plane of the cell What stage of meiosis is characterized by the separation of the sister chromatids? - ANSWER Anaphase II Which statement accurately describes a diploid cell? - ANSWER Contains 2 copies of each chromosome Which of the following statements regarding haploidy is true? - ANSWER Each haploid cell contains one chromosome of each homologous pair of chromosomes Diploid cells contain homologous chromosomes. While homologous chromosomes are very similar and contain the same loci, they are not identical. Which statement correctly explains why homologous chromosomes are not identical? - ANSWER The two members of a homologous pair originated from different parents/different individuals Which of the following statements about results of meiosis is correct? - ANSWER The chromosome number is reduced by one-half. What process leads to the creation of "sister chromatids"? - ANSWER DNA replication

If two chromosomes of a species are the same length and have similar centromere placements and yet are not homologous, what is different about them? - ANSWER Both genetic content and banding pattern How does crossing over contribute to genetic variation? - ANSWER It creates new DNA sequence combinations Which statement best describes the overall function/purpose of interphase? - ANSWER To duplicate the majority of the cell's internal contents How are viral genomes and eukaryotic genomes similar? - ANSWER They have the ability to pack a genome into a small volume What term refers to the proteins that the DNA wraps and organizes around? - ANSWER Histones Which technique can be used to specifically identify areas of a chromosome that are composed of heterochromatin? - ANSWER C-banding Which of the following statements about heterochromatin is FALSE? - ANSWER Heterochromatin replicates early in the S phase What is the diploid chromosome number for humans? - ANSWER 46 How many chromosomes would be expected in a human egg cell? - ANSWER 23 What process involves the shuffling of the genetic information between the two members of a homologous pair? - ANSWER Crossing over Organized by centrioles, what structures are important in the movement of chromosomes during cell division? - ANSWER Spindle fibers What is the name of the membranous structure that compartmentalizes the cytoplasm of eukaryotic organisms? - ANSWER endoplasmic reticulum

contains the n complement), how many chromosomes would one expect in the body (somatic) cells of the female offspring? - ANSWER 25 What is the outcome of synapsis, a significant event in meiosis? - ANSWER side-by-side alignment of homologous chromosomes If a typical G1 nucleus contains 2C (two complements) of DNA, a gamete that is haploid (n) contains 1C of DNA. - ANSWER True During meiosis, chromosome number reduction takes place in anaphase II. - ANSWER False A bivalent at pachytene contains four chromatids. - ANSWER True The meiotic cell cycle involves two cell divisions but only one DNA replication - ANSWER True An organism with a haploid number of 10 will produce 1024 combinations of chromosomes at the end of meiosis. - ANSWER True An organism with a diploid chromosome number of 46 will produce 2^23 combinations of chromosomes at the end of meiosis. - ANSWER True Eukaryotic chromosomes contain two general domains that relate to the degree of condensation. These two regions are ________. - ANSWER called heterochromatin and euchromatin Chromatin of eukaryotes is organized into repeating interactions with protein octomers called nucleosomes. Nucleosomes are composed of which class of molecules? - ANSWER histones Which of the following is a prime number? - ANSWER 5 Mendel crossed peas with round, green seeds with peas having wrinkled, yellow seeds. All F1 plants had seeds that were round and yellow. Predict the results of testcrossing these F1 plants. - ANSWER 1/ round, yellow; 1/4 round, green; 1/4 wrinkled, yellow; 1/4 wrinkled, green

Albinism in humans is inherited as a simple recessive trait. Two normal parents have five children, four normal and one albino. What are the most likely genotypes of the parents? - ANSWER Aa x Aa Albinism in humans is inherited as a simple recessive trait. A normal male and an albino female have six children, all normal. What are the most likely genotypes of the parents? - ANSWER male: AA; female: aa All EXCEPT which one of the following factors were crucial to the success of Gregor Mendel's experiments? - ANSWER He kept detailed quantitative records. He observed only one or very few traits in any given experiment. He chose traits that were not greatly influenced by the environment. He always allowed all pea plants to self-fertilize, avoiding contamination from other individuals. ANSWER: He always allowed all pea plants to self-fertilize, avoiding contamination from other individuals. Mendel's unit factors in pairs are most accurately known to be __________. - ANSWER two alleles on paternal and maternal homologs Which two genotypes in an individual would be expressed as the same phenotype in a diploid organism?

• ANSWER Homozygous dominant and heterozygous Which of the following statements is an example of independent assortment? - ANSWER A tall pea plant is no more or less likely to have round seeds than a dwarf pea plant. Which of the following statements is true regarding a trihybrid cross between two true-breeding homozygous individuals with contrasting phenotypes? - ANSWER The least frequent F2 phenotypic class is recessive for all three traits. Consider this cross: DdEe x DdEe If this cross produces 320 individuals, how many of them are expected to display the dominant phenotype for both of the genes? Find the probability and then multiply it by the total number of individuals. - ANSWER 180

The ability to taste the chemical phenylthiocarbamide (PTC) results from a dominant allele (T) and not being able to taste PTC is the result of having two recessive alleles (t). The ability to roll one's tongue is the result of a dominant allele on a second gene (R). Consider that two parents who are both taster, rollers have a child that is a non-taster, non-roller. What is the probability that their next child will have the same phenotype as the parents? - ANSWER 9/ Which of the following is responsible for the control of sex determination and sexual differentiation? - ANSWER sex chromosomes What causes the abnormal chromosome numbers seen in disorders like Klinefelter syndrome (47,XXY) and Turner syndrome (45, X)? - ANSWER improper segregation of sex chromosomes during meiosis When considering the sex chromosomes, pseudoautosomal regions refer to - ANSWER homologous regions of the X and Y chromosomes Which statement about Barr bodies is true? - ANSWER They ensure that males and females have equal "doses" of the genes on the X chromosome. How many Barr bodies would be found in a human with the karyotype 48, XXYY? - ANSWER 1 Which of the following is a correct statement about linkage groups? - ANSWER It represents some of the genes located on the same chromosome. When conducting crosses involving two X-linked genes, what is the explanation for the new phenotypes that are sometimes observed (i.e. the phenotypes not seen in the parents)? - ANSWER Crossing over occurred and genes were exchanged between homologous chromosomes What is the theoretical maximum limit of observed recombination due to crossing over? - ANSWER 50% As the distance between genes increases, the results of mapping experiments are less accurate. Which statement explains the reason for this? - ANSWER Multiple-strand exchanges are more common. Of the DNA markers listed below, which one is not useful for mapping purposes? - ANSWER Chiasmata

Crossing over normally involves an exchange of genetic material between all of the following except - ANSWER nonhomologous chromosomes If two genes do not assort independently, they are considered to be - ANSWER linked Assume that an AaBb plant is crossed with an aabb plant. Four different genotypes (AaBb, Aabb, aaBb, aabb) are observed in the offspring, and there are approximately 25% of each genotype represented. These results are consistent with - ANSWER independent assortment When two gene loci are located on nonhomologous chromosomes, these genes are expected to assort independently. - ANSWER true When two gene loci are located close together on the same chromosome, these genes are expected to assort independently. Selected Answer: FalseAnswers:True False - ANSWER false What assumption can be made if a cross between AaBb and aabb plants results only in offspring that have the same genotype as the parents? - ANSWER complete linkage The cross AB/ab X ab/ab produces the following progeny: AB/ab 404, ab/ab 396, aB/ab 97, Ab/ab 103. From these data, one can conclude that the A and B loci assort independently. - ANSWER false What term refers to the phenomenon in which one crossover decreases the likelihood of crossovers in nearby regions? - ANSWER positive interference In humans, which sex is considered homogametic? - ANSWER female Consider that hemophilia is caused by a sex-linked recessive gene. If a man with hemophilia marries a phenotypically normal woman whose father had hemophilia, what is the probability that they will have a child with hemophilia? - ANSWER 1/

There are six different codons that all specify the amino acid leucine. What is the term that refers to this phenomenon? - ANSWER degenerate How many different codons code for amino acids? - ANSWER 61 How many different codons direct the ribosome to stop translation? - ANSWER 3 What term refers to the process of making RNA from a DNA template? - ANSWER transcription What term refers to the process of making protein from an RNA template? - ANSWER translation What gene region is responsible for helping the RNA polymerase determine where to begin transcribing DNA into RNA? - ANSWER promoter In prokaryotes, what subunit of the RNA polymerase is responsible for binding to the promoter sequence? - ANSWER 𝞼 In eukaryotes, what are the two main types of post-transcriptional modifications that are done to the mRNA? - ANSWER The addition of a 7-mG cap at the 5' end of the transcript and the addition of a poly-A sequence at the 3' end of the message. Why are most eukaryotic mRNAs shorter than the actual genes that encode them? - ANSWER Eukaryotic genes contain both introns and exons. Which of the following does not play a role in "charging" the tRNA molecules? - ANSWER rRNA Which statement regarding translation elongation is true? - ANSWER After translocation has occurred, the uncharged tRNA exits the ribosome via the E site, the P site is occupied by the tRNA carrying the polypeptide chain, and the A site is open to bind another charged tRNA. When the ribosome moves down the mRNA, it moves in the - ANSWER 5' to 3' direction.

Which of the following is a true statement regarding eukaryotic translation? - ANSWER In eukaryotes, mRNAs are much longer lived than in prokaryotes. Consider the following DNA molecule: 5' GTA ACC GGA 3' 3' CAT TGG CCT 5 If this molecule were transcribed, what would be the resulting RNA molecule? - ANSWER 5' GUA ACC GGA 3' Which of the following DNA sequences might code for the polypeptide sequence Gly-Leu-Asp? - ANSWER 3' CCA AAC CTG 5'' What type of chemical bond does the ribosome make? - ANSWER peptide bond When does the ribosome stop adding amino acids to the end of the growing polypeptide chain? - ANSWER It encounters a stop codon. Consider that a certain protein is 630 amino acids in length. What would be the minimum number of DNA bases necessary to encode all of the instructions to make it? - ANSWER 1890 Where would the anticodon be found? - ANSWER tRNA If B is an intron that is located between two exons (A and C), how will this region of mRNA appear after it is transcribed and processed by splicing? - ANSWER A-C The genetic code is "triplet." What does this mean? - ANSWER There are three nucleotides in mRNA that code for an amino acid. If a mutation causes multiple contiguous (side-by-side) amino acid changes in proteins, what type of mutation is this? - ANSWER frameshift What is the start codon found in both prokaryotes and eukaryotes? - ANSWER AUG

During the production of RNA, what RNA sequence would the DNA template sequence 3'-TAGCTG-5' be transcribed to produce? - ANSWER 5' AUC GAC 3' Which of the following would be a function of exons? - ANSWER They code for the amino acids that will make up a polypeptide. Which of the following would be an appropriate description of cancer? - ANSWER genetic disorder at the cellular level Why does the abundance of cyclins fluctuate at various times during the cell cycle? - ANSWER Different cyclins combine with protein kinases at different stages of the cell cycle to affect the cell cycle. The ras gene family plays a role in - ANSWER signal transduction In normal cells, the role of p53 in the cell cycle is - ANSWER to temporarily arrest the cell cycle in G before entering S. What is the difference between proto-oncogenes and oncogenes? - ANSWER Oncogenes are mutant forms of proto-oncogenes. What is metastasis? - ANSWER the ability to form secondary tumors at another site Which of the following statements is true? - ANSWER At least two mutational events are required for a cell to become cancerous. What term refers to a condition when a person has too many or too few of a specific chromosome? - ANSWER Aneuploidy What is the specific term that describes the loss of one chromosome? - ANSWER monosomy How might gene duplications arise? - ANSWER uneven crossing over during meiotic prophase

Errors during what phases of meiosis are responsible for the production of aneuploids? Select all that apply. - ANSWER anaphase II anaphase I What is the difference between polyploidy and aneuploidy? - ANSWER Polyploids have extra copies of every single chromosome, while aneuploids may have an extra copy of just one chromosome. Consider a diploid species where 2N = 30. How many chromosomes would be present in a monosomic individual? - ANSWER 29 If a chromosome lacks certain genes, what has most likely occurred? - ANSWER deletion The failure of the chromosomes to separate normally during cell division is called - ANSWER nondisjunction What three general mechanisms appear to be involved in the conversion of proto-oncogenes to oncogenes? - ANSWER point mutations, translocations, overexpression Cancer can result from genome instability - ANSWER true What term refers to an agent that is capable of causing damage to DNA? - ANSWER carcinogen In order to control the cell cycle, cyclins interact with - ANSWER cyclin dependent kinases What is the function of the retinoblastoma protein (pRB) in regulating the cell cycle? - ANSWER tumor supressor Which of the following represent mutant versions of genes that are normally involved in promoting the cell cycle? - ANSWER oncogenes

Which statement explains why the ethical, legal and social implications of DNA research should be carefully considered? - ANSWER although many genetic diseases can now be detected, technology has not given us the power to cure them What was the first hormone to be made by recombinant bacteria? - ANSWER insulin When the human genome was sequenced, what is a surprising feature that was discovered? - ANSWER That only about 2 percent of the genome encodes proteins Which of the following represents a true statement concerning DNA microarrays? - ANSWER They can be used to screen for changes in gene expression between normal and cancer cells. Which of the following is a true statement concerning synthetic genomes? - ANSWER They have successfully created new prokaryotic cells. How can genome-wide association studies be used? - ANSWER To correlate traits or diseases with variations in the genome Transgenic crops are generated for all of the following reasons EXCEPT - ANSWER to increase the number of different plant species used in agriculture When a foreign gene is introduced into a plant or animal, that organism is referred to as - ANSWER transgenic What was the first functional genome to be synthesized? - ANSWER Mycoplasma mycoides What term refers to a hybrid protein that consists of amino acid sequences from two separate proteins?

• ANSWER Fusion protein What was the first recombinant protein to be extracted from milk and approved for medicinal use in humans? - ANSWER Antithrombin

Which of the following transgenic farm animals has been successfully produced using modified growth hormone genes? - ANSWER salmon Approximately how often do SNPs occur in the human genome? - ANSWER every 100-300 nucleotides Which field of genomics seeks to improve the selection of medicines for treating individuals? - ANSWER Pharmacogenomics Rational drug design involves trial and error testing of chemicals in lab animals. - ANSWER false Which statement best describes the overall goal of gene therapy? - ANSWER Cure a patient Can genes in their natural state as a produce of nature be patented? - ANSWER no What type of testing allows for the analysis of potential phenotypes of using parental DNA samples? - ANSWER Preconception testing SNPs contain - ANSWER variable base sequences and are variable in the population Which of the following is a potential use for DNA microarrays? - ANSWER scan a population of nucleic acids for abundance and mutations What enzyme is responsible for generating restriction fragments? - ANSWER Endonuclease What term refers to probes that will hybridize only with a complementary sequence and not with other sequences that may vary by as little as one nucleotide? - ANSWER allele-specific oligonucleotides (ASOs) When valuable proteins are produced in genetically modified plants and animals, this is known as - ANSWER biopharming How are RFLPs typically used? - ANSWER To map genes and construct DNA fingerprints