Genetics Final

Dr. Teeter 312 Exam Final

Is it better to have a large sample size in genetic crosses?

Yes, larger sample sizes can produce phenotypic ratios closer to the expected ratios.

b/b; s/s

The cell of a mature pea plant have 14 chromosomes. How many chromosomes does a nucleus in the pea endosperm contain?

7

Autosomal Recessive

B/B; e/e

What is the apparent purpose for X inactivation in humans and other mammals?

It allows for the levels of expression of genes on the X chromosome to be similar in males and females.

The attachment point on the chromosome for spindle microtubules is the:

centromere

In pedigree analysis, the proband is:

The individual having the trait or disorder from whom the pedigree is initiated.

A new muntjac species that you are studying has 9 different chromosomes. Like all mammals, the muntjac is diploid. How many crhomosome’s would you expect to see in a normal (non-gamete) cell from this organism?

18

The process that converts the information in DNA into RNA is:

Transcription

Sister chromatids separate at which stage?

Anaphase of mitosis and anaphase II of meiosis.

0.4

A form of a gene that has a slightly different DNA sequence than other forms of the same gene but encodes the same type of an RNA or protein is called a(n):

Allele

If a human trait is never passed from gather to son, it is likley that this trait is:

X-linked.

If a typical somatic cell (non-sex) of a mammal has 32 chromosomes, how many chromosomes are expected in each gamete of that organism.

16

Two green corn plants are crosses and produce these offspring: 2/3 green, 1/3 white. What is the genotypes of the green progeny?

A/a

1/16

A mother of blood type A gives birth to a child with blood type O. Which of the following could NOT be the blood type of the father?

AB

Alleles of genes that cause autosomal recessive disorders must be inherited from _______ in order for the offspring to be affected by the disorder.

Both parents.

A mother with blood type A has a child’s with blood type A. Give all the possible blood types for the father of this child

A,B,AB,O

In the diploid cells of an organism, there can be _____ different alleles of a given single copy nuclear gene>

one or two

If a women has red-green colorblindness (an X-linked recessive trait), her father must also have the disorder.

True

Severity of symptoms of cystic fibrosis may vary from one patient to the next. This variation seen is representative of:

variable expressivity.

Meiosis results in diploid cells.

False

Mitosis results in two daughter cells that are identical to the starting cell

True

The feathers of erminette fowl are grayish. A cross of two erminettes produced a total of 48 progeny, consisting of 24 erminettes, 13 blacks, and 12 pure whites. What appears to be the genetic basis of the erminette phenotype?

Incomplete Dominance

Which of these options are NOT prokaryotes

Viruses

Freckles are caused by a dominant allele. A man has freckles but one of his parents does not have freckles, What is the man’s genotype?

Heterozygous

A Barr body is a(n):

Inactivated X chromosome, visible in the nucleus of a cell that is from a female mammal with normal chromosomes.

In a flowering plant, the male part of the flower (the stamen) produces haploid microspores that divide by ____ to eventually produce sperm.

spermatogenesis.

The uptake of DNA from the surrounding medium and its incorporation into the bacterial genome is called____.

transformation

Human cells that have an extra copy of chromosome 18 are

trisomic

A bacterium that is unable to grow on minimal medium is said to be

auxotrophic

If you attempt to grow an auxotrophic mutant on minimal media, what will happen?

Nothing

Hardy and Weinberg’s achievements in genetics was demonstrating mathematically that dominant alleles should increase in frequency over time in a population.

False

Which mechanism of gene transfer in bacteria require direct physical contact between donor and recipient cells?

Conjugation

p = 0.6 and q = 0.4

The ratio of the observed number of double recombinants to the expected number of double recombinants is the _____.

Coefficient of coincidence

Antibiotic resistance in a population of bacteria is spread rapidly because the gene conferring antibiotic resistance is usually:

A bacterial plasmid gene

The recessive lethal allele is in tight coupling linkage with the b allele so almost all of the b/b offspring will also be l/l and thus die before they can be observed.

Which of the following is true about bacteria strain with the genotype met+, bio+, thr+, ley-, thi+, str ^s

It is sensitive to streptomycin.

Non-disjunction occurs most often in ______, and is oftern due to the failure of proper chromosome pairing in proper crossing over.

Mitosis and Meiosis II.

Lac and Azi will rarely be transferred together.

Double-stranded, circular, extra chromosomal DNA elements such as F factors and R are known as:

Plasmids.

An F plasmid in E. coli will replicate itself via ______ in conjugation

Rolling circle replication

A karyotype might NOT be useful in which of the following circumstances?

A genetic disease runs in a family and is caused by a single nucleotide substitution in a gene.

A B = 7.5 % and a B = 42.5%

Interference occurs when:

One crossover inhibits another.

True or false? Linked genes appear i a 9:3:3:1 ratio in dihybrid crosses.

False

Reciprocal translocation

In a given population, the A allele is at a frequency of 0.8 and the a allele is at a frequency of 0.2. Assume H-W equilibrium, what should the frequency be of A/A homozygotes in the population?

0.64

In growing fruit for agricultural purposes, why might a growing a triploid strain be desirable?

It would be sterile, and therefore seedless.

Polyploids have ____.

More than two sets of chromosomes

Definition of aneuploidy

The addition or loss of less than a full set of a chromosome or chromosome pair.

20 or 22

Assume that an individual of A/a B/b genotypes is involved in a testcross and four classes of testcross progeny are found in equal frequencies. Which of the following statements is TRUE?

The genes A and B could be located on different chromosomes or on the same chromosome and very far apart.

You are analyzing an unusual DNA sequence from a tardigrade, and find that it only contained 10% thymine. In this case, how much of this sequence would you expect to be guanine?

40%

What is the steps (3) of how information is normally transferred between biological molecules (aka the central dogma)

DNA > RNA > Protein

What are the structures in a cell that group genes together, are composed of chromatin (DNA and proteins), and become visible under a light microscope during mitosis?

Chromosomes

Anaphase of meiosis II

To provide food for the developing embryo in flowering plants, a tissue called endosperm is produced through double fertilization. Endosperm has a ploidy of:

3n

If two genes are so tightly linked that no crossing over occurs between them what will the progeny be?

Al the progeny will be parental types (non-recombinant)

8%

What are the assumptions if the Hardy-Weinberg equilibrium

• Random Mating

• Little or no mutation from one allele to another

• Little or no migration in or out of the population

• A large population

In examining meiotic chromosomes from a mouse, you observe a loop structure on one of the chromosomes. This indicates that ______.

The mouse may have a heterozygous inversion

In prokaryotes, genes are often found in operons. What is an operon?

A promoter, regulatory sequences, and protein coding sequences from multiple genes. All of the protein coding genes are transcribed in a single mRNA.

Bacteriophage engage in two interactive cycles with bacteria. What are those cycles?

Lytic and lysogenic

Which explanation is one of the reasons for the ability of influenza virus to evolve rapidly?

It has a segmented RNA genome and can easily re-shuffle segments between strains.

If both lactose and glucose are in the media for E. coli, is the beta-galactosidase (Z) gene expressed at a high level?

No

You identify an enzyme whose function seems to be associated with acetylate lysin residues in histone tails. What is the enzyme most likley associated with?

Activation of gene expression.

A researcher is performing an Ames test to study a novel compound. She mixes the compound with an extract of liver enzyme and different auxotrophic strains of bacteria. She then plates the bacteria on minimal media plates. If this compound is a strong mutagen, what would she see?

Many colonies.

Gene regulation in eukaryotes can take place a variety of levels from transcriptional to posttranslational. At what level is genetic regulation most likely in prokaryotes.

Transcriptional

A geneticist uses genetic engineering to treat patients who have an immune disorder caused by a mutation in the gene for adenosine deaminase. The geneticist removes white blood cells from the patients and then infuses the treated cells back into the patient. This is an example of which type of gene therapy?

Somatic gene therapy.

A nonsense mutation in a gene would lead to which of the following?

A protein that is shorter than normal.

A lac operon of genotype lacl(-), lacP(+), lacO(+), lacZ(+), lacY(+) will produce beta galactosidase and permease when:

whether lactose is present or not.

If a person is exposed to a chemical mutagen that damages their DNA in such a way as to predispose to cancer, will this person pass this cancer predisposition down to their children?

Maybe. If the cancer causing mutations happen in germline cells, there is a chance that a cancer predisposition could be passed down to their children.

Which of the following statements about cancer and mutations is NOT true?

Cancer cells usually differ from normal cells by just on mutation.

In human gene therapy, ______ are commonly used to insert genes into recipient cells.

Adeno-associated viruses

How would you expect DNA methylation to alter gene expression?

Measurably decrease expression.

A cancer cell was identified as having inappropriate expression of telomerase. Which of the following would be the BEST treatment that could prevent this cell line from dividing indefinitely.

A drug that methylates the promoter of the telomerase gene.

What specifically do most people inherit when they inherit a predisposition to particular cancer such as retinoblastoma?

A loss of function mutation in one copy of a tumor suppressor gene.

The ______ is a cis-acting DNA element that binds to RNA polymerase II.

promoter

The lac repressor protein controls expression of the lac operon by binding to the _____.

Lac operator site to repress expression.

What is the modification of histones associated with the nucleosomes of actively transcribed genes?

Rich in acetyl groups (Hypoacetylated)

In comparing tumor cells to normal cells from the same individual, what phenomenon is commonly seen?

Loss of heterozygosity

What type of virus best describes the novel coronavirus that causes COVID-19

RNA Virus

The polymerase chain reaction uses specially designed ____ to amplify specific regions of DNA in a test tube.

Primers.

The gene p53 is found to have a loss of function mutations in many different cancers. Because of its role in the cell, it is sometime referred to as the “the guardian pf the genome”. Which of the following terms is the best description of p53?

Tumor suppressor gene

The loss of which of the following repair mechanisms results in the condition known as Xeroderma Pigmentosum?

Base excision repair

What type of function is often carried out by the products of tumor-suppressor genes?

Inhibition of cell division

What is the function of dideoxynucleosides in Sanger DNA sequencing?

They stop (terminate) synthesis at a specific site, so the base at that site can be determined.

The lac operon inducer (allolactose or IPTG) enables transcription by binding to the:

repressor.

What is the origin of the CRISPR-Cas9 system

A type of immune system found in bacteria

A number of somatic translocations have been associated with specific types of ______in humans. An examples of this is the “Philadelphia chromosome”, a chromosome 9:22 translocation.

Cancer.

An enhancer is best described as:

A transcription factor that acts to promote the expression of specific genes.

Evidence that the development of cancer is a multistep process includes the:

Observation that certain tumor-suppressor genes and oncogenes are involved in a sequential manner in the development of colon cancer.

A condition in which a gene or group of genes is expressed all the time is______.

Constitutive

What is a transposable element

A segment of DNA that can move around in the genome.

Which explanation is one of the reasons for the ability of the influenza virus to evolve rapidly.

It has segmented RNA genome and can easily reshuffle segments between strains.

What is not a typical mechanism by which a proto-oncogene is converted to an oncogene?

Complete deletion of the proto-oncogene