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78 Cards in this Set

  • Front
  • Back

What is it called when a piece of a chromosome breaks off and joins a nonhomologous chromosome?


Which phase is it best to obtain chromosomes to prepare a karyotype?

late prophase or metaphase

What is true about linkage and how close genes are on a chromosome?

The closer they are, the lower the probability that they will experience crossover between them.

Give an example of epistasis.

In many animals, one genotype prevents any fur color from developing.

The pedigree in figure 15.3 shows the transmission of a trait in a particular family. Based on this pattern of transmission, the trait is most likely:


How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?


Why did Mendel's F1 generation always look like one of the parents?

One of the phenotypes showed complete dominance.

When two plants are crossed, their children show a 3:1 ratio for a particular trait. What does this suggest?

The parents were both heterozygous for a single trait.

What does a nonreciprocal crossover cause?

Deletion and duplication

What is the genotype of individual II-5


Why are men more often affected by sex-linked traits than women?

males are hemizygous for the X chromosome

What is the probability that individual III-1 is Ww?


What is the best treatment for PKU?

regulate the diet of the patient to severely limit the uptake of the amino acid.

What is the best statement for the addition rule of probability?

the probability that either one of two independent events will occur.

What does a frequency of 50% recombination indicate?

The two genes are likely to be located on different chromosomes.

What is the chance of getting a homozygous recessive offspring phenotype from someone with homozygous recessive and someone that is a heterozygote?


What best describes the fact that cystic fibrosis affects the lungs, the pancreas, the digestive system, and other organs?


Between which two genes in figure 15.1 would you expect the highest frequency of recombination?

A and G

Recombination between linked genes comes about for what reason?

crossovers between these genes result in chromosomal exchange.

Why are linked genes inherited together?

they are located close together on the same chromosome

What is the best way to describe SRY?

it is a gene region present on the y chromosome that triggers male development.

What is meant by the terms monohybrid cross and dihybrid cross?

a dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid involves only one.

Two people who can see color have a color-blind son. What is the genotype of each parent?

XRX1 and XRY

Give an example of polygenic inheritance.

Skin pigmentation in humans

Why were all of Thomas Hunt Morgan's F2 generation flies with white eyes male?

the gene involved is on the X chromosome.

What would be the features for ideal fetal testing?

lowest risk procedure that would provide the earliest, most reliable info

What would you conclude about Marfan Syndrome based on its symptoms?

It is pleiotropic

Which event in Meiosis I is mendel's second law of independent assortment based in?

Alignment of tetrads at the equator

What is the first event in the differentiation of gender called in humans?

Activation of SRY in male embryos and masculinization of the gonads

What is the centimorgan equal to?

1% frequency of recombination between two genes

What is the meaning of the 20th century chromosome theory of inheritance?

mendelian genes are on specific loci on the chromosome and in turn segregate during meiosis


Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive sscactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. The relationship between genes S and N is an example of:


What human aneuploidy generally has the most severe impact on the health of the individual?

47, +21


Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails?


What is a syndrome?

A group of traits typically found in conjunction with a particular chromosomal aberration or gene mutation.


In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?

Roan times roan


Abnormal chromosomes are frequently found in malignant tumors. Errors such as translocations may place a gene in close proximity to different control regions. Which of the following might then occur to make the cancer worse?

Expression of inappropriate gene products


In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short?



A couple has a child with Down syndrome. The mother is 39 years old at the time of delivery. Which of the following is the most probable cause of the child's condition?

One member of the couple underwent nondisjunction in gamete production.

What is the source of the extra chromosome 21 in an individual with Down Syndrome?

Nondisjunction or translocation in either parent.


From your understanding of the cell structure, when the newly made polypeptide is to be secreted from the cell where it has been made, what must occur?

Its signal sequence must lead it to the ER, from which it goes to the Golgi.


How do we describe transformation in bacteria?

Assimilation of external DNA into a cell.


In his transformation experiments, what did Griffith observe?

Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.


An Okazaki fragment has which of the following arrangements?

5' RNA nucleotides, DNA nucleotides 3'


At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' C C T A G G C T G C A A T C C 5' An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?

5' A C G U U A G G 3'


Which of the following is a function of a signal peptide?

To translocate polypeptides across the ER membrane.


Which of the following would you expect of a eukaryote lacking telomerase?

A reduction in chromosome length in gametes.


Which of the following help(s) to hold the DNA strands apart while they are being replicated?

Single-strand binding proteins


The nitrogenous base adenine is found in all members of which group?



It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in which of the following?

Sequence of bases


Heterochromatin is __________, whereas euchromatin is ________________

Highly condensed, less compact


Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells are impaired in what way?

They cannot repair thymine dimers.


A frameshift mutation could result from:

Either an insertion or a deletion of a base


Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction?

DNA polymerase III


Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?



What is the effect of a nonsense mutation in a gene?

It introduces a premature stop codon into the mRNA.


To repair a thymine dimer by nucleotide excision repair, in which order do the necessary enzymes act?

Endonuclease, DNA polymerase I, DNA ligase


What is a ribozyme?

An RNA with enzymatic activity.


Which of the following can be determined directly from x-ray diffraction photographs of crystallized DNA?

The diameter of the helix


Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication?

Double-stranded DNA, four kinds of dNTPS, primers, origins


Which of the following nucleotide triplets best represents a codon?

A triplet at the opposite end of tRNA from the attachment site of the amino acid.


What is the function of the release factor (RF)?

It binds to the stop codon in the A site in place of a tRNA.


There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that:

The rules for base pairing between the third base of a codon and tRNA are flexible.


A new DNA strand elongates only in the 5' to 3' direction because:

DNA polymerase can only add nucleotides to the free 3' end.


A tRNA has its 3' end projecting beyond its 5' end. What will occur at this 3' end?

The amino acid binds covalently.


The leading and the lagging strands differ in that:

The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.


In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after he has removed its 5' cap and poly-A tail. Which of the following would you expect him to find?

The molecule is digested by exonucleases since it is no longer protected at the 5' end.


What is meant by the description "antiparallel" regarding the strands that make up DNA?

The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.


What is the function of topoisomerase?

Relieving strain in the DNA ahead of the replication fork.


Which of the following is the first event to take place in translation in eukaryotes?

The small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA.


If a cell were unable to produce histone proteins, which of the following would be a likely effect?

The cell's DNA couldn't be packed into its nucleus.


Which of the following does not occur in prokaryotic and eukaryotic gene expression, but does in eukaryotic gene expression?

A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.


During splicing, which molecular component of the spliceosome catalyzes the excision



What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?


It joins Okazaki fragments together.


A particular triplet of bases in the template sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is:



A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein. How many amino acids are made in this process? This is best explained by the fact that:

Many noncoding stretches of nucleotides are present in mRNA.


Which of the following investigators was/were responsible for the following discovery? In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.

Erwin Chargaff


What is the function of DNA polymerase III?

To add nucleotides to the 3' end of a growing DNA strand.