Test 2 Flashcards
What do tumor suppressor proteins do to cell division?
They inhibit it
Cell division, which is the climax of the cell cycle, consists of
cytokineses plus mitosis or meiosis
The G0 phase of the cell cycle is distinguished by
the absence of preparation for DNA synthesis Correct
The mitotic spindle is made of
microtubules
You are examining the rapidly dividing cells of a fish embryo and notice a cell that seems to contain two nuclei with complete nuclear envelopes and decondensing chromosomes. The middle of the cell is pinched inward. This cell must be in
telophase
After a single cell undergoes meiosis in a male, how many sperm cells will be produced?
4
The distribution of DNA into homologous pairs of chromosomes allows
cells to reduce their number of chromosomes by half during meiosis Correct
Normal cell division requires what kind of proto-oncogenes and what kind of tumor suppressor genes.
activated proto oncogenes and inactivated tumor suppressor genes
If exposure to sunlight causes a mutation in a single proto-oncogene in a diploid cell so that it becomes hyperactive, then
the cell might produce a protein that pushes it into rapid cell division
cancer in humans is caused by
both environmental and genetic factors
an allele is
a version of a gene
If a person has one copy of each of two different alleles for a given gene, the person is ________ for that trait.
heterozygous
Which of the following symbols correctly represents a person who has a homozygous genotype?
WW
Mendel’s laws were able to accurately predict the pattern of inheritance for situations in which
one allele completely makes another allele
Each time a person has another child, the chance that the parent passes on a given allele to a child
is the same
A Punnett square is used to
to predict the outcome of a genetic cross
An plant with the genotype Aa mates with a plant with the genotype AA. Which of the following is true?
half of the offspring will be Aa
Two parents have ABO blood group genotypes of IAi and IAIB. Which of the following blood types could NOT belong to one of their children?
O
One of the first medical tests a newborn receives determines if the child has phenylketonuria (PKU). PKU is the result of a mutation in a single gene that causes mental retardation and a host of other phenotypes (light hair and skin color, eczema, and a “mousy” smell). By detecting PKU early, doctors are able to reduce the effect of this condition with a modified diet. PKU is an example of
pleiotropy
Two genes control fur color in Labrador retrievers. The first gene determines whether the pigment to be deposited in the hair will be black or brown. The second gene determines whether the pigments are put into the dog’s hair at all. A dog homozygous for the recessive allele of this second gene will be yellow because no pigment is deposited in its fur. This is an example of
epistatsis
Chromosomes that are NOT involved in determining gender are known as
autosomes
How do genes on autosomes play a role in sex determination?
The SRY gene product has an effect on autosomal genes Correct
Inheritance is said to be both stable and variable because
most of the time, genetic material is transferred with complete accuracy to the next generation while still creating unique individuals
Which of the following statements about crossing-over is true?
It disrupts the linkage between genes
Genes that are located on opposite ends of the same chromosome are
affected by crossing-over so frequently that they may appear to undergo independent assortment
Which of the following genetic changes would NOT be heritable?
a mutation in a skin cell
An allele that appears to “skip generations” is most likely=
recessive
Most inherited human disorders are the result of
recessive mutations of genes located on autosomes
A man is a carrier for a recessive disease allele. A woman is not a carrier and does not have the disease. The couple has four children and
none of the children have the disease
Even though it is deadly, the Huntington disease allele can remain in the population, because
people with the disorder often live long enough to reproduce
A woman who is a carrier for a recessive X-linked disorder has children with a man who does not have the disease. Which of the following is true of the couple’s children?
Their sons have a 50 percent chance of having the disorder
During cell division, a piece of a chromosome breaks away and is added to the end of its homologue. The homologue with the addition is an example of
duplication
An XX individual develops as a male. Which of the following statements offers the most likely explanation?
A piece of a Y chromosome has become attached to one of the X chromosomes
The tendency to develop diseases, such as cancer and heart disease, is
the result of the interaction of multiple genes and environmental factors
Which of the following would NOT be a required biological property of genetic material?
It must exist in paired copies
All cells in an organism contain a full copy of that organism’s DNA. Your ears do NOT produce digestive enzymes because
different genes are expressed in different parts of an organism
Estrogen is a hormone that binds to a receptor on the surface of some cells. This binding causes regulatory molecules in the nucleus to interact with a segment of DNA that precedes some genes. This interaction activates the gene and causes gene expression. The segment of DNA that the regulatory molecules bind to is called
promoter
the hydrogen bonds in DNA hold together what?
The bases on one strand of DNA are held to the bases on the other strand
What part of a nucleotide accounts for the genetic variation between individuals?
base
Assume a certain molecule of DNA is composed of exactly 22 percent adenine. How much cytosine would you expect to find in this molecule?
28 percent
To start DNA replication, the bonds holding the strands together are broken, and the molecule begins to unwind. Which of the following statements best summarizes what happens next?
Each old strand acts as a template for a new strand
A rapidly dividing cell is exposed to a chemical that converts the bond that forms between adenine and thymine to a covalent bond. Which of the following is most likely to occur?
DNA replication would not occur because the two nucleotide strands that make up the DNA molecule would not be able to separate
Benzopyrene is a compound found in cigarettes that binds to the base guanine in DNA. This distorts the DNA double helix and causes changes in DNA sequence. Based on this information, benzopyrene is a
mutagen
A mistake during which of the following processes would have the most long-lasting effects on an organism and its offspring?
a replication in germline cells
Which of the following must occur for a mismatch error to be repaired?
DNA repair proteins identify damaged DNA
Most eukaryotic DNA is
noncoding
A segment of DNA is present in a gene, is transcribed, but is not used in translation. This segment of DNA is a(an)
intron
If their food source changes from lactose to arabinose, bacteria turn off their genes for lactose enzymes and turn on their genes for arabinose enzymes. Why don’t bacteria express the genes for both lactose and arabinose enzymes all the time?
To prevent the waste of energy and resources on unneeded protein production
The enzymes involved in ATP synthesis in the mitochondria are likely to be encoded by ________ genes
housekeeping
Which of the following might lead to a genome copy number variant in which the individual has only one copy of a gene instead of the normal two copies?
chromosomal deletion
Prokaryotes lack membrane-bound organelles and thus do not have nuclei; therefore
prokaryotic transcription and translation both take place in the cytoplasm
Which of the following does NOT take place in the nucleus?
translation
The key enzyme used during transcription is
RNA Polymerase
During RNA splicing
introns are removed from RNA, and the remaining exons are connected to form a mature mRNA
Which of the following is NOT a feature of the genetic code?
Every individual has a different genetic code
Which molecules are involved in translation?
mRNA, tRNA, and rRNA
If a particular segment of DNA has the base sequence TAC, what will be the base sequence of the anticodon of the tRNA that carries the amino acid encoded by that stretch of DNA?
UAC
It is possible for a mutation to occur and yet not alter the end product of translation if
the new codon encodes the same amino acid
When one base is inserted in the DNA sequence of a gene, the result is a(n) ________ mutation
frameshift
