BIO 1010
Which two people would have the most different Y chromosome?
a father and his daughter's biological son
What is apoptosis?
a form of regulated cell death
Which combination contains the normal chromosome number?
a human egg - 23; a human sperm - 23; a human zygote - 46
Which couple could have a boy with Duchenne muscular dystrophy (DMD)?
a male with DMD and a homozygous dominant female
If an individual has a germ cell mutation, which of these is a possible source of that mutation?
a maternal or paternal allele
What is an "inherited" or "hereditary" cancer?
a mutation that predisposes an individual to cancer passed from parent to child
Which statement accurately describes cancer development?
a proto-oncogene and a tumor suppressor gene acting together
In order for a child to develop cystic fibrosis _____.
a sperm carrying a CF allele must fertilize an egg that also has that allele
What kind of inheritance occurs if red flowers crossed with white flowers produce offspring with red patches and white patches on their flower petals?
codominance
Amniocentesis can detect:
chromosome abnormalities in the fetus.
A black dog is bred with a brown dog, and all the puppies have patches of black and brown. The color coat alleles for black and brown are an example of _____.
codominance
How does an XX female inherit her two chromosomes?
One is from her mother and one is from her father.
In meiosis, sister chromatids separate during _____.
meiosis II
A patient has a mutated BRCA2 gene and a normal BRCA1 gene. Select the TWO answers that are correct.
-The patient has a lesser risk of developing ovarian or breast cancer than a patient with a normal BRCA2 gene and a mutated BRCA1 gene. -The patient has an increased risk of developing ovarian or breast cancer than a patient with normal BRCA1 and BRCA2 genes.
Dimples are a dominant inherited trait. If both parents are nondimpled, what are the chances that their first child will be born with dimples?
0%
What are the chances that a curly-haired father and a straight-haired mother can give birth to a child with curly hair?
0%
For the scenario in animation 11.9, what is the probability that an offspring will have the less severe form of the disease?
1/16
Mexican hairless dogs are hairless because of a dominant allele of a particular gene. Homozygous dominant dogs die in utero (before being born). What is the probability of two hairless dogs having a hairy puppy?
1/2
Two genes assort independently. A prospective mother is homozygous recessive for gene "A" and homozygous dominant for gene "B." The father is heterozygous for gene "A" and homozygous recessive for gene "B." What is the probability that their child will be heterozygous for both the "A" and "B" genes?
1/2
For the scenario in animation 11.9, what is the probability that an offspring will not have the disease?
12/16
A diploid cell of baker's yeast has 32 chromosomes. How many chromosomes are in each of its haploid spores?
16
How many chromosomes are in a human sperm?
23
Assume a phenotype is determined by one gene with a dominant allele and a recessive allele. If both parents are heterozygous, what is the probability of an offspring being a carrier of the recessive allele?
50%
Quitting smoking reduces a woman's risk of developing cancer by _____.
30%
An alien has 82 total chromosomes in each of its body cells. The chromosomes are paired, making 41 pairs. If the alien's gametes undergo meiosis, what are the number and arrangement (paired or not) of chromosomes in one of its gametes?
41 unpaired chromosome
How many chromosomes are in a normal human cell?
46
A human female has _____ chromosomes in each skin cell and _____ chromosomes in each egg.
46; 23
A meiotic error occurred during gamete formation, resulting in an egg that has 24 chromosomes. If that egg is fertilized by a normal sperm, how many chromosomes will be in the zygote?
47
An individual inheriting the genotype aaBbCc falls in the _____ foot phenotype.
5
A grandfather has an X-linked disease. His wife does not have the disease and she is not a carrier for it. What is the probability that their daughter's sons will have the disease?
50%
A man with straight hair marries a woman with wavy hair. What is the chance that their first child will have wavy hair?
50%
An alien species has 102 chromosomes in its diploid somatic cells. Its haploid gametes will have _____ chromosomes.
51
In a mating of two people of medium height (where three genes control height): AaBbCc x AaBbCc produce _____ distinct phenotypes determined by the number of genes inherited.
7
Assume a phenotype is determined by one gene with a dominant allele and a recessive allele. If one parent is heterozygous and the other parent is homozygous dominant, what is the probability of producing a homozygous recessive offspring?
75%
Assume a phenotype is determined by one gene with a dominant allele and a recessive allele. If one parent is homozygous recessive and the other is heterozygous, what is the probability that an offspring will have the recessive phenotype?
75%
How do doctors test for the presence of a BRCA1 mutation?
A DNA sample is extracted from the nuclei of white blood cells for genetic testing.
How do haploid gametes result in diploid offspring?
A haploid egg and a haploid sperm fuse to form a diploid zygote that grows by mitosis after fertilization.
What is an insertion mutation?
A nucleotide is inserted in a gene sequence, which alters all subsequent codons.
A woman is heterozygous for the CF-associated gene (the alleles are represented here by the letters A and a. Assuming that meiosis occurs normally, which answer choice represents eggs that she can produce?
A or a
A DNA molecule containing a gene has the sequence AACT on one strand. During replication, DNA polymerase synthesizes the sequence TTGT on the new strand. Which of these is the most likely new allele of the original strand after replication?
AACA
Assume a phenotype is determined by one gene with a dominant allele and a recessive allele. If one parent is homozygous dominant (AA) and the other parent is homozygous recessive (aa), what genotype(s) might their offspring have?
Aa
Which behavior can help reduce the risk of developing mutations?
All Of These
Which of these is a normal function of tumor suppressor genes, such as BRCA1 or p53?
All Of These
Which statement is true for the younger brother of a 29-year-old woman with breast cancer?
All of these
What is the role of BRCA1 in normal cells?
BRCA1 is a tumor suppressor.
How does an acquired mutation in a gene alter the function of a cell?
Base pair mutations in a gene are passed directly into mRNA via transcription.
A male inherits a high-risk BRCA1 allele. His sister inherits the same allele. Which statement is true?
Both siblings have a greater risk of developing breast cancer relative to males and females, respectively, without BRCA1 mutations.
Why is it possible for two healthy parents to give birth to a child with a genetic defect such as cystic fibrosis?
CF is only evident in individuals with two mutant alleles; a healthy parent could carry both a defective allele and a normal allele.
Why do people with "inherited cancer" often develop cancer at a relatively young age?
Cancer cannot be truly inherited, but certain alleles weaken the normal control points that prevent cancer, and this causes cancer to appear earlier in life.
A test designed to look for different alleles of a gene (e.g., the BRCA1 gene) is based on differences in _____.
DNA sequences
Assume that Emily (who has CF, a recessive disease (aa)) decides to have children with a man who does not have CF and who has no family history of CF. What combination of gametes can each of them produce, and what is the probability that they will have a child who is a carrier for CF?
Emily: aa, man: AA; 100% probability
Why do some people have unusual chromosome combinations, such as XYY and XXX?
Errors occurred in chromosome segregation during meiosis in their fathers or mothers.
Which of these is a likely result of nondisjunction in human meiosis?
aneuploid eggs or sperm
What would be the best way to distinguish between two alleles and two genes?
Examine their DNA; the DNA sequences of two different alleles would be more similar than the sequences of two different genes.
A "healthy living" or a "clean lifestyle" will guarantee that you will not develop any mutations in your DNA.
False
A mismatch that occurs during DNA replication always results in a mutation.
False
Predict the sex of a baby with an X sex chromosome.
Female
Predict the sex of a baby with an XX pair of sex chromosomes.
Female
_____ mutations can be passed from parent to offspring.
Germ line
What is meant by incomplete dominance?
Heterozygotes have a phenotype that is a mixture of the two alleles.
Homologous chromosomes behave differently in mitosis and meiosis. What process do they go through in meiosis that does not occur in mitosis?
Homologous chromosomes pair up with each other.
How is codominant inheritance different from incomplete dominant inheritance?
In codominance, two alleles are expressed equally; in incomplete dominance, heterozygotes have an intermediate phenotype.
What is the p53 gene and how can its mutation cause cancer?
It is a tumor suppressor gene that normally promotes apoptosis, and which causes cancer when it fails to induce apoptosis in rapidly dividing cells.
Which statement is true about Y chromosome analysis?
It is commonly used to determine paternity and ancestry.
What does it mean to say that a person has a heterozygous genotype for a disease and no disease phenotype?
It means that the person does not show symptoms of the disease if the disease allele is recessive.
A cell has an inactivating mutation in one of its two p53 alleles. If this cell sustains DNA damage (e.g., to the HER2 gene), what is likely to happen?
It will undergo apoptosis.
Predict the sex of a baby with an XXY combination of sex chromosomes.
Male
Why are more males than females affected by X-linked recessive genetic diseases?
Males have a Y chromosome that cannot mask the X-linked recessive allele.
Why are X-linked traits more commonly expressed in males than in females? Select the TWO answers that are correct.
Males have only one X chromosome, whereas females have two Females have two X chromosomes, so one can mask the effects of the other.
What does it mean for a trait to be both polygenic and multifactorial?
Multiple genes each produce aspects of a trait, and environmental factors influence the expression of those genes.
A healthy mother has no family history of cystic fibrosis. Her husband's brother has cystic fibrosis. Is the mother predicted to pass the cystic fibrosis allele to her children?
No
If two genes are located next to one another on the same chromosome, can you use the Punnett square to assess inheritance of the two genes?
No
One of your good friends has a family history of breast cancer. She has her BRCA1 and BRCA2 alleles tested, and no detrimental mutations are found. She tells you she is so relieved to know that she will not develop breast cancer. Is she correct that she will not develop breast cancer?
No
Why is type O Rh-negative the "universal donor"?
No surface markers are present on the O Rh-negative blood cells to react with the recipient's immune system.
If a man has an X-linked recessive disease, can his sons inherit that disease from him?
No, all his sons inherit their X chromosomes maternally.
Can males be carriers of an X-linked trait?
No, because males have only one copy of the X chromosome
In diploid organisms, having two homologues of each chromosome can be beneficial if one allele of a gene encodes a nonfunctional protein. Can haploid organisms avoid the negative effects of nonfunctional alleles?
No, because there is only one allele for the gene in each cell, and the nonfunctional allele has no other allele to mask it.
How are polygenic and multifactorial traits different?
Polygenic traits are genetically based, whereas multifactorial traits have both genetic and environmental influences.
How are proto-oncogenes and tumor suppressor genes different?
Proto-oncogenes promote cell division when a cell is ready, and tumor suppressor genes halt cell division when a DNA sequence needs correction or repair.
Why does wearing sunscreen reduce cancer risk?
Sunscreen can reduce the chance of mutations caused by exposure to UV radiation present in sunlight.
What is the genotype of a person with cystic fibrosis?
The genotype includes two mutant CFTR genes, one each on the homologous chromosomes for chromosome 7.
What may happen when a mutation changes the amino acid sequence of a protein?
The protein may become less effective, more effective, or altogether nonfunctional.
What is meant by codominance?
The two alleles in a heterozygote each produce their own distinct phenotype equally.
Which statement is true of a single human gamete?
There is one allele per trait on each chromosome.
How do the two alleles of the CFTR gene in a lung cell differ?
They are inherited from different parents.
What is different about red blood cells from a person with type AB blood, compared to those from other blood types?
They carry A and B type surface markers, so they are universal acceptors of blood.
Independent assortment results in great genetic variation.
True
Which woman would be most likely to benefit from genetic testing for breast cancer?
a 25-year-old woman whose mother, aunt, and grandmother had breast cancer
We would all have many more mutations in our genes if not for the _____.
activity of repair enzymes
At which point does a mutation exert its potentially dysfunctional effects in a cell?
after a protein is produced
If a nondisjunction occurs during meiosis I _____.
all four resulting cells will be aneuploid
A chemical that causes alterations in DNA is a _____, and if this chemical causes cancer it is called a(n) _____.
all of these
A gamete is aneuploid if _____.
all of these
A gene encodes a protein of 350 amino acids. A mutation creates an allele that only has the first 120 amino acids. What could happen to this mutant allele?
all of these
A mutation can cause a change _____.
all of these
If cells from a malignant breast tumor in a 27-year-old woman were examined, what would be expected?
all of these
Which phrase accurately describes meiosis?
all of these
Which statement is true of a single human liver cell?
all of these
Why are all babies in the United States tested for PKU (phenylketonuria) at birth?
all of these
Two copies of a gene have identical regulatory sequences, but different coding sequences. These copies can be referred to as _____.
alleles
Which of these can result in a trisomy such as Down syndrome?
an egg with 24 chromosomes fertilized by a sperm with 23 chromosomes
When DNA damage is not repaired at cell cycle checkpoints, what normally occurs?
apoptosis
Women can inherit alleles of a gene called BRCA1 that puts them at higher risk for breast cancer. The alleles associated with elevated cancer risk are dominant. Of the genotypes listed below, which carries the lowest genetic risk of developing breast cancer?
bb
If two women have identical alleles of the suspected 20 height-associated genes, why might one of those women be 5 feet 5 inches tall and the other 5 feet 8 inches tall?
because environmental factors also play a role in the phenotype of this trait
Tumors that will not spread throughout the body are _____, and those that do spread are termed _____.
benign; malignant
Carrying an extra copy of chromosome 21 is also known as _____.
both trisomy 21 and Down syndrome
A potential cancer-causing gene coding for a protein with cell cycle control responsibilities is a _____, and a gene coding for a protein that stimulates cell division is a _____.
carcinogen; proto-oncogene
If meiosis were to fail and a cell skipped meiosis I, so that meiosis II was the only meiotic division, how would you describe the resulting cells?
diploid cells with 23 pairs of chromosomes
A zygote is _____ because it has _____ chromosomes.
diploid; 46
A woman is heterozygous for the CF-associated gene (the alleles are represented here by the letters A and a). Assuming that meiosis occurs normally, which of the following represents eggs that she can produce?
either A or a
An individual's genotype predicts an adult height of 6.5 feet, but that individual grows to only 5.5 feet in adulthood. What accounts for the difference in height?
environmental factors
DNA mutations can arise from uncorrected errors in DNA replication, inheritance, and _____.
environmental insults
A pregnant woman has amniocentesis in order to _____.
examine the embryonic/fetal karyotype
A mutation in a single allele of a tumor suppressor gene is sufficient for a cell to become cancerous.
false
A person inherits a functional cystic fibrosis allele from both parents. This person will have cystic fibrosis.
false
What is the end result of meiosis?
haploid cells
Investigators at a crime scene have isolated DNA from a Y chromosome and have analyzed it for STRs. They have a prime suspect, but he is not cooperating. However, several of his relatives are willing to help by donating DNA samples. Which relative will have the most similar Y chromosome?
his father's father
What information can be deduced from a pedigree? Select the TWO answers that are correct.
how an X-linked trait is passed down over generations the probability of a female being a carrier of an X-linked allele
A nondisjunction occurs during meiosis II of sperm formation. Are the two homologues of the affected chromosome in aneuploid gametes identical to one another or different from one another?
identical
What is the result of the mitosis checkpoint being passed before the cell is ready?
improperly aligned chromosomes that are not equally distributed to daughter cells
The principle that alleles of different genes are distributed independently of one another during meiosis is _____.
independent assortment
A person has the identical BRCA1 mutation in every somatic cell in her body. What is the most likely source of this mutation? Please choose the correct answer from the following choices, and then select the submit answer button. smoking
inheritance from one of her parents (via the sperm or egg)
Which is the correct order of events in which breast cancer might develop?
inheritance of a mutant BRCA gene > replication errors create an oncogene > mutation of p53 > additional mutations permit spreading
At what point during the cell cycle do chromosomes initially consist of two sister chromatids?
interphase
In an otherwise normal cell, what happens if one mistake is made during DNA replication?
is at increased risk of developing breast cancer
Which family history most strongly suggests a risk of inherited breast cancer due to BRCA1 mutations?
many female relatives diagnosed with breast cancer at an early age
What meiotic event produces four gametes with abnormal numbers of chromosomes?
meiosis I nondisjunction
Up to 40% of human height can be attributed to the environment instead of genetic factors; thus, we call height inheritance _____.
multifactorial
Which inheritance pattern includes an environmental contribution?
multifactorial
Meiosis differs from mitosis in the _____.
number of chromosomes in each ending cell
A visual representation of the occurrence of phenotypes across generations is called a _____.
pedigree
Human skin color ranges from very light to dark black, with many distinct skin tones in between. What type of inheritance pattern governs skin color?
polygenic inheritance
An allele that reveals itself in the phenotype only if the organism has two copies of that allele is a _____ allele.
recessive
One of the purposes of meiosis is to _____.
reduce the chromosome number in each resulting cell by half
A woman has cystic fibrosis. Therefore:
she must have inherited a cystic fibrosis allele from both her mother and father
What causes nondisjunction during meiosis II?
sister chromatids fail to separate
For the scenario described in the animation, what action could be taken to reduce the risk of cancer?
smoking cessation
Has Emily met, surpassed, or is she working toward the median survival rate for people with CF?
surpassed
When we say a trait has incomplete dominance, what do we mean?
that the phenotype of heterozygote is an intermediate between that of both homozygous phenotypes
When amniotic fluid is tested for chromosome analysis, whose karyotype is being examined?
the embryo's
Besides recombination, what other event in meiosis increases the genetic diversity of the gametes?
the random line-up and separation of maternal and paternal chromosomes
Children often have many of the phenotypes of their parents because _____.
they inherit half of their genetic material from each parent
What is the purpose of cell cycle checkpoints?
to ensure that cell cycle phases proceed only when the cell is ready
What is the normal function of a proto-oncogene?
to help the cell divide appropriately
Which of these can be determined by amniocentesis and karyotyping?
trisomy 21
Using a technology called pre-implantation genetic diagnosis to detect and select embryos that do not carry defective alleles, some parents now are able to have children who do not carry an inherited mutated gene.
true
Which combination of mutations is the most likely to convert a normal cell to a cancerous cell?
two mutated p53 alleles, two mutated BRCA1 alleles, one activated allele of HER2
Genghis Khan ruled the largest empire in the world, pillaging his way across Mongolia and Asia in the 13th century. Today, 16 million men living in the same region are his descendants. What chromosome(s) do you think scientists examined in order to determine that these men are related to Genghis Khan?
y
Give two ways meiosis would differ without independent assortment?
~Gametes would have all maternal chromosomes or all paternal chromosomes. ~The genetic diversity generated by meiosis would be limited to recombination.
In what two ways does recombination contribute to offspring diversity? Select TWO that apply.
~It increases the genetic diversity among gametes produced by an organism. ~It yields chromosomes that contain both maternal and paternal DNA.
How do meiosis I and meiosis II differ? Select the TWO answers that are correct.
~Meiosis I divides homologous chromosomes, whereas meiosis II divides sister chromatids. ~Meiosis I is preceded by DNA replication, whereas meiosis II is not preceded by replication.
Select three possible ways mutations can be acquired. Select the THREE answers that are correct.
~being exposed to substances that damage DNA ~leaving mistakes uncorrected during DNA replication ~inheriting mutations from one's parents
Select the activities that are likely to lead to exposure to a mutagen. Select the THREE answers that are correct.
~consuming alcohol ~applying inorganic pesticides ~drinking filtered water
What genes are mutated in the scenario from the animation? Select the TWO answers that are correct.
~p53 ~BRCA1
