Genetics Ch. 1-5 HW/Quiz Questions
Gene
- A chromosomal region that codes for a functional transcript. - A functional unit of heredity.
Hereditary genetics
- observing phenotypes in offspring to understand gene inheritance. - tracing pedigrees to determine patterns of gene transmission within a family.
Molecular genetics
- the subfield of biology that studies the molecular structure and function of genes. - using recombiant DNA in subcloning techniquees. - identifying gene mutations associated with a genetic disease.
Normally in humans, a mutant gene on the Y chromosome will be inherited in which way?
All of the sons of a parent with the mutant gene will receive it but none of the daughters will.
A cross between an AABB individual and an aabb individual will produce what type of offspring?
All will be AaBb.
Who discovered the basic principles of heredity?
Gregor Mendel
Which organism did Gregor Mendel use to discover the basic principles of genetics?
Pisum sativum (pea plant)
Select the definition of aneuploidy.
the addition or loss of less than a full set of chromosomes or chromosome pairs
In what way have humans been applying the principles of heredity for millennia?
the domestication of plants and animals
Match the checkpoint to its function.
G1/S checkpoint: - maintains cell until necessary enzymes for replication are synthesized. G2/M checkpoint: - detection of DNA damage after replication. Spindle‑assembly checkpoint: - ensures that each chromosome is attached to spindle fibers from opposite poles.
Classify each statement as describing a gene, chromosome, or genome.
Gene: - determines a particular characteristic of an organism. - codes for a specific protein or RNA. - acts as the basic unit of heredity. Chromosome: - is a contiguous piece of DNA. - is a unit of DNA carrying genetic information encoded in genes. - functions to package, organize, and regulate access to DNA. - is the largest molecule in the cell. - is a linear or circular molecule. Genome: - may include plasmids. - describes the collection of all of the replicable genetic material of a cell or organism. - each organism has one. - encodes all the heritable traits of an organism
Of the following ideas postulated by Gregor Mendel, which one requires at least two genes to be demonstrated?
Genes assort independently in humans.
Classify each action as belonging to genetics, genomics, or both.
Genetics: - study individual genes. - generate mutants. Genomics: - study interactions between many genes. - assemble a map of all chromosomes. - use whole-organism approach. Both: - study DNA.
In fruit flies, gray bodies (G) are dominant over black bodies (g), and brown pigments (N) are dominant over yellow pigments (n). Each individual possesses two alleles for each trait. If a fly that is homozygous dominant for both traits is crossed with a fly that is homozygous recessive for both traits, what is the predicted genotype of the offspring?
GgNn
Which statement below defines epistasis?
when one locus affects or covers the outcome of another locus
Which statement identifies what The Green Revolution relied upon genetic applications to accomplish?
expand the world's food production
Match the scientists with their seminal work.
- Germ‑plasm theory: August Weismann. - Cell theory: Matthias Schleiden and Theodor Schwann. - Rules of inheritance: Gregor Mendel. - Polymerase chain reaction: Kary Mullis - Theoretical three‑dimensional DNA structure: James Watson and Francis Crick.
Meiosis and mitosis are both forms of cell division. However, the outcomes of these processes differ. Consider a diploid organism with two sexes.
- Independent assortment results in alleles for a gene being passed separately to gametes during meiosis. - Sister chromatids are not genetically identical as a result of crossing over during meiosis. - Mitosis produces two identical diploid daughter cells.
Which practices in agriculture and animal domestication demonstrate a rudimentary understanding of heredity and genetics?
- Nomads selected the fastest horses for breeding. - Farmers planted seeds from trees that produced the largest, sweetest fruits and not from trees that produced the smallest or inedible fruits. - Primitive societies were more likely to kill wolves that were too aggressive and keep the less aggressive ones as pets and hunting companions.
Chrmosome
- Threadlike DNA molecules that are visble during mitosis. - Large genetic element that carries genes essential to cellular function.
In butterflies, sex is determined by the ZW sex‑determination system. Female butterflies are heterogametic and have both a Z sex chromosome and a W sex chromosome for sex determination. In contrast, male butterflies are homogametic and have two Z sex chromosomes. Select all of the relatives from which a female butterfly could have inherited her Z sex chromosome.
-father. -paternal grandfather.
What will be the genotypic ratio in the offspring of two Aa parents that are crossed with each other?
1 : 2 : 1
Which genetic condition is found at an unexpectedly high frequency among the Hopi Native Americans?
Albinism
The white‑eyed mutation in Drosophila, studied by Thomas Hunt Morgan, was the first clear case of sex‑linked inheritance.
All of the males had white eyes and all of the females had red eyes.
How are mitochondrial genes typically inherited?
An individual inherits their mitochondrial DNA from their mother.
Which statement describes the central dogma of biology?
DNA is transcribed into RNA. RNA is translated into an amino acid sequence.
Suppose two parents, a father with the genotype AaBbCcDdee and a mother with the genotype aaBbCCDdEe, want to have children. Assume each locus follows Mendelian inheritance patterns for dominance. What proportion of the offspring will have each of the specified characteristics? Round your answers to two decimal places.
same genotype as the father: 0.03 same genotype as the mother: 0.03 phenotypically resemble the father: 0.14 phenotypically resemble the mother: 0.14 phenotypically resemble neither parent: 0.71
Which of these describes a genome?
the collection of genetic material in a cell or organism
In humans, what normally results in the male sexual phenotype?
the presence of the SRY gene on the Y chromosome
How does the structure of DNA encode genetic information?
the sequence of bases
What are checkpoints?
transition points during the cell cycle that ensure all cellular components are functioning properly
Cell division by mitosis is a mechanism of asexual cell replication. Some single‑celled organisms reproduce by cell division, and cell division enables multicellular organisms to grow and to repair damaged cells. Which is a product of cell division by mitosis?
two cells genetically identical to the original cell
Which characteristic would not be considered useful for a model genetic organism?
a long generation time
In humans, oculocutaneous (OCA) albinism is a collection of autosomal recessive disorders characterized by an absence of the pigment melanin in skin, hair, and eyes. That is, normal pigmentation (𝐴)(A) is dominant over albino characteristics (𝑎)(a) . For this question, assume the phenotype is determined by a single gene with two alleles. If both parents display the albino phenotype, what are all of the possible genotypes that may be observed in their offspring?
aa only
In humans, oculocutaneous (OCA) albinism is a collection of autosomal recessive disorders characterized by an absence of the pigment melanin in skin, hair, and eyes. That is, normal pigmentation (A) is dominant over albinism (a). For this question, assume it is a single gene with two alleles. If both parents display the albino phenotype, what possible phenotypes may be observed in their offspring?
albinism only
What are the multiple forms of one gene called?
alleles
Allele
an alternative forms of a particular gene.
What is the most inclusive definition of a model organism (model system)?
an organism with a biological system that is representative of the same system in other organisms
In which stage of meiosis does the separation of homologous chromosomes occur?
anaphase 1
Population genetics
calculating genotype frequencies to understand phenotype changes in a population
What are the structures in a cell that group genes together, are composed of chromatin (DNA and protein), and become visible under a light microscope during mitosis?
chromosomes
The somatic cell of a rat contains 42 chromosomes42 chromosomes (2𝑛=42).(2n=42). How many chromosomes and how many DNA molecules would the primary oocyte of this rat have?
chromosomes: 42 DNA molecules: 84
Meiosis results in genetic variation among its product cells. One source of this genetic variation is the random distribution of maternal and paternal chromosomes, and the other source of genetic variation is
crossing over occurring at prophase I.
What concept proposes that traits acquired in a person's lifetime become incorporated into that person's hereditary information and are passed on to offspring?
inheritance of acquired characteristics
What is the complete set of genetic instructions for an organism?
its genome
Mendel's principle of segregation can be explained by what process?
meiosis
What process involves the separation of chromosomes in the division of somatic, nonsex, cells?
mitosis
The study of the chemical nature of the gene, and how genetic information is replicated and expressed, is part of what division of genetics?
molecular genetics
In humans, oculocutaneous (OCA) albinism is a collection of autosomal recessive disorders characterized by an absence of the pigment melanin in skin, hair, and eyes. That is, normal pigmentation (𝐴)(A) is dominant over albinism (𝑎)(a) . For this question, assume the phenotype is determined by a single gene with two alleles. If two people have normal pigmentation, what possible phenotypes may be observed in their offspring?
normal pigmentation or albinism
What are the functions of mitotic cell division?
organism growth replacement of cells asexual reproduction
What early concept of heredity proposed that genetic information in the form of particles called gemmules travels from different parts of the body to reproductive organs?
pangenesis
What is the physical appearance or manifestation of a characteristic called in genetics?
phenotype
What division of genetics is essentially a study of evolution?
population genetics
An individual possesses two alleles at a locus and these two alleles separate when gametes are formed, one allele going into each gamete. This genetic concept is known as the
principle of segregation.
Humans with only one sex chromosome (XO) usually have underdeveloped sexual characteristics and are sterile.
Turner syndrome
Which of the statements is not a difference between mitosis and meiosis?
Sister chromatids separate during mitosis but not during meiosis.
What happens during anaphase II of meiosis?
Sister chromatids separate from each other and migrate to opposite ends of the cell.
Preformationism
Genetic information is inherited from one parent or the other, not both.
Germ‑plasm theory
Reproductive cells have complete genetic codes for their species.
If an Aa individual is crossed to an aa individual, what will be the phenotypic ratio in the offspring?
1:1
A human male with the chromosome constitution of XXXYY would contain how many Barr bodies in his somatic cells?
2
How many ova, plural for ovum, can be produced from two primary oocytes through meiosis?
2
The principle of independent assortment involves at least how many different gene pairs?
2
A maternal effect can cause the offspring phenotype ratio to depart from that of classic Mendelian inheritance. In a species of snail, the dominant allele N codes for right-handed shell coiling and recessive allele n codes for left-handed shell coiling. If an Nn female with right-handed shell coiling mates with an Nn male, what is the shell coiling phenotypic ratio of their offspring?
4, right-handed coil : 0, left-handed coil
Assume that a cell has six chromosomes while it is in the G1 stage of the cell cycle. How many chromosomes and how many DNA molecules will it have in the G2 stage?
6 chromosomes and 12 DNA molecules
Suppose a diploid slime mold is completely heterozygous at all 12 of its chromosomes (2𝑛=12).(2n=12). How many different combinations of gametes can be produced by this slime mold, assuming no homologous recombination between chromosomes?
64 different combinations
X-linked red-green color blindness in humans is a recessive condition.
A color‑blind woman must have had a color‑blind father.
Which of the statements can be concluded from Gregor Mendel's experiments with pea plants?
A heterozygous phenotype is the same as a homozygous dominant phenotype. Allelic combinations for different genes may differ between parents and their offspring.
In humans, oculocutaneous (OCA) albinism is a collection of autosomal recessive disorders characterized by an absence of the pigment melanin in skin, hair, and eyes. That is, normal pigmentation (𝐴)(A) is dominant over albino characteristics (𝑎)(a) . For this question, assume the phenotype is determined by a single gene with two alleles. If both parents have normal pigmentation, what are all of the possible genotypes that may be observed in their offspring?
AA, Aa, or aa
Which organism would not be considered a useful model genetic organism?
Bos taurus (the cow)
Pangenesis concept
Cells in different tissues have unique genetic codes that are transferred to the gonads to produce gametes.
Who was a nineteenth‑century biologist who put forth the theory of evolution through natural selection and published his idea in the book entitled On the Origin of Species?
Charles Darwin
The dominance pattern of a gene can be determined from the phenotypes of the parents and offspring. In the examples below, assume that each parent is homozygous for the specific allele and that the progeny are heterozygous. Classify each example as either complete dominance, incomplete dominance, or codominance. You are currently in a sorting module. Turn off browse mode or quick nav, Tab to items, Space or Enter to pick up, Tab to move, Space or Enter to drop.
Complete dominance: - A pea plant with smooth seeds and a pea plant with wrinkled seeds produce a pea plant with smooth seeds. Incomplete dominance: - A black sheep and a white sheep produce a gray lamb. - A mother with straight hair and a father with curly hair have a son with wavy hair. Codominance: - A mother with type A blood and a father with type B blood have a daughter with type AB blood. - A white cow and a red bull have a calf that is white with red spots (roan colored).
A man, Joe, has classic hemophilia, an X‑linked recessive disease. Classify each person depending on whether or not Joe could have inherited the hemophilia gene from him or her.
Could have inherited: maternal grandmother maternal grandfather Could not have inherited: paternal grandmother paternal grandfather
Which statements describe Y‑linked traits?
Female offspring cannot inherit the trait. All male offspring of affected fathers will express the trait.
Identical, or monozygotic, twins develop from a single egg fertilized by a single sperm. Monozygotic twins are genetically identical because they originate from a single zygote that split into two. Caroline Loat and her colleagues examined nine measures of social, behavioral, and cognitive ability in 1000 pairs of both male and female identical twins. Their study found that pairs of male twins tended to be more alike in their prosocial behavior, peer problems, and verbal ability scores than pairs of female twins. Which statement explains this observation?
Females are mosaic for the expression of heterozygous X‑linked loci, because females undergo random X‑inactivation.
In the XX‑XO mechanism of sex determination, which of the statements is true?
Females have two X chromosomes (XX) and males have one X chromosome (XO)
What happens during anaphase I of meiosis?
Homologous chromosomes separate, but sister chromatids remain joined at their centromeres.
When Mendel crossed a plant homozygous for round seeds to another plant homozygous for wrinkled seeds, he found that all the progeny had round seeds.
How is this explained? The allele for round seeds is dominant to the allele for wrinkled seeds.
The fruit fly Drosophila melanogaster has four pairs of chromosomes, whereas the housefly Musca domestica has six pairs of chromosomes.
How many different combinations of chromosomes are possible in the gametes of the fruit fly? chromosome combinations in fruit flies: 2^4 = 16 How many different combinations of chromosomes are possible in the gametes of the house fly? chromosome combinations in house flies: 2^6 = 24
Color blindness is a sex‑linked recessive trait. A female is color blind in one eye, but not both.
Select the explanation for this condition: -random X-chromosome inactivation Is it possible for a male to have different color‑blindness phenotypes in each eye? yes, in an XXY male with a different active X in each eye
Classify the traits as inherited or acquired.
Inherited: - blonde hair. - attached earlobes. - cystic fibrosis. - face shape. Acquired: - ability to read. - muscle mass from strength training. - small sature due to malnurishment. - fetal alcohol syndrome.
Classify descriptions as pertaining to prokaryotic cells, eukaryotic cells, or both.
Prokaryotes: - lack mitochondria. - localize genome in the cytoplasm. Eukaryotes: - include algae. - contain a nucleus. Both: - contain enzymes.
What characteristic makes prokaryotic cells different from eukaryotic cells?
Prokaryotic cells do not contain membrane‑bound organelles.
Classify whether each gene regularly exists in a hemizygous state.
Regularly hemizygous: -a muscular dystrophy gene on the X chromosome in a normal human male. -a transgenic gene inserted into only one chromosome of a mouse. Not regularly hemizygous: -a muscular dystrophy gene on an X chromosome in a normal human female. -a gene on chromosome 21 in an individual with Down syndrome.
A yellow female Labrador retriever was mated with a brown male. Half of the puppies were brown, and half were yellow. Explain how the same female, when mated with a different brown male, could produce only brown offspring.
The first male was bb Ee, and the second male was bb EE.
What happens during telophase II of meiosis?
The nuclear membrane begins to form around haploid sets of chromosomes.
How is a true breeding round‑seeded pea plant different from a hybrid round‑seeded pea plant?
They have the same phenotype but different genotypes.
In cats, curled ears result from an allele, Cu, that is dominant over an allele, cu, for normal ears. Black color results from an independently assorting allele, G, that is dominant over an allele for gray, g. A gray cat homozygous for curled ears is mated with a homozygous black cat with normal ears. All the F1 cats are black and have curled ears. What phenotypes and proportions are expected from the two crosses?
Two of the F1 cats mate: 9/16 black cats, curled ears; 3/16 black cats, normal ears; 3/16 gray cats, curled ears; and 1/16 gray cats, normal ears. An F1 cat mates with a stray cat that is gray and possesses normal ears: 1/4 black cats, curled ears; 1/4 black cats, normal ears; 1/4 gray cats, curled ears; and 1/4 gray cats, normal ears.
Hemophilia is called "the royal disease" because many European royal families had members with the condition. Hemophilia is a recessive, X‑linked disorder. Queen Victoria was unaffected by hemophilia, but was a carrier of the hemophilia gene (XHXh). Suppose Queen Victoria's husband, Prince Albert, was affected with hemophilia (XhY).
What is the percent probability that a son of Queen Victoria and Prince Albert would be unaffected by hemophilia? probability of unaffected son: 50% What is the percent probability that a daughter or son of Queen Victoria and Prince Albert would be affected by hemophilia? probability of affected child: 50% What is the percent probability Queen Victoria and Prince Albert would have one affected male and then one affected female? probability of one affected male and then one affected female: 6.25%
Phenylketonuria (PKU) is a disease that results from a recessive gene. Two normal parents produce a child with PKU.
What is the probability that a sperm from the father will contain the PKU allele? -1/2 What is the probability that an egg from the mother will contain the PKU allele? -1/2 What is the probability that their next child will have PKU? -1/4 What is the probability that their next child will be heterozygous for the PKU gene? -1/2
In watermelons, bitter fruit (B) is dominant over sweet fruit (b), and yellow spots (S) are dominant over no spots (s). The genes for these two characteristics assort independently. A homozygous plant that has bitter fruit and yellow spots is crossed with a homozygous plant that has sweet fruit and no spots. The F1 are intercrossed to produce the F2.
What will be the phenotypic ratio in the F2? -9/16 bitter fruit, yellow spots; 3/16 bitter fruit, no spots; 3/16 sweet fruit, yellow spots; and 1/16 sweet fruit, no spots If an F1 plant is backcrossed with the bitter, yellow‑spotted parent, what phenotypes and proportions are expected in the offspring? -All bitter fruit with yellow spots. If an F1 plant is backcrossed with the sweet, nonspotted parent, what phenotypes and proportions are expected in the offspring? -1/4 bitter fruit, yellow spots; 1/4 bitter fruit, no spots; 1/4 sweet fruit, yellow spots; and 1/4 sweet fruit, no spots
What is a cross that occurs between two individuals that differ in two characteristics?
dihybrid cross
Which term describes the situation, for X‑linked genes, in human and Drosophila males who have only one X chromosome?
hemizygous
What term describes an individual possessing two of the same alleles at a gene locus?
homozygous
Fur color in a species of mouse is controlled by a single gene pair. BB animals are black and bb animals are white. Bb animals have gray fur and each hair is gray. What type of interaction is being shown by the two alleles in heterozygous animals?
incomplete dominance