BISC 104, Ch. 10: Genetics
Epigenetic disruptions of which part of the human genome may be involved in many cancers?
"dark genome"
What would be the genotype of an individual that is true breeding for the recessive form of a trait?
(lowercase) pp
Select all the examples of codominance.
-ABO blood groups in humans -roan color pattern of cattle and horses
Match the phenotypes with the description of how they can be represented in a pedigree.
-Solid symbol: Choice, individuals exhibiting the trait of interest individuals exhibiting the trait of interest -Half-filled symbol matches: heterozygous individuals that are carriers of a trait heterozygous individuals that are carriers of a trait -Clear symbol: Choice, homozygous individuals that do not exhibit the trait of interest homozygous individuals that do not exhibit the trait of interest
Select all of the hypotheses that are part of Mendel's model of the hereditary process.
-The two alleles that an individual possesses do not affect each other. -The presence of an allele does not ensure that a trait will be expressed in the individual that carries it. -Each parent contains two copies of the factor governing each trait. Parents transmit factors rather than traits to their offspring.
Which of the following answers correctly describes a true-breeding plant?
-When cross-pollinated with another true-breeding plant of a different variety offspring show the dominant trait. -When self-pollinated, the offspring produced have the same variety of a trait as the parents.
Select all of the characteristics of the mutation that causes Tay-Sachs disease.
-autosomal -rare in most human populations -recessive -causes deterioration of brain
Which of the following are examined in the cells obtained from amniocentesis or chorionic villus sampling to assess the genetic state of the embryo or fetus? Select all that apply.
-chromosomal karyotype -genetic markers -enzyme activity
Select all of the following that describe genetic counseling.
-helps parents determine risk of having a child with a genetic disorder -assesses genetics of early embryo
Select all of the characteristics of the garden pea that made it easy for Mendel to study heredity using these plants.
-reproductive organs are enclosed within the flowers -cross-fertilization is easy to execute -large numbers of offspring are produced
How many of the 23 pairs of human chromosomes are sex chromosomes?
1 pair
List in order how a Mendelian trait is influenced by a particular gene, beginning with the first step at the top.
1. individual gene is "read" from the chromosomal DNA by enzymes that create an RNA transcript2. RNA transcript is edited t remove unnecessary bits3. RNA transcript leaves the cell nucleus4. mRNA is delivered to ribosomes to determine the amino acid sequence of a particular polypeptide
In a cross between plants with the genotype RrYy, what proportion of the offspring are predicted to show the recessive phenotype for both traits?
1/16
After further study, Mendel concluded that the 3:1 ratio he had observed in the F2 generation was in fact a disguised ______ ratio.
1:2:1
How many of the 23 pairs of human chromosomes are autosomes?
22 pairs
About what percent of the F2 individuals in one of Mendel's monohybrid crosses showed the dominant trait and were true-breeding?
25%
About what percent of the F2 individuals in one of Mendel's monohybrid crosses showed the dominant trait but were not true-breeding?
25%
In this Punnett square of a trait that shows simple dominant/recessive inheritance, the phenotypic ratio in the offspring is predicted to be
3:1
Based on the Punnett square shown _____ of the offspring are predicted to be heterozygous
50%
In a cross between individuals that are heterozygous for two traits with simple dominant/recessive inheritance, the ratio of phenotypes in the offspring is predicted to be ______.
9:3:3:1
What would be the human blood type phenotype of an individual with the genotype IAIB?
AB
When Mendel crossed true-breeding plants displaying alternate forms of a trait, what were the F1 results?
All F1 plants displayed the dominant form of the trait.
Alternate forms of a gene that lead to alternative traits are called
Alleles
Which of the following sentences best describes the relationship between an allele and a gene?
Alleles are alternative forms of a gene.
A gamete contains one copy of each ______, which contain alleles of many different genes.
Chromosome
__________ methylation can shut down an entire chromosome or turn a particular gene ON or OFF during development.
DNA
When does DNA methylation occur?
DNA methylation occurs when embryonic stem cells mature into tissue-specific stem cells.
What type of cross is used to study the inheritance of two separate traits?
Dihybrid cross
In Mendel's experimental design, the offspring that result from crossing P (parental) generation plants are called the ______ generation.
F1
In Mendel's experimental design the ______ generation is produced by self-fertilization and contains individuals displaying the recessive phenotype.
F2
In Mendel's experiments the recessive allele re-emerged in 25% of the offspring of the ______ generation.
F2
Who counted the numbers of pea plant offspring when trying to understand heredity?
Gregor Mendel
Huntington's disease
Huntington's disease
Crossing pea plants to better understand heredity was first completed by ______ in the 1790s, but in the 1800s, ______ actually counted the pea plant offspring in order to collect quantitative data.
Knight; Mendel
Match the following generations involved in Mendel's experimental design to the correct description: P generation F1 generation F2 generation
P generation: true-breeding generation, producing only offspring of the same variety when self-pollination occurs true-breeding generation, producing only offspring of the same variety when self-pollination occurs F1 generation: generation resulting from a cross of two true-breeding varieties exhibiting alternative traits generation resulting from a cross of two true-breeding varieties exhibiting alternative traits F2 generation: generation resulting from the self-fertilization of the previous generation generation resulting from the self-fertilization of the previous generation
A technique used to visualize the possible results from a cross is called a ______.
Punnett square
What type of experimentation did Gregor Mendel conduct with the pea plants?
Quantitative
Mendel's model of the hereditary process includes which of the following hypotheses?
The presence of an allele does not ensure that a trait will be expressed in the individual that carries it. Alternative forms of a factor can lead to alternative traits.
True or false: Parents, that are heterozygous carriers of a recessive allele responsible for a serious genetic disorder may not exhibit the clinical disorder themselves, but could have a child that has the clinical disorder.
True
If an individual in the parental generation is heterozygous for two genes (gene W and gene S), what combinations of alleles could their gametes possess?
WS, Ws, wS, and ws
What symbols are used to represent the sex chromosomes of a human female?
XX
Match each type of sex chromosome aneuploidy to its correct description.
XXX --> triple X female XXY --> Klinefelter syndrome XO --> turner syndrome OY --> nonviable
A sterile male that is ______ has Klinefelter syndrome, characterized by many female body characteristics and possible diminished mental capacity. A sterile female that is ______ has Turner syndrome, characterized by short stature and immature sex organs.
XXY; XO
What is the genotype of the generation IV male at the far left of this pedigree for red-green color blindness? Assume XR represents a normal allele, and Xr represents the allele for color blindness.
X^rY
What human chromosome contains few functional genes, most of which are responsible for features associated with "maleness"?
Y
Nondisjunction of the Y chromosome results in the formation of _____ sperm.
YY
Gametes inherit one ______ for a given trait from each parent.
allele
The phenotype of an organism is determined by which ____________ their chromosomes possess for a specific trait.
alleles
This law states that the two _______ of a trait separate from each other during the formation of _______.
alleles, gametes.
What effect would changes to the core histones have on gene expression?
alter the ability of a cell's gene expression machinery to access a gene
Nondisjunction occurs when chromosomes fail to separate during meiosis, and results in aneuploidy, which is ______.
an abnormal number of chromosomes
What occurs when nondisjunction leads to an abnormal number of chromosomes?
aneuploidy
Based on the pedigree, what type of inheritance occurs in albinism? In this pedigree, half-filled symbols indicate individuals that exhibit normal phenotypes but are carriers.
autosomal recessive
Twenty-two pairs of human chromosomes are similar to one another in size and morphology and are collectively called ______.
autosomes
Select the processes that are examples of epigenetic modifications.
chemical modifications of histones methylation of DNA bases
Observations that chromosomes pair with one another during meiosis were consistent with Mendel's laws and led to the formulation of the
chromosomal theory of inheritance
In 1902, Walter Sutton formulated the chromosomal theory of inheritance, which explains that genes are located on
chromosomes
In a pedigree, each symbol represents an individual in the family history, with ______ representing females and ______ representing males.
circles; squares
What type of inheritance is occurring when there is not a dominant allele in the heterozygote and the effects of both alleles are fully expressed?
codominance
Because both the IA and IB alleles are expressed simultaneously in heterozygotes, these human blood type alleles are ______.
codominant
When both alleles are fully expressed in a heterozygous individual, the alleles are said to be ______.
codominant
The gradation in phenotypes that result when multiple genes act jointly to influence a trait is called ______.
continuous variation
The factors that can disguise Mendelian segregation are
continuous variation, pleiotropic effects, incomplete dominance, environmental effects, and epistasis.
Select all the examples of pleiotropic effects.
cystic fibrosis sickle-cell disease
A ______ cross is one examining the inheritance of two separate traits.
dihybrid
Mendel used a ______ cross to study the likelihood that two separate traits would be inherited together.
dihybrid
If the unknown organism is homozygous dominant, all offspring will show the ____________ phenotype.
dominant
Mendel's F1 generation exhibited only the ______ which masks other alleles that are present.
dominant
In Mendel's crosses of purple-flowered plants with white-flowered plants, the trait expressed in F1 individuals was called the ______ trait. and the trait not expressed in the F1 plants was called the ______ trait. .
dominant, recessive
Even though the mutation causing Huntington's disease creates a ______ defective allele, the disease persists because its symptoms usually develop ______.
dominant; after age 30
Even though the mutation causing Huntington's disease creates a ______ defective allele, the disease persists because its symptoms usually develop ______. Multiple choice question.
dominant; after age 30
In ______, changes in phenotype are heritable but do not involve changes to the DNA sequence.
epigenetics
Thus, half of the gametes carry one allele of a ______, and the other half carry the other allele. Then, ________ of an egg by a sperm creates a new individual that now possesses two factors for each trait, just like the parent.
gene, fertilization
The way in which _________ interact with the environment to produce individuals with differing personalities is the subject of continuing intensive study.
genes, genetics, or DNA
What is the process of identifying parents at risk of producing children with genetic defects and of assessing the genetic state of early embryos?
genetic counseling
This set of alleles is referred to as the organism's ____________ .
genotype
What term defines an individual's particular alleles?
genotype
When viewing a dominant phenotype, the ____________ can be unknown.
genotype
An individual's _______ refers to the specific alleles or genes they possess, whereas their ______ is the physical expression of those genes.
genotype, phenotype
In a Punnett square the ______ are listed in the cells within the square.
genotypes of potential offspring
What genetic disorder is caused by sex-linked recessive inheritance of a mutant allele?
hemophilia IX
The tendency for traits to be passed from parent to offspring is called ______.
heredity
The fact that most people resemble their parents because traits are passed from parent to offspring is called
heredity or inheritance
A dominant phenotype can be either homozygous dominant or ______
heterozygous
In a testcross, the unknown individual is ______ if half the offspring have the dominant phenotype and half the offspring have the recessive phenotype.
heterozygous
When an individual has two different alleles for a trait they are considered ______.
heterozygous
Based on its inheritance pattern, what would be the genotype of an individual who has sickle-cell disease?
hh
Chemical modification of ______ proteins around which DNA wraps is an epigenetic process that alters gene expression.
histone
An individual with two of the same alleles for a trait is considered ______.
homozygous
To determine the genotype of an individual with a dominant phenotype, with what type of individual must it be crossed?
homozygous recessive
To perform a testcross, Mendel crossed individuals exhibiting the dominant trait with individuals with a ______ genotype.
homozygous recessive
What is occurring when the heterozygous phenotype is intermediate between the phenotypes of the parents, such as pink-flowered offspring from a red-flower parent and a white-flowered parent?
incomplete dominance
Mendel also conducted a series of dihybrid crosses and established his second law, the law of _______.
independent assortment
Mendel's law of ______ states that genes located on different chromosomes are inherited independently of one another.
independent assortment
Two of the genes encoding blood-clotting proteins are located on the human X chromosome, which means that recessive mutations in these genes causing hemophilia VIII or hemophilia IX will be expressed more often in ______.
males
Due to nondisjunction of the Y chromosome, offspring with the genotype XYY are ______.
males of normal appearance
Alleles are found on the chromosomes and are distributed to gametes during ______.
meiosis
Humans who have lost one copy of an autosome are ______, and humans who have gained an extra autosome are ______.
momosomic; trisomic
In polygenic inheritance, ______.
multiple genes act jointly to influence a trait
What mechanism can favor rare alleles that are advantageous in certain environmental conditions?
natural selection
A failure of chromosomes to separate during meiosis is called and can lead to aneuploidy.
nondisjunction
Pleiotropy is when ______.
one gene affects many characters
In studies of human heredity, a family tree in genetics is called a
pedigree
The term _______ refers to the outward expression of a trait, either physically, microscopically, or metabolically.
phenotype
Which of the following are traits Gregor Mendel studied in pea plants? Select all that apply.
plant height flower color seed color pod color
When one gene affects many traits, it is called a ______ effect.
pleiotropic
What type of inheritance is occurring when multiple genes act jointly to influence a character, with the character often showing a range of small differences?
polygenic
What type of inheritance results in a distribution of phenotypes known as continuous variation?
polygenic inheritance
The differences in a single DNA nucleotide between a gene in one person and the same gene in another person are called single nucleotide _______ or SNPs
polymorphism
Parents conceiving by in vitro fertilization have a well-established screening procedure available to them known as
preimplantation genetic screening.
Pea plants were perfect for Mendel's heredity studies because they are small, mature quickly, have many varieties, and ______.
produce large numbers of offspring
Select all of the conditions that can be hereditary.
propensity to suffer strokes depression diabetes alcoholism
Genes are 'read' from the chromosomal DNA to create RNA that is then translated to produce ______, which influence the phenotype of an individual.
proteins
Genes influence the phenotype by specifying the kinds of ______ present in cells.
proteins
By mating the unknown dominant organism with a homozygous ____________ organism, the genotype can be determined from the offspring.
recessive
Crossing an individual displaying the dominant phenotype, but an unknown genotype with a homozygous is an ex
recessive
If the unknown is a heterozygote, the ________ phenotype can be present in some of the offspring.
recessive
Each ________ is a tiny protein-assembly plant and uses the sequence of the mRNA to determine the amino acid sequence of a particular polypeptide.
ribosome
Two of the seven characteristics Mendel studied in his experiments were the color and texture of ______ and pods.
seeds
Mendel's first law, called the law of ______, states that the two alleles of a trait separate during the formation of gametes, so that half the gametes will carry one copy and half will carry the other copy.
segregation
Using information from genetic crosses in pea plants, Mendel formulated his first law, the law of ____________.
segregation
This law states that alleles of a trait ________ independently during the formation of gametes, such that one allele does not influence the inheritance of another.
separate
One pair of the 23 pairs of human chromosomes are the _______ chromosomes and consist of two similar chromosomes in females and two dissimilar chromosomes in males.
sex
Based on the pedigree, what type of inheritance occurs with red-green color blindness? In this pedigree, half-filled symbols indicate individuals that exhibit normal phenotypes but are carriers.
sex-linked recessive
Select all of the following genetic disorders that exhibit autosomal recessive inheritance.
sickle-cell disease Tay-Sachs
A ____________ can determine the genotype of a dominant phenotype.
testcross
Mendel devised a simple and powerful procedure called the ______ to determine if an individual displaying the dominant phenotype has a homozygous or heterozygous genotype.
testcross
Mendel's law of segregation states that ______.
the alleles of a trait separate during gamete formation so that half of the gametes carry one copy and half carry the other copy
Which of the following correctly describes nondisjunction?
the failure of chromosomes to properly separate during meiosis
Humans who have lost an autosome usually do not survive development, but humans who have gained an autosome, a condition known as _______, may survive for some period of time if the gained chromosome is either number 13, 15, 18, 21, or 22.
trisomy
A self-pollinating ____ -breeding plant produces only offspring with the same trait variety.
true or pure
An array of genes in humans called_________ suppressor genes cancer in normal cells
tumor
The chromosomal theory of inheritance is supported by the fact that diploid cells have _______ copies of each chromosome and gametes have only one.
two
