POB Test 3
Inversion
(genetics) a kind of mutation in which the order of the genes in a section of a chromosome is reversed
Law of Segregation
- Each individual has two factors for each trait. - The factors segregate (separate) during the formation of the gametes. - Each gamete contains only one factor from each pair of factors. - Fertilization gives each new individual two factors for each trait.
Law of Independent Assortment
- Each pair of factors separates independently (without regard to how the others separate). - All possible combinations of factors can occur in the gametes.
A normal male marries a color-blind woman. What percent of their female children will be color-blind?
0%
In guinea pigs, B = black, b = brown, S = short hair, s = long hair. A heterozygous black, short-haired animal reproduces with a brown, long-haired animal. What is the expected phenotypic ratio of the offspring?
1 black short hair, 1 black long hair, 1 brown short hair, 1 brown long hair
What are the chances that two individuals with wavy hair (an incomplete trait) will have a curly-haired child? Curly hair and straight hair exhibit incomplete dominance.
25%
What are the chances that two individuals with wavy hair (an incomplete trait) will have a curly-haired child? Curly hair and straight hair exhibit incomplete dominance. 25% 75% 50% none
25% Given that WW = curly hair, ww = straight hair, and Ww = wavy hair, if both parents have wavy hair then their genotype is Ww. A cross of Ww × Ww would yield a 25% chance for WW (curly,) a 50% chance for Ww (wavy), and a 25% chance for ww (straight), The ratio would be 1:2:1.
Meiosis results in a change in chromosome number indicated by
2n to n.
Color-blindness is inherited as an X-linked recessive trait. A male who is color-blind marries a heterozygous woman. What percent of their total children will be color-blind?
50%
The four o'clock flower is an example of incomplete dominance: R = red, r = white, and Rr = pink. If two hybrids are crossed, what are the chances that an offspring will have pink flowers?
50%
If a woman is a carrier for the color-blind recessive allele and her husband has normal vision, what are their chances that a son will be color-blind? None, because the father is normal. 50%, since the mother is only a carrier. 100% because the mother has the gene. 25% because the mother is a hybrid. None since the son will also be just a carrier
50%, since the mother is only a carrier. The mother is XBXb and the father is XBY. With this combination of genotypes, any son will have a 50% chance of inheriting the color-blind allele because the father can only give the Y chromosome and the mother can give either the normal allele or the color-blind allele.
If the diploid chromosome number is 16, the chromosome number of each gamete will be
8
In humans, aniridia, a type of blindness, is due to a dominant allele A. Migraine headaches are due to another dominant allele M. If a man who suffers from both conditions (AaMm) marries a woman who suffers from both (AaMm), what are the chances of an offspring expressing both traits.
9/16
Deletion
A change to a chromosome in which a fragment of the chromosome is removed.
Turner Syndrome
A chromosomal disorder in females in which either an X chromosome is missing, making the person XO instead of XX, or part of one X chromosome is deleted.
Codominance
A condition in which neither of two alleles of a gene is dominant or recessive.
Dihybrid cross
A cross between individuals that have different alleles for the same gene
Monohybrid cross
A cross between individuals that involves one pair of contrasting traits
Pedigree
A diagram that shows the occurrence of a genetic trait in several generations of a family.
Karyotype
A display of the chromosome pairs of a cell arranged by size and shape.
Multiple alleles
A gene that has more than two alleles ex: blood type
trisomy
A genetic condition of having three chromosomes instead of two. The conidtion causes various birth defects
incomplete dominance
A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.
A pheasant breeder starts with two birds in the P generation, one of which is AA and the other is aa. If he takes two of the birds from the F1 generation and breeds them together, what can he expect in his F2 offspring?
AA, Aa, and aa.
Some plants fail to produce chlorophyll, due to a recessive trait. If we locate a pea plant that is heterozygous for this trait, self-pollinate it, and harvest the seeds, what are the likely phenotypes of the resulting offspring?
About one-fourth will be white and three-fourths green since it is similar to a monohybrid cross
X-linked
Alleles located on the X chromosome
Linkage group
Alleles of different genes that are located on the same chromosome and tend to be inherited together
Hemophilia
An X-linked recessive disorder in which blood fails to clot properly, leading to excessive bleeding if injured.
Recessive Allele
An allele that is hidden whenever the dominant allele is present
Dominant Allele
An allele whose trait always shows up in the organism when the allele is present.
Allele
An alternative form of a gene.
nondisjunction
An error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from each other.
Hypercholesterolemia
An excessive amount of cholesterol in the blood
Which is NOT true according to Mendel's law of segregation?
An individual can have either both dominant alleles, both recessive alleles, or a dominant and recessive allele.
Color-blindness
An inherited inability to distinguish between certain colors. Absence or deficiency of one of the three types of cones. x-linked recessive
Heterozygous
An organism that has two different alleles for a trait
Homozygous
An organism that has two identical alleles for a trait
Genotype
An organism's genetic makeup, or allele combinations.
Phenotype
An organism's physical appearance, or visible traits.
Autosomes
Any chromosome that is not a sex chromosome
Sickle Cell
Autosomal recessive genetic disorder that causes a malformation of hemoglobin molecules, causing red blood cells to form a sickle shape
Which of the following is NOT a frameshift mutation of the nucleotide sequence CATUAUCCC?
CATUAUCGC
translocation
Change to a chromosome in which a fragment of one chromosome attaches to a nonhomologous chromosome.
Monosomy
Chromosomal abnormality consisting of the absence of one chromosome from the normal diploid number
During the process of transcription, the information in
DNA is converted into RNA information.
In a Mendelian monohybrid cross involving two homozygous genotypes, the ____ generation is always completely heterozygous. F1 P P2 F2
F1 If the parents are homozygous (AA and aa), then any offspring could only have one of each of the two allele choices (Aa) and be heterozygous. The F2 being a cross between two heterozygotes would have a mixture of all three possible genotypes (AA, Aa, aa). An F3 generation would also show a mixture of the three possible genotypes.
Which of the following statements is NOT true about oogenesis in humans?
Four equal size daughter cells will form.
Upon examination, a cell is found to have twice as much DNA as the normal diploid state but is no longer in the process of replicating the DNA. All of the DNA is found within a single nucleus. Which stage of the cell cycle is this cell in?
G2 phase
Cystic Fibrosis
Genetic disorder caused by a defect in the CFTR gene,which is responsible for the formation of a trans-membrane chloride ion transporter; causes the mucus of the body to be viscous
Which of the following is NOT correct concerning the law of independent assortment?
It follows the observation that all maternal chromosomes end up in the egg.
The individual(s) credited with the discovery of the structure of DNA is (are)
James Watson and Francis Crick.
An individual who has an XXY combination of sex chromosomes is said to have _____ syndrome. Klinefelter Turner Down cri du chat
Klinefelter Klinefelter syndrome is the inheritance of two X chromosomes and one Y chromosome. Turner syndrome is the inheritance of a single X chromosome (XO). Down syndrome, or trisomy 21, is nondisjunction of the 21st chromosome. This leads to an extra copy of the chromosome. Fragile X syndrome results from a repeated segment of nucleotides on the X chromosome. Cri du chat syndrome is a deletion of a portion of chromosome 5.
Locus
Location of a gene on a chromosome
Which of the following is the correct sequence for the cell cycle?
S-G2-M-G1
If a cell stops at the G1 checkpoint, this is most likely due to what problem?
There is DNA damage
Down Syndrome
Trisomy 21
Sex Chromosomes
X or Y
Klinefelter syndrome
XXY
Genes on the ___ chromosome determine if the sex of a child will be male or female. Y X 21st 5th
Y All humans are female by default, but if the Y chromosome is present and produces the hormones associated with maleness, then the individual will be male.
Testcross
a cross between an organism whose genotype for a certain trait is unknown and an organism that is homozygous recessive for that trait so the unknown genotype can be determined from that of the offspring
In peas, yellow is dominant over green in seeds. With which of these is it best to cross a yellow-seeded pea plant to determine whether it is homozygous or heterozygous? a pure yellow-seeded plant a green-seeded plant a heterozygous yellow-seeded plant or a pure yellow-seeded plant a heterozygous yellow-seeded plant
a green-seeded plant Where Y = yellow and y = green, in a testcross a known genotype must be used to cross with the unknown genotype. In this case it would be yy for green seeds since this is the recessive trait. Depending on the genotype, the organism with the dominant characteristic would be either (YY × yy) 100% dominant phenotype or (Yy × yy) 50% dominant phenotype and 50% recessive phenotype.
Which of the following proteins would you expect to be a coded for by a proto-oncogene?
a growth factor receptor
The location of a gene on a chromosome is called
a locus
The location of a gene on a chromosome is called a linkage group. a locus. a linkage map. an allele.
a locus. A gene is found at a particular location (locus) on a chromosome. The two alleles for that gene are found at the same loci on homologous chromosomes.
A color-blind (recessive trait) woman will pass the allele to
all her children
A color-blind (recessive trait) woman will pass the allele to her sons only. all her children. her daughters only. none of her children. her husband.
all her children. If color-blindness is recessive, then an affected woman must carry a copy of the allele on both of her X chromosomes. This is the only allele she has to pass to any of her offspring. Daughters may or may not be color-blind, depending on the X donated by the father. Since she is the one who gives the X chromosome to her sons (the father gives the Y that determines maleness), all of her sons must be color-blind.
Alternative forms of a gene that influence the same trait and are found at the same location in homologous chromosomes are called
alleles
Alternative forms of a gene that influence the same trait and are found at the same location in homologous chromosomes are called incomplete dominance. genotypes. phenotypes. alleles.
alleles. Genotype describes the genetic makeup of an individual, while phenotype describes the appearance of the individual based on which allele is expressed. Codominant and incomplete dominance describe instances where one allele is not completely dominant over the other.
What are alleles?
alternative forms of a gene for a single trait, such as blue eyes or brown eyes
During what stage do homologous chromosomes separate from each other?
anaphase I
During what stage of meiosis do sister chromatids separate from each other?
anaphase II
The part of a transfer RNA molecule that binds to the codon is the
anticodon.
Mendel's law of segregation implies that the two members of an allele pair are distributed to separate gametes. are distributed to the same gamete. are assorted dependently. are segregated pairwise.
are distributed to separate gametes. By examining the F2, generation Mendel was able to see that a heterozygous plant had two alternate forms for the trait that he was studying. Either of these two traits could be passed on to offspring. This demonstrated that the two forms separated during the formation of gametes.
The function of transfer RNA is to
carry amino acids to ribosomes.
Polygenic Inheritance
combined effect of two or more genes on a single character ex: skin
DNA does NOT have which of the following characteristics?
contains adenine, guanine, cytosine, and uracil
Which refers to the loss of a portion of a chromosome? deletion duplication translocation inversion
deletion Translocations occur when a segment of DNA moves from one location in the genome to another. Deletions are loss of a portion of a chromosome. Duplications occur when the genetic information from one sister chromatid is placed onto the other chromatid, along with the original copy of the genetic material, resulting in an extra or duplicate section of DNA. An inversion refers to the changing of direction of a segment of DNA while it stays in the same location on the same chromosome. Monosomy refers to the loss of an entire chromosome through nondisjunction during meiosis.
If the normal nucleotide sequence was TACGGCATG, what type of gene mutation is present if the resulting sequence becomes TAGGCATG?
deletion mutation
If a chromosomal segment appears more than once in the same chromosome, it is termed a(n) inversion. duplication. translocation. deletion.
duplication. Translocations occur when a segment of DNA moves from one location in the genome to another. Deletions are losses of portions of a chromosome and duplications occur when the genetic information from one sister chromatid is placed onto the other chromatid, along with the original copy of the genetic material, resulting in an extra or duplicate section of DNA. An inversion refers to the changing of direction of a segment of DNA while it stays in the same location on the same chromosome. Polyploid refers to the inheritance of additional sets of chromosomes; such individuals would be 3n, 4n, etc. depending on how many additional sets they have.
Hydrangeas are a flowering plant with large showy blooms. When a plant is grown in aluminum-rich soil it has blue flowers. If the same plant is transplanted into soil that is lacking aluminum, the flowers produced will be pink. This is an example of
environmental effects
Hydrangeas are a flowering plant with large showy blooms. When a plant is grown in aluminum-rich soil it has blue flowers. If the same plant is transplanted into soil that is lacking aluminum, the flowers produced will be pink. This is an example of polygenetic inheritance. incomplete dominance. environmental effects. codominance.
environmental effects. Codominance occurs when the heterozygote shows both of the parental phenotypes equally. Incomplete dominance is when the organism can express three different variations for a particular trait. Since the phenotype of the flowers depends on an external condition, this is an example of environmental effects on gene expression. Polygenic inheritance is when two or more genes regulate a trait. Monohybrid inheritance is when a trait has a dominant and recessive variation.
sex-linked
gene located on the X or Y chromosome
Which of the following sex-linked diseases is characterized by the absence of a clotting factor? Duchenne muscular dystrophy None of the answer choices is true. hemophilia color-blindness
hemophilia Hemophilia is characterized by the absence of a clotting factor.
What lines up at the metaphase plate during both metaphase I of meiosis and metaphase of mitosis?
homologous chromosomes for meiosis, each chromosome is composed of two sister chromatids for mitosis
In a testcross, an organism with a dominant phenotype, but unknown genotype is crossed with which of the following to establish its genotype?
homozygous recessive
The correct sequence of events in the production of a polypeptide is
initiation - elongation - termination.
An intervening sequence of DNA that is NOT expressed is called a(n)
intron
Poly-X female
is when a female has more than two X chromosomes.
Considering that males can have Klinefelter (XXY) syndrome, XYY, and normal XY chromosomal combinations, and females can have Turner (XO) syndrome, poly-X (XXX, XXXX), and normal XX combinations, it is obvious that
maleness results from the minimal presence of one Y chromosome.
In which stage of mitosis do the chromosomes line up in the center of the cell?
metaphase
Chromosomal mutations
mutations that affect the number or structure of chromosomes
When homologous chromosomes fail to separate during meiosis, this is termed
nondisjunction
In semiconservative DNA replication, each new double helix formed will have
one new and one old strand in each helix.
Cold weather can change the ______ of a Himalayan rabbit.
phenotype
What genetic disorder is associated with the lack of an enzyme necessary for the normal metabolism of the amino acid phenylalanine?
phenylketonuria (PKU)
Traits that are controlled by several sets or pairs of alleles, such as skin color and height in humans, are the result of what form of inheritance?
polygenic
Traits that are controlled by several sets or pairs of alleles, such as skin color and height in humans, are the result of what form of inheritance? incomplete dominance codominance simple Mendelian inheritance polygenic
polygenic Polygenic inheritance would mean that there were multiple genes at different locations and possibly on different chromosomes all controlling one trait. Simple Mendelian genetics would indicate a simple dominant/recessive relationship, whereas codominance would be a system where alleles both show in the offspring and incomplete domanance would be a case where heterozygotes would show a different phenotype than either of the homozygotes.
When two or more genes with multiple alleles affect the same trait in an additive fashion, it is termed
polygenic inheritance.
Which sequence of stages in mitosis is correct?
prophase, metaphase, anaphase, telophase
Which type of genes, when abnormally activated so that protein is always present and active, can result in cancer?
proto-oncogenes
Because one original strand of the double-stranded helix is found in each daughter molecule, the replication process is called
semi-conservative
Which genetic disorder is associated with an irregular shape of the red blood cells?
sickle cell disease
Which genetic disorder is associated with an irregular shape of the red blood cells? cystic fibrosis (CF) Marfan syndrome Huntington disease sickle cell disease
sickle cell disease Sickle cell disease is an irregular shape of the red blood cells. Marfan syndrome is associated with a defect in the elastic connective tissue protein called fibrillin. Huntington disease is caused by a mutation to the protein huntingtin. Phenylketonuria (PKU) is associated with the lack of the enzyme necessary for the metabolism of phenylalanine. Cystic fibrosis (CF) is associated with a faulty protein channel in the cell membrane.
Which does NOT describe a function of the DNA polymerase molecule?
synthesize the proper nucleotide to match with the base read on the old strand
The nuclear membrane reappears in mitosis during
telophase
An XXX female would most likely result from nondisjunction in in both the mother and father during gamete formation. the mother during egg formation. the father during sperm formation. neither the mother nor the father.
the mother during egg formation. Since the father usually has only one X chromosome to give to a gamete, extra copies of X chromosomes must arise from nondisjunction in the mother.
Which of the classes of RNA molecules carries the amino acids that are added to the growing polypeptide chain?
transfer RNA
Which is the process by which a protein is constructed in the cytoplasm of eukaryotic cells?
translation
A person who has an extra copy of a chromosome is said to have nondisjunction. trisomy. monosomy. duplication.
trisomy. Duplication occurs when the genetic information from one sister chromatid is placed onto the other chromatid, along with the original copy of the genetic material, resulting in an extra or duplicate section of DNA. Monosomy refers to the loss of an entire chromosome through nondisjunction during meiosis, while a trisomy refers to the gain of an entire chromosome also through nondisjunction during meiosis. Nondisjunction occurs when homologous chromosomes fail to separate during meiosis I or sister chromatids fail to separate during meiosis II.
In which kind of cross could you expect to find ratios of 1:1:1:1 among the offspring? monohybrid cross dihybrid cross two-trait test cross one-trait test cross
two-trait test cross The 1:1:1:1 ratio is expected when an organism heterozygous for two traits is crossed with an organism that is homozygous recessive for both traits. This is also a test cross that is frequently used to determine the genotype of organisms that show the dominant traits.
Duplication
when mutations produce an extra part or copies of chromosomes
A woman who can roll her tongue (presumably dominant) is married to a man who cannot. Two of their four children can roll their tongues and two cannot. If A = roll tongue and a = cannot roll tongue, then what is the genotype of the parents?
woman Aa; man aa
A woman who can roll her tongue (presumably dominant) is married to a man who cannot. Two of their four children can roll their tongues and two cannot. If A = roll tongue and a = cannot roll tongue, then what is the genotype of the parents? woman Aa; man AA woman Aa; man aa woman Aa; man Aa woman AA; man aa
woman Aa; man aa Since "cannot roll tongue" is recessive, the father must be aa. If some of the children can roll their tongue and some others cannot, then the mother must have had both alleles (heterozygous), Aa.
