Chapter 12 & 13 Text Exam
Genetic exchange between two arms of a chromosome pair is more likely to occur if the distance is great. This is called...
Crossing over
A fatal human disease in which the faulty gene codes for abnormal gland secretions leading to liver and lung failure is called _________.
Cystic fibrosis
The most common fatal genetic disorder of Caucasians is...?
Cystic fibrosis
When Mendel crossed dark purple-flowered pea plants with white flowered pea plants, he never got any pea plants with light purple flowers. This was counter to the theory of what?
codominance or blending inheritance...
On eof the main reasons genes assort independent of one another is that they are on _______________ chromosomes.
different
An individual possessing both kinds of alleles of two different traits is called ____________.
dihybrid
Individuals carrying two "factors" (alleles) for most traits are:
diploid
Mendel referred to the trait that was expressed in the hybrid, F1 or the first filial generation as
dominant
Mendel's law of segregation states that during meiosis, the factors that control each trait separate, and only ___________ from each pair is/ are passed to the offspring.
factor (allele)
If a XY individual had a deletion of the SYR gene, they would develop as a...
female
The ____________ produced by each parent are shown along the sides of a Punnett square.
gametes
The allelic make up of an individual is referred to as its ____________
genotype
When two haploid gametes contain two different alleles of a given gene, the resulting offspring is called...
heterozygous
A diploid organism that has two identical alleles for the same trait is called ______ for that particular trait.
homozygous
Humans who have lost even one copy of an autosome are called...
monomsomic
Occasionally, chromosomes fail to separate during meiosis, leading to a condition in which the diploid number is not normal. This phenomenon is called...
nondisjunction
A deletion of a particular stretch of chromosome 15 can cause either Prader-Willi syndrome or Angelman syndrome, depending on the _________origin of the normal and deleted chromosome.
parental
An organism's ____________is determined by its genotype
phenotype
The observable outward manifestation (appearance) of the genes of an individual is referred to as its ____________
phenotype
A gene for a particular trait that is only expressed in the presence of another gene of the same kind is called a ___________ gene.
recessive
An allele that is present but unexpressed is _____________
recessive
Hemophilia is a ____________ condition
recessive
Yellow-seeded plants might be homozygous or heterozygous. We could find out which by crossing these plants with true-breeding ______-seeded plants.
recessive homozygous
Two genes are involved in the same biochemical pathway and are investigated using a dihybrid cross. They interact in such a way that one (gene A) interferes with the expression of the other (gene B). We call this phenomenon...
Epistasis
Punnett square can be used to determine what three things?
Gametic possibilities, phenotypic ratios, and genotypic ratios.
The passing on of traits from parents to offspring is called?
Heredity
What term is used to describe an organism that has the genotype Bb?
Heterozygous
What is human hereditary disease that is caused by a dominant allele but does not show up in affected individuals until they are in middle age?
Huntington's disease
In meiosis the way in which a chromosome pair separates does not affect the way other pairs separate, is called Mendel's law of ________.
Independent Assortment
Huntington's disease is caused by an autosomal dominant allele. It is a lethal disease, but it persists in the human population. Why?
It presents symptoms in humans after they've already reproduced.
Why is the white-eye phenotype always observed in males carrying the white-eyed allele?
Males have only one X. White-eye is a sex-linked trait.
ABO Blood group expression is an example of ________________.
Multiple alleles
How do multiple crossovers lead to restoration of the paternal combination of genes?
Multiple crossovers between 2 genes can reduce the perceived genetic distance.
The theory of chromosomal inheritance was first proposed by?
Walter Sutton
Sex-linkage in humans occurs when an allele is located on the ___ chromosome.
X
The white eye mutation in Drosophila was shown to be sex-linked and caused by gene residing on chromosome _______.
X chromosome
In Drosophila, the sex of an individual is influenced by the number of copies of which chromosome?
X chromosomes
What is a polygenic trait?
A single phenotypic trait is determined by more than one gene
How many Barr bodies does a normal human female contain in her cells?
1
What is the probability of obtaining an individual with the genotype CC from a cross between two individuals with the genotypes CC and Cc?
50%
A dihybrid cross between a plant with long smooth leaves (both dominant) and a plant with short hairy leaves produces a long smooth F1. If this F1 is allowed to self-cross to produce an F2, what would you predict for the ratio of F2 phenotypes?
9 long smooth:3 long hairy:3 short smooth:1 short hairy
In a typical Mendel experiment on pea-seed color, if the dominant yellow seed-bearing plant (homozygous) was crossed with the recessive green seed-bearing plant, and then F1 were allowed to self fertilize, the next generation (F2) will show what ratio of each kind?
9:3:3:1
List Mendel's five element model
1. Parents transmit discrete traits to their offspring 2. Each individual receives two genes that encode each trait. 3. Traits have alternative forms (alleles) 4. The two alleles remain discrete-they neither blend with neither blend with, nor alter each other. 5. The present of a particular allele does NOT ensure the trait it encodes will be expressed.
What is the probability of rolling three sixes by tossing a die three times?
1/216
An heterozygous individual is one that carries ______________ different alleles for a given gene.
2
A cell with three X chromosomes will contain how many Barr bodies?
2 Barr bodies
Down syndrome is the result of nondisjunction of chromosome __________ during meiosis.
21
Monohybrid cross between two purple heterozygous (Pp) flower pea plants will produce what phenotypic ratio?
3:1
A single gene has 3 or more alternative forms. These are called _________________.
Alleles
A dog's phenotype can be determined how?
By its genotype
A 39 year old woman is in her sixth week of pregnancy. Due to her advanced maternal age, she is at risk for having a baby with Down's syndrome. Which testing method can be done at the earliest time possible?
Chorionic villi sampling
In a heterozygous individual the allele being expressed is ___________
Dominant
The most common condition of trisomy, in which three copies of a chromosome are present instead of the normal two, is of chromosome...?
Down Syndrome
Lethal form of disjunction
OY nonviable zygotes
When a single gene influences multiple phenotypic traits the effect is called?
Pleiotropy
A useful device for predicting the possible offspring of crosses between different genotypes is the ____________ _______________.
Punnett square
What was the the appearance of F1 generation of a monohybrid cross of purple (PP) and with white (pp) flower pea plants?
Purple
Let P = purple flowers and p = white, and T = tall plants and t = dwarf. What would be the appearance of a plant with the genotype PpTt?
Purple and tall
What type of offspring do true-breeding plants always produce if crossed with another true-breeding plant of the same trait?
Same as the parent
How many traits and variants of each trait is/are demonstrated in a monohybrid cross?
Show only 2 variations of a single trait
Let P = purple flowers and p = white, and T = tall plants and t = dwarf. Of the 16 possible gamete combinations in the dihybrid cross, how many wold be the phenotype white and tall?
Solve
Let P = purple flowers and p = white, and T = tall plants and t = dwarf. What combinations of gametes could be produced by a heterozygote for both the traits?
Solve
A Barr body is typically found in the nucleus of what type of cell?
Somatic cells of female
The geneticist who discovered the white eye mutation in Drosophila and helped establish that genes are carried on chromosomes was __________?
T.H. Morgan
What is a testcross used to determine?
The genotype of an individual with dominant phenotype
How does maternal inheritance of mitochondrial genes differ from sex linkage?
The mitochondria does not come from the sperm, only the egg. As a result, females AND males are equally affected.
Amniocentesis is a procedure that is normally used for what purpose?
To collect fetal cells from the amniotic fluid for examination
A human female with only one X chromosome is said to have a condition called...
Turner syndrome
In sickle cell anemia, the defective hemoglobin differs from the normal hemoglobin by a single _______ ______ substitution.
amino acid