Chapter 11 (Test 3) Flashcards
The Blending Concept of Inheritance theory:
This theory stated that offspring would have traits intermediate between those of the parents.
_______ wanted to develop a theory of evolution based on hereditary principles; blending theory was of no help.
Charles Darwin
_______ was an Austrian monk.
Mendel
Mendel formulated two fundamental laws of heredity in the early ____
1860s
Mendel had previously studied _____ and ______ at the University of _____.
science and mathematics; vienna
At the time of Mendel’s research, he was a substitute _____ teacher at a local technical high school.
science
Because Mendel had a mathematical background, he used a statistical basis for his __________
breeding experiments
Mendel’s particulate theory is based on the existence of minute particles—now called _____.
genes
Mendel chose the garden pea, _______ , because peas were easy to cultivate, had a short generation time, and could be cross-pollinated by hand.
Pisum sativum
From many varieties, Mendel chose __ true-breeding varieties for his experiments.
22
_______ varieties had all offspring like the parents and like each other.
True Breeding
Mendel confirmed that his tall plants always had tall offspring, i.e., were true-breeding, before crossing two different strains that differed in only one trait—this is called a ______.
monohybrid cross.
A ______ is between two parent organisms true-breeding for two distinct forms of one trait.
monohybrid cross
Mendel tracked each trait through ___ generations.
2
__ generation is the parental generation in a breeding experiment.
P
__ generation is the first-generation offspring in a breeding experiment.
F1
__ generation is the second-generation offspring in a breeding experiment.
F2
He performed _______ , i.e., pollen of tall plant to stigma of short plant and vice versa.
reciprocal crosses
He found that the __ plants resembled only one of the parents.
F1
Characteristics of other parents reappeared in about 1/4 of __ plants; 3/4 of offspring resembled the __ plants.
F1, F2
The laws of Segregation? (4)
- Each organism contains two factors for each trait.
- Factors segregate during the formation of gametes.
- Each gamete contains one factor for each trait.
- Fertilization gives each new individual two factors for each trait.
The gene _____ is the specific location of alleles on homologous chromosomes.
Locus
Alternative versions of a gene are called ____
alleles
A ______ masks or hides expression of a recessive allele; it is represented by an uppercase letter.
Dominant allele
A _____ is an allele that exerts its effect only in the homozygous state; its expression is masked by a dominant allele; it is represented by a lowercase letter.
Recessive Allele
The process of _____ explains Mendel’s law of segregation.
meiosis
In Mendel’s cross, the parents were true-breeding; each parent had two identical alleles for a trait–they were ______, indicating they possess two identical alleles for a trait.
Homozygous
_________ genotypes possess two dominant alleles for a trait.
Homozygous Dominant
__________ genotypes possess two recessive alleles for a trait.
Homozygous recessive
_______ genotypes possess one of each allele for a particular trait.
Heterozygous
The allele not expressed in a heterozygote is a _______ allele.
Recessive
_____ refers to the alleles an individual receives at fertilization (dominant, recessive).
Genotype
______ refers to the physical appearance of the individual (tall, short, etc.).
Phenotype
A __________ is between two parent organisms that are true-breeding for different forms of two traits; it produces offspring heterozygous for both traits.
Di-hybrid cross
The ___________ only applies to alleles on different chromosomes.
law of independent assortment
A ________ is used to determine the probability of genotypes and phenotypes among offspring.
Punnett Square
_________ is the likely outcome a given event will occur from random chance.
a. For example, with every coin flip there is a 50% chance of heads and 50% chance of tails.
Probability
The _________ of probability states that the chance of two or more independent events occurring together is the product of the probability of the events occurring separately.
Product rule
The ________ of probability calculates the probability of an event that occurs in two or more independent ways; it is the sum of individual probabilities of each way an event can occur; in the above example where the phenotype unattached earlobes is dominant (EE, Ee, and eE), the chance for unattached earlobes is ¼ + ¼ + ¼ = ¾.
Sum Rule
A _____ is used to determine if an individual with the dominant phenotype is homozygous dominant or heterozygous for a particular trait.
Testcross
By Mendel performing a ______, the law of segregation was supported.
testcross
A ________ is used between an individual with the dominant phenotype and an individual with the recessive phenotype to see if the individual with the dominant phenotype is homozygous or heterozygous.
one trait testcross
A ________ tests if individuals showing two dominant characteristics are homozygous for both or for one trait only, or heterozygous for both.
two trait testcross
In ________ genetics problems, the individual has four alleles, two for each trait.
dihybrid
Genetic disorders are medical conditions caused by a ______ of alleles on the autosomal chromosomes.
Single pair
An _____ is any chromosome other than a sex (X or Y) chromosome.
autosome
In a pedigree chart, males are designated by _____, females by _____
squares; circles
A _____ is a heterozygous individual with no apparent abnormality but able to pass on an allele for a recessively-inherited genetic disorder.
Carrier
Relatively harmless disorder resulting from an accumulation of methemoglobin in the blood.
- Cause and genetic link still remain a mystery.
- Symptoms include bluish-purple skin due to inability to clear abnormal blue protein from blood.
Methemoglobinemia
People with methemoglobinemia lack the enzyme diaphorase, which is coded for by a gene on chromosome 22.
methemoglobinemia
This is the most common lethal genetic disease in Caucasians in the U.S.
Cystic fibrosis
About 1 in 20 Caucasians is a carrier, and about 1 in 3,000 newborns have this disorder.
Cystic fibrosis
Autosomal Recessive Disorders:
Methemoglobinemia and Cystic fibrosis
Autosomal Dominant Disorders:
Osteogenesis Imperfecta and hereditary Spherocytosis
This is an autosomal dominant disorder that affects one in 5,000 newborns and is distributed equally around the world.
Osteogenesis Imperfecta
Affected individuals have weakened brittle bones. Additional symptoms include unusual blue tint in the sclera of the eye, reduced skin elasticity, weakened teeth, and sometimes heart valve abnormalities.
Osteogenesis Imperfecta
This genetic blood disorder results from a defective copy of a gene found on chromosome 8.
-Symptoms include: spherical shape of red blood cells, and enlarged spleen.
Hereditary Spherocytosis
________ is exhibited when the heterozygote has an intermediate phenotype between that of either homozygote.
Incomplete dominance
True-breeding red and white-flowered four-o’clocks produce ____-flowered offspring.
pink
In _________ the dominant allele does not always determine the phenotype of the individual.
incomplete penetrance
________ is an example of incomplete penetrance.
polydactyly
________ describes a gene that affects more than one characteristic of an individual.
Pleiotropy
_________ examples include Marfan syndrome, porphyria, and sickle-cell anemia.
Pleiotropy
Marfan syndrome?
- The mutated gene is on chromosome 15.
- Symptoms include disproportionately long arms, legs, hands, and feet; weakened aorta; poor eyesight.
Porphyria?
- This disease is caused by a chemical insufficiency in the production of hemoglobin.
- Symptoms include photosensitivity, strong abdominal pain, port-wine-colored urine, and paralysis in the arms and legs.
Sickle-cell anemia?
- This disease is the most common inherited disorder in African Americans, affecting about 1 in 500.
- The gene is on chromosome 11.
- In affected individuals, the red blood cells are shaped like sickles—an abnormal hemoglobin molecule, Hbs, causes the defect.
_________ occurs when one trait is governed by two or more sets of alleles
Polygenic inheritance
_________ are controlled by many genes and may be influenced by environmental factors.
Polygenic traits
An ______ gene is any gene located on the X chromosome; term is used to describe genes on the X chromosome that are missing on the Y chromosome.
X-linked
_______- have an XY sex chromosome system similar to the human system; experiments can be correlated to the human situation.
fruit flies
