Ch. 14 Quiz (Exam 5)

a combination of polygenic inheritance and environmental factors. -Several genes (polygenic inheritance) control height in humans, giving an overal normal distribution. Environmental factors such as nutrition smooth out the curve.

skin pigmentation in humans.

P, F₁,F₂ -Mendel started with true-breeding P generation plants, and in a typical experiment generated two subsequental generations, called F₁and F₂.

four...one -GgTt individuals can produce the following gametes: GT, Gt, gT, and gt. A ggtt plant can produce only gt

That the parents were both heterozygous for a single trait.

It is homozygous at two loci. -An organism having a pair of identical alleles at a given locus is said to be homozygous for that locus. Here, the plant is homozygous at loci A and C.

1) The mode of inheritance of the condition. 2) The genotypes of individuals in the pedigree (as far as can be known) based on their phenotype and the phenotypes of their parents or children. 3) The probability that certain individuals will have the condition. This requires assigning probability values to some individuals who genotypes cannot be determined with certainty. It also requires an understanding of how and when to apply the mulitplication and addition rules.

He or she will show some symptoms of the disease. - A heterozygote will produce both normal and abnormal hemoglobin.

an alternate version of a gene. -A diploid organism carries two alleles for each autosomal gene. The two alleles are found are found at comparable locatioins (loci) on homologous chromosomes. The alleles may be identical or slightly different, but they affect the same genetic character.

A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid cross involves only one.

Red shows incomplete dominance over white. -Red shows incomplete dominance over white, and the F1 is therefore pink.

ultrasound imaging, chorionic villus sampling, amniocentesis -Both CVS and amniocentesis involve the preparation of a karyotype using fetal cells.

1 black eyes, green skin : 1 black eyes, white skin : 1 orange eyes, green skin : 1 orange eyes, white skin -Sam's genotype is BbGg, and Carole's genotype is bbgg.

bbgg -This is an extension of the single character testcross you worked with in the activity on monohybrid crosses.

dihybrid -The cross is examining two characters.

both parents are heterozygous for both genes -Such a result indicates that the genes assort independently and that, for each gene, the alleles exhibit a dominant/recessive relationship.

1 black eyes, green skin, two eyes : 1 black eyes, green skin, one eye : 1 black eyes, white skin, two eyes : 1 black eyes, white skin, one eye : 1 orange eyes, green skin, two eyes : 1 orange eyes, green skin, one eye : 1 orange eyes, white skin, two eyes : 1 orange eyes, white skin, one eye -This is a tough problem; you had to expand your Punnett square to accommodate another character. However, 1:1:1:1:1:1:1:1 ratio is the expected outcome of a BbGgCc x bbggcc cross.

Mendel's law of independent assortment is being violated. -If the genes for eye color and skin color assorted independently, then the outcome of this cross would have been a 1:1:1:1 ratio.

BBGg -All of the offspring have black eyes, and there is a 3:1 ratio of skin color.

1 AB : 1 aB

Cross the green-pod plant with a yellow-pod plant. -A cross between a plant of unknown genotype and one that is known to be homozygous recessive is called a test cross because the recessive homozygote tests whether there are any recessive alleles in the unknown. Because the recessive homozygote will contribute an allele for the recessive characteristic to each offspring, the second allele (from the unknown genotype) will determine the offspring's phenotype.

law of segregation

the law of segregation states that two alleles for a gene separate during gamete formation, and end up in different gamete. in the other gamete will receive the recessive allele (g). The law of segregation accounts for the prediction that 50% of the offspring of the test cross will have green pods and 50% will have yellow pods.

It is very likely that at least one of Woody Guthrie's parents also have had the allele for Huntington's disease. -Unless the disease is caused by a new mutation, which is quite rare, individuals with a dominant condition must have inherited the dominant allele from one of their parents. As it happens, Guthrie's mother also died of Huntington's disease.

All of the gametes from a homozygote carry the same version of the gene while those of a heterozygote will differ.

gametes, progeny

True -Since there exist dominant and recessive versions of many genes, a phenotype that is based upon the dominant version will be expressed in both homozygous (AA) and heterozygous (Aa) genotypes.

False

none

25 -The offspring would be in a 3:1 ratio of normally pigmented mice to albino mice

ttpp -The smallest phenotypic group consists of the homozygous recessive plants, which in this case are short and white flowered.

Meiosis. -The role of meiosis is to separate homologous chromosomes and their respective alleles, which are assorted in an independent manner.

Fusion of gametes -During fertilization, gametes bring together homologous chromosomes to generate a diploid individual.

Alleles of different genes segregate from one another in a random manner. -The random distribution of alleles is required for independent assortment.

False -The principle of independent assortment is best illustrated by events that take place during metaphase I, during which nonhomologous chromosomes segregate independently of each other.

Two -The gametes would be either RY or rY.

AaBb, aabb -The offspring of these parents would have a phenotypic ratio of 1:1:1:1.

pleiotropy

is a mating between individuals who have different alleles at one genetic locus of interest. To carry out such a cross, each parent is chosen to be homozygous or true breeding for a given trait. When a cross satisfies the conditions for a monohybrid cross, it is usually detected by a characteristic distribution of second generation (f2) offspring that is sometimes called the monohybrid ratio. Example ww x RR wR wR wR wR RR, Rw, Rw, ww

is a cross between F₁offspring of two individuals that differ in two traits of particular interest. For example BB x bb.

occurs when the phenotype of the heterozygous genotype is distinct from and ofthen intermediate to the phenotypes of the homozygous genotypes. For example, the snapdragon flower is either homozygous for red or white. when the red homozygous flower is pair with the white homozygous flower, the results yield a pink snapdragon. (the trait are combined)

occurs when the contribuitions of both alleles are visible in the phenotype. For example in Co-dominance, a red homozygous flower and a white homozygous flower will produce offspring that have red and white spots.

a phenomenon win which the expression of one gene depends on the presence of one or more modifier genes. A gene who phenotype is expressed is called epistatic, while one whose phenotype is alter or suppressed is called hypostatic.