WORKSHEET BIO 208 Unit 2 Spring2008

Also review list of objectives, notes, textbook, and homework assignments

  1. Animals can teach us genetics! Match

Heterozygotes will exhibit two distinct proteins on A. Manx cat

their red blood cells

Show a dominant and recessive relationshipB. Coat coloration in cats

An allelic seriesC. Labrador retriever dogs

A dominant homozygote is lethalD. Piebald spotting in beagles

Coat coloration is determined by 2 distinct genesE.MN antigens

Shows variable expressivityF. A and O blood alleles

A qualitative, or continuous, traitG. Calico cat

Females mosaics for X-linked heterozygous color genes H. Height of an individual

  1. If Mendel only knew then what we know now.

EPISTASISDOMINANCE

CODOMINANCEINCOMPLETE DOMINANCE

PENETRANCEALLELE

EXPRESSIVITYRANDOM SEGREGATION

INDEPENDENT ASSORTMENT

  1. The expression of both alleles of a heterozygous gene pair is called:
  2. The degree to which a genotype is expressed in the phenotype:
  3. The suppression of one gene by another non allelic gene :
  4. The % of individuals of a genotype that show the expected phenotype:
  5. Each gamete receives one allele of a gene :
  6. When a single gene heterozygous genotype results in a phenotype intermediate to the two alleles :
  7. The alleles of one gene pair are inherited independently from those of another gene pair :
  8. An alternative form of a gene:
  9. The expression of one allele to the exclusion of the other in a heterozygote:

PED'IGREE, n. from L. pes,pedis, foot. Lineage; line of ancestors from which a person or tribe descends; genealogy.

  1. Examine the pedigree below

Why is this NOT a Y linked trait?

Could this be an X – linked trait?

Is this inherited in an autosomal dominant or autosomal recessive manner? How do you know for sure?

Which three modes of inheritance are possible for this trait. Show your reasoning by indicating possible genotypes for each individual

  1. It is probable that a probability question is in the future

From the cross AaBbccDdEeff X AABbCcDdeeFf what is the probability of obtaining the genotype AabbCcDDEeff in the progeny?

  1. Epistasis with two genes!

In horses, a dominant B will give the horse a black color, and a b will give the horse a chestnut color. However, when a dominant W is present in the second gene pair, the horse will be white no matter what. If the second gene pair is ww, then the horse will be the color of whatever the first gene pair is made of. If a heterozygous white (BbWw) mare is crossed with a heterozygous white (BbWw) stallion, what could the offspring's phenotype and genotype be?

  1. Fill in the disorder

XY femaleCri du ChatDown syndrome

XX maleAnhydrotic ectodermal dysplasia Patau syndrome Hemophilia Polydactyly

Phenylketonuria AchondroplasiaAlkaptonuria

  1. Male, small testes, infertility
  2. Female may not have ovaries or a uterus
  3. Female heterozygotes have patches of skin that lack sweat glands
  4. Inability to clot blood due to lack of a clotting factor
  5. Dominant allele results in extra fingers and toes
  6. Recessive allele prevents metabolism of phenylalanine
  7. Dominant allele affects cartilage growth needed for bone lengthening
  8. Retardation, higher risk of Alzheimer disease
  9. Babies usually do not live beyond a year, deaf, blind
  10. Microcephaly, abnormal larynx anatomy
  11. Metabolic disease part of phe pathway, black urine
  12. 5 disorders that can be detected by karyotype
  1. And let’s not forget human sex….. Arrange in the correct chronological order: TDF, SRY, testosterone, male embryo, testes, Y chromosome
  1. Fly sex…………

In Drosophila sex is determined by the ratio of the number of X chromosomes to the number of sets of autosomes. Female ratio is 1 or greater, while males have a ratio of 0.5 or less. Identify the sex of the following flies

  1. XY fly with 2 sets of autosomes ______
  2. XXY fly with 2 sets of autosomes ______
  3. XX fly with 3 sets of autosomes ______
  1. AND……………Bird sex…..

In birds, the male is the homogametic sex. Females are ZW. A dominant sex-linked allele, ZSgives silver feather color. Zs gives gold. Mate a silver female with a gold male. How can you identify male and female offspring by feather color alone?

  1. Who did it?

a. ______Random X-chromosome inactivationEdwards

b. ______Characterized trisomy 21Klinefelter

c. ______Characterized trisomy 18Barr

d. ______Discovered independent assortment Mendel

e. ______Chromosomal theory of inheritanceDown

f. ______Characterized XXY malesSutton, Boveri

  1. Do you know your numbers?

a.number of chromosomes in a human diploid cell ______

b.number of chromosomes in a human haploid cell ______

c.number of chromosomes in a human Turner syndrome cell ______

d.number of chromosomes in a human trisomic cell ______

e.number of chromosomes in a human triploid cell ______

f.number of chromosomes in ahuman cell with a Robertsonian fusion __

g.number of chromosomes in a human fertilized egg ______

h.number of chromosomes in a normal human sperm ______

  1. Ploidy, somy, and more Fill in:

RECIPROCAL TRANSLOCATIONMONOPLOID

LOCUSMONOSOMY

TRIPLOIDTRISOMY

TETRAPLOIDBARR BODY

  1. Position a gene occupies on a chromosome ______
  2. X chromosome in mammals seen as heterochromatin ______
  3. An aberrant chromosome number in which a normally diploid cell has 3 copies of 1 chromosome ______
  4. An exchange of non-homologous chromosomes ______
  5. An aberrant chromosomal condition in which a cell has 1 copy of a chromosome and 2 copies of all others ______
  6. An individual possessing 4 sets of chromosomes ______

13. Deletion,Translocation, Inversion, Duplication, ORMosaicism?

a. ______Involved in 46, 5p-

b. ______May result in a position effect which affects gene expression

c. ______May result in pseudodominance of an allele which is normally recessive to a dominant allele

d. ______Two genetically distinct populations of cells in a single individual

e. ______Will result in abnormal gamete formation (more than one answer)

f. ______Involved in familial Down syndrome

g. ______Lethal if it occurs in the same region of two homologous chromosomes

h. ______No loss or gain of genetic material is involved (2 answers)

i. ______Cell will have 45 chromosomes

j. ______Increase of genetic material, may be tandem or reverse

k. ______46, XX/45, X (one individual)

14. Fill in the blanks on the pathway for phenylalanine metabolism. The arrows represent a mutant enzyme (and corresponding gene) that does not function in the pathway.

15. MORE??

a. When true-breeding tall stem pea plants are crossed with true-breeding short stem pea plants, all of the ______plants, and 3/4 of the ______plants had tall stems. Therefore, tall stems are dominant

  1. A genetic cross between two F1-hybrid pea plants having yellow seeds will yield what percent green-seeded plants in the F2 generation? Yellow seeds are dominant to green.
  1. To identify genotype of yellow-seeded pea plants as either homozygous dominant (YY) or heterozygous (Yy), you could do a test cross with plants of genotype ___.
  1. In Mendel's experiments, if gene for tall (T) plants was incompletely dominant over gene for short (t) plants, what would be the result of crossing two Tt plants?
  1. A genetic cross of inbred snapdragons with red flowers with inbred snapdragons with white flowers resulted in F1-hybrid offspring that all had pink flowers. When the F1 plants were self-pollinated, the resulting F2-generation plants had a phenotypic ratio of 1 red: 2 pink: 1 white. The most likely explanation is:
  1. A woman with type A blood and a man with type B blood could potentially have offspring with which of the following blood types?
  1. A pea plant is heterozygous for both seed shape and seed color. S is the allele for the dominant, spherical shape characteristic; s is the allele for the recessive, dented shape characteristic. Y is the allele for the dominant, yellow color characteristic; y is the allele for the recessive, green color characteristic. What will be the distribution of these two alleles in this plant's gametes?
  1. Which of the following genetic crosses would be predicted to give a phenotypic ratio of 9:3:3: 1?

SSYY x ssyy or SsYy x SsYy or SSyy x ssYY or ssYY x ssyy

  1. In a dihybrid cross, AaBb x AaBb, what fraction of the offspring will be homozygous for both recessive traits?
  1. Following a SsYy x SsYy cross, what fraction of the offspring are predicted to have a genotype that is heterozygous for both characteristics?
  1. In a dihybrid cross, SsYy x SsYy, what fraction of the offspring will be homozygous for both traits?
  1. Hemophilia in humans is due to an X-chromosome mutation. What will be the results of mating between a normal (non-carrier) female and a hemophiliac male?
  1. A human female "carrier" who is heterozygous for the recessive, sex-linked trait causing red-green color blindness has a child with a normal male. What proportion of their male progeny will have red-green color blindness?
  1. A human female "carrier" who is heterozygous for the recessive, sex-linked trait red color blindness, marries a normal male. What proportion of their female progeny will show the trait?
  1. A rooster with gray feathers is mated with a hen of the same phenotype. Among their offspring, 15 chicks are gray, 6 are black, and 8 are white. What is the simplest explanation for the inheritance of these colors in chickens? What offspring would you predict from the mating of a gray rooster and a black hen?
  1. A man has six fingers on each hand and six toes on each foot. His wife and their daughter have the normal number of digits. Extra digits is a dominant trait. What fraction of this couple's children would be expected to have extra digits?
  1. A woman has the rare (hypothetical) disease called bent fingers. She has children with a normal man, and all of their sons but none of their daughters have bent fingers. What is the mode of inheritance of bent fingers? a. Autosomal recessive b. Autosomal dominant c. X-linked recessive