BIOL239 Lecture Notes - Xyy Syndrome, Zygosity, Barr Body

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brownalligator985

5 Apr 2013

School

University of Waterloo

Department

Biology

Course

BIOL239

Professor

Christine Dupont

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Document Summary

Chromosome # is not same as haploid # Trisomies of chromosome 1 and 2 usually result in spontaneous abortion. Trisomy 21 less of an impact. downs syndrome. well tollerated. Polydactally (extra toes) is accociated with trisomy 13 chromosome 21. At meiosis 1 - nondisjunction happens and chromosomes travel together into one egg. at meiosis 2 splits normally, but there are double the chromosomes in egg. At meiosis 2 - 1st meiosis occurs normally, but at meiosis 2, nondisjuction occurs and one set of chromosomes do not get pulled appart and travel into one of the eggs. If happens in meiosis one, all gametes will be abnormal. If it happens in meiosis two, 50% of gametes will be normal, other two will not be. Need to have one copy of x chromosome because need copy of proteins. Females have 2 genes dosages for x. Have to bring it down to 1 bc we dont want double the amoint.

Related Questions

___1. Nationally, the most common cause of Down Syndrome is
a. nondisjunction of Chromosome 21 during meiosis
b. translocation of Chromosome 21 onto another chromosome
c. inversion of a large section of Chromosome 21
d. deletion of the Down Syndrome gene
___2. In humans, sex is determined by
a. The presence or absence of the Y chromosome
b. The ratio of X chromosomes to sets of autosomes
c. The temperature during fetal development
d. Which parent is stronger at the time of conception
___3. A translocation is
a. a chromosomal abnormality in which a piece of one chromosome breaks off and attaches to a different chromosome
b. an abnormality in which the chromosomes are translocated out of the nucleus
c. a condition in which the chromosome has broken in two places and come back together with the middle segment backward
d. an abnormality in which there is an extra copy of one chromosome
___ 4. In snapdragons, a red-flowered plant crossed with a white-flowered plant produces all pink-flowered offspring. But crossing two pink-flowered plants produces red, pink, and white in a 1:2:1 ratio. This is a good example of
a. Incomplete dominance
b. Dominance of the red allele over the white allele
c. Lethal effects of the pink allele
d. Sex-linkage of the flower-color alleles
___ 5. If a person with type AB blood marries a person with Type O blood, what blood types are possible in their children? (Assume this trait is a single-gene trait, not complicated by interaction with other genes).
a. A, B, AB, or O
b. A or B only
c. AB or O only
d. AB only 2
___6. In what phase of meiosis are haploid nuclei first formed? a. Anaphase I b. Metaphase II c. Telophase II d. Metaphase I e. Telophase I
___7. What is the phenotype of a heterozygous tall pea plant? a. tall b. Tt c. TT d. tt e. dominant
___ 8. If genes A and B are far apart on a chromosome, and A and C are close together, which of the following observations is expected?
a. Crossing over will occur more often between A and C than between A and B
b. Crossing over will occur at equal frequencies between A and C, and between A and B
c. Crossing over will occur more often between A and B than between A and C
___9. Sometimes an organismâs genotype for one gene masks the effect of a different gene. This phenomenon is called
a. Dominance
b. Incomplete dominance
c. Co-dominance
d. Epistasis
e. Variable expressivity
___10. The dominant allele of a gene is
a. The one that is expressed most often in a population
b. The one that is expressed most often in any particular cross
c. The one that is expressed in an individual that has two different alleles
d. The one that is most healthy to have, that gives the greatest fitness
___11. In human cells, DNA replication occurs
a. In S phase of interphase
b. In G1 phase of interphase
c. In G2 phase of interphase
d. In prophase of mitosis
e. Whenever the cell needs to read the DNA to make proteins
___ 12. A process in which recipient cells take up genes from DNA molecules floating free in the surrounding medium is called
a. conjugation
b. specialized transduction
c. generalized transduction
d. transformation 3
___ 13. Most calico cats are female. However, a few rare males are observed. What is the genotype of a male calico cat?
a. X BX 0
b. X OY
c. X BY
d. X BYY
e. X BX OY
___ 14. A type of red-green color-blindness is a sex-linked (X-linked) recessive trait in humans. Can a woman have this type of color-blindness?
a. Yes, a woman could be color-blind if her mother and father were both heterozygous.
b. Yes, a woman could be color-blind but only if she has an abnormal number of sex chromosomes.
c. No, women can't show sex-linked traits because they lack a Y chromosome.
d. No, women can't show sex-linked traits because they have two X chromosomes.
e. Yes, a woman could be color-blind if her father was color-blind and her mother was a carrier (heterozygous).

Question 1 Select one answer.

Two heterozygous individuals are crossed. What percentage oftheir offspring will be heterozygous?

a)50%

b)75%

c)100%

d)25%

Question 2 Select one answer.

In peas purple is dominant to white for flower color. A purpleflower is crossed with a white flower. All the offspring (over 100plants) produce purple flowers. What is the genotype of the purpleflower?

a)pp

b)Either PP or Pp

c)PP

d)Pp

Question 3 Select one answer.

A heterozygous germ cell undergoes meiosis. The gametes will

a)only have the recessive allele

b)only have the dominant allele

c)either have the dominant or the recessive allele

d)have both the dominant or the recessive allele

Question 4 Select one answer.

Sex-linked disorders

a)are always dominant are

b)always recessive

c)can be either dominant or recessive

d)are neither dominant nor recessive

Question 5 Select one answer.

A nucleus is built around chromatids which have separated. Thisoccurs during which stage of meiosis?

a)Telophase II

b)Metaphase I

c)Metaphase II

d)Telophase I

Question 6 Select one answer.

The condition of having anincorrect number of chromosomes is called ____________.

a)nondisjunction

b)aneuploidy

c)epistatis

d)trisomy

Question 7 Select oneanswer.

In humans females are

a)XY

b)YY

c)none of these

d)XX

Question 8 Select oneanswer.

Autosomal means that the gene isfound on the

a)X chromosomes

b)the Y chromosome

c)either the X or the Ychromosome

d)neither on the X nor theY

Question 9 Select oneanswer.

What organism did Mendelstudy?

a)Roses

b)Ants

c)Peas

d)Yeast

Question 10 Select oneanswer.

Huntington's disease is anautosomal dominant disorder. If two individuals who areheterozygous at this locus breed, what are the chances that theiroffspring will develop Huntington's?

a)100%

b)75%

c)50%

d)25%

Question 11 Select oneanswer.

Plum gametes have 24 chromosomes.How many chromosomes would a zygote have?

a)12

b)24

c)36

d)48

Question 12 Select oneanswer.

Hydrangeas are blue in acidicsoil with available aluminum, and they are pink in alkaline soilwithout available aluminum, but they cannot be orange under anysoil condition. The color of hydrangeas is affect by

a)genetics only

b)the environment only

c)genetics and theenvironment

Question 13 Select oneanswer.

Somatic mosquito cells have 6chromosomes. How many chromosomes do gametes have?

a)3

b)6

c)12

d)24

Question 14 Select oneanswer.

Alleles are different versions ofa

a)Gene

b)Phenotype

c)Genotype

d)Chromosome

Question 15 Select oneanswer.

A female producesgametes:

a)that have either an X or a Ychromosome

b)That have 2 Xchromosomes

c)that have a Y chromosomeonly

d)that have an X chromosomeonly

Question 16:

use the following infromation to answer the next 4 questions

In dogs, colored fur (E) is dominant to un-colored fur (e).Blackfur color (B) is dominant to brown fur color (b). The E gene isepistatic to the B gene. A yellow male dog is mated to a blackfemale. the male's parents were both brown dogs. The female'smother was yellow and her father was brown

Q1 of 4: what is the genetype of the male dog in thisexample

a)eeBb

b)eeBB

c)ee

d)eebb

Q2 of 4: What is the genotype of the female dog in thisexample?

a)EeBb

b)EEBB

c)EeBB

d)EEBb

Q3 or 4: What percentage of their puppies will be yellow?

a)100%

b)75%

c)50%

d)25%

Q4 of 4: what percentahe of the puppies will be homozygous forthe B gene.

a)100%

b)75%

c)50%

d)25%

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BIOL239 Lecture Notes - Xyy Syndrome, Zygosity, Barr Body

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