BIOL1102 Lecture Notes - Lecture 21: Barr Body, X-Inactivation, Color Blindness

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pearcrab619

7 Jun 2018

School

Flinders University

Department

BIOD Biodiversity and Conservation

Course

BIOL1102

Professor

Karen Burke da Silva

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Problem solving with Mendelian genetics:

Meiosis, mitosis, or impossible?

a. Meiosis I (one a and one A cross over, same for B and D)

b. Not possile there is o a i here, oly As

c. Meiosis I (there is no recombination between centromere and a/A locus but there is

in B and D)

d. Not possible (somehow lost a b)

e. Meiosis II

f. Meiosis II

g. Meiosis II

h. Not possible (too many chromosomes, too many sister chromatids)

i. Mitosis

j. Not possible (different alleles. Mitosis is DNA replication and separation)

Tongue rolling:

- In humans, there is a gene that controls formation (or lack thereof) of muscles in the

tongue that allow people with those muscles to roll their tongues, while people who

lack those muscles cannot roll their tongues

- The aility to roll oes togue is doiat over non-rolling

- The ability to taste certain substances is also genetically controlled

- PTC, which some people can taste (the dominant trait), while other cannot (recessive

trait)

- Let R represent tongue-rolling, r represent a non-roller, T represent ability to taste

PTC, and t represent non-tasting

- Suppose a woman who is both a homozygous tongue-roller and a non-PTC-taster

marries a man who is a heterozygous tongue-roller and is a PTC-taster, and they

have three children:

o A homozygous tongue-roller who is also a PTC taster

o A heterozygous tongue-roller who is also a taster

o A heterozygous tongue-roller who is a non-taster

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Document Summary

In humans, there is a gene that controls formation (or lack thereof) of muscles in the tongue that allow people with those muscles to roll their tongues, while people who lack those muscles cannot roll their tongues. The a(cid:271)ility to roll o(cid:374)e(cid:859)s to(cid:374)gue is do(cid:373)i(cid:374)a(cid:374)t over non-rolling. The ability to taste certain substances is also genetically controlled. Ptc, which some people can taste (the dominant trait), while other cannot (recessive trait) Let r represent tongue-rolling, r represent a non-roller, t represent ability to taste. If the first child (homozygous tongue-roller also ptc taster) marries someone who is heterozygous for both traits, draw the punnet square that predicts what their children will be. The formation of barr bodies is the strategy that humans use for what is called dosage compensation. For many genes encoded on the x chromosome, cells from both males and females are designed to work with a single dose of the genes.

Related Questions

I am somewhat new to this site although I am a member, so I havethese questions I have answerd most of them my self yet I wouldlike to see if any experts, or people with some knowledge couldcould go ahead and do them so i can see if I am correct or not. Idont actually expect anybody to be able to make a punnet square, asI myself had to make my punnet squares on paper. But these are thequestions below, I will put my answers the ones I have gotten in () but if you are either able to tell me if im correct or if notshow me some sort of steps to becoming correct? Thanks ZackCross.

Solve all of these problems using a Punnett Square. ( I Havedone this mostly on paper)

In certain bacteria, an oval shape (A) is dominant over round(a) and thick cell walls (B) are dominant over thin (b). A bacteriaheterozygous for both oval shape and a thick cellwall was crossed with a round bacteria with a thin cell wall.Describe the phenotype of the offspring.

(My answer not sure if correct but I got : Oval Thick wall: Oval Thin wall : Round thick wall: Round thin wall

1:1:1:1)

2. The ability to roll the tongue sideways (A) is dominant overthe inability to roll one's tongue (a). In humans, non-attachedearlobes (B) are dominant over attached earlobes (b). Two parentswith attached earlobes can roll their tongues. They are bothheterozygous for the tongue rolling trait.

What is the genotype of the mother? ( I got Bb Aa)
What is the genotype of the father? ( I got Bb Aa)
What are the possible gametes from the mother? ( I gotBA Ba Ab ab)
What are the possible gametes from the father? ( I got BA Ba Abab)
Draw the Punnett square, and combine the gametes to produceoffspring( I did on paper)
What is the phenotypic ratio of these offspring? (Didn'tunderstand?)

A man heterozygous for non-attached earlobes can roll histongue. A woman with attached earlobes can roll her tongue. Assumeboth are heterozygous for the tongue-rolling trait.
1. What is the genotype of the mother?
2. What is the genotype of the father?
3. What are the possible gametes from the mother?
4. What are the possible gametes from the father?
5. Draw the Punnett square, and combine the gametes to produceoffspring
6. What is the phenotypic ratio of these offspring?
In summer squash, white fruit color (W) is dominant over yellowfruit color (w) and disk-shaped fruit (D) is dominant oversphere-shaped fruit (d). If a squash plant purebreeding for whiteand purebreeding for disk-shaped fruit is crossed with a plantpurebreeding for yellow, sphere-shaped fruit, what will thephenotypic and genotypic ratios be for:
1. the F₁ generation?
2. the F₂ generation?

Any Help would be greatly apretiated I don't understand how thepoint system works but I did purchase the membership package thingso I do believe I will be able to award someone with these karmapoints which I purchased.

Which of the following statements are true. CHALLENGE BIOLOGYQUESTION PLEASE EXPLAIN IF POSSIBLE:

a. In meiosis, the chromosomal material doubles during the lastpremeiotic interphase.

b. The greater the number of chromosome pairs, the greater isthe effect of meiosis in producing genetically distinctgametes.

c. The diploid number of chromosomes is half the haploidnumber.

d. A cell that will not divide again remains in the GÂ2 stage ofinterphase.

e. The correct sequence of events during meiosis is: synapsis âdyad formation â chiasma formation

f. In an organism with n = 3, there is a 1 in 8 probability of agamete with all maternally derived chromosomes contributing to theproduction of a zygote.

g. An organism with n = 3 can produce 8 different kinds ofgametes in relation to combinations of maternal and paternalchromosomes.

h. Separation of sister chromatids occurs during anaphase I ofmeiosis and is the physical basis for the law of independentassortment.

i. A single diploid cell that undergoes meiosis in the maletestis will produce 4 genetically different gametes ifcrossing-over is ignored.

j. The independent alignment of different tetrads at metaphase Iof meiosis is the physical basis of the law of independentassortment.

k. If a diploid cell has 20 pairs of chromosomes, there will be10 tetrads during prophase I of meiosis.

l. If a diploid cell has 20 pairs of chromosomes, there will be20 bivalents during prophase I of meiosis.

m. If a diploid cell has 20 pairs of chromosomes, there will be80 chromatids present during metaphase of mitosis.

n. If a diploid cell has 20 pairs of chromosmes, the organismcan make 20² types of gametes if crossing-over isignored.

o. Segregation of sister chromatids occurs during anaphase I ofmeiosis and is the physical basis of the law of segregation.

p. For an individual with a diploid number of 30 chromosomes,there will be 60 chromatids at metaphase I of meiosis.

q. For an individual with a diploid number of 30 chromosomes,there will be 15 tetrads at metaphase II of meiosis.

pucetermite199

___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).

BIOL1102 Lecture Notes - Lecture 21: Barr Body, X-Inactivation, Color Blindness

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