BIOL 112 Lecture Notes - Lecture 4: R.W.D. Molenbeek, Meiosis

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Dent lecture 4: linkage and the genetics of. Appears in 1/4 of children of unaffected parents. The colorblindness results from a gene on the x chromosome that is nonfunctional (cannot make protein properly - mutated) Y chromosome always has the recessive allele because it doesn"t have a gene for colorblindness. Y is small and does not have a gene for colorblindness. The absence of a gene is a type of allele. Hemizygous - is when a gene is missing from one of the chromosomes (only on 1/2 chromosome) Carriers - if you cross a colorblind man with a normal homozygous woman, all children are normal but females will be heterozygous. Linkage is the result of two genes being on the same chromosome. Wild type allele - the predominant allele (>99% ) in a population. Mutant allele - defective alleles; a change from the wild type allele, typically the result of a recent mutation.

Related Questions

1.A homozygous red-eyed female Drosophilamates with a red-eyed male Drosophila. What proportion of thefemale offspring will have white eyes?

75%

25%

100%

2.Red-green colorblindness is a recessive X-linked trait.If a female is red-green colorblind, which of the following isTRUE?

Her father mustbe colorblind.

Both herparents are carriers of the recessive allele.

Both herparents must be colorblind.

Her mother mustbe colorblind.

Women cannotexhibit red-green colorblindness because they have two Xchromosomes.

3.Allelesare

recessive traits.

dominant traits.

exact copies of the same trait.

alternate versions of the same trait

4.Using three bases torepresent each amino acid in a polypeptide

ensures that other organisms can read the codetoo.

prevents the wrong amino acid from being incorporated into aprotein.

ensures that DNA can replicate properly.

ensures that all amino acids are represented at least once bythe code.

5. If an organism's DNA contains 20%adenine nucleotides, what percentage of its DNA is composed ofguanine nucleotides?

6. Atrue-breeding tall pea plant is crossed with a tall pea plant ofunknown parentage. Which of the following iscorrect?

Some shortindividuals may appear in the F2 generation.

Some of the F1generation will be short.

All of theoffspring (F1) will be short.

Over severalgenerations, no short individuals will appear.

7.Morgan breeds and sells snakes. He knows that he can makethe most money by breeding and selling albino snakes. Albinism is arecessive trait. His female albino corn snake just produced 6offspring. Two displayed normal coloration and 4 were albino. Whatdo you know about the genotype of the father?

He could beeither heterozygous or homozygous dominant.

He must behomozygous recessive.

There is notenough information to determine the father's genotype.

He must beheterozygous.

8.During the elongation cycle of translation, the A site ona ribosome functions in

releasing thecompleted polypeptide.

holding apolypeptide as amino acids are added.

attaching thesmall subunits of rRNA to the large subunit.

receiving a newtRNA with the correct amino acid.

9.Whichof the following is an incorrect match?

translation -polypeptide formation

transcription -tRNA formation

translation -mRNA binding to rRNA

replication -copying of DNA

10. Thethree steps that are required for DNA replicationare

base doubling,unwinding, and joining.

unwinding, basedoubling, and base pairing.

unwinding,complementary base pairing, and joining.

unwinding,transcription, and translation.

11.Thex-ray diffraction pattern of DNA discovered by Rosalind Franklinshowed that DNA

contains alphahelices and beta sheets.

contains betasheets arranged in a repeated pattern.

has a repeatedpattern.

is both helicaland has a repeated pattern.

12.Which of the following is TRUE?

All traits onthe sex chromosomes are associated with sexual development.

Females can beheterozygous for sex-linked traits.

Males areheterozygous for the SRY gene.

Men pass theirX-linked traits to their sons.

13.Martha has a widow's peak and attached earlobes. Martha's dad had astraight hairline and unattached earlobes. What is Martha'sgenotype?

Answer withBRIEF EXPLANATIONS please

if more than 2answers you given are wrong, low star, pretty much no pts!

indigojackal331

___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).

The A antigen (the protein that makes A blood A blood) is embedded in the red blood cell (RBC) membrane. Blood group A individuals will automatically carry antibodies (proteins that are in the blood plasma-liquid part of blood) that will attack blood group B cells. Blood group B individuals will carry antibodies that will attack blood group A cells. Blood group O individuals, lacking either of the A or B antigens will carry BOTH types of antibodies and will attack either A or B cells. When there is a transfusion with incompatible blood groups, cells can clump creating blockages in arteries throughout the body. Other pathways can lead to the lysing of RBCâs which will release their contents into the bloodstream elevating these component in the blood which can have sever effects on the heart (potassium primarily-in case you are interested).

Remember, the Rh is a typical one gene, two allele scenario. Rh+ blood can accept Rh+ or Rh- blood. A person with Rh- blood can only receive Rh- blood. Unlike ABO where an individual manufactures the antibody to an antigen they lack without prior exposure, the Rh factor requires previous exposure to illicit an immune response. If a Rh- person is exposed to Rh+ blood, the individual will create the antibody against the Rh antigen. Now, if Rh+ blood is introduced into this individual again, the recipientâs blood contains anti-Rh antibodies and will attack the Rh+ cells-Bad news for the recipient. This is the same thing that happens with an Rh- mom who gets pregnant with an Rh+ baby. By the time the first Rh+ baby is born and blood mixing may have occurred during late pregnancy (small breaks in the placenta can cause some of babyâs blood to mix with that of mom), first baby escapes unharmed. Subsequent babies arenât so lucky.

If there are small tears in the placenta (which are normal), momâs anti Rh antibodies can go in and attack the Rh+ babyâs blood. This can kill the baby. Now, Rh- moms are given a substance that will coat the babyâs RBCâ; kind of like putting them into stealth mode so they canât be seen by momâs immune system. Later-poof, out pops unaffected baby.

1. What blood type(s) can be given to an A positive individual?

2. If you have B negative blood, what blood types can you receive?

3. What blood types can an O negative receive? O positive?

4. If a man is blood group B and his wife is blood group A what blood type(s) are you 100% sure they could produce in their children?

5. If you have a blood group O father and a blood group B mother, can they produce an O child? Explain your answer.

6. You have a male friend who is blood group AB. He is successful in business but knows very little about biology. His wife just had an O child. Knowing that you have been studying the genetics of blood groups, he asks you for an education on blood groups. What do you think about this situation?

7. A woman is AB and her husband is A. They have a B child. What are all the blood groups possible in their children if he is heterozygous?

8. A woman is Rh- and her husband is Rh+. Their first baby is Rh-. What is the genotype, with respect to Rh, of the parents? What is the probability their next child will be Rh+? Does the woman have to worry about any issues with future children? Explain!

BIOL 112 Lecture Notes - Lecture 4: R.W.D. Molenbeek, Meiosis

BIOL 112 Full Course Notes

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