CMU Genetics Week 2: Chapter 3 & 4

What is the advantage of performing CVS over amniocentesis?

CVS can be done earlier than an amniocentesis

Which of the following is true about the genetic disease muscular dystrophy (MS)? Duchenne muscular dystrophy affects females at a higher frequency than males. MS is inherited in an autosomal dominant manner. MS results from a gene located on the Y chromosome. MS is X-linked. None of the above

MS is X-linked.

The loss of a single chromosome is known as

Monosomy

In autosomal recessive traits, unaffected parents can have affected children. True False

True

Individuals with Klinefelter's syndrome have XXY sex chromosomes. True False

True

Which type of genetic condition is much more common in males than females? X-linked recessive dominant autosomal recessive autosomal mutations UV radiation

X-linked recessive

Sickle-cell disease is found commonly in people whose ancestors are from parts of Northern Europe. inherited as a dominant trait a result of no hemoglobin hemoglobin being produced. a result of deformed cells that are fragile and break open easily all of these

a result of deformed cells that are fragile and break open easily

Jacobs syndrome?

an extra Y chromosome (XYY)

Which of the following statements is true about sex-linked traits? a. X-linked recessive genes are never expressed in males. b. In general, males are affected by X-linked recessive disorders far more frequently than females. c.Fathers do not donate their Y chromosome to their sons. d. All of these statements are true.

b. In general, males are affected by X-linked recessive disorders far more frequently than females.

Homologous chromosomes ____.

carry the same genes at the same positions.

Sperm and oocytes are ooploid aneuploid haploid diploid polyploid

haploid

An individual with only one X chromosome and no other sex chromosome is female Is male is never conceived never develops completely has Jacobs syndrome

is female

In autosomal recessive traits, unaffected parents can have affected children. True False

true

Meiosis involves chromosomal reduction division. True False

true

Mothers who are over the age of 35 have a higher likelihood of genetic defects in their unborn children. True False

true

Nondisjunction leads to aneuploidy. True False

true

Telomeres play a role in aging. True False

true

DEF: Phenotype

what an organism looks like

Fetal DNA from maternal blood: risk level? what does it tell us?

-No risk of spontaneous abortions -only detects fathers DNA and can determine the sex of the baby

An unaffected man and an unaffected woman have a son with Lesch-Nyhan syndrome, an X-linked recessive trait. What are the chances that a daughter of this couple will have the disease Lesch-Nyhan syndrome? 0 1/4 ½ ¾ Cannot be determined

0

Name 3 tests and during what stage of pregnancy they can occur

1. Amniocentesis (>16 weeks) 2. Chorionic Villus sampling (CVS) ( 10-12 weeks) 3. Fetal DNA from maternal blood

Name 4 ways the chromosome can structurally change

1. Deletion 2. Duplication 3. Inversion 4. Translocation

What are the 2 major effects of aneuplody?

1. Mental retardation 2. Early miscarriagess

Two parents are both heterozygous, carrying the autosomal recessive albino allele, a, and the wild type allele, A. What is the chance that they will have a child that will be albino? 1/2 1/4 2/3 1/3 4/4

1/4

A male has a Y-linked trait that causes fragile teeth, but unlike other Y-linked traits he is fertile. How many of his sons and daughters will have the trait of fragile teeth? 0% of sons and 100% of daughters 25% of sons and 50% of daughters 50% of sons and 0% of daughters 75% of sons and 75% of daughters 100% of sons and 0% of daughters.

100% of sons and 0% of daughters.

If a normal somatic cell from a certain diploid species contains 32 chromosomes, a sperm or an oocyte contains ___________ chromosomes.

16

Under what circumstances would it be recommended that a woman undergo amniocentesis? The woman will be 35 years of age or older at the time of birth. The woman has already had a child with a chromosomal aberration. Either parent has a known structurally abnormal chromosome. The woman is a carrier of a genetic disorder on the X chromosome. All of these are reasons for a woman to undergo amniocentesis.

All of these are reasons for a woman to undergo amniocentesis.

Which describes a homozygote? There is only one copy of a gene for a particular trait. Displays an intermediate phenotype compared to the two extremes. Two different alleles for a trait in an individual. The physical appearance of an organism with respect to a trait. Both alleles for a trait are the same in the individual.

Both alleles for a trait are the same in the individual.

Which of the following is true about the genetic disease cystic fibrosis (CF)? CF affects the gall bladder. CF patients produce abnormal blood cells. CF produces excessive accumulation of phenylalanine in the blood. CF causes improper metabolism in nerve cells. CF demonstrates autosomal recessive inheritance.

CF demonstrates autosomal recessive inheritance.

Congenital generalized hypertrichosis (CGH) is an X-linked dominant condition that produces dense hair on the face and upper body. What is the chance that a male affected by this condition will pass it on to his daughters (assume the mother is unaffected)? a. 0% b. 25% c. 50% d. 100% e. 75%

D: 100%

Which of the following is true about the genetic disease Duchenne muscular dystrophy (DMD)? DMD affects females at a higher frequency than males. DMD is inherited in an autosomal dominant manner. DMD results from a gene located on the Y chromosome. DMD is inherited as a sex-linked trait. There are three forms of X-linked muscular dystrophy.

DMD is inherited as a sex-linked trait.

Mendel's law of independent assortment states that....

Each pair of alleles segregates independently of other pairs of alleles during meiosis

Monosomy involving an autosomal chromosome is never fatal.

FALSE

Which of the following is true about the genetic disease familial hypercholesterolemia (FH)?

FH is an example of incomplete dominance

An amniocentesis can be performed at anytime during a pregnancy. True False

False

Only a few types of aneuploids are known in newborns because...?

Most aneuploids are lethal early in development causing spontaneous abortions

Only a few types of aneuploids are known in newborns because: Only a few chromosomes undergo nondisjunction Most types of aneuploids are lethal early in development Most aneuploids do not have a phenotype so go undetected throughout life All of the above

Most types of aneuploids are lethal early in development

Trisomy 13 -AKA? -survival? -malformations?

Patau Syndrome -survival: 1-2 months

During which phase of meiosis does crossing over occur? Metaphase I Metaphase II Prophase II Prophase I Interphase

Prophase 1

If a parent has an autosomal recessive trait then we know what about their children? (note: in this problem we do not know anything about the other parent)

The children will either have the trait or be carriers (heterozygotes).

If a parent has an autosomal recessive trait then we know what about their children? (note: in this problem we do not know anything about the other parent) They must all have this trait as well None of them can have this trait This parent will not be able to have children The children will either have the trait or be carriers (heterozygotes). No predictions can be made.

The children will either have the trait or be carriers (heterozygotes).

Mendel's Law of Segregation states that The two copies of a gene separate from each other during meiosis. Members of a gene pair segregate into gametes independently of other gene pairs. Genes pair with each other. Gene segregation results in a fixed gene population. Segregation may result in UV mismatch repair.

The two copies of a gene separate from each other during meiosis.

Which of the following trisomies is the least likely to lead to a live births? Trisomy 21. Trisomy 13. Trisomy 18. Trisomy 1. All of these trisomies can lead to live births.

Trisomy 1

In hemophilia A, clotting factor _______ is either absent or present in reduced amounts.

VIII

Which of the following properties is characteristic of an autosomal recessive pattern of inheritance? An important protein in the body is produced incorrectly or not at all. If both parents are affected then all children are affected. Male and female children are affected in roughly equal numbers. All of these are true. None of these are true.

WRONG If both parents are affected then all children are affected. WRONG male and female children are affected in roughly equal numbers

The end result of meiosis is: four cells with a diploid number of chromosomes two cells with a diploid number of chromosomes six cells with a haploid number of chromosomes four cells with a haploid number of chromosomes two cells with a haploid number of chromosomes

WRONG two cells with a haploid number of chromosomes

Genetic risks are evaluated by analyzing family history assessing if other family members had birth defects or not the woman's age assessing if other members of the family had developmental disabilities or not all of these

all of these

Under what circumstances should a couple meet with a genetic counselor? if the woman will be over 35 years of age at the time of birth couples who are first cousins or other blood relatives couples who come from ethnic groups in which certain types of genetic defects are more common couples who have already had a child with a genetic disorder all of the these

all of these

Different versions of genes are called_____. Homologues Alleles Autosomes Sister Chromatids Centromeres

alleles

A recessive allele is an allele that expresses its phenotypic effect even when it is present with a dominant allele an allele whose phenotypic effect is not expressed in a heterozygote genetic variance at a single locus attributable to dominance of one allele over another the result of two crossovers occurring in a chromosomal region under study a change in allelic frequency due to sampling error

an allele whose phenotypic effect is not expressed in a heterozygote

Jacobs syndrome involves an extra Y chromosome (XYY) an extra X chromosome (XXX) a deletion of Y the chromosome a deletion of X chromosome too many autosomal chromosomes

an extra Y chromosome (XYY)

What is the distinctive pattern of inheritance found for X-linked recessive traits? a. Affects only males. b. Affected males have an affected father. c. Hemizygous males and homozygous females are affected. d. Mutant characters are combined. e. Affected individuals will always have an affected parent and an unaffected parent.

c. Hemizygous males and homozygous females are affected.

In X-linked recessive disorders, daughters of affected males are usually __________. carriers homozygous mutant none of these affected

carriers

Which chromosome below is the smallest in size? chromosome 22 chromosome 1 X chromosome chromosome 12 chromosome 2

chromosome 22

Which of the following is true about Huntington's disease (HD)?

dominant mutation

An individual with a "normal" set of chromosomes is called a(n) ______

euploid

Nondisjunction refers to: failure of cells to separate properly during mitosis failure of chromosomes to separate properly during meiosis a failure to properly partition the organelles and the cytoplasm a specific mutation in a single gene.

failure of chromosomes to separate properly during meiosis

Structural changes in chromosomes never lead to genetic defects. True False

false

The Y chromosome has the same genes as found on the X chromosome. True False

false

Turner's syndrome individuals have only a Y chromosome.

false

Polyploidy involves a lower number of chromosomes within cells occurs when there are extra copies of one particular chromosome can detect chromosomal changes involves additional copies of all chromosomes in a cell involves a gain or loss of chromosomes

involves additional copies of all chromosomes in a cell

What is considered the main risk factor for Down syndrome?

maternal age

The loss of a single chromosome is known as monosomy trisomy bi-directional equality palindrome

monosomy

The most common cause of both trisomy and monosomy is mutations carcinogenic agents smoking nondisjunction none of the above

nondisjunction

If a child has an autosomal dominant trait, then we know who else has this trait? At least one of their siblings One of his biological parents Both parents must either have the trait or be a carrier Neither parent has the trait. None of the above.

one of his biological parents

A genotype is how an organism physically appears due to the interaction of recessive alleles only the genetic make-up of an organism due to the mixed interplay of mutations the result of similar alleles

the genetic make-up of an organism

Which of the following trisomies is the least likely to lead to a live births?

trisomy 1

Aneuploidy is a major cause of reproductive failure in humans. True False

true

At the end of meiosis, the number of chromosomes in each daughter cell is halved because meiosis has

two cell divisions and one DNA replication

Why are pedigrees constructed? to help track down repeat criminals to use evidence collected for crimes when a family member requests genetic counseling to understand Mendelian mutations when doctors think it necessary as additional evidence in a criminal case

when a family member requests genetic counseling