Chapter 3 & 4 - Inheritance, Sex, and Chromosomes

A normal human somatic cell carries ______ pairs of chromosomes for a total of ______.

23 ; 46

In most animals, a cell will contain the following number of chromosomes after mitosis:

2n

Meiosis I reduces the chromosomes from what ploidy?

2n to n

In his classical experiments with white-eyed fruit flies, Morgan obtained red-eyed F1 individuals by crossing white-eyed males with red-eyed (wild-type) females. When he crossed F1 males and females, he obtained an F2 generation with an overall ratio of _____.

3 (red-eyed individuals):1 (white-eyed individuals)

Insert a number into the blank: Most human somatic cells contain a total of ____ chromosomes.

46

What is chromatin?

A complex between DNA and proteins that is found in eukaryotic cells

A key difference between daughter cells resulting from mitosis and meiosis is that:

After meiosis, cells are haploid. After mitosis, cells are diploid.

When you consider only the sex chromosomes, what types of gametes are produced by a female individual of a species with the XY system of sex determination?

All gametes carry a X chromosome.

One form of hereditary deafness is inherited with an X-linked recessive allele. What can be expected for the offspring of a deaf mother and a father with normal hearing?

All of the sons will be deaf and all of the daughters will have normal hearing. Reason: Sons will express the deafness allele inherited from their mother since the the Y chromosome from their father does not have carry any alleles to mask it.

This diagram represents a cell that has an original diploid number (2n) of four chromosomes. The cell is shown in which phase of cell division?

Anaphase II of meiosis

Define autosomes.

Any chromosome that is not a sex chromosome

Name 2 aspects of meiosis that contribute to genetic diversity in a population.

Crossing-over Independent assortment

What chromosomes determine a female, male?

Female: XX Male: XY

During which part of interphase do cells achieve the majority of their growth?

G1

Hemophilia is inherited with an X-linked recessive allele. Which term describes the genotype for a male who has this blood-clotting disorder?

Hemizygous

Name 2 events of telophase I of meiosis.

Homologs have reached their respective poles. The nuclear membrane reforms in many species.

In which of the following does DNA replication NOT occur: A. Interphase of mitosis B. Interphase 1 of meiosis C. Interphase 2 of meiosis D. None of the above

Interphase 2 of meiosis

Humans who have two X chromosomes and a Y chromosome (XXY) are said to have ____ syndrome.

Klinefelter

The chromosomes line up across the middle of the cell during:

Metaphase

During which of the following phases are tetrads organized along a plate in the center of the cell?

Metaphase of meiosis I

The kind of nuclear division followed by cell division that results in two daughter cells containing the same number and type of chromosomes as the original parent cell is called ___.

Mitosis

What results in two daughter cells containing the same number and type of chromosomes as the original parent cell

Mitosis

During what stage of meiosis II does the nuclear envelope break down?

Prophase II

Humans carrying an X and no second sex chromosome (XO) are said to have ________ syndrome

Tendler?

Name 3 events that occur during prophase of mitosis.

The chromatin condenses into more compact structures. The centrosomes move apart. The nucleolus becomes less visible.

Name 2 the events that occur during pro-metaphase.

The nuclear envelope completely breaks down. Chromosomes attach to the microtubules through the kinetochore.

What makes the chromosomes come together for crossing over?

The synaptonemal complex

Mitosis produces two diploid daughter cells, while meiosis produces four haploid daughter cells. T/F

True

_______ genes are those that are physically located on the X chromosome.

X-linked

What is the inheritance pattern for a trait that is more likely to occur in females and which is seen in every generation?

X-linked dominant

What is the inheritance pattern for a trait that generally affects more males than females and will never pass from father to son?

X-linked recessive

What is the inheritance pattern for a trait that more commonly affects males than females and can often be observed in brothers or fathers of a woman who has affected sons?

X-linked recessive

In his large-scale crosses between red-eyed males and white-eyed females, Bridges observed a small proportion (about 1 in 2000) of white eyed female offspring which he determined to be XXY individuals. How did these individuals obtain their sex chromosomes? Multiple choice question.

XX from their mother, Y from their father

The male is ___ and the female is ___.

XY, XX

Which of the the following genotypes corresponds to a white-eyed male fruit fly?

X^wY

A fruit fly with the genotype XwXw is ____.

a white-eyed female

In his classical experiment with white-eyed Drosophila flies, Thomas Hunt Morgan crossed red-eyed (wild-type) females with white-eyed males. He then crossed the red-eyed F1 generation fruit flies with each other and discovered that, while the F2 generation included both red-eyed and white-eyed individuals, ____.

all white-eyed individuals were male

Define crisscross inheritance.

an inheritance pattern in which males inherit the character of a trait from their mothers, while daughters inherit the character from their fathers.

The two pairs of sister chromatids separate and move to opposite poles best describes what phase of cell replication?

anaphase I of meiosis

What describes cells or organisms whose chromosome sets are not all complete?

aneuploids

In humans, if a non-disjunction event leads to an individual that is XXY, they would:

be male because they have a Y chromosome

During the G1 part of interphase, ______.

cells grow in size

Define Germ cells

cells that produce gametes, or 'sex cells'.

What ensures that cell cycle events occur in the proper sequence?

checkpoints

Chromosomes usually exist in the nucleus as what?

chromatin

What is the name for the diffuse complex of DNA and proteins in a eukaryotic cell?

chromatin

The anaphase stage of meiosis I is characterized by the separation of the two _______ of a tetrad from each other and their migration to opposite poles of the cell.

chromosomes

The structures within all living cells that contain the genetic material are called ___.

chromosomes

The structures within living cells that contain the genetic material are best defined as what?

chromosomes

During prophase of mitosis, chromosomes ______ into discrete structures. Furthermore, the two _______ separate moving towards the poles and the mitotic _______ begins to form.

condense, centrosome, spindle

The interchange of corresponding chromatid segments of homologous chromosomes during prophase I of meiosis is called ______.

crossing over

Define hemizygous

describes the genotype for genes present in only one copy in an otherwise diploid organism, such as X-linked genes in a male.

In a ______ cell, each type of chromosome is a member of a pair.

diploid

Humans with Turner syndrome are _____.

female (anuploid)

Cells that are destined to undergo meiosis and produce gametes are called _____ cells.

germ(line)

Meiosis produces cells that contain _____.

half the number of chromosomes found in other cells within the same organism

Hemophilia is an X-linked recessive trait. One of the conditions that must be met for a female child to have hemophilia is that ______.

her father must have hemophilia

One form of hereditary deafness is inherited with an X-linked recessive allele. A woman with normal hearing has a son with hereditary deafness. The woman's genotype at this gene locus is ______.

heterozygous

Synapsis is the process by which _____.

homologous chromosomes recognize each other and begin to align themselves in prophase I

Meiosis increases genetic diversity in a population through crossing-over and by _____ assortment of parental chromosomes.

independent

In eukaryotes, ______ is the type of cell division that is responsible for the production of gametes.

meiosis

In ______ of meiosis, the bivalents (which are also termed tetrads) are aligned along the center of the cell.

metaphase I

Bridges observed that in a cross between white-eyed females and red-eyed males, the majority of the progeny were red-eyed females and white-eyed males. However, a very small number of males had red eyes, and females had white eyes. Bridges proposed this was due to _______ in meiosis.

nondisjunction

Trisomies occur due to _____.

nondisjunction

In meiosis, crossing-over refers to the physical exchange of pieces between _____.

nonsister chromatids of homologous chromosomes

The of a eukaryote is the organelle that contains most of the genetic material found in the cell.

nucleus

What organelle found in eukaryotic cells that contains the hereditary material?

nucleus

During ______, pairs of sister chromatids become attached to kinetochore microtubules which emanate from opposite poles of the cell.

pro-metaphase

If the chromosomes decondense during the preceding interphase, they recondense during _____ II of meiosis.

prophase

The two halves of a chromosome after DNA has been replicated are the:

sister chromatids

A cell _____ is any cell of the body that is not a gamete or precursor to a gamete.

somatic

In G0, what cells are actively going through mitosis?

somatic cells

During prophase of meiosis I, homologous chromosomes recognize and begin to align with each other via a process called ____.

synapsis

During the zygotene stage of meiosis I, the _______ complex aligns homologous chromosomes.

synaptonomal

During ______ of meiosis, the pairs of sister chromatids have reached the opposite poles of the cell, where in most cases, nuclear membranes begin to form around them.

telophase I

A bivalent is also called a ____, because it is composed of four chromatids.

tetrad

A trait that a son can inherit only from his mother must be due to an allele found on ______.

the X chromosome

A bivalent, or tetrad, consists of _____

two pairs of sister chromatids of homologs

A diploid cell is defined as a cell that has ______.

two sets of chromosomes

Color blindness is due to an X-linked recessive allele. To be color blind, females must inherit ______ copy(ies) of this allele and males must inherit ______ copy(ies).

two; one