Quiz 8

Human cells have 46 chromosomes in their nuclei. When considering all 46 chromosomes, how many sister chromatids are there total in a human cell immediately after interphase?

92

The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?

Anaphase

The centromeres arrive at the poles and nuclear envelopes form during which phase of mitosis?

Telophase.

What must happen before a cell can begin mitosis?

The chromosomes must be duplicated.

Both mitosis and meiosis are precede by

interphase

Gametes are produced by

meiosis

If it weren't for ____, chromosome number would double with every generation of sexual reproduction

meiosis

Variation occurs when chromosomes are shuffled in _____.

meiosis

Mitosis occurs in ____; meiosis occurs in ____

somatic or body cells ... germ cells in the testes or ovaries

Mitosis and cytokinesis result in the formation of ____; meiosis and cytokinesis result in the formation of ____

two diploid cells; four haploid cells

Cancer is caused by

uncontrolled cell division

Homologous chromosomes posses the same genes arranged in the same order but may posses different _____ of some of the genes

versions

Which of the following is a key difference between meiosis and mitosis?

Synapsis occur

Within one chromosome, what is the relationship between the sequence of bases in DNA of one sister chromatid compared to the other?

The sequences are identical

In bacterial cells, binary fission involves

distribution of a copy of the single parental chromosome to each daughter cell

Which statement regarding sexual reproduction is true?

Sexual reproduction is more likely to increase genetic variation than is asexual reproduction

In humans, the haploid number of chromosomes is 23. Independent assortment has the possibility of producing ____ different gametes

2 (23)

Each somatic cell in an individual with Down syndrome contains _____ chromosomes.

47

Jacobsen syndrome, which can cause heart defects, intellectual deficiencies, and bleeding disorders, is caused by a deletion of the terminal end of chromosome 11. What method could you use to determine whether an individual has Jacobsen syndrome?

Perform a karyotype using a person's white blood cell

The statement regarding prokaryotes is false?

Prokaryotic chromosomes are more complex than those of eukaryotes

The centromeres move away from each other and the nuclear envelope breaks up during which phase of mitosis?

Prophase

Crossing over occurs during

Prophase I

Although in humans there are 22 pairs of autosomal chromosomes, only three different chromosomal trisomies are commonly seen in newborns. Of the remaining 19 autosomes, many trisomies have not been seen in newborns. Why not?

Trisomy for the autosomal chromosomes is often lethal, and the affected embryos are miscarried

The correct order of events during meiosis is

prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.

During meiosis, segments of non sister chromatids can trade places. This recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?

prophase II

One version of a gene may encode ____, whereas a different version of the same gene may encode ____

red eyes; white eyes

Which of the following indicates Turner syndrome?

XO

With the exception of identical twins, siblings who have the same two biological parents are likely to look similar, but not identical, to each other because they have

a similar but mot identical combinations of genes

Which process leads to most genetic variation sexually reproducing organisms?

crossing over independent orientation of chromosomes in meiosis random fertilization

At the end of the mitotic phase, the cytoplasm divides in a process called

cytokinesis

Which type of organisms commonly demonstrates polyploidy?

flowering plants

A cell preparing to undergo meiosis duplicates its chromosomes during

interphase

If a chromosome fragment breaks off and then reattaches to the original chromosome, but in the reverse direction, the resulting chromosomal abnormality is called a(n)

inversion

Cancer is not usually inherited because

the chromosomal changes in cancer are usually confined to somatic cells

Describe the relationship between a chromosome and a sister chromatid

Joined identical copies of duplicated chromosome are called sister chromatids

The chromosomes line up in the center of the cell during which phase of mitosis?

Metaphase

Looking through a light microscope at a cell undergoing division, you see that the condensed chromosomes have lined up along the midline of the cell. The homologous pairs are NOT joined i tetrads. Each chromosome takes its own place in line, independence into homologous , You are witnessing

Metaphase of mitosis

Normal human gametes carry ____ chromosomes

23

Why are individuals with an extra chromosome 21, which causes Down syndrome, more numerous than individuals with an extra chromosome 3 or chromosome 16?

Extra copies of the other somatic chromosomes are probably fatal

You suspect that a serious development disorder is due to a chromosome abnormality and prepare a karyotype from an affected individual. In analyzing the karyotype, how could you distinguish trisomy from a chromosome structural defect such as a duplication?

In trisomy there would be one extra chromosome; in a duplication, the number of chromosomes would be normal, but one chromosome would have two copies of a portion of thechromosome

Independent orientation of chromosomes at metaphase I results in an increase in the number of

possible combinations of characteristics

The term binary fission is best applied to ____

prokaryotes

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing ____ chromosomes

16

Trisomy for most autosomes is fatal, yet trisomy or even tetrasomy (four copies) of the X chromosome is not. What is the explanation for this difference?

Only one copy of the X chromosomes is functional within any given cell, regardless of the total number of X chromosomes

You are a medical student and are reviewing a case study about a past patient. The patient was 4 feet 8 inches tall at age 38, was unable to have children, and had an above-average intelligence. The patient also had an irregular number of chromosomes. What diagnosis would you give the patient?

Turner Syndrome

Meiosis starts with a single diploid cell and produces

four haploid cells

Fertilization joins _____ to produce a _____.

haploid gametes ... diploid zygote

During prophase I

homologous chromosomes stick together in pairs.

At a chiasma, two _____ are attached to each other

homologous or non sister chromatids