Biology 156 Chap 8

Which of the following statements is true?

Meiosis is sometimes called reduction division.

What must happen before a cell can begin mitosis?

The chromosomes must be duplicated, which occurs during interphase.

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

cytokinesis. Cytokinesis is the division of the cytoplasm that occurs in conjunction with telophase, the last phase in mitosis.

Many people with XY chromosomes and androgen insensitivity syndrome (AIS), like Katie, are not diagnosed until later in life, rather than at birth. Why is that?

Babies with XY chromosomes and AIS usually appear to be normal females at birth. It is not until they have a hernia, or fail to menstruate, before a doctor would investigate further.

What are telomeres?

regions of DNA at the end of chromosomes which do not code for making proteins

How many autosomes do humans have?

44

Which of these cells is (are) haploid?

After Meiosis I and Meiosis II (C &D)

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

Anaphase Sister chromatids separate and start their migration toward opposite poles during anaphase.

How is the aging process linked to telomeres?

Cells with short telomeres can no longer divide, so damaged tissues cannot be repaired.

Which of the following most accurately describes Katie's situation?

Katie was born with testes, but her cells did not respond to the testosterone those testes produced.

If you look through a microscope and see a cell with chromosomes lined up vertically what stage of cellular reproduction are you looking at?

Meiosis I is the only time that chromosomes line up by homologous pairs.

When are chromosomes duplicated?

We can see that the chromosomes are duplicated and lined up by homologous pair. That only happens at the start of meiosis I

Many enzymes are named for the substrate on which they work, either to build or disassemble molecules. Also, enzyme names often end in "-ase." For example, lactase is the enzyme that breaks down lactose. With a name like "telomerase," we can deduce that telomerase is probably

an enzyme that regulates the assembly of DNA at the ends of chromosomes

During cell division, the DNA is in a coiled up and compacted form called ___. When the cell is not dividing, the DNA is in long thin fibers called ___.

chromosomes, chromatin

There are nearly 30 different disorders of sexual development. Who can have these disorders?

people with either XX or XY chromosomes

Meiosis is the process that:

produces haploid gametes in diploid organisms

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

prophase Prophase is the first phase of mitosis, when the centrosomes begin moving toward opposite poles and the nuclear envelope breaks up

The correct order of events during meiosis is

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

During meiosis, segments of nonsister 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 I.

A cell preparing to undergo meiosis duplicates its chromosomes during

interphase.

Gametes are produced by _____.

meiosis

Genetic variation is NOT increased by:

mitosis

The failure of a chromosome pair to separate during meiosis is called:

nondisjunction

Which of the following events have not yet occurred? Select all that apply.

separation of sister chromatids into distinct cells production of four haploid gametes

A karyotype would be helpful in diagnosing or determining:

-Down syndrome, due to an extra chromosome -21 Klinefelter syndrome, due to an extra X chromosome -Turner syndrome, due to a missing sex chromosome -the sex of a person all of the above

Crossing over of chromosomes during meiosis shuffles parental chromosomes, resulting in a genetically unique child. Select the three true statements about crossing over.

-During meiosis II, sister chromatids separate into four different gametes. -During prophase I of meiosis I, homologous paternal and maternal chromosomes pair up and undergo crossing over. -A hybrid chromosome that has crossed over will contain pieces of both the maternal and paternal chromosomes.

A certain species of animal has six pairs of chromosomes. How many DNA molecules are present in the nuclei of these animals during G2 phase?

24 DNA replication is completed during S phase, which occurs prior to G2 phase. Since each chromosome (12) is replicated, there are 24 DNA molecules in the nucleus during G2 phase

Gametes:

in humans contain 23 chromosomes

Rank from the first event to the last event, left to right.

1. homologous chromosomes pair up 2. nonsister chromatids form chiasmata 3. crossing over occurs 4. homologous chromosomes separate 5. sister chromatids separate 6. four haploid gametes are produced

If an organism's gamates have 5 chromosomes how many chromosomes will one of its body cells contain just before mitosis begins?

10 If the hypothetical organism has 5 chromosomes in one of its gametes, then it must have 10 chromosomes in a body cell. Just before mitosis, the chromosomes in a body cell are duplicated, but the sister chromatids remain joined together. So you will see 10 (duplicated) chromosomes in a typical body cell.

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

16

Normal human gametes carry _____ chromosomes.

23

Which of the following checkpoints does not occur late in G1?

A check that chromosome replication has been successfully complet

Building Vocabulary: Cell Division pt 1

Asexual reproduction is a means of creating new individuals solely by mitosis, the form of cell division that creates genetically identical daughter cells.

Which of the following biologically describes a hermaphrodite?

Earthworms can fertilize each other to produce offspring

True or false. Mitosis takes place during M phase of the cell cycle, which is longer than interphase.

False Mitosis does indeed take place during M phase, but M phase is shorter than interphase; cells spend most of their time in interphase.

How does the karyotype of a human female differ from the karyotype of a human male?

Females have two X chromosomes, and males have X and Y chromosomes

Which of the following has the greatest potential as a cancer treatment?

Find a way to turn off the gene for making telomerase in cancer cells, since the cells would stop dividing when the telomeres were gone.

Gender identity is a person's personal sense of being a man or a woman. Katie says at the end of the clip that, given the traditional definitions of sex, she can't say whether her sex is male or female, but that her gender identity is definitely that of a woman. What does this indicate about gender identity?

Gender identity is mostly likely the result of a combination of physical, physiological, and social factors

How does meiosis differ from mitosis?

In meiosis four daughter cells are produced, while in mitosis two daughter cells are produced.

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

Metaphase occurs in the middle of mitosis, when the chromosomes line up in the middle of the cell.

Which process is going on in your hand right now?

Mitosis goes on continuously in most parts of the body, whereas meiosis takes place only in the gonads.

Which of the following problems during DNA replication is being illustrated with the kids in the video?

Nucleotides at the ends of the DNA strands are lost when DNA replicates.

Which of the following describes how we inherit our chromosomes?

One of each of the homologous chromosomes comes from our father, and the other of each of the homologous chromosomes comes from our mother.

Building Vocabulary: Cell Division pt 2

Sexual reproduction, in contrast, generates genetically unique offspring. To accomplish this, an organism must produce gametes-- sperm and egg -- through the process of meiosis. The cells produced this way will be haploid, meaning that they contain a single set of chromosomes. Such cells are produced only in the gonads.

Which of the following is the best option if Katie wants to have children?

She can adopt children.

In the video, the narrator says that Katie had her testes removed, and now takes pills to give her more appropriate hormones. What is the most likely explanation?

Since Katie has no ovaries to produce estrogen, she likely takes an estrogen supplement that supports her gender identity

Which cells are most likely to have the gene for making telomerase switched on?

The cells in a developing embryo.

What joins duplicated chromosomes?

The centromere is the point of attachment between two duplicated chromosomes

Which of the following is NOT true about naked mole rats?

Their cells do not produce telomerase.

The 23rd pair of chromosomes in human females is ___, and the 23rd pair of chromosomes in human males is ___.

XX, XY

An orderly picture of magnified images of stained chromosomes is called:

a karyotype

Homologous chromosomes:

carry the same genes in the same places

Meiosis starts with a single diploid cell and produces

four haploid cells.

Except for the sex chromosomes, the members of a homologous pair of chromosomes:

have the same gene content are the same shape are the same size all of the above

During prophase I of meiosis,

homologous chromosomes stick together in pairs.

What is the function of cell division?

to enable a multicellular organism to grow to adult size to replace worn out or damaged cells to produce gametes for sexual reproduction