Meoisis Study SET CH

How does chromatid cohesion as maintained by cohesin proteins differ in mitosis and meiosis?

-Cohesion between sister chromatids is maintained during anaphase I of meiosis but not during anaphase of mitosis. -During anaphase I of meiosis, the destruction of cohesin proteins along the chromosome arms appears to be what allows homologous chromosomes to separate. However, cohesin proteins at the centromeres remain intact, maintaining sister chromatid cohesion and holding sister chromatids together. It's not until anaphase II, when cohesin proteins at the centromeres are destroyed, that sister chromatids finally separate. In mitosis, homologous chromosomes never pair, and destruction of cohesin proteins at the centromeres during the first (and only) nuclear division allows sister chromatids to separate.

Meiosis Only

-synapsis occurs -Crossing over occurs -independent assortment of paternal and maternal chromosomes -chromosome number is reduced from 2 sets to one set -during first nuclear division, chromosomes line up at the equatorial plate in pairs -during the first nuclear division, homologous chromosomes separate and move to opposite poles -There are 2 nuclear division with no DNA replication between them -During the first nuclear division, sister kinetochores fuse and are attached to the same pole

Which of the following describes meiosis II in humans?

1N -> 1N -

If sister chromatids failed to separate during meiosis II, what would the resulting gametes look like?

2 gametes will be normal, 1 gamete will have 2 of the affected chromosomes, and 1 gamete will have 0 of the affected chromosomes

If crossing over occurs between two chromatids on a single pair of homologous chromosomes, how many gametes will have a recombinant phenotype?

2 of the 4

Arrange the following events in the proper order in which they occur during meiosis I.1 = Separation of homologous chromosomes2 = Synapsis3 = Crossing-over4 = Independent assortment

2, 3, 4, 1

Anaphase 2 only

Centromeres split Sister chromatids separate and are pulled to opposite poles of the cell chromosomes change from duplicated state to unduplicated state

Anaphase 1 only

Chiasmata break Members of each homologous pair go to opposite poles of the cell Sister chromatids remain attached Each homologue moves to one pole, taking both sister chromatids iwth it Chromosomes remain duplicated

Neither anaphase 1 nor anaphase 2

Chromosomes begin to condense Crossing over occurs Spindle begins to form Nuclear membrane reforms DNA replication occurs

Both mitosis and meisosis

Chromosomes condense before they attach to the spindle

Random orientation of chromosomes during meiosis increases the amount of variation in the next generation. What other process during meiosis leads to an increase in variation in the next generation?

Crossing over between homologous chromosomes

In germline cells, when does DNA replicate?

During S phase

What event in meiosis I leads to the cell becoming haploid rather than the separation of sister chromatids?

Formation of bivalents lead to spindle fibers from opposite poles attaching to homologous chromosomes.

During anaphase I of meiosis, ____I____ move towards opposite cell poles, whereas during anaphase II of meiosis, ____II____ are separated.

I = homologous chromosomes; II = sister chromatids

Why are two phases of meiosis necessary?

In order to both reduce the chromosome number and separate sister chromatids

How does crossing over increase variation in a population?

It produces offspring with combinations of alleles that neither parent carried

Both Anaphase 1 and anaphase 2

Kinetochore microtubules shorten

Neither mitosis nor meisois

Nuclear division occurs twice but cytokinesis occurs only once

Synapsis of homologous chromosomes and crossing-over take place during

Prophase 1

Which of the following is not haploid?

a cell in prophase 1

The 2 members of each homologous pair are pulled to opposite poles of the cell while sister chromatids remain attached during

anaphase 1

Sister chromatids separate and are pulled to opposite poles of the cell during

anaphase 2

Which of the following events occur during prophase I?

breakdown of nuclear envelope, condensation of chromosomes, and movement of centrosomes

Which of the following is unique to meiosis?

crossing-over

At the end of meiosis II, there are

four haploid cells, with each chromosome consisting of a single chromatid.

Mutations can occur in any cell of the human body that contains DNA. However, only mutations in ________ can be passed on to the next generation.

germ-line cells

Daughter cells produced in meiosis have

half the number of chromosomes as daughter cells produced in mitosis.

At the end of meiosis I, each daughter cell is

haploid, and each chromosome consists of two chromatids.

The four daughter cells produced in meiosis

have one of each pair of chromosomes found in the parent cell.

Mitosis only

homologous chromosomes behave independently of each other DNA replication is folllowed by a single nuclear division -The new cells produced are genetically identical to each other and to the original cell -During the first nuclear division, sister chromatids separate and move to opposite poles

Synapsis is the side-by-side alignment of

homologous chromosomes.

The function of sexual reproduction is to increase variation within populations. Meiosis is the molecular mechanism that leads to sexual reproduction. As such, some of the features that make it unique lead to genetic diversity. Which of these unique features are responsible for increasing genetic diversity?

homologous recombination and reduction division

Unpaired chromosomes line up along the metaphase plate during

metaphase 2

Random orientation of homologous chromosomes occurs in ________ of meiosis.

metaphase I

Chromosomes line up in pairs along the _______ plate during ______

metaphase, metaphase 1

Suppose you have a multicellular eukaryotic organism that is composed entirely of haploid cells. This organism would produce gametes by the process of

mitosis

Centromeres divide in

mitosis and meiosis II.

A crossover in meiosis is an exchange of genetic material between

non-sister chromatids of homologous chromosomes.

The spindle apparatus is fully formed by the end of

prometaphase II.

A new spindle apparatus begins to form in 2 separate haploid cells during

prophase 2

Which of the following events occur during anaphase I?

separation of homologous chromosomes

Separation of ________ occurs in anaphase II of meiosis. Multiple Choice

sister chromatids

Crossing over is possible due to what event that occurs in meiosis I but not mitosis?

synapsis

Which of the following features are unique to meiosis?

synapsis, homologous recombination, and reduction division

Nuclear envelopes reform around 2 separate haploid nuclei during

telophase 1

Nuclear envelopes reform around 4 separate haploid nuclei during

telophase 2

The number of cells produced in meiosis is

twice the number of cells produced in mitosis.

A tetrad is made up

two homologous chromosomes, each consisting of two chromatids.