Meiosis and Cell Cycle Flashcards

Flashcards for Meiosis and Cell Cycle Study Questions

How many times does cytokinesis occur in reproductive cell division?

Two

Females have a homologous pair of sex chromosomes which are .

XX

What is the haploid number of chromosomes in humans?

23

Crossing over occurs during which phase?

Prophase I

The number (46 for Humans) is also known as the 2n number.

The diploid

Meiosis I is also called __division because the 2n is divided to form the n chromosome number.

Reduction

Homologous chromosomes _ or pair during prophase I to form a tetrad.

Synapse

How many nuclear chromosomes do humans have?

46

Matching pairs of chromosomes are called .

Homologous chromosomes

Most spontaneous abortions or miscarriages are due to .

Chromosomal abnormalities

are all the chromosomes except the sex chromosomes.

Autosomes

Reproductive cell division results in the production of _ haploid gametes that are all genetically different.

Four

When a zygote is formed it contains two sets of chromosomes, one from the male parent and one from the female parent. This is called the ____number or 2n.

Diploid

A zygote is formed by the union of a _ and .

Sperm and egg/ovum

Which phase of meiosis I reduces the chromosome number from diploid to haploid?

Anaphase I

During the _ phase, of interphase, each chromosome in the cell duplicates to form an identical copy of the chromosome.

S

Sperm and ova are collectively known as _ which are also known as sex cells.

Gametes

Males only have one chromosome and only one _ chromosome which make up their sex chromosomes, where females have a pair of XX chromosomes.

X, Y

Sperm and the ova each contain chromosomes which is the haploid number.

23

__occurs during prophase I and is the process of exchanging genetic information, which results in the increase in genetic variation.

Crossing over

Define asexual reproduction.

reproduction involving only one parent. It produces genetically identical offspring.

Why is crossing over important?

increases genetic variation in offspring

Humans have DNA molecules, __chromatin fibers, and _ chromosomes in every nucleated somatic cell.

46, 46, 46

The three stages of cell cycle are DNA replication, separating DNA into two equal parts and ___.

Cytokinesis

_ is programmed cell death.

Apoptosis

_ and _ are two types of karyokinesis or nuclear division.

Mitosis and Meiosis

The _ gene inhibits cell division and the mutant form accounts for 50% of all cancers.

P53

Interphase is broken down into three subphases G1, and _, and sometimes a __, which is a resting phase.

S, G2, G0

In which subphase does the DNA replicates ___.

S

List the five phases of mitosis in order.

Prophase, Metaphase, Anaphase, Telophase

A is made up of DNA wrapped around a protein called histones.

Nuclesome

In anaphase, the enzyme cleaves the centromere which allows the chromatids to separate.

Separase

The two sister chromatids are held together by a __.

Centromere

During __, the chromosomes align along the equatorial plane.

Metaphase

_ is the phase where sister chromatids separate.

Anaphase

During _ the nuclear envelope reforms and chromosomes uncoil and become invisible chromatin fibers.

Telophase

and are the two oncogenes that mutate, resulting in most human cancers.

Ras and Myc

Why is cytoplasm division different in plant and animal cells?

Plant cells form a cell plate, animal cells form a cleavage furrow

The checkpoint determines if the cell divides, rest, or dies and is the most important checkpoint in the cell cycle.

G1

__ tumors are enclosed, contained, and non- metastatic, while _ tumors are not contained and metastasize very rapidly to other tissues.

Benign, Malignant

When cells lose their , it allows the cancerous cells to metastases to other tissues of the body.

Anchorage

The _ located at the kinetochores, depolymerize the spindle fibers , which separated the daughter chromatids during anaphase..

Kinetochores

What causes the cells to elongate during anaphase and telophase?

The elongation of microtubules

Cyclin dependent kinase combines with cyclin to form the _ which allow the cell to proceed through the G2 checkpoint.

Mitosis promoting factor (MPF)

The cell produced by the fusion of an egg and a sperm is the __.

zygote

Why don't plant cells form a cleavage furrow during cytokinesis?

Because they have a cell wall

Which of the following represents the correct order of the subphases of of interphase?

G1 -> G0 -> S -> G2

The structure that organizes the protein subunits of the mitotic spindle is the:

Centrosome

Crossing over results in __.

Homologous chromosomes that are still the same shape and size but no longer contain the same genetic sequence