Cell Cycle, Mitosis and Meiosis

Cell Cycle

An ordered sequence of events in the life of a cell


A process of nuclear division in eukaryotic cells divided into four stages: prophase, metaphase, anaphase, and telophase; conserves chromosome number; daughter cells (2) are genetically IDENTICAL, clones of each other; associated with asexual reproduction

What are the four stages of mitosis?

Prophase- chromosomes PREPARE
Metaphase- chromo. line up in the MIDDLE
Anaphase- Chromo. get pulled APART
Telophase- TWO new nuclei form


The first stage of mitosis, in which the chromatin condenses making chromosomes visible with a light microscope, the mitotic spindle begins to form, and the nucleolus disappears and nuclear envelope starts to deteriorate


The second stage of mitosis, in which the spindle is complete, spindle fibers attach, are all aligned at the metaphase plate (middle)


The third stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell (moving AWAY or APART).


The fourth and final stage of mitosis, in which daughter nuclei are forming at opposite ends of the cell and cytokinesis has typically begun (cytokinesis is NOT part of mitosis!); in animal cells, the cytoplasm pinches in creating a cleavage furrow, in pl


The division of the cytoplasm to form two separate daughter cells immediately after mitosis (or four after meiosis)


A cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. Each chromosome consists of one very long DNA molecule and associated proteins


Our DNA and proteins when the cell is NOT dividing; a mass of very long, thin fibers that are not visible with a light microscope

Somatic Cells

Any cell in a multicellular organism except a sperm or egg or their precursors; diploid (2n)


A haploid (n) reproductive cell, such as an egg or sperm.

Sister Chromatids

Two copies of a duplicated chromosome attached to each other; While joined, two sister chromatids make up one chromosome. Chromatids are eventually separated during mitosis or meiosis II


In a duplicated chromosome, the region on each sister chromatid where they are most closely attached to each other


The period in the cell cycle when the cell is not dividing. During interphase, cellular metabolic activity is high, chromosomes (DNA!!) and organelles are duplicated, and cell size may increase. Interphase often accounts for the majority of a cell's life

binary fission

A method of asexual reproduction by "division in half." In prokaryotes (BACTERIA), binary fission does not involve mitosis

sexual reproduction

A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the two parents; genetically different

diploid cell

A cell containing two sets of chromosomes (2n), one set inherited from each parent; somatic cells/body cells

haploid cell

A cell containing only one set of chromosomes (n); gametes/sex cells/sperm/egg


The double reduction of chromosome number in a diploid cell; producing four genetically DIFFERENT cells at the end of the second division; the daughter cells have HALF the number of chromosomes as the original cell; does NOT create offspring, just cells

What happens in Meiosis I?

In meiosis I homologous chromosomes pair up, and each pair separates, producing two haploid cells with their sister chromatids still joined.

What happens in Meiosis II?

These cells differ genetically from each other and from the cells of the parents; Unlike in meiosis I, neither cell duplicates its' chromosomes; each cell contains a single set of chromosomes with its sister chromatid attached; Meiosis II will separate th

What happens in Interphase?

During the interphase prior to meiosis, chromosomes replicate and the cell grows

What are the three roles of Mitosis?

Asexual Reproduction

What are the 3 Main Phases of the Cell Cycle?

Interphase (G1, S, G2 phases)

S Phase of interphase

The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated; At the beginning of the phase, each chromosome is single. At the end, after DNA replication, each chromosome consists of two sister chromatids.

G2 phase of interphase

The second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs; This is the third subphase of interphase is a period of metabolic activity and growth. During this phase the cell makes final preparati

G1 phase of interphase

The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins; During this time the cell grows by producing proteins and organelles

Of what two processes does cell division consist of?

Mitosis and Cytokinesis
Cell division consists of two processes: mitosis and cytokinesis. Mitosis� division of the nucleus and its chromosomes� is divided into four phases: prophase, metaphase, anaphase, and telophase. Mitosis is followed by cytokinesis,

Prophase II

Chromatin condenses, each chromosome now has two chromatids attached by centromere; The nuclear envelope breaks down again allowing the chromosomes access to the cytoplasm; Remember: Crossing over only happens in prophase I (this is what increases genetic

Metaphase II

This phase occurs when the chromosomes line up similar to the metaphase stage of mitosis (middle of cell); Spindle fibers attach to the centromere in preparation for pulling the chromatids apart

Anaphase II

Spindle fibers again attach to centromere; sister chromatids separate (the centromere splits) and move towards opposite ends of the cell; They are now individual chromatids instead of chromosomes; Each end of the cell has 23 chromosomes (they are referred

Telophase II

Chromosomes unravel and become chromatin; Nuclear envelope reappears; The final stage of meiosis
results in four daughter cells (4 sperm or 4 egg cells); Each cell contains � the amount of DNA from the original cell (haploid, or n)


A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division. A centrosome has two centrioles.


a diploid cell resulting from the fusion of two haploid gametes; a fertilized egg


An organism in the earliest stage of development

Prophase I

The chromosomes condense, and the nuclear envelope breaks down, crossing-over occurs

Metaphase I

Pairs of homologous chromosomes move to the equator (middle) of the cell.

Anaphase I

Spindle fibers move homologous chromosomes to opposite sides

Telophase I/Cytokinesis

Cytoplasm divides (telophase), 2 daughter cells are formed (cytokinesis); nuclear membrane forms around each cluster of chromosomes

Crossing Over

the exchange of genetic material between homologous chromosomes during meiosis (Prophase I only!)


A pair of chromosomes form tetrads made up of four chromatids; seen during meiosis I

Fraternal Twins

Twins who come from two different eggs fertilized by two different sperm

Identical twins

twins who come from one fertilized egg; twins having the same heredity

Stem cells

unspecialized cell that can give rise to one or more types of specialized cells; also known as undifferentiated cells


disorder in which some of the body's cells lose the ability to control growth; uncontrolled cell growth


mass of rapidly dividing cells that can damage surrounding tissue


the process by which cancer spreads from one place to another


Causing no harm


harmful; could result in death

Cell differentiation

the process by which a cell becomes specialized for a specific structure or function.

Cell specialization

separate roles for each type of cell in multicellular organisms

Eukaryotic Cell

cell with a nucleus (surrounded by its own membrane) and other internal organelles; large more complex; include all protists, fungi, plants and animals

Prokaryotic Cell

cell that does not have a nucleus or other membrane-bound organelles; small; includes bacteria


A form of asexual reproduction in which a new organism grows out of the body of a parent.

Asexual reproduction

Form of reproduction requiring one cell/organism; creates identical clones; identified with mitosis


A new organism produced by a living thing

Daughter cell

The product of cell division.

Mother cell

A cell before cell division starts; this is the cell that creates the daughter cells


A complex molecule containing the genetic information that makes up the chromosomes.