cell cycle notes

Word Parts– NEW

• Mito – thread-like• Inter - between• Meta - middle• Ana - away• Telo - end• Phase – change• Kinesis – to split• Gameto – sex cell• Soma - body

– OLD

• Cyto - cell• Pro – before• Di – two• Hap - half• Homo – same• A – not• Osis - process

Cell Cycle

IPMAT+C

Two Types of Reproduction

• Sexual Reproduction (meiosis): requires two parents of the opposite sex and gametes: sperm and egg

• Asexual Reproduction: when one parent produces one or more identical offspring

3 Examples of Asexual Reproduction

1. Clone: creation of a genetically identical organism from one that already exists

2. Budding: group of cells that can be pinched off from the parent to form a new individual

3. Regeneration: re-growth of a missing part

4. Binary Fission: one cell divides into 2 separate genetically identical cells.

The Cell Cycle

Includes all other phases the cell goes through as it grows and replicates (divides)

It can be divided many different ways

• IPMAT+C

• Interphase + Mitosis + Cytokinesis

• Interphase + M Phase

M-Phase

Events of the Cell Cycle

3 Phases of Interphase

1. G1 - when the cell grows

2. S - when DNA (Chromosomes)replicates

3. G2 - the cell prepares for Mitosis

Chromosomes

Genetic information is passed from one generation to the next on chromosomes

– Each chromosome consists of 2identical “sister” chromatids.

– Each pair of chromatids is attached at an area called the centromere.

The M Phase

Also known as Cell Division

Divided into Mitosis and Cytokinesis:

– Mitosis – (PMAT)

– Cytokinesis – when the cell splits into 2 identical cells

Mitosis

Mitosis - the asexual reproduction of a somatic (body) cell

Mitosis is divided into 4 phases:1. Prophase

2. Metaphase

3. Anaphase

4. Telophase

Interphase•The phase of the cell cycle in which the cell increases in size and duplicates chromosomes

Prophase

• The phase of mitosis in which the chromatin coils into visible chromosomes, centrioles separate, and spindle fibers appear

Spindle forming

CentromereChromosomes(paired chromatids)

MetaphaseCentriole

Spindle Fibers

The phase of mitosis in which the chromosomes line up at the equator of the spindle and chromatids are attached by the centromeres to a separate spindle fiber

AnaphaseSister Chromatids

The phase of mitosis when the centromeres split and the chromatid pairs of each chromosome are pulled apart by microtubules

Telophase

The last phase of mitosis, when the chromosomes migrate to opposite ends of the cell, two new nuclear envelopes form, and the chromosomes uncoil to prepare for their own independent existence

Cytokinesis

The last phase of the cell cycle when the cell’s cytoplasm divides and separates into 2 new cells

Cytokinesis of Plants

A structure called the cell plate forms midway between the divided nucleus

Cell wallCell plate

Cyclin

• The protein cyclin regulates and controls the cell cycle.

• When cyclin is defective the cell loses control of the cell cycle and the cells grow uncontrollably.

Contact Inhibition• When cells have contact with each

other they know to stop growing

• Normal Growth

CUT

CancerCancer is when cells have lost their ability

to control their growth rate/cell cycle

A mass of cancer cells are called a tumor

Cancer cells may break loose from tumors and spread throughout the body, disrupting normal activities and causing serious medical problems or even death.

- Draw

Meiosis

“The Making of Me”

Chromosome Number

All organisms have a different number of chromosomes

Humans have 46 total:• 23 from dad• 23 from mom

Fruit Flies have 8 total: • 4 from dad• 4 from mom

Fruit Fly’s Chromosomes

• Each chromosomes that comes from the male parent has a matching chromosome from the female parent and is called Homologous

• A cell that contains both sets of homologous chromosomes is said to be diploid (2N)

– For Humans, the diploid number is 46 (2N=46)

– For Fruit Flies, the diploid number is 8 (2N=8)

• The gametes (sperm and egg) have a single set of chromosomes

• These cells are called haploid & written as (N)

– For Humans, the haploid number is 23 (N=23)

– For Fruit Flies, the haploid number is 4 (N=4)

Meiosis has 2 Cycles: Meiosis I

Prophase I Metaphase I Anaphase I Telophase I and

Cytokinesis

Interphase I

Meiosis I

Meiosis II

Telophase II and

CytokinesisProphase II

Metaphase II Anaphase IITelophase I and Cytokinesis I

Meiosis II

Gamete Formation

In male animals, meiosis results in four equal-sized gametes called sperm.

In female animals, only 1 egg is formed. The other 3 cells, called polar bodies, are not involved in reproduction.

Comparing Mitosis and Meiosis

Mitosis:

• Results in the production of two genetically identical diploid cells

• Each daughter cell receives an EXACT copy of chromosomes

Meiosis:

• Produces four genetically different haploid cells

• Each daughter cell receives HALF the number of chromosomes

• How sexually reproducing organisms produce gametes (sperm & egg)

Questions:

1. How many chromosomes do you have?

2. If a cell with 8 chromosomes goes through mitosis, how many chromosomes will the daughter cells have?

3. If a cell with 24 chromosomes goes through meiosis, how many chromosomes will the daughter cells have?