Cell Reproduction

How do cells make new cells?

Cell Reproduction

• Reproduce: process by which living things give rise to other living things– Two Types of Cell Reproduction

• Asexual: one parent offspring is identical• Sexual: two parents offspring is not identical

Types of Asexual Reproduction

• 1-Binary Fission– Primary way that bacteria (unicellular) cells

reproduce

Binary Fission Clip

• http://www.classzone.com/cz/books/bio_07/resources/htmls/animated_biology/unit2/bio_ch05_0149_ab_fission.html

2-Budding

• Usually seen in yeast cells

• Cell replicates when a piece of the cell pinches off and separates from the parent cell

3-Spore

• Found in fungi, algae, protozoa

• Airborne cells that are released from the parent. They are enclosed and developed when the environment is appropriate

4-Regeneration

• Ability to re-grow lost parts

• Found in starfish, earthworms, some reptiles

5-Vegetative Propagation

• Regeneration in plants from an area that is remaining

6-Mitosis

• The process where animal cells divide

• This is a type of asexual reproduction

• Body cells (somatic cells) go through the process of mitosis

Sexual Reproduction in cells

• Meiosis – Process where sex cells are made in the

gonads• Gonads organs where sex cells are made

– Male testes make and house sperm– Females ovaries make and house eggs

We will discuss meiosis later!!!!

What structures are mainly in charge of cell replication?

• Chromosomes are composed of DNA and in charge of replication• Only visible during cell division as X shaped structures. • Humans have 46 chromosomes (23 pairs). • Each X shaped chromosome consists of 2 “sister” chromatids

produced during replication Called DIPLOID 2N• The “sister” chromatids are attached at an area called the

centromere

Cell Cycle

• Why is the cell cycle called a cycle?

• Why do you think it’s important for a cell to grow in size during its cell cycle?

Cell Cycle- The Cell’s Timeclock

Cell Cycle- is the series of events that takes place in a cell leading to its division and

duplication

• http://www.cellsalive.com/mitosis.htm

Interphase: not part of mitosis

• Interphase-(technically not part of mitosis, but it is included in the cell cycle)

• Cell is in a preparing for mitosis, performing cell functions

• DNA replicates (copies)• Organelles double in number, to prepare for

division– G1 - First growth– S - synthesis (copy DNA)– G2 - Second growth

Process of Mitosis

• http://www.neok12.com/php/watch.php?v=zX5c687103030a0864645802&t=Cell-Division

• http://www.johnkyrk.com/mitosis.html

Prophase

• Spindle forms

• Centrioles move to opposite poles

• Chromosomes become visible

• Nuclear membrane breaks down in prometaphase

Metaphase

• Chromosomes line up along the equator

Anaphase

• Centromeres divide

• Chromatids separate and move to opposite poles

Telophase

• Nuclear membrane forms around each group of chromosomes

• Chromosomes unwind, nuclear membrane forms again

Cytokinesis begins

• Cell pinches inward and forms two daughter cells

Visit this website

http://www.neok12.com/php/watch.php?v=zX645478027c03150f647502&t=Cell-Division

http://www.johnkyrk.com/mitosis.html

It will show you an animation of mitosis

Results of Mitosis

• Same number of chromosomes from generation to generation (46 in humans)

• Each daughter cell (offspring) gets exact copy of chromosomes

Consequences of Incorrect Mitosis

• Cancer: uncontrolled mitotic division in cells– Timeclock (cell cycle) does not work properly

http://www.hhmi.org/biointeractive/cancer/angiogenesis.html

Plant Mitosis

• Same process as in animal cell but plants don’t have the centrioles and a cell plate forms

Uses for Mitosis

• Replicate young embryonic cells

• Replicate body (somatic) cells. Skin, blood cells

• Repair damaged cells

• Controls cell growth and death. – Cytokinins: chemicals that regulate cell

replicating