Cell Division

3.1 Cell Division Cell division occurs in all organisms, but does different things or functions. Unicellular organisms reproduce through cell division. Multicellular organisms use cell division to grow, develop, repair themselves, and reproduce.

Genetic Material The genetic material of a cell contains information needed for the cell’s growth and other activities. When a cell divides into two new cells, each cell receives a full set of genetic material. The genetic material is contained in DNA molecules.

DNA DNA stands for deoxyribonucleic acid DNA is a molecule that contains information for an organism’s growth and functions. James Watson and Francis Crick discovered the shape of DNA and made a model of it in They showed that DNA Twists like a ladder or a Double helix

DNA and Chromosomes DNA is stored in the nucleus of a cell DNA is wrapped around proteins to be made smaller or more compact in structures called chromosomes. DNA is replicated or copied so each new cell gets a copy.

Chromosomes Chromosomes consists of 2 chromatids held together by a centromere. Humans have 46 chromosomes, 23 from mom and 23 from dad

Cell Division Cell Division is involved in growth, development and repair. Through cell division a single cell becomes 2, and then they divide into 4 cells and so on. Even when a person, animal or plant stops growing cell division still occurs because old cells need replaced with new ones. Cells don’t live forever Throat cells only last a few days

Cell Growth A large organism (animal or plant) does not have bigger cells then a smaller organism, it simply has more cells. Cells grow in size but there is a limit to how big they can grow. If cells get to big they can’t function properly (do their jobs correctly)

Cell Development A multicellular organism starts as a single cell and grows into a larger one through cell division. But as an organism develops each cell specializes and takes on a specific job. Blood cells, muscle cells etc. All cells have the same DNA and parts but they perform a specific job.

Cell Repair If you have ever had a cut or broken bone, your body has repaired itself through cell division. As cells age and die, they need to be replaced. Some cells last a long time and others wear out quickly Skin cells- age very quickly Brain cells- live very long and don’t get replaced often

3.1 Question: ____is a molecule that contains the information for a cell to grow and develop and is stored in a nucleus. A. Chromosomes B. RNA C. DNA D. Ribosomes E. Water

3.1 Question: DNA is wrapped around proteins to be made into_____. A. Nucleotides B. RNA C. DNA D. Ribosomes E. Chromosomes

3.1 Question: Cell Division helps multicellular animals to ______. A. get smarter B. grow, develop, and get smarter C. grow, develop, and repair D. turn purple E. reproduce

3.2 Cell Cycle Living things grow, reproduce, and die in a process called a life cycle. Cells have life cycles too, called the cell cycle. The cell cycle is the normal sequence of development and division of a cell. Cell cycle has 2 phases Interphase and Mitosis (Cell Division)

3.2 Cell Cycle Interphase is the part of the cell cycle during which a cell carries out its normal functions and it is NOT dividing. Mitosis is the part of the cell cycle during which the nucleus divides. Only eukaryotic cells go through mitosis. The purpose of mitosis is to move DNA and other material in position for cell division. Cytokinesis- division of the cytoplasm and all organelles

Interphase: normal activities

Mitosis- Division of the Nucleus

Cytokinesis- Division of cytoplasm and other organelles

3.2 Cell Division Cell division produces two genetically identical cells- they have the same DNA If a skin cell divides you then have 2 identical skin cells Mitosis has 4 phases- Prophase, Metaphase, Anaphase, and Telophase

3.2 Prophase The first phase of mitosis DNA condenses (becomes smaller) into chromosomes The chromosomes become visible The membrane around the nucleus breaks down

First

3.2 Metaphase Second phase of mitosis Chromosomes line up in the middle of the cell

3.2 Anaphase Anaphase is the 3 rd phase of Mitosis The chromosomes split and are pulled to opposite sides of the cell.

3.2 Telophase Telophase is the 4 th phase in mitosis A new membrane forms around the chromosomes to form a nucleus Chromosomes return to their threadlike form

Recap Interphase- The cell is doing its daily functions or jobs Mitosis- Nucleus is preparing for Division and there are 4 phases- prophase, metaphase, anaphase, and telophase Cytokinesis- The cytoplasm divides resulting in 2 identical cells.

3.2 Question: ____is the part of the cell cycle during which the cell is not dividing and just carrying out its normal functions. A. Prophase B. Mitosis C. Cytokinesis D. Anaphase E. Interphase

3.2 Question: ____is the division of the cytoplasm at the end of mitosis. A. Prophase B. Mitosis C. Cytokinesis D. Interphase E. Anaphase

3.2 Question: ____ is the phase of mitosis where the chromosomes first appear. A. Metaphase B. Prophase C. Telophase D. Anaphase E. Interphase

3.2 Question: is the part of mitosis where a new nuclear membrane forms and chromosomes turn threadlike. A. Metaphase B. Prophase C. Telophase D. Anaphase E. Interphase

3.2 Question: This is the phase of mitosis where the chromosomes line up in the middle. A. Metaphase B. Prophase C. Telophase D. Anaphase E. Interphase

3.2 Question: This is the phase in mitosis where the chromosomes separate and get pulled to opposite sides of the cell. A. Metaphase B. Prophase C. Telophase D. Interphase E. Anaphase

3.3 Cell Division for Unicellular Organisms For unicellular organisms cell division produces 2 new organisms. This form of reproduction is called asexual reproduction. Asexual reproduction is where a parent organism produces offspring that are genetically identical to the parent. Asexual reproduction involves one parent

3.3 Types of Asexual Reproduction Binary Fission is a type of asexual reproduction and occurs when the parent replicates it’s DNA and then splits in two. Budding- is a process where an organism develops tiny outgrowths called buds which break off to form a new organism. Regeneration- is a process in which missing body parts are replaced. (Starfish, some plants)

Binary Fission

Budding

Sexual Reproduction vs. Asexual Repro. Two parents involved Offspring’s genes are combined from two parents Reproduce more slowly Advantages: increased genetic variation Disadvantages: slower, more energy required, must find a mate One parent organism Offspring’s genes are identical to parents Reproduces quickly Advantages: fast and easy Disadvantage: not much genetic variation

3.3 Question: _____is where a parent organism produces offspring that are genetically identical to them. A. Binary Fission B. Sexual Reproduction C. Asexual Reproduction D. Regeneration E. Splitting in half

3.3 Question: _____occurs when the parent organism replicates its DNA and then splits in two. A. Binary Fission B. Sexual Reproduction C. Asexual Reproduction D. Regeneration E. Mitosis

3.3 Question: ____is the process in which body parts can be replaced. A. Binary Fission B. Sexual Reproduction C. Asexual Reproduction D. Mitosis E. Regeneration

3.3 Question: ____takes longer but results in genetically different offspring. A. Binary Fission B. Sexual Reproduction C. Asexual Reproduction D. Regeneration E. Mitosis