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 1953.

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 3rd phase of Mitosis The chromosomes split and are pulled to

opposite sides of the cell.

3.2 Telophase

Telophase is the 4th 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