Cell Reproduction Why do cells divide Reproduction Growth

Why do cells divide? Reproduction Growth Repair Volume too large for surface area (restricts

Types of Reproduction • Asexual reproduction is production of offspring from 1 parent. The

Methods of Asexual Reproduction 1. binary fission – DNA replicates and cell divides ex:

2. spore formation – single cell reproductive structures produced by organisms such as fungi

3. budding - • cell nucleus and cytoplasm divide unequally, the smaller “bud” pinches

4. vegetative propagation • “runners” - plants send out horizontal stems that take root

In preparation for cell division, DNA clumps together and shortens to form chromosomes DNA

chromatin centromere Chromosome Each ½ = chromatid

• Each kind of eukaryotic organism has a specific # of chromosomes in

THE CELL CYCLE • The events that occur during the cell cycle are a

1. Interphase • Cell grows • Produces new organelles • Copies DNA

• Mitosis is the division of the nucleus or genetic material of a

• Mitosis is followed by the division of the cytoplasm, cytokinesis

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Cell Reproduction

Why do cells divide? Reproduction Growth Repair Volume too large for surface area (restricts diffusion) How does the cell know how to divide? The DNA has the instructions for all of the cell’s activities.

Types of Reproduction • Asexual reproduction is production of offspring from 1 parent. The genetic material is identical to the parent (DNA replication). • Sexual reproduction is the formation of a new individual from the union of 2 sex cells (gametes). gametes The offspring will have the traits of both parents.

Methods of Asexual Reproduction 1. binary fission – DNA replicates and cell divides ex: prokaryotes

2. spore formation – single cell reproductive structures produced by organisms such as fungi

3. budding - • cell nucleus and cytoplasm divide unequally, the smaller “bud” pinches off ex: yeast, hydra

4. vegetative propagation • “runners” - plants send out horizontal stems that take root when they touch the ground • ex: strawberries

In preparation for cell division, DNA clumps together and shortens to form chromosomes DNA + protein → chromatin → chromosome

chromatin centromere Chromosome Each ½ = chromatid

• Each kind of eukaryotic organism has a specific # of chromosomes in its body cells (somatic cells). ex: humans 46, corn 20 • When a cell reproduces, each daughter cell will need a full set of chromosomes. These #’s are pairs of chromosomes. ex: Humans get one of each pair (23) from mother and one of each pair from father.

THE CELL CYCLE

THE CELL CYCLE • The events that occur during the cell cycle are a continuous process. • The cell cycle can be broken down into two major steps: (1) interphase and (2) mitosis

1. Interphase • Cell grows • Produces new organelles • Copies DNA

• Mitosis is the division of the nucleus or genetic material of a cell. • Mitosis can be broken down into four phases: § Prophase § Metaphase § Anaphase § Telophase 2. Mitosis

• Mitosis is followed by the division of the cytoplasm, cytokinesis