Cell Division and Asexual Reproduction

Asexual reproduction

1 parent produces offspring, which are genetically identical to the parent

3 Example of Fission

1. Bacteria: A single-celled organism that has no nucleus or cell walls and reproduce by splitting in two. 2. Paramecium is a single-celled organism that reproduces by splitting in two. 3. Protists have a nucleus and are therefore eukaryotic. Some protists contain chloroplasts and make their own food, and others don't. But all reproduce by splitting in two by fission.

Anaphase (apart stage) 2 steps

1. Centromere of each chromosome splits, pulling chromatids apart. Each chromatid is now called a chromosome. 2. Spindle fibers pull the chromosomes to opposite sides of the cell and the cell stretches out. (short form: chromatids pulled apart; chromosomes move to ends of cell)

Prophase (preparing stage) 4 steps

1. Chromatin in the nucleolus condenses into pairs of sister chromatids known as chromosomes. 2. The pairs of centrioles move to opposite ends of the cell. 3. Spindle fibers form between centrioles, making a bridge across the cell. 4. The nuclear membrane begins to break down. (Short form: prepares; centrioles form, nuclear membrane disappears)

Metaphase (middle stage) 2 steps

1. Chromosomes line up across the middle of the cell. 2. Spindle fibers attach to the chromosomes at its centromere. (Short form: chromatids in middle, spindle fiber attached to centromere)

Telophase (two cells stage) 3 steps

1. Chromosomes stretch out and become chromatin again. 2. The spindle fibers break down. 3. The nucleus and nuclear membrane appear. (short form: two cells forming; nuclear membrane reappearing)

3 Main Stages of the Cell Cycle

1. Interphase 2. Mitosis 3. Cytokinesis

3 examples of Vegetative Propagation

1. Spider plants reproduce new plants by the division of cells from roots or runners. These can be placed in water or soil to produce another plant. Spider plants also reproduce sexually. 2. Strawberries reproduce new plants by the division of cells from runners or roots. Strawberries also reproduce sexually. 3. Division of the roots reproduces new mint. Mint also reproduces sexually.

3 Example of Parthenogenesis

1. Whiptail Lizards: A female whiptail lizard may produce eggs that develop into genetically identical versions of itself. In some species, there are entire clonal populations of this lizard. Most whiptail lizard species do reproduce sexually, though. 2. Turkeys show a strong tendency towards parthenogenesis. They can produce eggs without fertilization. Turkeys can also reproduce sexually. 3. Eggs are produced in the mothers without fertilization then a nymph is born that is identical to the mother except for size. Most colonies of aphids are all females, but a few do have males and can reproduce sexually.

Name 5 types of Asexual reproduction

1.Fission 2.Fragmentation 3.Parthenogenesis 4.Vegetative Propagation 5.Budding

Preparing for Division stage of Interphase

After DNA is replicated, animal cells produce a pair of centrioles that will help it divide. At the end of interphase, the cell is ready to divide.

Budding

Cell division produces a bud. As the bud grows, it forms an identical copy of its parent, then separates from the parent and becomes independent. An example is yeast. These organisms may also reproduce sexually. The "choice" between sexual and asexual reproduction is often determined by environmental conditions.

Growing stage of Interphase

Cell grows to full size and produces all the organelles it needs.

replication

Cell makes an exact copy of the DNA found in its nucleolus

Copy DNA stage of Interphase

Cell makes an exact copy of the DNA found in its nucleolus. After replication, the cell contains two identical sets of chromosomes.

chromosomes

DNA and proteins form threadlike structures in the nucleus.

Daughter cells

During the cell cycle, a cell grows, prepares for division, and divides into two new cells

Vegetative Propagation

New plants can be produced from sections of parent plants that are cut off. Cambium cells from stems, roots and leaves of a parent plant can take root and sprout. New plants reproduced in this way are genetically identical to the parent plant. We see this in spider plants and willow trees, for example. Note that these plants also reproduce sexually by making seeds.

Fission

Single celled organisms, such as paramecium and bacteria, reproduce by splitting in two. This is often the only mode of reproduction for these organisms.

Fragmentation

Some animals can grow from a separate piece of a parent animal. This happens in only the simplest animals, such as some flatworms. These animals may also reproduce sexually.

Parthenogenesis

Some animals may produce eggs that develop directly into offspring without fertilization. Common examples occur in insects, reptiles and fishes. Often, these organisms may also reproduce sexually. The "choice" between sexual and asexual reproduction is typically determined by environmental conditions.

Example of Fragmentation

Some flatworms can grow by cell division from a fragmented section of its body.

cell cycle

The regular sequence of growth and division that cells undergo

Cytokinesis

This phase begins during mitosis. As cytokinesis continues, the cell splits into two daughter cells that each end up with an identical set of chromosomes and about half the organelles of the parent cell. (short form: Daughter cells formed; each re-enters interphase)

Mitosis

This stage is when the cell's nucleus divides into two new nuclei and one set of DNA is distributed into each daughter cell

Stages of Interphase

a. Grows b. Replicates DNA c. Prepares for division

Stages of Mitosis (PMAT)

a. Prophase b. Metaphase c. Anaphase d. Telophase

Budding

cell cycle produces a bud that grows from parent then detaches and becomes independent

chromosome

contains a pair of sister chromatids and a centromere.

Parthenogenesis

egg develops into offspring without fertilization

Vegetative Propagation

offspring develops from part of parent plant

Fragmentation

offspring is produced from a piece of the parent organism in simple animals

Fission

one cell splits into 2 offspring

chromatid

one half of a chromosome.

chromatin

part of a chromatid