Cell Division, Chromosomes, and Cell Differentiation

Main Reasons Why Cell Divides

• Larger cell demands more place for the DNA.
• Larger cells result in less moving nutrients and waste materials across the cell membrane.

Information Overload

Cell grows, information is used to build the molecules needed for cell growth. DNA doesn't increase.

Exchanging Materials

Food, oxygen, water enter by the cell membrane, waste products also go out like that.

Division of the Cell

Forms 2 daughter cells. Cell division: process in which a cell divides into 2 daughter cells.

Asexual Reproduction

1 parent, cell divides by fission, little chances of genetic variation, found in bacteria, 2 offspring.

Sexual Reproduction

2 parents, cell divides by meiosis, genetic variation, found in mammals, 1 offspring.

Both

Forms of reproduction, involve living things, produce offspring.

Chromosomes: Packages of DNA

Prokaryotic Chromosomes

Lack of nuclei, DNA is found in cytoplasm.

Eukaryotic Chromosomes

More DNA, multiple chromosomes. Chromatin: complex of a chromosome and protein.

Cell Cycle

During the cell cycle, cell grows, prepares for division, divides into 2 daughter cells.

Eukaryotic Cell Cycle

1. G1: Cell growth
2. S: DNA replication
3. G2: Preparing for cell division
4. M: Cell division, process of mitosis

Mitosis: division of the cell nucleus. Cytokinesis: division of the cytoplasm.

Cytokinesis (Animals)

Cell membrane is drawn inward until the cytoplasm is pinched into 2 nearly equal parts. Each part contains its own nucleus.

Cytokinesis in Plants

Cell membrane is not flexible enough, cell plate forms halfway between the divided nuclei. A cell wall then forms in between the 2 new membranes and completes the process.

Regulate Cell

Cyclin

Protein that regulates, produced in all the non-dividing cells, stop virus.

Regulatory Proteins

Internal, regulates all that happen inside the cell. External: in charge of everything that happens inside the cell, skin, hair, bones, speed up or slow down the cell cycle. Growth factor: stimulate the growth and division of cells.

Apoptosis

Suicide mechanism, programmed to die, breaking down, clean.

Cancer

Disorder in which body cells lose the ability to control growth. Cancer cells do not respond to the signals that regulate the growth of most cells, resulting in the cells dividing uncontrollably. Tumor: cancer cells form a mass of cells. Benign tumor: does not spread. Malignant tumor: invade and destroy surrounding healthy tissues. Cancer cells spread, absorb the nutrients needed by other cells, block nerve connections, and prevent the organs they invade from functioning properly. Cancer is a cause of defects in the genes that regulate cell growth and division. Treatments: surgery, radiation (chemotherapy) specialize.

Cell Differentiation

Embryo: development stage, from which adult organisms are gradually produced. During the development process, an organism's cells become more differentiated and specialized for particular functions.

Differentiation

Process by which cells become specialized. During the development of an organism, cells differentiate into many types of cells.

Mapping Differentiation

Process that determines a cell's ultimate identity, such as whether it will spend its life as a nerve or a muscle.

Differentiation in Mammals

Cell differentiation is controlled by a number of interacting factors in the embryo, many of which are still not well understood. Adult cells generally do reach a point at which their differentiation is complete when they can become other types of cells.

Totipotent

Cell types that can develop into any type of cell in the body.

Blastocyst

Ball of cells with a cluster of cells inside known as the inner cell mass.

Pluripotent (Inner Cell)

Cell can develop into any of the body's cell types, although they generally cannot form the tissue surrounding the embryo. Stem cells: unspecialized cells from which differentiated cells develop. Adult stem cells: they are multipotent, brain, muscles, heart. Embryonic stem cells: they are more versatile, capable of producing every cell type in the body.