Cell Growth and Reproduction Interphase and Mitosis

Reasons for Cell Division Cell Size is Limited Diffusion is inefficient if cell is too large. Growth of Organism Repair Cuts, Scrapes, Broken Bones

2 types of cell division Mitosis-produces body, or somatic cells. Meiosis-produces sex cells, or gametes

Chromosome Structure Each chromosome consists of 2 identical parts called chromatids joined together at a centromere.

Section 1 Chromosomes Chromosome Structure

Chromosome Numbers of Various Organisms

III. Two Types of Chromosome Autosome – does not determine the gender of an organism. Sex chromosome – determines the gender of an organism. Male (XY) Female (XX)

Chromosomes (Continued) In sexually reproducing organisms chromosomes occur in pairs. Homologous chromosomes- Members of a pair have the same size and shape and carry the same genetic information Diploid-Cells that contain both members of a pair (2n)=46 Somatic Cells– Body Cells (Skin Cells) Haploid-cells that have only one member of a pair (n)=23 Gamete – Sex Cells (Sperm & Egg Cells)

Cell Division Produces two “daughter” cells that are identical to the original parent cell. Parent Cell 23 Pair = 46 Chromosomes Daughter Cell 23 Pair = 46 Chromosomes Daughter Cell 23 Pair = 46 Chromosomes

The Cell Cycle – sequence of growth and division of a cell Interphase G1 S G2 Mitosis Prophase Metaphase Anaphase Telophase cytokinesis REMEMBER!!!! (IPMAT)

Interphase Longest period of the cell cycle G1-chromosomes not visible; protein synthesis; growth S-chromosomes (double) – form sister chromatids G2-chromosomes condense; protein synthesis; centrioles replicate; growth

Mitosis-nuclear division Prophase-longest stage of mitosis The chromatin condenses to form chromosomes. The nuclear envelope breaks down Centrioles migrate of opposite ends of the cell Spindles form between centrioles

Metaphase Spindles attach to centromeres Chromosomes line up on the middle or equator of the cell

Anaphase The spindles pull the sister chromatids of a chromosome to opposite ends of the cell.

Telophase Chromosomes unwind Spindles break down Nucleolus reforms Nucleus forms around each set of chromosomes

Cytokinesis Stage in which cytoplasm divides Membrane forms between the two new nuclei In animal cells, membrane pinches in along the equator until the two new cells are separated. Plant cells have a rigid cell wall that prevent pinching; cell plate forms along the equator and a cell wall forms along each side of the cell plate until the two new cells are separated.

Mitosis guarantees genetic continuity. New cells are identical to original cell. Cells perform specific functions Examples- blood cells, nerve cells, bone cells, etc Tissues- group of cells that work together to perform the same function Examples - blood, nervous, bone, etc. Organs-Made up of tissues that work together to perform a specific activity Examples - heart, brain, skin, etc. Organ systems -multiple organs work together to perform a specific function for the organism. Examples - circulatory system, nervous system, skeletal system, etc. Entire living things that can carry out all basic life processes. Examples - bacteria, amoeba, mushroom, sunflower, human

Control of the cell cycle Enzymes monitor cell progress during the cell cycle Cancer-uncontrolled cell division Tumor-mass of cancerous cells Metastasis-cancer cells spread Leading cause of deaths related to cancer Causes of cancer Problems with the genes Cigarette smoke Air and water pollution UV radiation Viral infections

Pictures and examples are taken from various websites.