Biology Notes:

1. Cell Theory:
-all living things are made up of cells
-the cell is the basic structural and functional unit of life
-all cells arise from pre-existing cells

2. Classification of Cell:
Prokaryotic Cells
-small
-simple structure, no membrane-bound organelles
-single-cells organisms
-tangled/coiled DNA, no nucleus
-can often survive without oxygen

Eukaryotic Cells
-larger
-complex structure, with membrane-bound organelles
-unicellular or multicellular organisms
-DNA contained in nucleus
-require oxygen

3. Organelles
Mitochondria: breaks down sugar molecules into energy
Nucleus: controls cell activity
Chloroplasts: uses sun’s energy to make food through photosynthesis (plant only)
Vacuole: stores food, water, waste
Cell membrane: supports, protects, controls movement of materials in/out of cell
Cytoplasm: supports/protects cell organelles
Endoplasmic reticulum: carries materials throughout cell
Cell wall: supports and protects cell contents (plant only)

4. Cell Cycle
The two parts of the Cell Cycle are Interphase (cells repair any damages, reenergize, grows and prepares for division) and Mitosis/Cytokinesis (division of the cell into 2 identical “daughter” cells).

Cells divide for three reasons: growth, repair, and reproduction.

Interphase: longest stage, divided into three phases: first gap phase (G1) cells grow in size, new proteins and organelles are made
Synthesis phase (2) DNA is replicated (known as chromatin)
Second Gap Phase (G2) cells prepare for division

Mitosis:
Prophase: chromatin condenses to form chromosomes, centrioles move to each pole, nucleolus disappears, and nuclear membrane breaks down
Metaphase: spindle fibers attach to centromere, chromosomes line up at metaphase plate
Anaphase: spindle fibers shorten, sister chromatids separate and move to opposite poles
Telephase and Cytokinesis: cell membrane pinches inwards, cytoplasm splits in half, cells return to interphase

Cancer:
-genetic mutation of cells that cause them to undergo abnormal cell division
-instead of apoptosis (cell suicide) these cells divide uncontrollably
-cell division occurs so fast that these cells pile up on top of one another forming a tumor
-reduces the effectiveness of the surrounding tissue
-may invade and destroy neighboring cells
-may stimulate other cells to start replicating uncontrollably, spreading cancer

5. Cell Specialization:
?

6. Integumentary System:

7. Skeletal System: (study skeleton)

Axial system: essential bones, “central”
Appendicular: less essential, “exterior”

Main purposes of the skeletal system: support and shape, protection, movement, blood production

Fractures:
A fracture is a broken bone
Types of fractures:
Simple- broken, but not outside body
Compound- bone protrudes from body
Greenstick- a slight bend in young bones before they harden

Can be solved using pins, at fracture location, bones will produce lots of new bone cells and tiny blood vessels to rebuild bone
New cells cover both ends of the fracture, visible fracture line.

Osteoporosis: the older you get, the dense your bones are (less dense bones break easily)
Other factor: activities, diet, don’t smoke
Stem cells: stem cells are primitive or unspecialized; they can develop into nearly any type of body cell
-embryos have cells, embryonic stem cells can be used as a source of embryos (controversial)
-medical possibilities: stem cells can be extracted, turned into new bone cells and then injected into