1. Honors Biology 1 Additional Information B_2,3 Cell Structure, Function, & Division
B-2: Demonstrate an understanding of the structure and function of cells and their organelles;
Chapter 7 & 10
B-1.2, B-2.1-7

2. History of Cell Theory (see timeline on pg170)
Robert Hooke (1665)
looked at cork (outer bark of tree)
coined term “cell”; first to identify cell
Anton van Leeuwenhoek (1674)
Made a better microscope (more detail)
first to see living things in water
Matthias Schleiden (1838)
Noted all plants made of cells
Theodor Schwann (1839)
Noted all living things made of cells
Rudolph Virchow(1855)
Proposes that all cells come from existing cells completing the cell theory

3. ENDOSYMBIOTIC THEORY Lynn Margulis:
Hypothesized that the FIRST Eukaryotic cells evolved from prokaryotic cells…
By SYMBIOSIS… when two organisms depend on each other for survival.
The Endosymbiotic Theory (Examples…)
MITOCHONDRIA (cell developed into organelle)
Originally a prokaryotic cell that used aerobic respiration to provide energy for the host cell...
Host cell provided shelter
CHLOROPLASTS (cell developed into organelle)
Originally a prokaryotic cell that used photosynthesis to make food for host cell…

4. EVIDENCE for Endosymbiotic Theory
ORGANELLES - Mitochondria & Chloroplast
Similar size and structure of Bacteria
Have Ribosomes…
MEMBRANE - Double membrane similar to Bacteria
DNA - Contain own DNA, circular in structure like bacteria
Makes own proteins
REPRODUCTION - Replicate/divides on own through process of binary fission (like bacteria)

6. Peroxisomes
FUNCTION: protect the cell from its own production of toxic hydrogen peroxide. EX: white blood cells produce hydrogen peroxide to kill bacteria – the oxidative enzymes (like catalase) break down the hydrogen peroxide into water and oxygen

7. Centrioles (Animals Only)
Function: Helps w/ cellular division (mitosis) in animal cells
Plants have a similar more simple structure
Structure:
Paired cylindrical organelles near nucleus
Lie at right angles to each other

8. Cell Membrane Structure
Structure is referred to as a “fluid mosaic model” because proteins can travel within the membrane
Phospholipid bilayer —double layered sheet
hydrophilic (loves water) TAILS
hydrophobic (fears water) HEAD
provides flexible but tough covering
Protein molecules —act as channels and pumps to move large molecules thru membrane
Transporting (pumps and channels)
Receptors (translate chemical signals)
Enzymes
Anchoring cell
Carbohydrates —act as id card (are attached to lipid or protein)

10. Homeostasis
Water movement in plant and animal cells is similar but in plants the osmotic pressure that develops is called turgor pressure (caused by cell wall).
Hypotonic solutions cause cells to swell and push membrane against wall (turgid)
Hypertonic solutions cause cells to shrink/cell membrane pulls away from cell wall (plasmolysis)
If cells are placed in pure water (hypotonic) they could swell and burst - This doesn’t happen because:
Some cells have isotonic fluid around them so they are NOT in pure water. Ex: blood plasma isotonic
Plant cells and bacteria have cell walls, which are rigid and prevent bursting
Some cells can pump out water as it comes in
ACTIVE TRANSPORT…..

11. Sodium-Potassium Pump

12. COMPARISION Binary Fission Mitosis
Cell division in eukaryotes (growth, repair, regeneration)
Nucleus must be broken down and reformed
DNA copied (replication) and then must be packaged into Chromosomes (usually more than 1 chromosome)
Organelles must shared equally between the cells
Cell division in prokaryotic cells (asexual reproduction in bacteria)
4 step process:
Cell grows to twice its starting size
DNA copied (replication)
DNA moves (segregation) to opposite sides of cell
New cell wall and membrane form