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

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 http://www.flickr.com/photos/ricardipus/3614677971/

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…

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) http://learn.genetics.utah.edu/content/begin/cells/organelles/

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

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

Cell Membrane Structure Structure is referred to as a “fluid mosaic model” because proteins can travel within the membrane http://www.nature.com/scitable/topicpage/protein-function-14123348 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)

http://www.nature.com/scitable/topicpage/protein-function-14123348 http://learn.genetics.utah.edu/content/begin/cells/membranes/

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…..

Sodium-Potassium Pump

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