====== Cellular Biology ======


Cells are the smallest living units of an organism.
https://www.youtube.com/watch?v=URUJD5NEXC8

All cells have
  * membrane, separates cell interior from the environment
  * cytoplasm, jelly-like fluid
  * DNA, the cell's genetic material

Eukaryotic cell
  * advanced, complex, contains organelles, including nucleus
  * examples: plants, animals, fungi

Prokaryotic cell
  * simple, no organelles, no nucleus
  * always unicellular
  * examples: bacteria

organelle = "little organ", specialized function

nucleus - an organelle, has a membrane, contains DNA

DNA - dictates what the cell will do, and how it's going to do it
 
chromatin - the tangled, spread out form of DNA

chromosomes - When a cell is ready to divide, the DNA condenses into structures known as chromosomes.

nucleolus - a structure inside the nucleus where ribosomes are made

ribosomes - have the job of synthesizing proteins.  Float around in the cytoplasm outside the nucleus.


endoplasmic reticulum (ER) -   

mitochondria

==== Bacteria ====

https://www.youtube.com/watch?v=b15Hy3jCPDs

among the oldest living organisms

bad ones cause cholera, TB, plague, and others 

unicellular prokaryotes 

smaller than plant and animal cells

found everywhere in the environment

different shapes and sizes

does not have a nucleus, but does have a nucleoid

nucleoid - bacteria's version of a nucleus.  DNA floats in the cytoplasm in an area known as the nucleoid

bacteria have two types of DNA: plasmid and chromosomal


cell wall - bacteria has a cell wall, like plants, unlike animals

flagellum - whip-like structure for locomotion

 






10 times more bacteria cells than human cells in the human body

  * 37.2 trillion human cells in the human body
  * 370.2 trillion bacteria cells in the human body (10x)




Ninja Nerd: Cell Cycle: Interphase & Mitosis
https://www.youtube.com/watch?v=LUDws4JrIiI&list=PLTF9h-T1TcJi_1FdKlH4dbf_3uI4wuT99

Human cells
  * membrane or "wall"
  * nucleus, containing DNA
  * cytoplasm
    * organnelles

mytosis - cycle through which cells replicate

amytotic cells do not replicate

Three types of cells:
  * Labile - replicating all the time:  skin, GI tract, urinary tract
  * Stable - liver
  * Permanent - do not replicate, nerves, skeletal muscles


===== Cell Structure =====

Khan Academy, Cell Theory, Cell Structure
https://www.youtube.com/watch?v=Hmwvj9X4GNY

  * cellular membrane
  * nucleus
    * membrane
    * nucleolus - densely packed bundle of proteins, ribosomal RNA is produced here
    * DNA
      * chomatin
      * proteins
  * cytosol
  * ribosomes - translate mRNA into proteins, made of ribosomal RNA
  * endoplasmic reticulum - tunnels lead from nucleus to Golgi bodies, ribosomes attached.  These ribosomes output proteins into the tunnel so they can exit the cell.
  * Golgi bodies
  * organelle - membrane-bound subunit of a cell
    * vesicles - clump of protein surrounded by membrane, floating around in the cell. It can float to the cell wall where the membrane can merge with the cellular membrane allowing the protein to exit the cell.
    * lysosomes (animal) - contain enzymes that dissolve other things.
    * lytic vacuole (plant) - same purpose as lysosome 
    * mitochrondria - cellular respiration, where sugars are turned into ATP.  Contain their own DNA and can reproduce on their own.  Speculation: at one time, mitochondria may have been independent prokaryotes and later decided to live within a cell.
    * chloroplasts (plant) - photosynthesis, likewise has their own DNA and ribosomes
  * cell wall (plant, non-animal) - celulose, adds strength to cellular membrane
  * actin filaments - add structure to cell, facilitate transportation within the cell
  * microtubules - ?
  * centrioles - microtubules


  * prokaryote
    * bacteria
    * archaea
  * eukaryote
    * plants
    * animals
    * fungi

DNA, transcribed into mRNA, translated by the ribosomes into proteins

===== Mitochondria =====

Khan Academy, Mitochondria
https://www.youtube.com/watch?v=i1dAnpSFbyI

mitochondrion, singular from of mitochondria 

a membrane-bound organelle, much like the Eukaryote

ATP factory, releases energy used in the body for movement, thinking, etc.

in ATP form, you have adenosine triphosphate.  Remove one of the phosphate groups, energy is released.

glucose 

lots of mitochondria in the muscles

At one time, mitochondria were independent organisms, like bacteria.  Now living in symbiosis inside a cell.

outer membrane
  * phospho lipids - outer membrane of the mitochondria
  * porins - proteins, holes in the outer membrane, so some cells can pass thru

inner membrane 
  * phospho lipid
  * folds to increase surface area, crista (singular), cristae (plural)

intermembrane space
  * electron transport chain
  * ATP synthase

glycolysis occurs in cytosus