ap chapter 3

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ap chapter 3

cell membranes

1. Fluid mosaic model (moves & changes)
a. Molecules arranged in a sheet
b. Molecules are able to float around slowly
c. Double layer of phospholipid molecules
i. Heads are hydrophilic (water-loving)
ii. Tails are hydrophobic (water-fearing)
2. Cholesterol molecules need for membrane stability
3. Membrane proteins
4. Functions:
Barrier, identification, communication
Note 1: carbs & proteins dissolve in water so they can't get thru the barriers.
Note 2: carbs are the markers
Note 3: if you didn't have heads then the cells would be on top of the water

Membrane cell-identity markers

1. Glycoproteins form the glycocalyx (sugar coating)
a. surface coating
b. acts to identity cell as part of body
2. Enables body to identify "self" from foreign invaders

Note: 8 markers on the cell

Membrane protein functions

1. Receptors = binding site, communication
2. enzymes = assist in chemical reactions. out or in cell
3. channel proteins (gates) = doorway controls open or close
4. cell-identity markers = glyco-markers
5. cell-adhesion molecules = function as a unit/sheet (ex. skin peeling)

cytoplasm

Gel-like substance that includes organelles
Cytosol - watery intracellular fluid (gelatin like)

Endoplasmic reticulum

1. Membranous-walled canals/channels
2. Extend from nucleus to plasma membrane
3. Rough endoplasmic reticulum
a. Ribosomes
b. Function in protein synthesis and intracellular transportation (makes protein -transports inside the cell)
4. Smooth endoplasmic reticulum
a. No ribosomes
b. Synthesizes certain lipids (steroids) and carbohydrates
c. Creates (cell) membranes for use throughout the cell
d. doesn't make protein, b/c no ribosomes

If you have one cell that has more SER than RER what does the cell make?

lipids

Ribosomes

1. Attached to the rough endoplasmic reticulum
2. Free ribosome = immediate protein
3. Two subunits, a large subunit and a small subunit (only comes together to make protein)
4. Each subunit is composed of rRNA bound to protein
5. Responsible for the synthesis of proteins

Note 1: reads message out of nucleus to make protein
Note 2: protein & RNA

Golgi Apparatus

1. Membranous organelle consisting of cisternae
2. Processes protein molecules from the endoplasmic reticulum
3. Chemically alters proteins in cisterna
4. Creates vesicles. (can store for later use or transport out of cell)

Note 1: packages

Lysosomes

1. Cell's own digestive system
2. (make) Enzymes digest particles or large molecules or cells
3. Autolysis ("self-breakdown') - programmed cell death

Note 1: vesicle made by golgi.
Note 2: reuse protein - lysosome digests w/enzymes for reuse
Note 3: fights infection by digesting bacteria

Peroxisomes

1. Contains peroxidase & catalase
2. Detoxifies harmful substances
3. Neutralize free radicals, detoxify alcohol, other drugs and toxins
4. In all cells but abundant in liver and kidney (detoxifing organs)
Note 1: they can self-replicate
Note 2: Free radicals - peroxisome will kill these
Note 3: Ex. question: Taxas disease, neurological diease. 1st year of life then regress caused by lack of lysosome b/c of build up of garbage (worn out things or things you don't need anymore)

Mitochondria (5)

looks like bacteria
1. Double membrane, fluid - matrix
2. Inner membrane has folds - cristae
3. Embedded in inner membrane are enzymes to produce ATP
4. Power plant of cells
5. has its own DNA

can burn glucose, protein
RBC - can only use sugar b/c no mitochondria to make energy
cell w/no mitochondria can only make a little energy
02 destination is mitochondria - to make ATP

Cytoskeletan

1. Provides support, shape and allow movement (crawling WBC)
2. Microfilaments - protein
3. Intermediate filaments - protein, holds organelles in place
4. Microtubules - proteins. Hollow
a. Moves things around in cell (ex. spine to toe)
b. Causes movement of entire cell

centrosome

1. Plays an important role during cell division.
2. Essential for formation of microtubular cell extensions
3. Contains centrioles - move chromosomes during cell division

ex. neurons don't have centrioles=assumptions that the cell won't divide

cell extensions (2)

1. Microvilli - increase the surface area
a. Found in small intestines (absorbs nutrients) and renal tubules
2. Cilia and flagellum
a. Flagellum (pl. Flagella) are found only on human sperm cells
b. Cilia (sing. Cilium) (longer projection)- respiratory tract (ex. move mucous so it doesn't get in the lungs), fallopian tube (ex. move egg)

cilia function: move something acrfoss the surface of the cell

Nucleus (3)

control center, dna controls everything, cancer=dna damage
1. Nuclear envelope - double layer
a. Surrounds nucleus
b. Contains nuclear pores
2. Contains DNA:
a. Chromatin - threads or granules in nondividing cells
b. Chromosomes in early stages of cell division
c. DNA determines both structure and function of cells and heredity
3. Nucleolus
a. Collection (production) of RNA and protein (only when the cell is not dividing, disappears when cell divides)
b. Site of ribosome synthesis

Cell connections

How cells are held together. waterproof=damage takes time
1. Desmosomes - cytoskeletan (waterproof)
a. Fibers on the outer surface interlock with each other (btw cells)
b. Anchored internally by intermediate filaments (like velcro)
c. Located in outer skin cells
2. Tight junctions (almost glued together-watertight)
a. Molecules cannot permeate the cracks of tight junctions (watertight. ex. stomach, bladder, intestine=don't want anything leaking out)
b. Located between cells that form linings
3. Gap junctions (heart) communication center
a. Form gaps or tunnels (channels) that join the cytoplasm of two cells
b. Fuse two plasma membranes into a single structure
c. Molecules can pass directly from one cell to another
d. **Located in cardiac muscles

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