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chap 3 class lecture


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What are membranes made of?
Phospholipid bilayer ( phosphate heads on out outside & lipid tails on inside)
Which part is hydrophobic?
again lipids ( = phosholipid) are hydrocarbon chain that tells us it's hydrophobic; remember nonpolar wants to stay i the middle
Which part is hydrophillic?
phosphate heads, on the outside (know the phosphate structure) hydrophillic is polar, likes water
Structure of membrane
p. 47 shows hydrophobic chain & nonpolar
yello = cholesterol - gives fluid mosaid ability, tails don't stick together, contribute to tails from sticking together
integral protein
go all the way into membrane, used for transport, control what goes in and out of cells, act like receptors (hormones), act like transports (ion channels), work as identification marker (glycocalyx )
water soluble substances(sugar & ?) ones get through
with help of enzymes ( = proteins that accelerate or speed chemical reactions & not used up)
when cells are close together, name the molecules that join them together:
1. Tight junction
2. Desmosome
3. gap junction
what type of tissue has cells that are very close together?
epithelium: toward surface of apex (nucleus are toward bottom) are the tight junction
Tight junction (purpose/function)
Near apical surface, we see a zipper-like junctions stuff that prevents substances from going between cells (remember: underneath: it's mostly loosly connective tissue) so we have tight junction between lateral walls
Desmosome (purpose/function)
-simply anchors 1 cell to the next
Gap junction (purpose/function)
-allow communication or substances (ions, or any cytosol components, e.g. ions) to pass; this way ion concentration are equal throughout cell! primary purpose = communication; very abundant in the heart! -more prominent in certain cells!
Defn: the movement of water across the membrane from an area of low solute concentration to high solute concentration
Gap junction (purpose/function)
-allow communication or substances (ions, or any cytosol components, e.g. ions) to pass; this way ion concentration are equal throughout cell! primary purpose = communication; very abundant in the heart! -more prominent in certain cells!
Which direction will water go (low conc to high or high to low?)
Water will go from low-solute to high-solute, so both sides are equal in concentration
Assume you have a red blood cell, and this rbc has hemoglobin in it w/certain concentration, say it's isotonic (same concentration outside and inside) say a dr give you an iv, that has, water gluclose, tothe blood, all of a sudden, your blood stream has
rbc not permeable to substances to water, so which way will water move? it's more concentrated on outside, so water will move out of the cell. Red blood cells shrink in size (bec of loss of water). (So we can say the solution you added is hypertonic.)
What is the dr. gave you an IV that's hypotonic, so now your blood is more concentrated than the fluid that's entering the blood stream, which way would water move?
water will now move trom the blood stream into the cell. So cells will get bigger, so the solution that's more diluted is called hypotonic solution), which leads to swelling of the cells.
where in the book is this?
understand how it affects body, consequences in hypertonic, hypotonic, isotonic solutions
p. 68 & p. 69
How does osmosis differ from diffusion?
membrane is now permeable to solutes- instead of just the solvents!
Define diffusion
The movement of

Say a membrane is permeable to glucose molecule, if 1 side is higher in concentratio of glucose, it'll go from high-solute to low-solute area.
simple vs. facilitated diffusion
- goes on its own
-requires a membrane protein
book fig 3.5 : how does this passive process differ from active transport: compare 2
yellow - passive
white & purpose - require energy, goes against concentration gradient
ACTIVE transport has 2 requirements:
1) = movement of substances (solutes) against concentration gradient (high to low)
2) it takes energy to move the substance across
(you see this in the nervouse system, where ion gradient is imp - where you need to have positive charges on outside & negative charges on inside) in the neuron. That way when signal comes, than the positie charge will rush in, whole tranmission process involves depolarization, and this is how neurons conduct signals along nerves & we acativate muscles. Gradient also has a pump that pmps sodium out and potassium in (2 molecules), so you get a net positive charge outside & negative charge inside (seep. 380 in text). Since this is going against gradient, it requires energy.
From high-concentration to low-concentration is called?
Simple or facilitated
Vessicular transport
-utilizing the plasma or cell membrane to make vessicles to transport substances in & out of cells
In phatocytosis, cell membrane (double-layer phospholipid bilayer) microbes come in, membrane makes a vessible,s what's this called?
endocytosis - 2 mechanisms:
phagocytosis (eating ____) - engulfs large substances
phinocytosis (drinking of ____) _) - engulfs small substances. So this whole thing is called endocytosis: bringing it in.
...microbes, enzymes
enzymes binds to the vesicle : exocytosis brings it out
(still on the long neuron)
neurotransmiter vesicles - they get signals to tell vessibles to move toward the membrane, bind to the membrane, and than spit out neurotransmitters, which will bind to receptors on the next membrane.
vesicle moves to the membrane & moves it out
exocytosis (of microbes, neurotransmitters)
some move easier than others. In Golgi apparatus,
Cell cycle
inter phase (dna replication, division of chromosomes in nucleus ), miosis (telo, ana, meta, prophase, telephase) cytokinesis
where does nuclear division occur?
during Mitosis
when do we see chromosomes?
until we get to mitoss, when it's organized
what divides the cell?
cyto = cell
kinesis = movement

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