Unit 2: Cell structure & function

Slogan: Structure determines function. Energy Efficiency. Compartmentalization

Critical Unit Notes

2.1 membrane structure

Structure

Description

Example

Glycolipids

(Sugar lipid)

  • Used in Cell recognition

  • Bound to membrane LIPIDS

Glycoproteins

(Sugar protein)

  • Used in cell recognition

  • Bound to membrane PROTEINS

Integral Proteins

  • Act as transporters, enzymes, and links in cell adhesion

Peripheral Proteins

  • NOT embedded in membrane (sits on one side of the membrane)

  • Acts as transporters and activator of cell signals

Cholesterol

  • Temp./space buffer

  • allows for fluid movement

Glutanation: White blood cells attack blood cells that aren’t recognized;

blood clot → stroke → die

Membrane Proteins

Transport↴

  • May provide a hydrophilic channel that is selective for a particular solute

  • May change shape to get a substance across the membrane

  • Some proteins hydrolyze ATP to actively pump substances across the membrane

Enzymatic Activity↴

  • The active site may be exposed to substances in the adjacent solution

Signal Transduction↴

  • A membrane protein may fit the shape of a chemical messenger like a hormone

Cell-Cell Recognition↴

  • Some glycoproteins serve as ID tags

  • this type of cell bonding is short lived

Intercellular joining↴

  • Membrane proteins may hook together

  • This bond is long-lasting

Attachment to the cytoskeleton and extracellular matrix↴

2.2 Tonicity and Osmosis

Concentration: A RATIO of the amount of solute to the amount of solvent

  • Solute: a substance that is dissolved in water

  • Solvent: the substance into which solutes are dissolved

Diffusion: The process of random movement toward the state of equilibrium

Osmosis: The diffusion of water molecules across a semipermeable membrane/biological membrane

  • Fully passive; water naturally travels from areas of high water conc. (low solute conc.) to low water conc. (high solute conc.)

Aquaporins: Special protein channels that enhance the passage of water molecules through the plasma membrane found in certain cells

  • essentially allows water to travel faster through the membrane

Osmoregulation: The control of solute concentrations and water balance

Tonicity

  • the ability of a solution to modify the volume of cells by altering the water content

  • Tonicity COMPARES the concentration of two solutions

  • Hypertonic: when the concentration of a solution is higher than that of the solution you are comparing it too

    • hyper = higher

  • Hypotonic: when the concentration of a solution is lower than that of the solution you are comparing it to

    • hypo = lower

  • Isotonic: When the concentration of a solution is equal to the concentration of the solution you are comparing it to

    • Iso = equal

☆Solutes cannot move freely, but WATER can☆

Add visual examples from notes on pg.7

or some kind of explanation

2.3 Water potential

Water potential (Ψ): A measure of water’s potential to do work

2.4 Passive transport

2.5 Active transport

2.6 Cell structure and function

2.7 Cell size

Kahoot Questions!!

Go over prokaryotes vs Eukaryotes

  • prokaryotes: no nucleus, non membrane bound organelles

  • Eukaryotes: YES nucleus and membrane bound organelles

Prokaryotes have a LARGER Surface Area:Volume ratios than larger Eukaryotes

Prokaryotes have all ribosomes, cytoplasm, call membrane/wall

More folds (in ER and mitochondria) = more surface area = more efficiency

Rough ER- helps synthesize and package proteins for export

SMOOTH ER DETOXIFIES

If human cell is placed in pure water, the cells will gain water and possibly LYSE

Water potential moves from high to low water potential

Turgor pressure: when a plant’s vacuole exerts a pressure on the cell membrane, which then pushes up against the cell was

What molecules can easily diffuse/pass through the cell membrane without the use of protein channels? Small, non-polar/hydrophobic

High/more acidity is characterized by higher H+ ion concentration

Ions move through the membrane through a specialized ion channel

Mitochondria and chloroplasts are hypothesized to have been engulfed by an ancestor, what evidence supports this theory? The double membranes

Not evidence of the endosymbiotic theory?

  • Cells can survive on their own

How are ion pumps different from protein channels?

  • Ion pumps change shape when ATP attaches and detaches channels do not

Ribosomes are the reason for synthesizing proteins

Which organelle contains enzymes that are involved in the breakdown of harmful substances H2O2? Peroxisome

Plasmodesmata is a cell connection found in plain cells rather than animal cells

Which of the following organelles are found in the endomembrane system?

  • Nucleus, Rough Er, Golgi, Secretory vesicles, and plasma membrane

Essential Questions

1) Which molecules move across the membrane without energy? Small or large? Polar or non-polar?

2) When cells need to transport molecules that do not move easily across the membrane, how do they do it efficiently and effectively?

3) What organelles work together to help the cell process energy? What macromolecules are charged/utilized in this process?

4) What organelles work together to help the cell process information? What macromolecules are shared/utilized in this process?

5) What organelles work together to help the cell transport materials into, out of, and around cells? What macromolecules are shared/utilized in this process?

6) When materials are transported in and out of the cell, what determines how they move? How do cells maximize efficiency in this process?