Quiz 3- cells

The cell consists of what 3 major parts?

Nucleus, Cytoplasm, cell membrane (plasma membrane)

What does it mean if a cell can choose what to regulate in and out of the cell to maintain integrity?

Selectively permeable

The cell membrane consists of a bilayer of what?

Phospholipid molecules

What are the parts of a phospholipid molecules?

Polar heads, fatty acid tails, lipid tails

What molecules can move through the membrane easily?

O2, H2O, CO

What type of proteins does are in the cell membrane?

Globs, Rods, Fibers

Can water molecules pass through the membrane?

No- they need help from channel proteins

What is the function of carbohydrates?

Cell recognition and adhesion

What is the function of cholesterol?

Stabilize the membrane

What is the difference between passive and active mechanisms?

Passive- does not require energy

Active- uses cellular energy

What are the 4 types of passive mechanisms?

Diffusion, facilitated diffusion, osmosis, filtration

Diffusion

Molecules move from an area of high concentration to an area of low concentration until EQUILIBRIUM occurs.

Ex: Sugar or food dye

Facilitated Diffusion

Another form of diffusion where molecules move from an area of high concentration to an area of low concentration, but there is a selectively permeable membrane involved hindering the process.

Needs a helper protein

Glucose needs what to travel?

A carrier protein

Osmosis

Diffusion with water

What are the three types of osmosis?

Isotonic, hypertonic, hypotonic

Isotonic

Same outside and inside

Hypertonic

Higher osmosis pressure than body fluids

Cells shrink

Hypotonic

Lower osmosis pressure

Cells would swell

Filtrated Diffusion

Forces molecules thru membranes by hydrostatic pressure.

Used to separate solids from water

Explain the difference between diffusion and osmosis.

Both concentrations move from high to low, but osmosis uses a selective membrane.

Active Mechanism

Moves from low to high concentration region

Needs energy (atp)

Active transport

Career proteins with ATP live molecules across membrane

“Pumps”

Examples of pumps

Sugars, Amino Acids, Sodium, Potassium, Calcium.

What are two other processes that use cellular energy without crossing cell?

Endocytosis and exocystosis

Endocytosis

Pinocytosis- may take in water and the particles dissolved in it. (“cell drinking”)

PhagocytosiS- solids instead of liquids.(“cell eating”)

Receptor mediated endocytosis specific substances can enter

Exocytosis

Vesicle fuses with the membrane to expel substances from the cell.

Ex. Secretion of certain hormones.