Chapter 4, Part 1 (ANSC 199)

cell

smallest unit of life that can function independently and perform all the necessary functions of life

eukaryotic

• nucleus with DNA

prokaryotes

• no nucleus (DNA in cytoplasm)

• first cells on earth

examples of eukaryotes

plants, animals, yeast, algae

examples of prokaryotes

bacteria and archaea

structures common to ALL prokaryotes

• plasma membrane

• cytosol

• DNA

• ribosome

structures found in SOME prokaryotes

• cell wall

• capsule

• pilus

• flagellum

structures not found in plant cells

centriole

structures not found in animal cells

• chloroplast

• cell wall

• vacuole

plasma membrane

made up of two layers that are filled with a variety of pores, molecules, and channels

phospholipids

• hydrophilic head (glycerol linked to phosphorus molecule)

• hydrophobic tails (composed of C-H chains)

function of lipids

primarily provide structure

function of proteins

primarily provide function

types of protein molecules associated with plasma membrane

• receptor - bind to external chemicals that regulate processes within the cell

• recognition - give each cell a “fingerprint” that makes it possible to catch invaders

• transport - help polar substances pass through plasma membrane

• membrane enzyme - accelerate chemical reactions on the surface of the plasma membrane

integral proteins

• membrane-spanning

• hydrophobic interactions

• covalent bonds

peripheral proteins

• membrane-associated

• ionic interactions

• dipole interactions

importance of membrane surface molecular markers

key to the function of your immune system

tight junction

• holds sheets of cells together

• no fluid passage

desmosomes

• holds cells together

• allows fluids to pass between cells

gap junctions

movement of cytoplasm, molecules, and other signals

diffusion

Spontaneous movement of solute across the plasma membrane from higher to lower concentration

Facilitated diffusion

When molecules are passively transported across the plasma membrane through a carrier protein

Osmosis

Passive diffusion of water across a membrane from higher to lower concentration

Hypotonic

Water moves IN the cell (concentration low)

Hypertonic

Water moves OUT a cell (concentration high)

Aquaporins

Channel proteins that water diffuses through

Tonicity

Relationship between the concentrations of solutes inside the cell and the solutes outside the cell

Isotonic

Concentration of solutes outside the cell = the concentration inside the cell

Active transport

requires energy in order to move large molecules or to move substances against their concentration gradients

Primary active transport

Requires direct ATP

Secondary active transport

Uses ATP indirectly