BIO 103 Exam 3 Study Guide

Phospholipids

The lipid bilayer that forms the core of a cell’s membranes is composed primarily of

Sphingolipids

Which lipid category is important in nervous tissue despite being less abundant in biological membranes

glycerol phospholipids, sphingolipids, sterols

The three main classes of membrane lipids

Bilayer

When phospholipids are placed in water the spontaneously form _______

Unsaturated Phospholipids

Characteristics of the ER membranes contributes to its dynamic strucutre

Membrane proteins key functions that allow cells to maintain homeostasis

Attach the membrane to the cytoskeleton, receive external chemical messages, connect adjacent cells and hold them together\

Water molecules form the maximum number of hydrogen bonds

Why phospholipid bilayers form spontaneously in water

Transmembrane domains

Hydrophobic region of a transmembrane protein that anchors it in the membrane; are in contact with the nonpolar interior of the membrane, they consist primarily of nonpolar amino acid

Diffusion

Net movement of substances from regions of high concentration to regions of lower concentration

Dense, Gel-like structure

Characteristics of the plasma membrane due to its phospholipid composition

Facilitated Diffusion

Carrier-assistance in diffusion of molecules across a cellular membrane through specific channels from a region of higher concentration to lower; doesn’t require energy

Sugars, Ions, and Amino Amino Acid

Substances are transported across membranes by carrier proteins

Brownian Movement

Molecules and ions dissolved in water are in constant random motion

Cholesterol

Interacts with the nonpolar tails and increases fludity

Carrier Proteins

A second route for substances (Amino Acids, sugar, ions) to cross the plasma membrane

Solute

A molecule dissolved in a solvent; determines the osmotic concentration of the solution

Hydrostatic Pressure

The pressure of they cytoplasm pushing out against the cell membrane

Osmotic Pressure

The hydrostatic pressure necessary to stop the osmotic flow of water across a membrane.

Plants, Fungi, Prokaryotes, and many protists

Can resist the osmotic pressure which protects the cell from swelling and bursting

Higher Concentration

An aqueous solution with a lower concentration of solutes will have a _________ of free water molecules

Lower Concentration

An aqueous solution with a high concentration of solutes will have a _________ of free water molecules

Active Transport

Requires ATP; moves against the concentration gradient; low concentration to high concentration

Sodium (Na, Na+)

Pumped into the cell

Potassium (K, K+)

Pumped out of the cell

Sodium-potassium pump

Actively pumps 3 sodium ions into the cell while secreting 2 potassium ions out of the cell

ATP Hydrolysis

supplies the energy needed for coupled transport

Endocytosis

The uptake of material into cells

Cholesterol

acts as a stabilizer, maintaining membrane fluidity and helping in cell communication.

Proteins

What determines that the right molecules get in and out of the cell

Non-polar molecules

Oxygen, carbon dioxide, and vitamins are ________ which pass through the phospholipid bilayer easily

Peripheral Proteins

Help anchor the membrane to the cell’s interior scaffolding

Integral Proteins

long stretches of nonpolar amino acids and proteins that go through the membrane

Transmembrane Proteins

create selective channels that let specific polar or charged molecules (like ions) move in and out of the cell.

Carrier Proteins

embedded in the cell membrane in both active transport and facilitated transport

glycoproteins and glycolipids.

marker molecules that identify the cell type on the outer surface of the plasma membrane

Hypotonic

Lower solute outside → cell swells (lysis). ;Turgor pressure is observed when a plant cell's environment is

Cell Surface Marker

Often carbohydrate attached to lipid or protein

lose water and shrink.

The most likely outcome of red blood cells with internal salt concentrations of 0.85% being placed in a 4% salt solution is the cells would

Hypertonic

Higher solute outside → cell shrinks (crenation).