AP Biology Unit 2 Vocab

Small Nonpolar Molecules

Pass more easily through lipid bilayer

Large polar/charged Molecules

Don’t move easily through lipid bilayer

Protein Channels

Part of membrane that helps large, polar, and ion molecules cross membrane

Passive Transport

Diffusion of substances across a membrane with no energy invested

Diffusion

Tendency for molecules to spread out evenly into the available space (Molecules move from high to low concentration)

Dynamic Equilibrium

As many molecules cross membrane in one direction as the other. Equal movement in both directions (no net movement)

Concentration Gradient

The region along which the density of a chemical substance decreases (diffusion moves down/with gradient)

Osmosis

Diffusion of water (solvent) across a selectively permeable membrane

Goes from high to low solute concentration, ending with near equal solute concentration

Isotonic Solution

Solute concentration is the same as the region it is being compared to

No net water movement across the plasma membrane

Hypertonic Solution

Solute concentration is greater than the region is it being compared to

Cell loses water (water moves out when places in ______), so cell gets shriveled and shrunken

Hypotonic Solution

Solute concentration is less than the region it is being compared to

Cell gains water (water moves into cell when placed in a _______), so cell grows and could even burst

Osmoregulation

Control of solute concentrations and water balance, which is a necessary adaption for life in such environments

Contractile Vacuole

Adaptation Paramecium has where it is hypertonic to its pond water environment and this adaptation pumps water out of the cell

How Animal Cells React to Iso/Hypo/Hyper Solutions

Hypotonic- Animal cell will burst

Isotonic- Ideal environment for Animal cell

Hypertonic- Animal cell becomes shriveled

How Plant Cells react to Iso/Hypo/Hyper Solutions

Hypotonic- Plant cell in happy place (where it wants to be) because cell wall prevents cell from bursting creating turgor pressure which allows plant to stand up nice and tall

Isotonic- Plants will start to wild due to lack of turgor pressure (flaccid)

Hypertonic- Plant cell plasmolyzes (dries up) and the cell wall separates from the cell membrane

Facilitated Diffusion

Passive transport aided by proteins. Channe proteins are hallways and carrier proteins opens up one way and then opens up the other way to release molecules

Active Transport

Uses energy (ATP )to move solutes against their gradients, allowing cells to maintain concentrations

Transport Proteins

Required in active transport and are specific to what molecules they move

Sodium Potassium Pump

Energy used and protein is specifically shaped to fill the sodium and potassium

Proton Pump

Helps store energy that can be used for cellular work by pumping out H+ ions requiring energy and creating voltage across membranes

Cotransport

Coupled transport by a membrane protein (active transport of a solute indirectly drives transport of other solutes)

Ex. Sucrose H+ Cotransport (potential energy from high concentration of protons outside of cell used to bring sucrose into cell)

Bulk Transport

Active transport across plasma membrane by endocytosis and exocytosis

Exocytosis

Transport vesicles migrate to membrane, fuse with it, and release their contents (exo → exit)

Endocytosis

Cell takes in macromolecule to form vesicles from plasma membrane (involves different proteins)

3 types: Phagocytosis, Pinocytosis, and Receptor Mediated Endocytosis

Phagocytosis

Cell engulfs a particle in a vacuole and fuses with a lysosome to digest particle (cellular eating)

Pinocytosis

Molecules are taken up when extracellular fluid is gulped into tiny vesicles (cellular drinking)

Receptor Mediated Endocytosis

Binding of ligands (any molecule that binds specifically to a receptor site of another molecule) to receptors trigger vesicle formation

Cell Membrane

Protects cell from surroundings, maintains an internal environment that is different from the external environment, and determines which particles may enter or exit the cell

Phospholipids

Polar/Hydrophilic head and nonpolar/hydrophobic tail

Saturated Fatty Acid Tail

Packed more tightly, more rigid membrane, molecules pass through more easily (better at hot temperatures where membranes are likely to disintegrate)

Unsaturated Fatty Acid Tail

Packed more loosely, more fluid membrane, molecules pass through more easily (better at colder temperatures where cell membrane are usually to rigid, less likely to solidify)

Amphipathic

Molecules that have both hydrophobic and hydrophilic regions

Cholesterol

Vital component of cell membranes, helping it maintain an appropriate level of fluidity by managing space between phospholipids

Prevents extremes (hot→ disintegrate and cold → solidify) by keeping phospholipids an optimal distance from each other

Transmembrane/Integral Protein

Protein that extends across the entire membrane

Glycoprotein

Protein component embedded in the membrane and a carbohydrate protrusion that dangles out away from it (Cell to cell recognition)

Glycolipid

Carbohydrate extensions protruding from phospholipid (cell to cell recognition)

Peripheral Protein

Studded with these on one side of the protein

Fluid Mosiac Model

Cell membrane fluid due to cholesterol and from top view looks like a mosaic

Water Potential

Predicts the direction of water movement (water always moves from an area of high water potential to an area of low water potential)

Pressure Potential

Either 0 or positive (cannot be negative)

Solute Potential

Either 0 or negative (cannot be positive

Adding solute lowers the water potential

What is the water potential of a pure (distilled) water in an open container?

0 (Pressure = 0 and solute concentration = 0)

What is the water potential at dynamic equilibrium

Water potential will be equal for the environment and the cell

What is the ionization constant for NaCl?

2 (breaks apart in water)

Surface Area

Determines the amount of substances that can enter a cell from the outside environment and the amount of waste product that can exit to the environment

Volume

Determines the amount of metabolic activity a cell carries out per unit of time

What happens as a cell grows larger?

Volume increases more rapidly than surface area, so increased metabolic activity/need for resources/rate of waste production and if surface area isn’t large enough compared to volume the cell will be unable to bring in enough nutrients/expel enough waste

A cell with a bigger surface area/volume ratio

Is more efficient

Cells functioning for more absorption will have adaptations to increase surface area (ex. villi in small intestine and root hairs)

Microscopy

Biologists use microscopes and the tools of biochemistry to study cells

Light Microscope

Visible light passed through specimen and then through a glass lense, lense refract/bend light so that the image is magnified about (can only see the largest organelles- nucleus and mitochondria)

Electron Microscope

Uses electrons, more magnified, used to study subcellular structure

Scanning Electron Microscope

Focus a beam of electrons onto the surface of a specimen, providing images that look 3D

Transmission Electron Microscope

Focus a beam of electrons through a specimen (better to study the internal structure of a cell)

Cell Fractionation

Takes apart cells and separates the major organelles from one another

Centrifuge: Spins mixtures at different speeds (lower speeds → larger components pellet)