AP Biology - Unit 2

Prokaryotic Cells

don’t have a nucleus so chromosomes are held in the nucleoid region, structurally simple due to lack of membrane bound organelles

Eukaryotic Cells

have a nucleus where chromosomes are held, larger and more complex than prokaryotic cells

Multicellular Eukaryotes

composed of many/multiple cells; includes animals, plants, fungi, and algae

Unicellular Eukaryotes

composed of one cell

The Cell Theory

• All living things are composed of one or more cells

• Cells are the basic unit of structure and function in living things

• All cells come from other, previous cells

Organelle

name for a cell part with a specific function

ATP

a cell’s moment to moment energy source

Plasma Membrane

part of the cell that controls what enters and leaves the cell, present in all cells, barrier that surrounds cytosol

Cytosol

part of the cell where most chemical reactions that keep the cell alive occur, holds the cell’s organelles, gel-like, internal support of the cell

Chloroplast

organelle, found only in plant cells, that carries out photosynthesis

Cell walls

part of a plant cell that helps the plant cell maintain its structure by providing strength and rigidity

Nucleus

organelle, found within the cytosol, that holds chromosomes(genes/DNA)

Mitochondria

organelle that is the cell’s ATP producer, has a double membrane: outer=smooth, inner=highly folded for more surface area

Ribosome

organelle that is the cell’s “protein factories” that receive instructions(mRNA) from the nucleus to synthesize protein that is needed, can be found floating in the cytosol or bound to the rough ER

Golgi Apparatus

organelle that modifies/sorts proteins and packages them into vesicles

Centriole

during cell division, this organelle ensures that both daughter cells receive the right amount of chromosomes by organizing microtubes(spindle formation) to act as highways for the chromosomes

Vacuoles

organelle used for the temporary storage of water and materials in cells

Lysosomes

organelle, found only in animal cells, that digest macromolecules and recycle worn-out cell parts

Rough ER

organelle that synthesizes proteins that will leave the cell from the ribosomes bound to its structure

Smooth ER

organelle that detoxifies the cell and synthesizes lipids

Nucleolus

region of the nucleus where ribosomal RNA(rRNA) is synthesized so it can be combined with proteins to form the subunits of ribosomes before exiting via nuclear pores to assemble into ribosomes

Central Vacuole

organelle, found in plant cells, that stores lots of water and chemicals the plant needs

Vesicles

organelles that are used for the transport of materials around or out of the cell

Peroxisomes

organelle that breaks down toxic substances, like hydrogen peroxide, into water

Cilia 

organelle, attached to the surface of a cell, that aids the cell in movement

Plasmodesmata

small holes in the cell walls between plant cells that allows for nutrients and ions to be transfered

All membranes…

are made of phospholipids

The larger the surface area-to-volume ratio of a cell is…

the more efficient the cell is at moving materials across its plasma membrane

3 Organelles that have Double Membranes

Chloroplast, Mitochondria, Nucleus

Selective Permeability

the ability of membranes to regulate the substances that enter and leave

Micelle 

spherical configuration of phospholipids in water with a water free zone in the center

Liposome

spherical configuration of phospholipids in water that forms a phospholipid bilayer

Phospholipid Bilayer

two layers of phospholipids where heads face out to interact with water and tails cluster together inside to avoid water

Cholesterol in membranes…

maintains the fluidity at high and low temperatures; high temps: reduces movement, low temps: reduces tight packing of phospholipids

Fluidity of Membranes

keeps the membrane from being rigid, makes it flexible so proteins and lipids can move along the membrane

Simple Diffusion

the diffusion of small, nonpolar molecules, like CO2 and O2, across the phospholipid bilayer(high to low concentration)(no energy)

Facilitated Diffusion

the diffusion of larger, polar or charged molecules across the phospholipid bilayer by ways of protein channels or protein carriers(high to low concentration)(no energy)

Active Transport

the diffusion of molecules against the concentration gradient by ways of a protein pump(low to high concentration)(energy needed)

Hypertonic Solution

a solution with less solute concentration inside than outside, meaning the cell will lose water(Plant: plasmolyze, Animal: shrivel)

Hypotonic Solution

a solution with more solute concentration inside than outside, meaning the cell will gain water(Plant: turgid(normal), Animal: lyse)

Isotonic Solution

a solution with equal amounts of solute concentration inside and outside, meaning there will be no net movement of water(Plant: flaccid(droop), Animal: normal)

Aquaporins

protein channels, specific to water, the speed up the process of osmosis, the diffusion of water

Exocytosis

when a vesicle within the cell fuses with the plasma membrane and releases molecules or materials out of the cell

Endocytosis

the pinching of the plasma membrane to grab molecules or materials outside the cell and enclose them into vesicles within the cell

Phagocytosis

form of endocytosis where the plasma membrane swallows food particles or other cells

Pinocytosis

form of endocytosis where the plasma membrane “takes a sip” of the fluid outside of the cell

Receptor-mediated endocytosis

form of endocytosis where the plasma membrane will only pinch when a molecule outside binds to a receptor