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

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)

Organelle

name for a cell part with a specific function

ATP

a cell’s moment to moment energy source

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

organelles used for 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 attached to its structure

Smooth ER

organelle that detoxifies the cell and synthesizes lipids(new pieces of membrane) and hormones

All membranes…

are made of phospholipids

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 responsible for shipping proteins around or out of the cell

Peroxisomes

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

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

the more efficient the cell is at moving materials(energy/waste) across its plasma membrane

Cilia 

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

3 Organelles that have Double Membranes

Chloroplast, Mitochondria, Nucleus

Selective Permeability

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

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

Peripheral Proteins in membranes…

are attached to the polar heads of the phospholipid bilayer but don't extend into hydrophobic region

Transmembrane Proteins in membranes…

span the entire phospholipid bilayer

Integral Proteins in membranes…

are proteins embedded in the phospholipid bilayer

Simple Diffusion

diffusion of small nonpolar molecules like CO2 and O2(high→low concentration gradient)(no energy needed)

Facilitated Diffusion

diffusion of polar or charged molecules through a protein channel or carrier(high→low concentration gradient)(no energy needed)

Active Transport

diffusion against the concentration gradient by use of a protein pump(low→high concentration gradient)(energy needed)

Plasmodesmata

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

Fluidity of Membranes

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

Hypertonic Solution

A solution with more solute concentration within the cell than outside, causing water to leave the cell

Hypotonic Solution

A solution with less solute concentration within the cell than outside, causing water to enter the cell

Isotonic Solution

A solution with an equal amount of solute concentration within the cell and outside(water flows equally in and out)

Aquaporins

special channels that speed up the rate at which water can be diffused through a plasma membrane

Exocytosis

when a vesicle, filled with a substance, fuses with the membrane and releases the substance out of the cell

Endocytosis

when the cell membrane pinches, grabbing a substance outside the cell, and encloses it into a vesicle within the cell

Phagocytosis

type of endocytosis where the membrane swallows food particles or other cells

Pinocytosis

type of endocytosis where the membrane “takes a sip” of the fluid surrounding the cell

Receptor-mediated endocytosis

type of endocytosis where the membrane only pinches when a molecule outside the cell binds with a receptor on the membrane