AP Biology Unit 2

organelles

membrane-enclosed structures within a eukaryotic cell

eukaryotic cell

Cell with a nucleus and membrane bound organelles

prokaryotic cell

Cell with no nucleus nor membrane bound organelles

cytoplasm

the region in a cell between the cell membrane and nucleus; it contains the cell structures and oganelles

plasma membrane

The selective barrier that surrounds a cell; it controls what enters and leaves the cell

nucleus

chromosome-containing part of a eukaryotic cell

chromosomes

tightly coiled structures that carry the genetic information (can be seen during nuclear division)

ribosomes

made of ribosomal RNA and protein, synthesize proteins

endomembrane system

membranes that divide the cell into organelles such as the nuclear membrane, the endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, and the cell membrane.

Smooth Endoplasmic Reticulum

portion of the endoplasmic reticulum free of ribosomes, synthesize lipids, detoxifies the cell, and regulates calcium levels

rough Endoplasmic Reticulum

portion of the endoplasmic reticulum with ribosomes, produces and transports membrane and secretory proteins

glycoproteins

proteins with covalently-bonded carbohydrates that play a role in cell to cell interaction

transport vesicles

vesicles in transit from one part of the cell to another

Golgi apparatus

stack of membranes that modifies, sorts, and packages proteins from the endoplasmic reticulum

lysosome

membranous sac of hydrolytic enzymes, which the cell uses to digest unwanted materials

central vacuole

A large vacuole that rests at the center of most plant cells and is filled water a solutes. Help maintain the pressure of the plant cell wall.

mitochondria

chemically convert chemical (food) energy into usable ATP energy through cellular respiration

chloroplasts

contain chlorophyll which help absorb solar energy in order to convert carbon dioxide and water into sugars during photosynthesis

cell wall

extracellular structure specific to plant cells, protects the cell, maintains its shape, and prevents excessive water uptake

plasma membrane (cell membrane)

The boundary that separates the living cell from its surroundings

Selective permeability

_________ ____________ is a characteristic of cell membranes that means what passes in and out is regulated. It allows some substances to cross the membrane more easily than others.

Amphipathic

Having characteristics of being hydrophobic and hydrophilic, such as a phospholipid.

Phospholipid

The basic structural component and most abundant lipid of cell membranes is ____________.

Fluid Mosaic Model

Describes a membrane as a fluid structure with a "mosaic" of various proteins embedded in it.

Osmosis

The diffusion of water across a selectively permeable membrane.

Diffusion

A passive process that involves the movement of substances or molecules from high solute concentration to low. It is also the tendency for molecules to spread out evenly into the available space.

Active transport

Uses energy (usually in the form of ATP) to move solutes against their concentration gradients and to maintain concentration gradients that differ from their surroundings, i.e. sodium-potassium pump.

Endocytosis

The cell takes in macromolecules by forming vesicles from the plasma membrane.

Receptor-mediated endocytosis

Special receptor proteins catch molecules and bring them into the cell against a concentration gradient

Exocytosis

Transport vesicles migrate to the

membrane, fuse with it, and release their contents outside the cell

Cotransport

Occurs when active transport of a solute indirectly drives transport of other substances.

Peripheral proteins

Proteins bounded to the surface of the membrane.

Integral proteins

Proteins that penetrate the hydrophobic core.

Transmembrane proteins

Proteins that span the membrane.

What are some functions of membrane proteins?

Receive and transmit messages; channels and gates; pumps; enzymes; cell recognition

Hydrophobic (nonpolar) molecules

Can dissolve in the lipid bilayer and pass through the membrane rapidly, such as hydrocarbons.

Hydrophilic molecules

Do not cross the membrane easily, such as ions and polar molecules.

Transport proteins

Allow passage of substances across the membrane.

Channel protein

A type of transport protein that has a hydrophilic channel that certain molecules or ions can use as a tunnel.

Aquaporins

Channel proteins that facilitate the passage of water.

Passive transport

The diffusion of a substance across a membrane with no energy investment.

Concentration gradient

The region along which the density of a chemical substance increases or decreases.

Isotonic solution

Solute concentration is the

same as that inside the cell; no net water

movement across the plasma membrane.

Hypertonic solution

Solute concentration is

greater than that inside the cell; cell loses water.

Hypotonic solution

Solute concentration is less

than that inside the cell; cell gains water.

Osmoregulation

The control of solute concentrations and water balance that is a necessary adaptation for life in such environments.

Facilitated diffusion

Transport across a membrane that requires a protein channel or gate.

Gated channel

A type of ion channel that opens or closes in response to a stimulus.

Electrochemical gradient

Two combined forces that drive the diffusion of ions across a membrane: A chemical force (the ion's concentration gradient) and an electrical force (the effect of the membrane potential on the ion's movement).

How are large molecules transported?

Occurs by exocytosis and endocytosis and requires energy

What types of molecules can diffuse directly across the phospholipid bilayer?

Small nonpolar(hydrophobic) molecules

What are the major size limits upon cells?

Large cells create more work for DNA; Surface Area to Volume Ratio.

What structures would be found in all cells?

DNA, cell membrane, ribosomes.

endosymbiotic theory

theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms

types of prokaryotes

Bacteria and Archaea

Types of Eukaryotes

protists, fungi, plants, animals