Ch. 2 - The Cell Flashcards
(45 cards)
Functions of the plasma membrane
Separate the cell’s internal environment from its
external environment
Regulate what move in and out of the cell
Hold the cell in place
Communicate with neighboring cells and the rest of the body
Hold proteins in place
Water as a Solvent
Salt dissolves in it, oils and fats do not. Ions interact with its electrical charge. Oils and fats have an equal charge making them hydrophobic
Cholesterol
Important component in the cell membrane
Precursor for bile and steroid hormones
Fluid Membrane
Holds things in place, but like many boats on a lake
Membrane permeability
Molecules with no charge can pass through
Oxygen, carbon dioxide, steroids, fats
Charged molecules need channels or transport
Some very small molecules can pass through
Water, urea
Proteins in the cell membrane
Like the membrane, it has hydrophilic ends, and a hydrophobic middle
Transporter Proteins
The protein is involved in moving the molecule across
the membrane, usually the molecules are larger (glucose)
Receptor Proteins
A signal molecule (hormone) arrives at the cell and binds
with the receptor
This causes a change in the cell; the cell responds to the signal
Enzymes
Often bound in membranes
The cell regulates where chemical reactions take place
and assembly lines of enzymes can be formed to help reactions take place
Linker proteins
Proteins that pass through the cell membrane hold the cell in place
Identity marker proteins
Cell recognition proteins (egg and sperm)
Cell products are displayed (immune system)
Ion channels
A signal (ACh) causes channel to open When open, the channel allows Na+ ions to move in or out of the cell
Diffusion
The random movement of particles produces an equal
concentration in all areas of the solution
Osmosis
When particles are prevented from moving, water will move to equalize the concentration of dissolved particles
This will push water against gravity (energy)
Facilitated diffusion
The molecules are “helped” into the cell along the concentration gradient.
No energy is needed
Revolving door to the cell
Primary active transport
Energy is used to move particles against the concentration gradient
(i.e. the sodium / potassium pump)
Endocytosis
The cell extends itself around an object and brings it in inside the cell membrane in a vacuole
Exocytosis
A vacuole from the cell binds with the cell membrane
The content is dumped into the interstitial fluid or the blood
Cytoplasm
Contains cytosol and organelles
Cytosol
The fluid inside the cells and dissolved and suspended molecules
Organelles
Areas of the cell isolated from the rest of the cell by membranes; each with a specific function
Ribosomes
The assembly of proteins from amino acids (the primary structure of a protein)
Endoplasmic reticulum
Membrane folds outside the nucleus. Rough and smooth ER
RER
Holds ribosomes in place
Assembly of proteins
