Unit 5-Cellular Function Flashcards
What are the 6 different types of functions of proteins in a plasma membrane
Attachment to the cytoskeleton and extracellular matrix Signal transduction Transport Intercellular junctions Cell-cell recognition Enzymatic activity
Define diffusion
Molecules move down the concentration gradient
Does not require energy
Define passive transport
A type of transport that does not require energy such as diffusion
What is one of the most important substances that crosses membranes by passive transport
Water
Define osmosis
The diffusion of water across a selectively permeable membrane
Why are there a difference in water level but the concentration is equal
Because solutes attach to the water molecule so there are less free water molecules
Define tonicity
The ability of a surrounding solution to cause a cell to gain or lose water
What does the tonicity of a solution depend on
It’s concentration of solutes that cannot cross the plasma membrane relative to the concentration of solutes inside the cell
Define isotonic
No net movement ; equal
Normal for animal cells
Flaccid for plant cells
Define hypotonic
A solution with a solute concentration lower then that of the cell
The cell gains water and is lysed or bursts
Water moves into the cell
What plant cells like the best
Define hypertonic
A solution with a higher solute concentration
The cell shrivels
Water moves out of the cell
Define osmoregulation
The control of water balance
What types of molecules can cross the membrane unassisted what can not
Polar or charged substances need help to move across the membrane
While nonpolar hydrophobic molecules can dissolve and pass through
Define facilitated diffusion
The movement of substances across the membrane with the use of specific transport proteins
A type of passive transport because it does not require energy
What substances use facilitated diffusion
Many sugars
Amino acids
Ions
And even water because water is polar
Define an aquaporin
A type of protein channel used for water
Define active transport
A cell must expend energy to move a solute against its concentration gradient
ATP is used for the energy
Explain the process of active transport
Molecule attaches to specific binding sites on the transport protein ATP is used on the protein to change its shape so that the solute can be released on the other side the phosphate detaches and the transport protein returns to its original shape
Does an animal cell have more K+ inside or outside of its cell
INSIDE OF THE CELL
Is there a lower or higher concentration of sodium inside or outside of the cell
OUTSIDE
What is the transport protein called used to regulate the NA and K levels
The sodium potassium pump
Works by moving Na and K against their concentration gradients
How do large substances enter and exit a cell
Exocytosis and endocytosis
Define exocytosis
How the cell exports bulky materials such as proteins or polysaccharides
How does exocytosis work
A transport vesicle filled with macromolecules buds from the Golgi apparatus and moves to the plasma membrane once there it fuses and the contains spill out of the cell
Define endocytosis
A transport process that is the opposite of exocytosis. A cell takes in large molecules
Define phagocytosis
A type of endocytosis
Cellular eating
Engulfs a particle by wrapping the pseudopodia around it and packages it
What are the three types of endocytosis
Phagocytosis
Pinocytosis
Receptor-mediated endocytosis
Define pinocytosis
A type of endocytosis
Cellular drinking
Gulps little droplets of fluid into tiny vesicles
Not specific takes in anything
Define receptor mediated endocytosis
Highly selective
Has receptor proteins for specific molecules embedded in regions of the membrane
Coated protein
Used for cholesterol
Define thermodynamics
The study of energy transformations that occur in a collection of matter
What is the first law of thermodynamics
Aka law of energy conservation
Energy in the universe is constant
Energy can be transferred and transformed but not created or destroyed
Define the second law of thermodynamics
Energy conversions increase entropy (disorder/randomness) of the universe
Define an exergonic reaction
A chemical reaction that releases energy
Define an endergonic reaction
Yield products that are rich in potential energy
Define energy coupling
The use of energy released from exergonic reactions to drive essential endergonic reactions
What is the process called when a phosphate group is transferred to form ATP
Phosphorylation
Define a substrate
The specific reactant that an enzyme acts on
Define the active site
Where the substrate fits
Define induced fit
The enzyme starts with an empty active site and the substrate attaches to the active site and the active site changes slightly to fit the substrate
What describes the structure of a cell membrane
Proteins embedded in a bilayer of phospholipids
Chemical bonds in the gasoline in a cars tank and the movement of the car along the road
The first demonstrates what and what does the second part demonstrate
Potential energy
Kinetic energy
A plant cell placed in distilled water will ___; an animal cell placed in distilled water will __
Become turgid
Burst
The sodium concentration in a cell is 10 times less then the concentration in the surrounding fluid. How can the cell move sodium out of the cell
Active transport
The synthesis of ATP from ADP and P
Stores energy in a form that can drive cellular work
Facilitated diffusion across a membrane requires ___ and moves a solute ___ its concentration gradient
Transport proteins
Down
When comparing an uncatalyzed reaction to the same reaction with an enzyme catalyst is true
The catalyzed reaction will have lower activation energy
