biology
Because of the extremely cold temperatures, fish in arctic waters need to modify their cell membranes to make them more fluid. Which of these membranes would be the best choice for these animals?
membrane with lipids that have short tails and many unsaturated fatty acids
Unsaturated fatty acids
more fluid
low permeability
polar,organic, molecules
simple diffusion
no transport proteins required. • Only mol. that can pass freely through membrane can diffuse passively • Ex. Lipids, small nonpolar mol. such as O2
Increasing the temperature increases the rate of an enzyme- catalyzed reaction. Once a critical temperature is reached, the reaction stops. Why does this happen?
The increase in temperature alters the pH
Proteins that associate with the plasma membrane through non-covalent interactions with phospholipids or transmembrane proteins are called
peripheral
Is it possible for cells from the same multicellular organism to have different proteomes
Yes, because cells produce different proteins.
Endocytosis
plasma membrane folds inward, forms vesicle, brings substance in
Reactions that release free energy are
exergonic. spontaneous
Hypertonic
higher solute conc./lower water
Cell wall
structure easily distinguishes a plant cell from an animal cell
Km
substrate concentration at which velocity is half maximal value
Peripheral(extrinsic)proteins
- Bound to integral, not inside membrane - OR bound to polar head
Active transport
- Energy input - Against concentration gradient
integral(intrinsic)proteins
- Transmembrane proteins - Lipid-anchored protein
Label the steps in the correct order as they occur during feedback inhibition
A conformational change occurs in the enzyme (3) Excess product binds to the allosteric site of an enzyme (2) The product of a metabolic pathway accumulates (1) The activity of the enzyme is inhibited (4)
The Cell membrane is composed of
A phospholipid bi-layer
The cell theory
All living organisms are composed of one or more cells Cells are the smallest units of life New cells come only from pre-existing cells by cell division
Cholesterol
Animals only Stabilizes membrane
Membrane & Secreted Protein Synthesis
Begins in ER • Once formed, membrane proteins can be transferred to other parts of the cell (i.e. Golgi, lysosomes, plasma membrane, etc. • Transfer via vesicles
What do bacteria and some Eukarya have in common
Cell wall DNA
How do competitive and noncompetitive inhibitors differ in their effects on enzymes function?
Competitive inhibitors bind to the active site of an enzyme and noncompetitive inhibitors bind to an allosteric site Only the effects of competitive inhibitors can be overcome by increasing substrate concentration
Many Great Drugs work as
Competitors
A key similarity between simple and facilitated diffusion is that both require
Concentration gradients
Ways to Affect Enzyme Reactions
Concentration of substrate [S] • Concentration of enzyme • Heat • pH
The disease cystic fibrosis is a defect in chloride ion transport into the lungs such that the mucous in the lungs becomes dehydrated and thick and bacteria may grow in the lungs. What is the likely defect?
Defective plasma membrane proteins
types of transport that require a transport protein
Facilitated diffusion Active transport
statements comparing simple and facilitated diffusion
Facilitated diffusion, but not simple diffusion, requires a transport protein both require concentration gradients
membrane synthesis in eukaryotes
Happens at the ER membrane. • Membrane proteins are typically inserted starting at the ER too. • Carbs are added in the ER and Golgi
Affecting Enzymes: Heat
Heat in a system indicates how much molecules are moving.
An enzyme accelerated the rate of a chemical reaction by
Lowering the activation energy
parts of the endomembrane system
Mitochondria
Diffusion
Movement of a substance from a region where its concentration is high to a region where its concentration is low
Active transport
Movement of a substance from a region where its concentration is low to a region where its concentration is high with the aid of a transport protein and a source of energy.
Passive transport
No energy input
Where would peripheral (or extrinsic) membrane proteins likely reside with respect to the plasma membrane?
On the outside of the outer leaflet, facing the outside of the cell On the outside of the inner leaflet, facing the cytoplasm
exocytosis
Process by which materials packaged in vesicles are secreted from the cell
endocytosis
Process by which materials packaged in vesicles bring substances into cell
does a molecule flip-flop transversely across the membrane
Rarely
HIV is a viral disease. The cells are tricked into taking in viruses when the viruses activate a cell surface protein. How would you describe the manner in which the viruses get into cells?
Receptor-mediated endocytosis
key benefits of catabolic reactions
Recycling of organic building blocks Breakdown of organic molecules to obtain energy
ways that enzymes can increase the rate of a chemical reaction
Reduces the activation energy of the reaction Brings the reactants close to one another in the correct orientation
steps are incolved in an enzyme-catalyzed reaction
Substrates are converted to products Substrate binds to the enzyme at the active site. The enzyme undergoes conformational changes to bind the substrate closely Products are released from the enzyme and enzyme is reused.
steps of an enzyme catalyzed in order
Substrates bind to the enzyme at the active site (1) The enzyme undergoes conformational change to bind to substrate tightly (2) Substrates are converted to products (3) Products are releaed from the enzyme (4)
Vacuole
The organelle responsible for storing water in the plant cell is the
The two leaflets of a lipid bilayer are formed because
The polar head groups of phospholipids can interact with the polar interior and exterior of the cell
Increasing the temperature increases the rate of an enzyme-catalyzed reaction. Once a critical temperature is reached, the reaction stops. Why does this happen
The polypeptide chains in the enzyme denature
Select all of the statements that explain how different cells in the same organism produce different proteomes.
There may be differential gene regulation and alternative splicing. Two different cell types may produce different amounts of the same protein. Different cell types may alter their protein in different ways.
Pellagra:
Vitamin B3 (niacin) deficiencyNAD+ deficitloss of redox potential in cellular metabolism dermatitis, depression, diarrhea
During feedback inhibition, how does binding of the product inhibit enzyme function
When the excess product binds to the allosteric site, it causes a conformational change that prevents further binding of reactants to the active site
If you want to raise a Siamese cat with darker colors all over, where should you raise him?
a colder climate
Carbohydrates of the plasma membrane
are bonded to a protein or lipid. are located on the outer surface of the plasma membrane. can function as cell markers for recognition by other cells.
Phospholipids in the plasma membrane
can move within the bilayer
Facilitated diffusion
concentration is high to a region where its concentration is low through a passageway provided by a transport protein.
Isotonic
equal solute/water
Turgor pressure
force of water in cell that pushes against cell wall
Watermoves from
hypotonic to hypertonic
reasons why comeptitive and noncompetative inhibition of an enzyme are similar.
inhibitors can cause the rate of an enzyme-catalized reaction to decrease can impair the functioning of an enzyme
very low permeability
ions, atp,protiens,
Cold temp cholesterol
keeps membrane fluid
Warm temp cholesterol
less fluid
water flows from
low concentration to high
Hypotonic
lower solute conc./higher waters
Glycocalyx
protective coat in some bacteria & animal cells
Osmosis
simple diffusion of water across a selectively permeable membrane
active transport
solutes are moved across a membrane against their concentration gradient?
Coenzymes
some vitamins are coenzyme precursors
Mitochondria
the energy supplier for the cell? This organelle contains its own DNA
Double bond in acid tails
unsaturated kink in ta
Cofactors
usually a metal like zinc, calcium, magnesium, and iron
Vmax
velocity of reaction near maximal rate
high permeability
very small uncharged polar molecules
moderate permeability
water, urea
Cell Membrane
• Boundary • Bilayer • Selective permeability, regulates movement • Amphipathic