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