Bio 130 Exam 2

All cells have these

The Plasma membrane model is referred to as?

The plasma membrane is considered a mosaic of?

What is the purpose of the plasma membrane?

What is the extracellular environment?

What is the cytosol enviroment?

What is the main body of the plasma membrane made of?

What are the protein recognitions sites on the Plasma membrane?

This protein spans all the way through the membrane from one side to the other.

Phospholipids are amphipathic molecules. What does that mean?

The two leaflets of the plasma memb. are?

What are the two types of Integral or intrinsic membrane proteins?

These proteins have regions that are physically embedded in the hydrophobic portion of the phopholipid bilayer

For these proteins an amino acid of the protein is covalently attached to a lipid.

These proteins are noncovalently bound either to integral membrane proteins that project out from the membrande or to a polar head groups of phospholipids.

Approx how many of all genes encode transmembrane proteins?

Plasma membrane are important for ?

These can be used to predict the number if transmembrane proteins.

Is the trend of 20-30% gene encoding true for all facets of life?

How do you view the plasma membranes?

The sample is thin sectioned and stained with heavey metal dyes. These dyes bind tightly to the polar head groups but not the fatty acyl chains. This makes the membranes resemble railroad tracks

specialized form of TEM used to analyze the interior of the phospholipid bilayer. Samples frozen in liquid N and fracurted w/ a knife. the leaflets fracture into the P face (inside) and the Eface (outside). can provide significant details about the membrane protein

Most lipids can rotate freely around their long axes and move laterally within the membrane leaflet, thus membranes are concidered?

But “flip-flop” of lipids from one leaflet to the opposite leaflet does not occur spontaneously. what is needed to move the lipids

What does flippase require to move lipids?

Certain lipids associate strongly w/ eacgother to form what?

These lipid rafts have some differences than the rest of the membrane.

What are the factors that effect fluidity of te plasma membrane?

How does the length of fatty acyl tails effect fluidity?

how does the presence of double bonds effect the fluidity of plasma membranes.

How does the presence of cholesterol make the membrane less fluid like?

What ass the name of the experiments on lateral movements done in 1970?

Not all integral membrane proteins can move. depending on the cell tupe what percent are restricked in their movement?

What are the Integral membrane proteins may be bound to that restrict proteins from moving laterally.

Membrane proteins may be also attached to molecules that are outside the cell, such as the interconnected network of proteins that forms the

In Eukaryotes what systems work together to synthesize lipids?

These are made via enzymes in cytosol or taken into cells from food.

Where does the processing of the fatty acid process occur?

How are lipids transfed?

How do the lipids in the ER diffuse to the nuclear envelope?

Where are lipids transpoted?

these extract lipid from one membrane for insertion in another.

Except for proteins destined for semiautonomous organelles, most transmembrane proteins are directed to?

From the ER, membrane proteins can be transferred via _____ to other membranes of the cell

This is the process of covalently attaching carbohydrate to a protein or lipid.

Carbohydrate to lipid

Carbohydrate to protein

These can serve as a recognition signals for other cellular proteins. Play a role in cell surface recognition and helps protect proteins from damage

These are Glycosylation that have an attachment of carbohydrate to nitrogen atom of asparagine side chain

These are glycosylation that have addition of sugars to O2 atom of serine or threonine side chains. Occurs only in Golgi

Since the membrane is selectively poermeable only some ions and molecules can pass through. This ensures that?

What are the ways to move across the membranes?

Passive Transport can be broken down into two types:

No energy: Diffusion of solute through a membrane w/o transport protein

No energy: Diffusion of a solute through a membrane w/ the aide of a transport protein.

This requires energy - up or gainst gradient.

Barrier to hydrophilic molecules and ions due to

Rate of diffusion depends on?

Diethylurea diffuses______ faster through the bilayer than urea, due to nonpolar ethyl groups

Living cells maintain a relatively constant internal environment different from their external environment. What are the two types?

Equal water and solute concentrations on either side of the membrane

Solute concentration is higher (and water concentration lower) on one side of the membrane

Solute concentration is lower (and water concentration higher) on one side of the membrane

Water diffuses through a membrane from an area with more water to an area with less water

If the solutes cannot move, water movement can make the cell ____ as water enters or leaves the cell.

the tendency for water to move into any cell

How do cells maintain their size and shape?

shrinkage of a cell in a hypertonic solution

swelling and bursting of a cell in a hypotonic solution

What prevents mahjor changes in cell size?

pushes plasma membrane against cell wall

– plants wilting because water leaves plant cells

Freshwater protists like Paramecium have to survive in a strongly hypotonic environmene. To prevent osmotic lysis, _______ take up water and discharge it outside the cell

are transmembrane proteins that provide a passageway for the movement of ions and hydrophilic molecules across membranes

There are two classes of transport proteins based of type of movement

Form an open passageway for the direct diffusion of ions or molecules across the membrane. Most are gated

Name an example of a Channel transport protein

Also known as carriers Conformational change transports solute across membrane. Principal pathway for uptake of organic molecules, such as sugars, amino acids, and nucleotides

Transporter of single molecule or ion

Transporter of two or more ions or molecules transported in same direction

Transporter of Two or more ions or molecules transported in opposite directions

Movement of a solute across a membrane against its gradient from a region of low concentration to higher concentration. Energetically unfavorable and requires the input of energy

Active transport that uses a pump. Directly uses energy to transport solute

Active Transport that uses a different gradient.? Uses a pre-existing gradient to drive transport

Actively transports Na+ and K+ against their gradients using the energy from ATP hydrolysis

Na+/K+-ATPase 3 Na+ are exported for every

exports one net positive (+) charge

Used to transport large molecules such as proteins and polysaccharides

Material inside the cell packaged into vesicles and excreted into the extracellular medium. Plasma membrane invaginates (folds inward) to form a vesicle that brings substances into the cell

Three types of endocytosis:

ability to promote change or do work

Energy associate with movement

Energy due to location or structure

Chemical energy, the energy in molecular bonds, is a form of

1st law of thermodynamics

Second Law of Thermodynamics

What happens as entorphy increases in organisms?

Total energy is?

Energy transformations involve an increase in

Amount of energy available to do work

What is the formula for GIbbs free energy?

what do the symblos mean in Gibbs free energy equation?

Gibbs free energy reactions facts?

What is the key factor of the free energy change?

What is the formula for the free energy change?

?G<0 (negative free energy change)

?G>0 (positive free energy change)

What do cells use to drive rxns?

Can an endergonic rxn be coupled to an exergonic rxn?

give an example of a coupled rxn.

Since spontaneous rxns are not fast what do they need to spped up?

an agent that speeds up the rate of a chemical reaction without being consumed during the reaction

protein catalysts in living cells

RNA molecules with catalytic properties

Initial input of energy to start reaction. Allows molecules to get close enough to cause bond rearrangement. Can now achieve transition state where bonds are stretched

What are some Common ways to overcome activation energy?

location where reaction takes place

reactants that bind to active site

formed when enzyme and substrate bind

Substrate binding. Enzymes have a high specificity for their substrate

THis phenomenon in substrate binding that is an interaction also involves conformational changes

What are the two inhibition types?

Molecule binds to active site. Inhibits ability of substrate to bind – more substrate needed

Inhibitor binds to allosteric site, not active site

What are some other requirments for enzymes?

molecules permanently attached to the enzyme

usually inorganic ion that temporarily binds to enzyme

usually inorganic ion that temporarily binds to enzyme

Enzymes are effect by the environment. What is the biggest factor?

is found in all living organisms, and involved in cleaving tRNA molecules

Chemical rxns occur in _____ and each step is coordinated by a specific _____.

These pathways are exergonic and breakdown cellular components. These also are used for recycling building blocks.

These pathways are Endergonic, Synthesis cellular components, and must be coupled to exergonic rxn.

How is energy stored?

What are the two ways to make ATP?

Enzyme directly transfers phosphate from one molecule to another molecu

Energy stored in an electrochemical gradient is used to make ATP from ADP and Pi

rxn where Electron removed from one molecule is added to another

removal of electrons

addition of electrons

NAD+ means?

NADH is useful intwo ways:

Make large macromolecules or smaller molecules not available from food. Require energy inputs from intermediates (NADH or ATP) to drive reactions. Regulation of metabolic pathways

This turns genes on and off

Cell-signalling pathways like hormones

Feedback inhibition – product of pathway inhibits early steps to prevent over accumulation of product

Most lar molecules exist for a relatively short period of time. What is their breakdown called?

time it takes for 50% of the molecules to be broken down and recycled

All living organisms must efficiently use and recycle organic molecules. Expression of genome allows cells to respond to changes in their environment. How is this done?

mRNA degradation important. How so?

mRNA degradation takes place two ways:

mRNA degradation where enzymes cleave off nucleotides from end.

mRNA degradation where multiprotein complex uses exonucleases

A large complex that breaks down proteins using protease enzymes. these Proteases cleave bonds between amino acids

This tags target proteins to the proteasome to be broken down and recycled

Ubiquitin tagging allows the cell to:

Lysosomes contain ______ to break down proteins, carbohydrates, nucleic acids, and lipids

How do lysosomes take up digested substances?

Recyling worn out organelles using an autophagosome