Biology 2 exam

second exam

in what ways can some proteins move through a membrane?

Lateral movement through membrane (freely able to float)

kinks in tail are…

unsaturated fatty acids

straight tails are…

saturated fatty acids

Straight and kinked tails both can form…

phospholipid bilayers

phospholipid bilayers made with straight tails are…

more compact and has less fluidity

phospholipid bilayers made with kinked tails are…

less compact and has more fluidity due to the kinked tails.

why is fluidity of membrane important for animals?

they will be able to moderate what can and can’t go through

animals that live in warmer environments have a more…

compact phospholipid bilayer (saturated fats) due to not being too liquid

animals that live in colder environments have a less…

compact phospholipid bilayer (unsaturated fats) due to not being too solid

Cholesterol (amphipathic)

aids in the phospholipid bilayer by making it less compact

Mostly hydrophobic, but has a hydroxyl group which is hydrophilic

Amphipathic molecule

has both polar and non-polar regions

Cholesterol (what it does)

moderator of fluidity of membrane.

Brings it into a moderate range

if it gets too solid, makes it more fluid

if it gets too fluid, makes it more solid

What helps the phospholipid maintain it’s shape?

cholesterol giving it strength and rigidity

What determines most of the membrane specific functions?

Proteins embedded in the membrane

What prevents proteins from leaving membrane?

Polarity (an amphipathic molecule)

What is an embedded protein called?

Integral membrane protein

Integral membrane proteins are

partially hydrophobic and hydrophilic due to the different regions of polarity

Transmembrane proteins

Proteins that extend throughout the whole membrane due to different hydrophobic and hydrophilic regions. THE TWO ENDS ARE NOT THE SAME. ONE COULD BE A RECEPTOR WHICH MEANS ITS POINTING OUTWARD TO RECIEVE WHAT IT NEEDS

Peripheral membrane proteins

travel along the surface of membrane

what do membrane proteins do?

-transport (channel, carrier, some require energy some don’t)

-enzymes (if reactions need to take place near membrane it’ll be embedded in the membrane)

-attachment to extracellular matrix or cytoskeleton serving as an anchor

-cell to cell recognition to provide information

-cell to cell joining (ex: skin cells binding to other skin cells since they recognize what they are)

-Signal transduction way a cell reacts to a specific signal involving a receptor protein

Cell to cell recognition

Mostly a carbohydrate but there are two types: glycoprotein or glycolipid

Helps recognize foreign or non-foreign molecules which is important

Glycoprotein

carbohydrate and protein

glycolipid

carbohydrate and lipid

Sidedness in membrane proteins

If they are flipped won’t be able to do its function, have to be oriented in a specific, correct way

How do membrane proteins get to the membrane?

Through the ER system via the cytoplasm

If protein is not made in the cytoplasm, then where will it be made?

Bound ribosomes (rough ER)

Types of molecular transport

Passive diffusion (Simple diffusion, facilitated diffusion)

Active Transport

Passive diffusion

doesn’t require diffusion

Active diffusion

requires energy

Simple diffusion

Area of high to low. Works with nature going down it’s concertation gradient

specific to molecule

Does it till it reaches equilibrium

Facilitated diffusion

helping molecules and ions to travel from one side to the other going down it’s concentration gradient with the help of transport proteins

Osmosis

water goes to an area of low concentration to an area of high concentration since it’s a small enough molecule to dilute the solution until it reaches equilibrium

DOES NOT REQUIRE ENERGY

Sodium potassium pump

common in all animals

transport 3 sodium ions from the cytoplasm to the outside world. in return takes two potassium ions from the outside world into the cytoplasm

MOVING AGAINST CONCENTRATION GRADIENT

A transmembrane protein is going to have three binding sites to be liked with potassium, ATP will hydrolyze and release a phosphate group releasing a phosphate group. encourages a change shape

require energy (ATP)

Channel protein

provide corridors for specific molecules and ions to cross the membrane

Hydrophilic molecules traveling through membrane

Will not be able to penetrate through membrane without help of transport proteins

Most nutrients are….

hydrophilic molecules

(Hydrophilic)Fatty acids moving through molecule

will penetrate membrane without help

Do carrier proteins require enery?

No they don’t require energy but some use energy ATP

What determines if you need energy or not?

Through diffusion

Hypertonic

High solution, low water cell will shrivel

Hypotonic

Low solution, high water cell will explode, plant cell will be turgid

Isotonic

Water and solute solution is equal

Cells will usually be found in what type of solution?

Hypotonic, water wants to go in

What helps plant cells maintain balance?

Cell wall

Carrier proteins

One side will open for the certain molecule it’s looking for it and move it into the membrane through a slightly different shaped end. REQUIRE NO NET ENERGY

Active Transport

Against nature

USES ENERGY

Proton pump

Active transport

Goes against nature

Membrane potential

One side of the membrane (outside) is positive and the other is negative (inside)

Co-Transport system

artificially create a concentration gradient to be used to transport nutrients against its concentration gradient

Top of proton pump

Pushing H+ out, creating a concentration gradient

What occurs in a proton pump?

Membrane protein has two binding sites

one is binding site for H+, allowing H+ back into cell taking by ONLY bringing in other nutrients (ex: sugar)

Why is it important for H+ not to reach equilibrium in a cell?

Other nutrients can’t be taken in

Bulk transport (Two types)

Exocytosis, and endocytosis

Exocytosis

moving things out of cell in bulk

Example: make secretory proteins from endomembrane system, hormones are going to be transported with a vesicle and fuses with membrane and dumping out all it’s nutrients

Endocytosis

moving things into cell in bulk

Endocytosis has three versions, what are they?

Phagocytosis, Pinocytosis, Receptor-Mediated Endocytosis

Phagocytosis

“Cellular eating”

Engulfing another cell or nutrients, encloses it into a membrane compartment (food vacuole) digesting it

Pinocytosis

A smaller scale

“Cellular drinking”

Taking “sips” of molecules

Receptor-Mediated Endocytosis

Will have certain receptors on surface of membrane, and only certain molecules will bind to it. Cell will take the molecules making a vacuole for it

Metabolism

subtotal of all chemical reactions that occur in the cell. converts matter into a different form

Does all metabolism reactions require energy?

no

Catabolic reactions (catabolism)

breaking down of large molecules into smaller molecules (example: protein → amino acids)

Anabolic reactions (anabolism)

building smaller molecules, into bigger molecules

require catalyst (enzymes)

each reaction needs its own enzyme

ON TEST how many enzymes catalyzes a reaction

ONE ENZYME CATALYZES, ONE REACTION

(example: 10 reactions, 10 enzymes)

Why can only one reaction occur at a time?

Over time the shape of the substrate will change

ON TEST What is the output AND product in catabolic reactions?

Energy ATP

ON TEST What is the reactant in anabolic reactions"?

Energy ATP

What type of reaction is catabolic?

Exergonic

Exergonic

Energy is released, it’s the PRODUCT

What type of reaction is anabolic?

Endergonic

Endergonic

energy is needed, absorbed

Where is the energy that endergonic gets, from?

Exergonic reactions

What is ATP for energy?

The middleman, nucleic acids. Nucleotide with phosphate groups

ON EXAM What does the word Tri mean in ATP

means ATP has THREE PHOSPHATE GROUPS

How does ATP work as a middleman?

stores ATP

ATP

Energy

Adenine Tri-Phosphate

Energy stored in phosphate group

holding cell for energy

whene energy is needed…

cell will be access ATP through a hydrolysis reaction

What happens to the ATP during a hydrolysis reaction

one phosphate group will be snipped off, becomes a di-phosphate (only two phosphate groups) and in-organic phosphate

energy us then released

ON TEST where is ATP being made?

in cytoplasm and/or mitochondrial matrix

How is energy being reused?

ADP will be the input, attach an inorganic phosphate to ADP → ATP

anabolic/endergonic reaction

What is ATP after being broken down?

ADP (two phosphate)

ATP cycle

ATP is constantly being broken down for energy when the cell needs it, and constantly being remade whenever eating

When is ATP being used?

When the cell needs it

Enzymes

proteins

speed up metabolic reactions

Surcase

type of enzyme that helps speed up the process up a reaction without being consumed by the reaction

Do enzymes have a specific shape?

YES

Active site

where the reaction is going to happen

substrate

molecule will fit into that active site, enzyme will be worked here. Fits nicely, reaction will take place

Can a random molecule go into any active site?

No, because it doesn’t have the specific shape and doesn’t fit

Induced fit model

molecule is dynamic. When substrate binds to enzyme, it changes shape

Are enzymes reusable? Why?

Yes. Because they are not the reaction, they just help speed up the process and can be reused again

Cells are…

control freaks

How do cells regulate reactions?

Regulates how many enzymes there are

Competitive inhibition

A similar shape substrate will bind to the active site, preventing the actual substrate that needs to take it’s place. reaction can not occur

Non-competitive inhibition

Enzyme has two sites where enzyme can bind to, one of them being a regulatory site. A similar shaped substrate that can fit into that spot will bind to the regulatory site, changing the shape of the whole enzyme. The active site now has changed, and the correct enzyme can not bind to the active site. No reaction can take place

Regulatory site

can possibly change the shape of the enzyme

What would happen if enzymes were not regulated?

you’ll have a surplus of certain enzymes less of one

What reaction breaks down ATP?

A hydrolysis reaction occurs and breaks off one phosphate group

ATP is the…

input

Energy is the…

output