Biology test review

8.1

metabolism- refers to all of the chemical reactions (anabolic and catabolic) that occur in a living organism

metabolic pathway- linked series of chemical reactions occurring within a cell

• these are enzyme meditated, usually requiring a different enzyme at each step or stage

Induced fit- when an enzyme takes in the substrates it changes its shape slightly to either encourage bonds to form (anabolic) to break them apart (catabolic)

substrate specificity- enzymes have specific substrates

enzyme inhibitor- blocks the function of enzymes (competitive and non-competitive)

competitive inhibitors- interact with the active site. more substrate is needed to counter act the effect of the inhibitor

non-competitive inhibitors- interact with a secondary site (allosteric site), this interaction changes the overall shape of the enzyme thus blocking the active site.

statins- a group of medicines that can help lower the level of density lipoprotein (LDL) cholesterol in the blood.

• it’s the bad cholesterol and statins reduce the production of it inside the liver

• they are a competitive inhibitor of enzymes that produced cholesterol, this inhibition is temporary

penicillin

• background: bacteria walls are made of peptidoglycan

• the enzyme transpeptidase builds these walls by linking peptides together

• the antibiotic penicillin irreversibly binds to and permanently inhibits the activity of transpeptidase enzyme (non-competitive)

• as a result the cell walls cannot be made and the bacteria die

end-product-inhibition

• is used to regulate metabolic pathways

• the end product can bind to an allosteric state of the first enzyme in the pathway which slows the processes.

• ex: threonine is made into isoleucine, if too much isoleucine is made it will bind to the first enzyme to slow the process.

Cellular respiration

cell respiration- controlled release of energy from organic compounds to produce ATP

Aerobic vs. Anaerobic Respiration

• energy is neither created nor destroyed, energy is transferred or converted

• oxidation and reduction- this involves the transfer of electrons from one substance to another. this electron transfer also transfers potential energy

• oxidation results in lower potential energy. (red-higher potential energy)

electron carriers- can carry and give up electrons (therefore energy). they usually link oxidation and reduction in cells. NAD is the primary electron carrier.

• NAD to NADH is reduction

anaerobic respiration (fermentation)- allows for glycolysis- splitting of simple sugars (usually glucose) making a small amount of ATP

• the split is into two molecules called pyruvate

• 2 ATP molecules are produced

• pyruvate is further processed to release more energy

• this ATP yield is enough for small organisms like yeast and bacteria

Lactic acid Fermentation

• is in some animals, bacteria and some fungi

• makes a small amount of ATP

• makes lactic acid (lactate) as a waste product

• humans experience this when exercising due to oxygen debt

Alcohol Fermentation

• anaerobic

• in fungi, yeast, and some bacteria

• small yield of ATP

• produces ethanol (booze) and CO2 (bread)

• waste= CO2 ethanol

Glycolysis- small net gain of ATP without oxygen

step 1- Phosphorylation (addition of P) (glucose to hexose biphosphate)

• this required 2 ATP molecules

• this generate a hexose biphosphate molecule, this is unstable and allows the sugar to split easily

• makes molecules less stable therefore more reactive

step 2- lysis (hexose biphosphate to 2 triose phosphate)

• splits the hexose bisphosphate into 2 triose phosphate molecules

step 3- oxidation (is loss of electrons)

• involves another phosphorylation but does not require ATP. Inorganic phosphate Pi is added. two triose biphosphate molecules are produced. NAD is reduced to NADH + H.

step 4- ATP formation (2 pyruvate)

• involves the transfer of phosphate from each triose bisphosphate molecule to molecules of ADP. 4 ATP molecules are formed from the 4 Phosphate groups. (2 molecules of pyruvate remain)

end products: 2 ATP (2 lost and 4 gained), 2NADH +H, 2 Molecule pyruvate

Fate of pyruvate for animals

• if oxygen is low, pyruvate is used in lactic acid fermentation

• if oxygen is present, aerobic respiration continues, and pyruvate is absorbed into the mitochondrial matrix for aerobic respiration

4 stages of cellular respiration

1- glycolysis, 2-the link reaction, 3-the Krebs cycle, 4- oxidative phosphorylation

key understanding- in cellular respiration molecules are reduced and oxidized (glucose is oxidized and ADP is reduced to ATP)

aerobic respiration- requires oxygen and gives a large yield of ATP

Glucose + oxygen —-> Carbon dioxide + water + ATP energy

The Krebs cycle

know the differences between lactic acid fermentation and alcohol fermentation

the fate of the pyruvate

• if oxygen is deficient, pyruvate is used for anaerobic respiration

• if oxygen is present, aerobic respiration continues, and pyruvate is absorbed into the mitochondrial matrix where it is fully oxidized

Oxidative phosphorylation

• most ATP is made by ATP Synthase

• this is an integral protein that’s embedded in the membrane, it aids in facilitative diffusion of h+ ions, this causes the turning of the protein which helps turn ADP to ATP

• this enzyme works like a windmill, using the flow of ions to make ATP

• this current that turns this windmill is generate by electron transport chain

• there are many throughout the membrane and cristae

the inner membrane- holds special electron carriers to shuttle protons (ions) across the inner membrane into the Intermembrane space.

• the electron carriers (proton pumps) are energized by accepting electrons from NADH and FADH2, then passing electrons down the chain

• oxygen is the final acceptor in the ETC, O2 joins with the h+ ions to form water

• oxidative phosphorylation is divided into the ETC and Chemiosmosis

Chemiosmosis- the action of ATP synthase, the passive transport of protons down their concentration gradients back into the mitochondrion matrix.

Mitochondria

Cristae (long pieces of the membrane that exist throughout the mitochondria)- increase surface area

Inner Membrane- is where electron transport occurs, chain reaction and chemiosmosis

outer membrane- regulates transport in and out of the mitochondria (pyruvate in and ATP out)

Inter membrane- space where H+ ions concentrate

Matrix- link reactions in the Kreb cycle occur, and mitochondrial DNA can be found here

the mitochondria contains 70s ribosomes