Metabolism and Enzymes

Question 1

Metabolism

Answer 1

Taking energy in different forms, breaking into fundamental peices and building it into something useful

Question 2

Catabolsim

Answer 2

Breaking down of molecules

Question 3

Anabolism

Answer 3

Building up of molecules

Question 4

Sun

Answer 4

Direct source of energy from fusion reactions. Plants/organisms use energy (photosynthesis), use CO2 to make glucose molecules (cellulose)

Question 5

Enzymes

Answer 5

• Most are protiens
• Once it binds, creates enzyme-substrate complex
• Have active site where substrate binds
• Active site models: Lock and Key model (active site is perfect shape for substrate), Induced Fit model (active site/substrate can change slightly to fit substrate)
• Enzyme can build or break molecules, speed up reactions that would already happen in the body. Are catalysts and can be used several times
• Lower activation energy to break/build molecules
• Usually end w/ -ase (ex. lactase)
• Cofactors (inorganic molecule) and coenzymes (organic molecules) help
• Enzyme w/o cofactor: apoenzyme, w/ cofactor: holoenzyme
• Have ideal conditions
• Ex. Catalase - Hydrogen peroxide (H2O2) into water (40 million per second)
• Inhibition: Competetive: chemical blocking active site or Allosteric (binds to allosteric site and changes shape of enzyme or blocks activation site)
• Activation: Not produce until needed or activate w/ cofactors/coenzymes, pH or temperature

Question 6

Cofactors/Coenzymes

Answer 6

• Cofactors: inorganic molecule ex. heme, magnesium, zinc, pottasium
• Coenzymes: organic molecules ex. Thiamine/Vitamin B1 (vitamin derivatives)
• Coenzymes include: Tightly held (prosthetic) through covalent bonds (can be reused), and loosly held (cosubstrate) through weak bonds (must be regenerated)

Question 7

Enzyme optimal enviornment

Answer 7

• Temperature: Increase temp = increase activity as substrate/enzymes bump into each toher more. High temps can denature enzymes (teritary bonds). Most optimal at 36-37 degrees
• pH: Body uses energy to maintain pH, which can be used to activate/inhibit enzymes. Optimal pH depends on enzyme. In stomach: 2, In small intestine: 8, In blood: 7.4. As pH higher than optimal begins to denature proteins
• Concentration: More = more reactions but will plateu as all active sites are filled. Enzymes are saturated and functioning at maxiumum velocity. Almost linear until reaching Km - Michaelis contstant (1/2 of all sites filled). Will begin to curve after
• Km depends on type of concentration. Low Km=high affinity, High Km=low affinity

Question 8

Inhibition

Answer 8

Reversible Inhibition:
* Competitive: Resembles inhibitor Weak/noncovalent bonds (can be removed easily), binds to active site (out compete substrate). More substrate can out compete inhibitor to reverse inhibition. Vmax does not change, Km increases (lower enzyme affinity)
* Noncompetitive: Does not rememble substrate, binds to allosteric and changes shape of active site or blocks it. Substrate can still bind but it is not optimal (activity decreases). Vmax reduces, Km stays constant.
* Uncompetitive: Can only bind when substrate is in enzyme (site is created), deactivated enzyme. Vmax decreases, Km decreases.

Irreversible: Hard to unbind (covalent or non-covalent), only one that can be covalent. Blocks active site.

Some products can be inhibitors for enzymes higher up on the production chain

Ex. ACE inhibitor block angiotensin-converting enzyme (competitive), can’t convert Angiotensin 1 to Angiotensin 2. Angiotensin 2 can be involved in high blood pressure
Penicillin acts by inhibiting enzyme transpeptidase in bacteria which stops them from building cell wall