BIO 120: Exam 2 Study Guide

What is the difference between catabolic and anabolic pathways?

Catabolic:

-"Downhill"

-Release Energy

-Exergonic

-Spontaneous

-G

What are the two laws of thermodynamics?

First Law of Thermodynamics:

-Energy cannot be created or destroyed, it can only be converted from one form to another

-During every energy transfer or transformation, some energy is unusable, and is often lost as heat

Second Law of Thermodynamics:

-All systems tend to become more disorganized or random

-Increase in Entropy (randomness)

Energy flows into a system as ? and leaves as ?

Light, heat

-Energy flows into a system as light and leaves as heat

What does negative Gibbs Free energy mean?

It is catabolic, releases energy; spontaneous; doesn't requires energy

What is exergonic?

-Exergonic and endergonic releases to the free energy of a process - release of energy through work

Exergonic:

-Process with a net release of free energy and is spontaneous

-Catabolic

-G

What is endergonic?

-Exergonic and endergonic releases to the free energy of a process - release of energy through work

Endergonic:

-Absorbs free energy from its surroundings and is not spontaneous

-Anabolic

-G>0

-Requires energy

-Active transport

-Cell movements

-Anabolism

-ADP + P --> ATP

What is spontaneous?

-G

What is non spontaneous?

-G>0

-Non spontaneous

-The reaction is spontaneous in the reverse direction

-Need energy, its not free

-Photosynthesis

ATP is the energy currency of the cell that helps to fight against what (in terms of the 2nd law of thermodynamics)?

??

What are enzymes?

-Enzymes lower the energy barrier

-A catalytic protein

-Do not affect the change in free energy (G)

-The accelerate reactions that would occur eventually

-Reusable as long as they aren to denatured

-

How do enzymes help reactions?

-Enzymes speed up metabolic reactions by lowering energy barriers

What is the substrate?

-What the enzyme binds to to from an enzyme substrate complex

-The reactant that an enzyme acts on is called the enzyme's substrate

What relationship do a substrate and enzyme have?

"Puzzle piece", "lock and key"

-Enzyme-substrate complex

What is the binding site called in an enzyme?

-Active site

-Allosteric site

How does the enzymes environment affect the enzyme ability to function?

-An enzyme's activity can be affected by general environmental factors such as temperature and pH

-Chemical that specifically influence the enzyme

-Each enzyme has an optimal temperature and pH in which it can function, denatured when not at optimal conditions

-Optimal conditions favor the most active shape for the enzyme molecule

-Enzymes must be the right shape

-Amino acids changes (mutations) in an enzyme could alter its function

-Enzymes are proteins encoded by genes

-Changing the amino acid sequence will influence how it folds and what could bind in the active site

-Changes (mutations) in genes lead to changes in amino acid composition of an enzyme

-Altered amino acids in enzymes may alter their substrate specificity

-Regulation of enzyme activity helps control metabolism

-Chemical chaos would result if a cell's metabolic pathways were not tightly regulated

-A cell does this by switching or or off the genes that encode specific enzymes or by regulating the activity of enzymes

-Allosteric regulation: may either inhibit or stimuli an enzyme's activity

What is competitive inhibition?

-Another substrate binds into the active site

-Original substrate can not bind

-Competes for space

What is noncompetitive inhibition?

-Impede enzymatic reactions by binding to another part or allosteric site, of the molecule causing a shape change making the active site less effective

-2 Ways:

-Bond and cover the active site

-Change the shape all together

What is allosteric inhibition?

-Impede enzymatic reactions by binding to another part or allosteric site, of the molecule causing a shape change making the active site less effective

-2 Ways:

-Bond and cover the active site

-Change the shape all together

What is cooperative and feedback inhibition?

-Allosteric regulation: may either inhibit or stimulate an enzyme's activity

Cooperative:

-A form of allosteric regulation where the binding of one substrate molecule "primes" an enzyme to act on additional substrate molecules more readily

-Is allosteric because binding by a substrate to one active site affects catalysis in different active site

Feedback Inhibition:

-The end product of a pathway inhibits the function of an enzyme earlier in the pathway to prevent excess product form being formed

-Energy saver!

-Used in many metabolic mechanisms as a way to regulate its activity

-A pathway is not always "on" they cycle between active and inactive. One mechanism of regulation is called feedback inhibition

-The end product of a pathway shuts down the pathway

-Prevents a cell from wasting chemical resources by synthesizing more product than is needed

How are inhibitions in enzymes helpful?

-Prevents a cell from wasting chemical resources by synthesizing more product than is needed

??

What is cellular respiration?

-2nd Law of Thermodynamics

-Highly ordered and organized conditions are not highly favored and required energy to occur

-As a result thousands of reactions (helped by enzymes) are needed a day to maintain cellular organizations and need energy

-Body produces ATP

-Then uses ATP-ADP to promote energetically unfavorable but biologically necessary reactions

What organisms carry out respiration?

-Bacteria

-Protists

-Fungi

-Plants

-Animals

-Mitochondria

What is the end product of cellular respiration? (why is it done)

ATP

What type of pathway is cellular respiration?

Catabolic

What happens in glycolysis? What molecules made? What byproducts are made? Where does it occur? How do the products move into the mitochondria? Via what?

-Breaks down glucose into two molecules of pyruvate

-Occurs outside of mitochondria in the cytoplasm

-6 carbon glucose

-Make 2 pyruvate, NADH, 2 ATP

-Diffuses into mitochondria

-Goes to pyruvate dehydrogenase complex

-Converts 3C to 2C and Acetyl CoA

-CO2 is waste

-Off to Kreb's cycle

What happens in the Kreb's cycle? What comes out of it, waste products and reduced molecules?

-Acetyle CoA combine with oxaloacetate, goes through cyclic pathway

-Pyruvate is now completed, converted to CO2

-NADH

-FADH2

-ATP

-Completes the breakdown of pyruvate to CO2

What is the electron transport chain? Where does it occur? How?

-All energy that was in the glucose is now in NADH and FADH2

-Transfer those electrons to create an electrochemical gradient that will then flow back through (as hydrogen) ATp synstahse and convert ADP back to ATP for cellular work

-All done in the presence of oxygen

-In the inner membrane (cristae) of the mitochondrion

What is ATP synthase?

-Electron transfer in the electron transport chain causes hydrogen to be pumped out

-This creates an electrochemical gradient

-Hydrogen travels back across the

membrane through the ATP synthase complex

-ATP synthase uses the exergonic flow of hydrogen to drive phosphorylation of ATP

-Windmill, water wheel

Where is most of the ATP made?

-Oxidative phosphorylation in the ETC

-Electron transport chain

What is an oxidized molecule?

-Losing electrons

What is a reduced molecule?

-Gaining electrons

What happens when there is not oxygen present?

-Anaerobic respiration

-Fermentation

-Alcohol fermentation

-Lactic acid fermentation

What is fermentation and the lactic acid cycle?

Fermentation:

-Regenerates NAD+ so glycolysis can continue

-Two common types are alcohol fermentation and lactic acid fermentation

Alcohol Fermentation:

-Convert pyruvate to alcohol (ethanol)

-1. releases CO2 (bubbles)

-2. Ethanol made

-Pyruvate is converted to ethanol in 2 steps, with the first releasing CO2

Lactic Acid Fermentation:

-Build up is why your muscles are sore after a run

-1 step process

-Cheese and yogurt

-Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarce

-Pyruvate is reduced by NADH, forming la state as an end product with no release of CO2

What is photosynthesis? That is, what is the ultimate purpose of this set of biochemical reactions?

-The process that feeds the biosphere

-Energy transformation

-Converts light energy to the chemical energy of food

What organisms carry out this biochemical process of PSN? Autotrophs/heterotrophs?

-Autotrophs

Where in a cell do the reactions of PSN occur?

-Chloroplasts, leaves, chlorophyll, stomata

Describe the structure of a chloroplast, especially the number of membranes and how they are arranged:

-Chlorophyll = green pigment in chloroplasts

-Double membraned

-Thylakoid are discs inside

-Stomata is jelly/fluid

How does CO2 get into a leaf (the structure and the process)?

-Stomata

Know the chemical reaction formulas for both PSN and respiration:

PSN:

6CO2 + 6H2O ------> C6H12O6 + 6O2

Cellular Respiration:

C6H12O6 (s) + 6 O2 (g) → 6 CO2 (g) + 6 H2O (l) + energy

Under what circumstances would a plant give off more Co2 than it takes up?

What are the 2 sets of reactions that make up PSN (light reactions and Calvin Cycle)? What are the products and reactants of each?

Where EXACTLY does each reaction take place in the chloroplast (light reaction and Calvin Cycle)?

What are the most important PSN pigments?

What are the 3 phases of the Calvin Cycle?

What is the enzyme that fixes CO2 in the fixation of the Calvin Cycle?