BY123L Exam 2

What are enzymes composed of?

one or more polypeptide chain

What is a coenzyme?

an organic molecule

What are cofactors?

metallic ions (non-protein portion of enzyme) that will bind to either the active site to activate it or allosteric site (Opposite of it)

Can a protein activate without a cofactor?

no

What is a competitive inhibitor?

a molecule that competes with the substrate to bind in the active site of an enzyme

What is a noncompetitive inhibitor?

a molecule that binds to an allosteric site on the enzyme creating a conformational change so the substrate can no longer fit

Can competitive inhibitors be overridden? If so, how?

competitive inhibitors can be overridden by adding more substrate

Can noncompetitive inhibitors be overridden? If so, how?

noncompetitive inhibitors cannot be overridden

What does temperature determine?

the amount of kinetic energy

What would lowering the temperature do to an enzyme?

there is less kinetic energy so the products would form much slower

What do enzymes do?

speed up the rate of chemical reactions

How do enzymes speed of chemical reactions?

by lowering the activation energy

Are enzymes consumed in a reaction?

no

If something were to disrupt the bonds in an enzyme, what happens to the enzyme?

the function of the enzyme will be disrupted

Which reaction requires a higher activation energy, catalyzed or uncatalyzed?

uncatalyzed

What does an enzyme bind to?

a substrate

Where do substrates bind to enzymes?

the active site

What kind of fit is it when a substrate binds to an enzyme?

induced fit

What does specificity mean in terms of enzymes and substrates?

most enzymes are very specific so they perform one chemical reaction on one substrate

What are the two enzyme helpers?

coenzymes and cofactors

What would raising the temperature do to an enzyme?

the enzyme activity will increase

What happens to an enzyme at optimum temperature?

the enzyme activity is the highest it will get

If the temperature increases above the optimum temperature, what will happen to the enzyme?

the enzyme will begin to denature and the substrate can no longer fit so there will be a decrease in enzyme activity `

What does pH measure?

number of hydrogen ions in a solution

At what pH is there the highest enzyme activity?

optimum pH

What happens when you deviate from optimum pH?

there will be a decline in enzyme activity

What do inorganic ions interfere with in enzymes?

ionic bonds

Regarding enzyme concentration, having more enzymes will have what effect on the reaction?

the more enzymes there are, the faster the reaction will take place as long as the substrate is not limiting

Regarding substrate concentration, having more substrate will have what effect on the reaction?

the more substrate there is, the more the activity will increase up until the saturation point

What is the saturation point?

the max amount of activity where all enzymes are bound with substrate

What was the enzyme used in the lab for topic 6?

catecholase

What was the substrate in topic 6?

catechol

What was the optimum pH for catecholase?

8

What was the importance of potato juice in the enzyme lab?

the potato juice contained the enzyme catecholase

What is cellular respiration?

the process that organisms use to convert food to energy by breaking down carbohydrates (usually glucose)

During aerobic respiration, glucose reacts with oxygen to form what?

ATP

What does ATP stand for?

adenosine triphosphate

What is the primary energy molecule used in living things?

ATP

What is the equation for cellular respiration?

glucose + oxygen --> carbon dioxide + water + ATP

What is oxidation?

loss of electrons

What is reduction?

gain of electrons

What are the four metabolic pathways of cellular respiration?

1. glycolysis

2. transition reaction

3. Krebs Cycle

4. oxidative phosphorylation

Where does glycolysis occur?

cytoplasm

What happens in glycolysis?

glucose is broken down into 2 pyruvates (3C)

How much energy is required in glycolysis?

2 ATP

How much energy is made in glycolysis? What is the net?

4 ATP total, 2 net ATP

How is ATP made?

substrate level phosphorylation where a phosphate (Pi) is added to ADP

What is the major enzyme in glycolysis?

dehydrogenase

What are the products of glycolysis?

2 pyruvate, 2 ATP, 2 NADH

What is the transition reaction also called?

pyruvate oxidation

Where does the transition reaction occur?

matrix of mitochondria

What happens during the transition reaction?

pyruvate is converted to acetyl-CoA where carbon is removed in the form of CO2 and NaD is reduced to NADH

What are the products of the transition reaction?

2 acetyl-CoA, 2 CO2, 2 NADH

Where does the Krebs cycle occur?

matrix of mitochondria

Overall, what happens in the Krebs cycle?

acetyl-CoA (2C) combines with 4 carbon oxaloacetate (4C) to form 6 carbon citrate (6C)

What are the products of the Krebs cycle?

ATP, NADH, FADH2, CO2

For one acetyl-CoA, how many ATP are formed? CO2? NADH? FADH2?

1 ATP, 2 CO2, 3 NADH, 1 FADH2

Why do you use a blank for a spectrophotometer?

so that the machine knows what absorbance to measure meaning that once the blank has been zeroed, it will not record the absorbance of whatever is in the blank

What is a negative control?

experimental product where nothing happened, there was no change

What is a positive control?

experimental product in which a reaction did occur, there was a change

What happened to DPIP as it accepted hydrogens?

it decolorized

Where does the electron transport chain occur?

across the inner membrane of mitochondria

Where is the most ATP produced?

electron transport chain

In the ETC, each carrier alternates between what?

oxidized and reduced state

In the ETC, what happens to the electrons at each step?

they are moved down to a lower concentration gradient at each step

What happens to the hydrogens in the ETC?

hydrogens are pumped into the inner membrane space in order to partake in the proton gradient

How are the electrons pulled through the ETC?

oxygen pulls the electrons through the ETC due to high electronegativity

How is the energy of electrons transferred to the bonds of ATP?

through a process called chemiosmosis

Describe anaerobic respiration in animals

pyruvate+NADH→Lactate+NAD; only 2 ATP are made; toxic process because animal cells need oxygen

What is fermentation?

an alternative method of making ATP when O2 is not available

What is the end product of fermentation?

convert pyruvate to alcohol +CO2

What is a facultative anaerobe?

an organism that can live with or without oxygen

What is an obligate anaerobe?

Organism that will die in the presence of oxygen

What is an obligate aerobe?

an organism that cannot live without oxygen

What is the final electron acceptor in the ETC?

Oxygen

What was the respiration in plant embryos experiment testing for?

testing to see whether or not the seed's electron transport chain was working

What is succinate?

a substrate

What is malonate?

competitive inhibitor of succinate dehydrogenase

What is succinate dehydrogenase?

an enzyme found in the mitochondria

What is photosynthesis?

the process in which light energy is converted into chemical energy in the form of glucose

What is the equation for photosynthesis?

6CO2 + 12H2O + light energy = C6H12O6 + 6O2

Where is solar light energy trapped?

chloroplasts

What are photoautotrophs?

organisms that are able to undergo photosynthesis

What are the main pigments of photosynthesis?

chlorophyll a, chlorophyll b, carotenoids

Where are chlorophyll a and b found?

in the thylakoid membrane

Where must the light dependent reaction take place?

in light

Where does the Calvin cycle take place?

stroma of the chloroplast

What goes into the Calvin cycle?

ATP and NADPH

What are the products of the Calvin cycle?

carbohydrates

In the Calvin cycle, how is most of the energy stored?

by carbon dioxide fixation in energy-rich carbohydrates

The shorter the wavelength, the ____________ the energy

higher

Why do plants not absorb green colors?

the green color is a reflection because plants contain other pigments that absorb other colors

What is chromatography?

process of separating a complex mixture into its components based on solubility (polarity); more oxygen = more polar; zeaxanthin = xanthrophyll

What happens during mitosis?

DNA is duplicated and distributed evenly to two daughter cells

What is a genome?

the entire set of genetic material carried by a set of chromosomes

What are sister chromatids?

2 identical copies of DNA held together by a centromere

What is cytokinesis?

division of the cytoplasm

What happens in interphase?

chromosomes duplicate to prepare for cell division, DNA is replicated, enzymes and proteins synthesize to prepare for cell division

What happens during prophase?

nucleoli disappear, chromosomes condense, and spindle fibers form

What happens during metaphase?

chromosomes line up in the middle of the cell, centrioles are at opposite poles in cytoplasm