Biology 1124 Exam 3 (Questions 1-50)

What is metabolism?

the totality of an organisms chemical reactions

What are major metabolic processes organized into?

metabolic pathways

What are metabolic pathways?

a step-wise sequence of chemical reactions

How is each step in a metabolic pathway mediated?

by a specific enzyme

What are enzymes?

proteins that regulate metabolism

What do enzymes act as?

catalysts

What are catalysts?

chemical agents the speed up chemical reactions, but are not consumed by the reaction

What do enzymes control?

almost all chemical processes in cells

How many enzymes do cells contain?

thousands of different enzymes

What is the bonding site of an enzyme called?

active site

What does the sucrase enzyme do in the sucrose reaction?

sucrase enzyme will make it energetically favorable for this covalent bond to break

What is the name of the enzyme that breaks up sucrose?

sucrase

What is sucrose?

glucose + fructose

What are the two basic kinds of metabolic pathways?

catabolic

anabolic

What is a catabolic pathway?

complex molecules are broken down into simple molecules

What is an anabolic pathway?

biosynthesis pathways in which simple molecules are combined to form complex molecules

What do catabolic pathways do with energy?

release it

What do anabolic pathways do with energy?

consume it

What does metabolism work through?

coupled reactions

What are coupled reactions?

energy consuming reactions are coupled with energy liberating reactions

What do exergonic reactions do with energy?

release it

What do endergonic reactions do with energy?

consume it

What kind of reaction is a catabolic pathway?

exergonic

What kind of reaction is an anabolic pathway?

endergonic

What powers endergonic reactions?

exergonic reactions

What are the three main kinds of work cells do?

chemical

transport

mechanical

What is chemical work?

endergonic reactions that build molecules

What is an example of chemical work?

make polymers from monomers

What is transport work?

pumping substances across membranes against their concentration gradient

What is mechanical work?

beating cilia, muscle cell contraction, movement of chromosomes in cell division

What powers cell work?

ATP

What is ATP?

adenosine triphosphate

immediate source of energy for most metabolic reactions

What are the components of an ATP molecule?

triphosphate

ribose

adenine (nitrogenous base)

What is adenosine?

adenine + ribose

What charge is on the phosphate groups of the ATP molecule?

negative

What do the negative charges of the ATP molecule do?

repel each other and hold much potential energy

What is the exergonic reaction that powers metabolism?

the hydrolysis of ATP to ADP

what does lowercase "I" stand for?

inorganic phosphate

How does ATP perform cell work?

ATP phosphorylates to a key reactant or enzyme causing the next step in the metabolic pathway to be more energetically favorable

What does phosphorylate mean?

add phosphate group

How is glutamate made?

by adding an amino group to glutamic acid

What kind of reaction is glutamate?

endergonic because it is not energetically favored

What is ATP regeneration?

ATP is used in cells, and MUST be regenerated

In the ATP. cycle, what happens in the ATP to ADP part?

energy provided for cell work (anabolic pathways)

In the ATP cycle, what happens in the ADP to ATP part?

energy from metabolism (cellular respiration)

How many ATP/second do muscle cells use?

10 million ATP/second

What are enzyme energetics?

enzymes catalyze exergonic reactions by lowering the energy of activation

What is the energy of activation?

amount of energy reactants must absorb before a chemical reaction will start

If enzymes initiate reactions, what do they control?

rates of metabolism

What do most enzymes require for catalytic activity?

nonprotein helpers called cofactors