Micro Ch. 8 Flashcards by leah zimmerman

Pertains to all chemical reactions and physical workings of the cell

metabolism

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aka: biosynthesis

any process that results in synthesis of cell molecules and structures

anabolism

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building and bond-making process that forms larger macromolecules from smaller ones; requires the input of energy

anabolism

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breaks the bonds of larger molecules into smaller molecules and often releases energy

catabolism

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chemicals that increase the rate of a chemical reaction without becoming part of the product or being consumed in the reaction

enzymes

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a measureable resistance to a reaction which must be overcome for a reaction to proceed

energy of activation

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reactant molecule; enzymes bind to this during a reaction

substrate

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conjugated enzyme; an enzyme with its apoenzyme and cofactors

holoenzyme

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polypeptide or protein when in a conjugated enzyme structure

apoenzyme

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organic molecules (coenzymes) or inorganic elements

cofactor

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RNA molecules that catalyze reactions on other RNA

ribozymes

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Hypothesis that RNA was in fact the first genetic material within ancient cells

RNA Hypothesis

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enzymes that are transported extracellularly, where they break down large food molecules or harmful chemicals

exoenzymes

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enzymes retained intracellularly and function there

endoenzymes

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enzymes always present in relatively constant amounts, regardless of the cellular environment

constitutive enzymes

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enzyme in which its production is induced or repressed in response to changes in concentration of the substrate

regulated enzyme

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compound that loses electrons is ______

oxidized

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compound that receives electrons is ______

reduced

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chemically unstable enzyme due to changes in normal conditions

labile

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process by which weak bonds that collectively maintain the native shape of the apoenzyme are broken; causes extreme distortion of the shape; prevents substrate from attaching to the active site

denaturation

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the “mimic” competes with the substrate for the binding site; shuts down the enzyme

competitive inhibition

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negative feedback mechanism that can slow down enzymatic activity once a certain concentration of product is produced

noncompetitive inhibition

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regulator molecule does not bind in the same site as the substrate

noncompetitive inhibition

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a means to stop further synthesis of an enzyme somewhere along its pathway

enzyme repression

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as the level of the end product from a given enzymatic reaction has built to excess, the genetic apparatus responsible for replacing these enzymes is automatically suppressed

enzyme repression

enzymes are induced only when suitable substrates are present; production of the enzyme is induced by its substrate

enzyme induction

a chemical reaction that releases energy

exergonic

a chemical reaction that requires energy

endergonic

to add an inorganic phosphate

phosphorylate

metabolic pathway that converts glucose into pyruvate; the free energy released in this process is used to form ATP and NADH

glycolysis

a series of reactions that converts glucose to CO2 and allows the cell to recover significant amounts of energy

aerobic respiration

a form of respiration using electron acceptors other than oxygen; respiration without oxygen

anaerobic respiration

a series of redox reactions occurring during the final phase of the respiratory pathway

oxidative phosphorylation

production of ATP in cellular respiration; involves the pumping of protons through channels to establish a proton gradient; protons pass down the gradient which generates ATP

chemiosmosis

process in which enzymes can further reduce nitrite to nitric oxide, nitrous oxide, and nitrogen gas; important step in recycling nitrogen in the biosphere

denitrification

the incomplete oxidation of glucose or other carbohydrates in the absence of oxygen

fermentation

type of fermentation that occurs in yeast or bacterial species that have metabolic pathways for converting pyruvic acid to ethanol

alcoholic fermentation

type of fermentation that occurs when glucose is fermented to a mixture of lactic acid, acetic acid, and carbon dioxide

acidic fermentation; heterolactic fermentation

type of fermentation that produces a combination of acetic, lactic, succinic, and formic acids, and lowers the pH of a medium to about 4.0

mixed acid fermentation

acid that breaks down fatty acids joined to gylcerol

lipase

2-carbon units are transferred to coenzyme A, creating acetyl CoA, which enters the Kreb's cycle; can yield a large amount of energy

beta oxidation

enzymes that break proteins down to their amino acid components

proteases

the removal of an amino group from a molecule

deamination

the property of a system to integrate catabolic and anabolic pathways to improve cell efficiency

amphibolism

a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as pyruvate, lactate, glycerol, and glucogenic amino acids

gluconeogenesis

phase of photosynthesis which proceeds only in the presence of sunlight

light-dependent reactions

phase of photosynthesis which proceeds regardless of lighting conditions

light-independent reactions

energy packets that deliver solar energy; travels as waves

photons; quanta

green photosynthetic pigments that absorb light

chlorophylls

yellow, orange, or red photosynthetic pigments that absorb light

carotenoids

red or blue-green photosynthetic pigments that absorb light

phycobilins

chemical reaction in which molecules are broken down into smaller units through the absorption of light

photolysis

ATP formed through a series of sunlight-driven reactions in phototrophs

photophosphorylation

The main events of the reactions in photosynthesis that do not require light

The Calvin cycle

the beginning of the Calvin cycle; the point where CO2 is combined with a doubly phosphorylated 5-carbon acceptor molecule (RuBP); generates a 6-carbon compound that splits into two 3 carbon molecules of 3-phosphoglyceric acid (PGA)

carbon fixaton

oxygen-releasing photosynthesis; occurs in plants, algae, and cyanobacteria

oxygenic photosynthesis

sometimes needed for an enzyme to be fully functional

cofactor

these are either coenzymes or metal ions

cofactors

a class of RNA molecules that catalyze reactions on other RNA; their discovery is evidence to support the RNA hypothesis

ribozymes

a biological catalyst that lacks an essential cofactor

apoenzyme

two levels of protein structure that principally determine the active site of an enzyme

tertiary and quarternary

determines the 3-D shape in enzymes needed for substrate specificity

protein folding

active site of an enzyme is also known as the _____ _____

catalytic site

the region of an enzyme where the substrate binds; most "unique" feature of an enzyme

active site; catalytic site

enzyme bonding strength with a substrate

weak

inorganic cofactors

metallic trace elements

activates enzymes; helps to bring the active site and substrate close together; participates directly in chemical reactions with the enzyme-substrate complex

metallic trace elements

often binds within an enzymes active site and produces a unique active site for the substrate

cofactor

acts as an electron carrier for redox reactions in metabolism

coenzymes

often derived from vitamins; a type of cofactor that will act in conjunction with an enzyme to carry out activity

coenzymes

component of a coenzyme that is critical to nutrition and the metabolic function of coenzyme complexes

vitamins

regulated enzyme activity is completely dependent on ____________ concentration

substrate

what suffix denotes an enzyme?

-ase

how are most enzymes named?

by the action of the enzyme

will intracellular enzymes function anywhere if the conditions are right?

yes

an enzyme that works outside the cell in which it was produced

exoenzyme

an enzyme that works inside the cell in which it was produced

endoenzyme

constituents of a redox pair

electron acceptor and electron donor

a redox reaction involves coupling of which two types of reactions?

oxidation and reduction

a compound that loses electrons to an electron-accepting compound has been ________

oxidized

a compound that gains electrons from an electron-donating compound has been ________

reduced

conditions that can denature an enzyme and its function

pH, water concentration, salinity, and temperature

what actions could increase the rate of an enzymatic reaction that is currently not at optimal conditions?

slightly increase or decrease temperature, increase substrate concentration, increase enzyme concentration

regulated enzymes are induced or repressed according to the concentration of the ________

substrate

physical conditions needed for the optimal function of an enzyme include:

substrate concentration, temperature, and osmotic pressure

what does the phrase "enzymes are catalysts" mean?

enzymes are biological catalysts because they speed up the rate of a chemical reaction of microbes without becoming part of the products or consumed in the reaction;

explain competitive inhibition of an enzyme

a normal substrate competes for the active site of an enzyme with a competitive inhibitor ("mimic"); if the normal substrate attaches, the reaction proceeds; if the inhibitor attaches, the reaction is blocked

explain noncompetitive inhibition of an enzyme

an enzyme has 2 binding sites: an active site and a regulatory site; once a certain concentration is reached, the regulatory molecule binds to the regulatory site and changes the conformation of the active site so the substrate cannot attach

how does an enzyme contribute to a chemical reaction?

enzymes speed up the chemical reaction; uncatalyzed reactions do not generally occur fast enough for cellular processes

what happens when an enzyme is not at its optimal pH or temperature?

it becomes chemically unstable (labile); low temps inhibits catalysis; high temps denature apoenzymes; low or high pH or certain chemicals are denaturing agents

what are the differences between aerobic and anaerobic respiration?

aerobic respiration uses O2 as final electron acceptor whereas anaerobic respiration uses non-O2 compounds as the final electron acceptor; aerobic resp yields 36-38 ATPs, whereas anaerobic resp yields 2-36 ATPs

account for the ATP generated during aerobic respiration

4 ATP are produced by 2 are used up during process so there is a net of 2 ATP

how many ATP are produced by aerobic respiration in prokaryotes? eukaryotes? why the difference?

up to 38 in prokaryotes; less in eukaryotes; because energy is expended in transporting he NADH produced during glycolysis; bacteria lack mitochondria so no loss of ATP during transport of NADH

how does fermentation differ from respiration?

no Krebs Cycle; uses organic compounds as electron acceptor; yields a net 2 ATP

what products does fermentation yield?

alcoholic beverages; solvents; organic acids; dairy products; vitamins, antibiotics, hormones

general categories of fermentation products

alcoholic fermentation products and acidic fermentation products

what is photophosphorylation?

light-dependent reaction; channels in the thylakoids pump H+ into the inner chamber; ATP synthase phosphorylates ADP to ATP; NADPH and ATP are released into the stroma of the chloroplast

what is the Calvin Cycle?

light-independent reaction; occurs in the chloroplast stroma or cytoplasm of cyanobacteria; uses energy produced in the light phase to synthesize glucose

what is the function of light harvesting pigments in photosynthesis?

to gather light energy and transfer the energy to the reaction centers for the photo-induced redox processes

protein part of an enzyme; inactive

apoenzyme

nonprotein part of an enzyme; gives signal

cofactor

activated enzyme; ready to work

holoenzyme

six classes of enzymes

``` oxidoreductases transferases hydrolases lyases isomerases ligases ```

most common electron carrier; carries hydrogens and electrons from dehydrogenation reactions

NAD

Reduces to FADH2; Krebs

FAD

Reduces to NADPH; photosynthesis

NADP

3 part molecule: adenine, ribose, 3 phosphate groups bonded to the ribose

ATP

generation of ATP through a transfer of a phosphate group from a phosphorylated compound directly to ADP

substrate level phosphorylation

series of reactions that converts glucose to CO2 and allows the cell to recover significant amounts of energy (glycolysis, Kreb's Cycle, Electron transport chain)

aerobic respiration

facultative and aerotolerant anaerobes; uses only glycolysis; oxygen is not required

fermentation

final electron acceptor can be an oxidized compound (glycolysis, Kreb's Cycle, electron transport chain)

anaerobic respiration

glucose is enzymatically converted to pyruvic acid; synthesizes a small amount of ATP anaerobically

glycolysis

How many ATP are made and used during glycolysis; what is net ATP

4 made; 2 are used; net 2

What is pyruvic acid converted to before entering the Kreb's Cycle?

acetyl coenzyme A (acetyl CoA)

what are the main products of the Kreb's Cycle?

Reduced NADH and FADH2; 2 ATP

what is the flow of the respiratory chain (electron transport system)?

redox carriers receive electrons; electrons are passed from one redox molecule to the next; flow of electrons allows active transport of hydrogens outside the cell membrane; oxygen receives hydrogens and electrons and produces water

Micro Ch. 8 Flashcards

(116 cards)