Unit 6a -Metabolism and Enzymes Flashcards
Describe catabolism
- BREAKING DOWN nutrients to smler molecules to produce energy
- energy stored in bonds of ATP molecule, transported where needed
Describe anabolism
-BUILDING UP
stored energy is used to assemble new molecules from sm components produced from catabolism
What are the storage forms of energy? 3
ATP, NADH, FADH2
Describe the 3 stages of catabolism in simplified terms and steps
Stage 1: the gastrointestinal tract
digestion in the lumen of the GI tract
Stage 2: the cytosol
anaerobic respiration in the cell’s cytosol
Stage 3: the mitochondria
aerobic respiration in cell mitochondria
Describe catabolism in stage 1
Occurs in GI tract
Food is broken down in stomach, digested contents pass to sm intestine to further break down by enzymes
-hydrolysis
carbs broken down to monosaccs
fats broken to fatty acids + glycerol
proteins broken down to amino acids
Nutrient molecules absorbed by cells that line sm intestine, nutrients pass to blood or lymph, carried to organs/tissue, or to liver for more metabolism
Describe catabolic metabolism stage 2
occurs in cytosol
process of anaerobic respir catabolizes nutrients
acetyl coA transported thru cytoplasm to mitocchondria
Describe catabolic metabolism stage 3
Occurs in mitochondria
aerobic respir involves attachment of inorganic PO4 to a molecule of ADP to form ATP
ATP used by cell to carry energy
Catabolic pathways of proteins, carbs, and fats transfer energy stored in nutrients to ATP
Describe the ATP-ADP cycle
ATP -> Motion Active Transport biosynthesis -> ADP -> Oxidation of fuel molecules -> repeats
Describe anabolic metabolism
A biosynthetic process
Growing cells need additional proteins:
for the expanded cell membranes
to perform many other vital functions
Replacement molecules must be manufactured continuously
metabolic turnover
Describe dehydration synthesis
Important part of anabolism - the effect is opposite of hydrolysis
-monosaccs assembles to form chains of poly saccs [1 mono + 1 mono = 1 disacc + water]
-fat molecules formed from connection of glycerol + fatty acids
proteins created from chains of amino acids
Can an enzyme react with more than one particle? Explain why or why not
no, each enzyme only reacts with 1 molecule (substrate) to produce a new molecule (product)
What is an active site?
region of enzyme that binds to the substrate
What do enzyme names end in? Are they altered by reactions
-ase, not altered by reactions
Give an example of how an enzyme is named. What about transfer enzymes? Explain
Named for substrate it acts upon = lactase breaks down lactose
Transferases move a part of a molecule to another molecule.
EX. phosphotransferasse moves a phosphate group
Describe catalytic efficiency of enzymes. Give an example of it
enzymes act as catalyst to speed up reactions by lowering activation energy
increased rate of reaction is essential to life.
EX. CO2, wast product of respiration must be moved out of body. Carbonic anhydrase combines CO2 w/ water to form carbonic acid and bicarbonate ions
What is a cofactor? Give examples
Assistance of a nonprotein cofactor in order to complete a reaction.
EX. iron, zinc, copper, magnesium, potassium, calcium ions
Describe what co-enzymes are. Give some examples
nonprotein organic molecules that may also ac as cofactors - are often vitamins
may be temp or perma bound to enzyme
EX. nicotinamide Adenine dinucleotide (NAD), acetyle-coenzyme A (acetyl CoA), Flavin adenine dinucleotide (FAD)
Bonus: What are the abbreviations for NAD, Acetyle CoA and FAD
nicotinamide Adenine dinucleotide (NAD), acetyle-coenzyme A (acetyl CoA), Flavin adenine dinucleotide (FAD)
What factors affect enzyme activity?
Enzyme concen.
Effect rate is directly proportional (/)
Substrate concentration (/-)
Rate increases until enzyme is saturated
Temp [/]
Rate increases until denaturation of enzyme
pH [u but upside down]
Many enzymes max activity at pH near 7, most denature at high pH extremes except pepsin, optimum pH is 1.5
What is the name of enzymes affected by temperature?
thermolabile enzymes
What is a enzyme inhibitor
any substances that can decrease the rate of an enzyme-catalyzed reaction
What are the two categories of enzyme inhibitors/
irreversible + reversible
Describe what an irreversible inhibitor is. Give 3 examples
- Forms covalant bond w/ a functional group of the enzyme - renders enzyme inactive
EX. Cyanide ion - blocks mitochondrial e+ transport train, stops aerobic cellular respiration, antidote - Sodium thiosulfate
EX. Heavy metals - murcery + lead, combines with sulfhydryl groups on enzymes to cause neuro damage, treated w/ chelating agents
EX. Antibiotics - Penicillin, inhibits enzymes essential to life processes of bacteria - interferes with transpeptidase needed for bacterial cell wall construction
Describe reversible inhibitor
Reversibly binds to an enzyme so it can be removed.
2 types: competitive and noncompetitive
Explain what an competitive inhibitor does? What happens? Give an example of one
Competes w/ substrate for binding at active site of enzyme. Reversed by increasing conc of normal substrate. Compete is won by most concentrated molecule
Molecular structure similar to substrate of enzyme
EX. Sulfa drugs - folic acid need by bacteria is synth from p-aminobenzoic acid, resembles sulfanilamid
Sulfanilamide competes for active site = synth of folic acid slowed or stopped, bacteria prevent from multiplying
Describe a non competitibe inhibitor. What does it do? give an example of it
Binds to enzyme at location other than normal active site
no resemblance to normal enzyme substrate
interaction causes 3-D shape of enzyme + active site to change
enzyme no longer binds to normal substrate or it binds improperly so reaction is not catalyzed
more substrate does not reverse inhibition
EX. isoleucine feedback inhibitor
List the summar of enzyme inhibitor tree
inhibitor
[binds to enzyme] |
irreversible inhibitor | Reversible inhibitor
(cyanides, heavy metals) |
end——————————
[binds to active site] {binds not at active site]
competitive inhibitor Non compete inhibitor
sulfa drugs isoleucine feedback
ethanol inhib
What are the three control mechanisms of regulating enzyme activity?
activation of zymogens
allosteric regulation
genetic control
Describe what activation of zymogens are
Enzymes may be synthesizes as inactive precursors called zymogems or proenzymes
-stored in inactive state
- when needed zymogen is released and activated @ loc. of reaction
-activation usually involved cleavage of peptide bonds of zymogen
List some examples of zymogens and what their function is
Zymogen Active Enzyme Funct
Trypsinogen Trypsin Digest of proteins
Prothrombin thrombin Blood clotting
Proelastase elastase digest of proteins
Explain what allosteric regulation is
A combination of enzyme w/ compound that changes 3-d shape - compound called modulator
modulators may be activators to increase activity, inhibitors to decrease activity
Often loc. at key control points in cellular processes
Give and explain an example of allosteric regulation
synthesis of isoleucine
5 steps
product isoleucine binds to enzyme at first step, inhibits enzyme activity
no excess isoleucine is produces
when isoleucine lvls lower, enzyme will be more active and more isoleucine synthesized
What is feedback inhibition?
a process in which the end product of a pathway inhibits an earlier step in
the process
What is enzyme induction? Give an example of it
synthesis of an enzyme in
response to cellular need
Allows an organism to adapt to enviro changes
EX. Regulation of gluconeogenesis
- Activity of PEP carboxykinase increased during fasting, starvation and diabetes mellitus due to enzyme induction by glucagon
What can be used to clinically detect cell damage or uncontrolled growth?
Blood serum lvls of specific enzymes
List some enzymes in clinical diagnosies? Which ones are important for diagnosing diseases of heart, liver, panceas and bone?
Alkaline phosphatase – liver or bone disease
Amylase – pancreatic diseases
Lipase – acute pancreatitis
Alanine transaminase – hepatitis
Aspartate transaminase – hepatitis or heart
attack
Describe what an isozyme is
a slightly different form of the same
enzyme produced by different tissues
Have similar catalytic properties but different
physical properties
Assays for isozymes can pinpoint location and
type of disease more accurately
