What is metabolism?
totality of the physical and chemical processes that occur in a cell
What is anabolism?
synthesis of cell PRODUCTS; REQUIRES ENERGY
building up (ex. building up of glucose to make glycogen)
What is catabolism?
Breakdown of LARGER molecules into SMALLER ones; RELEASES energy; pathways of metabolic schemes are generally complex and detailed
ALL biochemical reactions need
the presence of a specific and special class of proteins called ENZYMES
What are the properties of enzymes?
- become physically attached to the substrate
- participate in bonding
- do NOT become part of its products
-Not used up by the chemical reaction
-Can function over and over again
Which describes energy of activation?
Minimum energy input necessary for reactants to form products in a chemical reaction
- less if enzyme IS PRESENT
- more if enzyme is ABSENT or low in concentration
What are the types of enzymes?
-simple
-protein alone
-conjugated or holoenzyme
- protein (apoenzyme) + non-protein (organic/inorganic cofactors)
What is an apoenzyme?
-is the PROTEIN part of an enzyme
-can be short or very long (100 amino acids-10^6 amino acids )
-Molecular complexity is organized 1-2-3-4
-UNIQUE ACTIVE OR CATALYTIC SITES for substrates to fit
What is a coenzyme?
complex organic molecules, several of which come from vitamins (ex. nicotinamide, riboflavin)
A DEFICIENCY in vitamins will PREVENT formation of holoenzymes affecting metabolism
NAD
nicotinamide adenine dinucleotide (coenzyme)
FAD
flavin adenine dinucleotide (coenzyme)
What do coenzymes do?
Carrier of functional groups (CO2,(NH3+ = amino group NH2), and others)
WORK with APOENZYME to perform necessary alterations in a substrate
REMOVAL of functional groups
SERVE as transient carrier of specific atoms or functional groups during metabolic reactions
What is a cofactor?
an enzyme accessory that can be organic (coenzymes) or inorganic such as (iron, manganese, or zinc ions)
Metals participate in PRECISE functions between the enzyme and the substrate
ENZYMES NEED COFACTORS
The role of cofactors are to?
ACTIVATE enzymes
Help bring the active site and substrate CLOSE together
Participate DIRECTLY in chemical reaction with the enzyme substrate complex
What is the active/catalytic site?
the specific region where the substrate BINDS to the apoenzyme, or the site for reaction catalysis
What are the steps in a chemical reaction
-Enzyme FITS substate at the active site and FORMS a complex
-Bonds are FORMED BETWEEN enzyme and substrate
-Reactions OCCUR on the substrate
-Cofactor AIDS in the reactions
-Product is FORMED AND RELEASED
- Enzyme ATTACHES to another substrate molecule
-Cycle repeats
Define an exoenzyme
-extracellular action
-hydrolysis
-penicillases, cellulose, amylase
Define an endoenzyme
-intracellular action
-most enzymes are of this type
What are constitutive enzymes?
enzymes that are ALWAYS present and in constant amount of cell regardless the amount of substrate
What are properties of regulated enzymes?
- are not in constant amount in a cell
-produced only when substrate is present (INDUCIBLE)
-turned off when substrate is absent (REPRESSED)
What factors can affect enzyme activity?
-temperature
-pH and chemicals
-osmotic pressure
-heavy metals
Describe denaturation
-occurs when weak bonds of apoenzymes are broken
-distorts the shape of the enzyme
-prevents the substrate from attaching to the active site
Transfer reactions can
ADD or REMOVE functional groups
A molecule can be
Oxidized or Reduced
Describe oxidation
the loss or donation of electrons
loss of energy
Describe reduction
gains or accepts electrons
gains energy
redox reactions are COMMON in microbial cells and indispensable for life processes
What are Oxireducatses?
A group of enzymes that can remove electrons from one substrate and add them to another
What are the patterns of pathways
linear, cyclic, branched
Describe competitive inhibition
other molecules with a structure similar to the normal substrate COMPETE to occupy the enzymes active site.
What is feedback control
When the end product is being fed back into the system, cancels an enzymes activity.
END PRODUCT BINDS TO AN ENZYME AND SHUTS DOWN THE PROCESS
What are allosteric enzymes?
Enzymes that have and additional regulatory site for the attachment of molecules other than the substrate.
Distort the active site so no binding to substrate occurs without denaturation
What is enzyme repression
Excess product turns OFF genetic program in DNA
Describe enzyme induction
-enzymes appear ONLY when suitable subtrates are present
-synthesis induced by its substrate
- Adaptation to the environment
What are the properties of ATP?
-high energy molecules
-STORES and RELEASES energy
-unique molecular structure
- a temporary energy repository
-bond releases energy when broken
-Negatively charged (PO4^3-)
What is aerobic respiration?
C6H12O6+6O2 ----> 6CO2 + 6H2O + energy (ATP and HEAT)
- organic compounds + oxygen ----> carbon dioxide + water +energy
- glycolysis
- krebs cycle (tricarboxyilic acid cycle)
-Electron Transport Chain (ETC)
Describe glycolysis
- OXIDATION of GLUCOSE into 2 MOLECULES of PYRUVIC ACID
-occurs in the CYTOPLASM
-most COMMONLY used sequence of reaction for the conversion of GLUCOSE into PYRUVATE
- produced 2 ATP's, 2 NADH's and 2 H2O molecules
-DOES NOT REQUIRE OXYGEN
Describe the Krebs Cycle/ Tricarboxylic Acid Cycle
- discovered by egleston and krebs
-occurs in the CYTOPLASM of PROKARYOTES and in the MITOCHONDRIA in EUKARYOTES
-processes the final 2 acetyl-CoA coming from PYRUVIC ACID obtained from the DEGRADATION of GLUCOSE 6C though GLYCOLYSIS
- cycle has 8 steps, REDUCES 2 FAD and 8 NAD's, releases 2 CO2 and PRODUCES 2 ATP by substrate level phosphoylation
Describe the Electron Transport Chain
-occurs in the CELL MEMBRANE of PROKARYOTES and in the MITOCHONDRIA of EUKARYOTES
- made of a chain of special redox carriers that recieved electrons from reduced carriers
-Produces about 34 ATPS and 6 H2O MOLECULES
-in aerobic metabolism, oxygen is the FINAL ELECTRON ACCEPTOR and combines with H ions (protons) to form water
- in anaerobic metabolism, other ions may act as the final electron acceptors
What is the Chemiosmotic Theory
- explains the origin and maintenance of electro-potential gradients across a membrane that leads to ATP synthase (oxidative level phosphorylation)
- the energy obtained is used to GENERATE up to 38 ATP
Describe Anaerobic Respiration
-fermentation
- the conversion of PYRUVIC ACID to ORGANIC ACID or alcohol (or other organic compounds, producing ATP
-organic molecules can serve as FINAL ELECTRON ACCEPTORS
- 2 ATP's maximum per glucose molecule
What is a Fermentor
A large tank used in industrial microbiology to grow mass quantities of microbes that can synthesize desired products
- equipped with the means to stir, monitor, and harvest products such as a variety of organic acids and alcohols in very large quanities
What is Amphibolism?
the property of a system to integrate catabolic and anabolic pathways to improve cell efficiency
Describe Amination
when pyruvic acid can be CONVERTED to amino acids by adding NH4+
Transamination is
when an amino acid and a carbohydrate make another amino acid
Deamination is
when amino acids can be used as a SOURCE OF GLUCOSE (glucogenisis) releasing NH4+
When an enzyme is inducive it means
it wants to add more, when a substrate is present
Allosteric inhibition is
when inhibitor BINDS to holoenzyme and CHANGES the shape; making the substrate unable to bind
exergonic is
a reaction that releases energy as it proceeds forward
endergonic is
reactions that proceed when energy is added
Cellular respiration is
O2 + organic molecule
Chloroplast take CO2 + H2O ----> glucose + oxygen
What is the name of the 3-carbon molecule produced in glycolysis?
pyruvic acid
what are the two MAIN products of aerobic respiration?
ATP and WATER
Name of the two carbon molecule that feed or enters directly into the krebs cycle
Acetyl-CoA
how many ATP's are produced from a glucose molecule in bacteria?
38