Chapter 5 Flashcards
Metabolism
Buildup and breakdown of nutrients within a cell; these chemical reactions provide energy and create substances that sustain life Catabolism + Anabolism
Catabolism
Breaks down complex molecules; provides energy and building blocks for anabolism; exergonic
Anabolism
Uses energy and building blocks to build complex molecules; endergonic
Metabolic pathways
Sequences of enzymatically catalyzed chemical reactions in a cell; pathways are determined by enzymes which are encoded by genes.
Collision Theory
Theory that chemical reactions occur when atoms, ions, and molecules collide
Activation energy
The collision energy required for a chemical reaction to occur
Reaction Rate
the frequency of collisions containing enough energy to bring about a reaction; can be increased by enzymes or by increasing temperature, pressure, or concentration
Catalysts
substances that speed up chemical reactions without being altered
Enzymes
biological catalysts; enzymes act on a specific substrate and lower the activation energy
Substrate
contacts the enzyme’s active site to form an enzyme-substrate complex; enzymes are unchanged here and can react with other substrates
Enzymes have _________ for particular substrates
specificity; e.g. enzymes that can hydrolyze starch can not hydrolyze cellulose. Key and lock idea.
Turnover number
The number of substrate molecules an enzymes converts to a product per second (generally 1-10,000 and as high as 500,00
Names of enzymes usually end in _____ and are grouped based on ____________.
-ase; the reaction they catalyze
Oxidoreductase
Type of enzyme; Oxidation-reduction reactions
Transferase
Type of enzyme; transfer functional groups
Hydrolase
Type of enzyme; hydrolysis (a chemical reaction in which water is used to break down a compound
Lyase
Type of enzyme; removal of atoms without hydrolysis
Isomerase
Type of enzyme; rearrangement of atoms
Ligase
Type of enzyme; joining of molecules; uses ATP
Components of Enzymes
Apoenzyme: protein portion Cofactor: nonprotein component e.g. Mg++; Coenzyme: organic cofactor e.g. folic acid, NAD, NADP, vitamin B complex Holoenzyme: apoenzyme plus cofactor
Apoenzyme
Component of an enzyme: protein portion
Cofactor
Component of an enzyme; nonprotein component e.g. Mg++; Coenzyme: organic cofactor e.g. folic acid, NAD, NADP, vitamin B complex
Holoenzyme
Component of an enzyme: Apoenzyme plus cofactor
Assist Enzymes (Coenzyme)
Nicotinamide adenine dinucleotide (NAD+), Nicotinamide adenine dinucleotide phosphate (NADP+), Flavin adenine dinucleotide (FAD), Coenzyme A
Factors that influence enzyme activity
Temperature, pH-, Substrate concentration, inhibitors, high temperature and extreme pH denature proteins; if the concentration of substrate is high (saturation), the enzyme catalyzes at its maximum rate
Competitive inhibitors
Fill the active site of an enzyme and compete with the substrate (think of isomers)
Noncompetitive inhibitors
interact with one another part of the enzyme (allosteric site) rather than the active site in a process called allosteric inhibition
Allosteric site
part of an enzyme; where non-competitive inhibitors attach
Feedback Inhibition
End-product of a reaction allosterically inhibits enzymes from earlier in the pathway (non-competitive inhibition) an example is cyanide which combines dehydrogenase with the cytochrome enzymes responsible for the transfer of hydrogen atoms during cellular respiration
Ribozymes
RNA that function as catalysts by cutting and splicing RNA
Oxidation
removal of electrons
Reduction
gain of electrons
Redox reaction
an oxidation reaction paired with a reduction reaction
ATP is generated by the __________ of ____ with the input of energy
phosphorylation; ADP; ATP is generated when high-energy PO4- added to ADP generates ATP
Oxidative Phosphorylation
Electrons are transferred from one electron carrier to another along an electron transport chain (system) on a membrane that releases energy to generate ATP
Photophosphorylation
Occurs only in light-trapping photosynthetic cells; light energy is converted to ATP when the transfer of electrons (oxidation) from chlorophyll pass through a system of carrier molecules
Carbohydrate Catabolism
The breakdown of carbohydrates to release energy: Glycolysis Krebs cycle Electron transfer chain (system)
Glycolysis
The oxidation of glucose to pyruvic acid produces ATP, and NADH Preparatory Stage: 2 ATP are used Glucose is split to form two molecules of glyceraldehyde 3-phosphate Energy conserving stage: The two glyceraldehyde 3-phosphate molecules are oxidized to 2 pyruvic acid molecules 4 ATP are produced 2 NADH Glucose + 2ATP + 2ADP + 2PO4- + 2NAD+ –> 2 pyruvic acid + 4ATP + 2NADH + 2H+ Overall net gain of two molecules of ATP for each molecule of glucose oxidized
Cellular Respiration
Oxidation of molecules liberates electrons to operate an electron transport chain Final electron acceptor comes from outside the cell and is inorganic ATP is generated by oxidative phosphorylation
Aerobic Respiration
Energy production with oxygen; the final electron acceptor in the electron transport chain is molecular Oxygen (O2)
Decarboxylation
loss of CO2
Krebs Cycle
Pyruvic acid (from glycolysis) is oxidized and decarboxylation (loss of CO2) occurs The resulting two-carbon compound attaches to coenzyme A, forming acetyl CoA and NADH Oxidation of acetyl CoA produces NADH, FADH2, and ATP and liberates CO2 as waste
Electron transport chain (system)
Occurs in the plasma membrane of prokaryotes; inner mitochondrial membrane of eukaryotes Series of carrier molecules (flavoproteins, cytochromes, and ubiquinones) are oxidized and reduced as electrons are passed down the chain Energy released is used to produce ATP by chemiosmosis
Carbohydrate Catabolism
Each NADH can be oxidized in the electron transport chain to produce 3 molecules of ATP Each FADH2 can produce 2 molecules of ATP
Fermentation
Releases energy from the oxidation of organic molecules Does not require oxygen Does not use Krebs cycle or ETC Uses an organic molecule as the final electron acceptor Produces only small amounts of ATP
Lactic Acid Fermentation
Produces lactic acid -homolactic fermentation: produces lactic acid only -heterolactic fermentation: produces lactic acid and other compounds Glucose is oxidized to pyruvic acid, which is then reduced by NADH
Alcohol fermentation
Produces ethanol + CO2 Glucose is oxidized to pyruvic acid; pyruvic acid is converted to acetaldehyde to ethanol
Biochemical Tests and Bacterial Identification
Biochemical tests identify bacteria by detecting enzymes (e.g. those involved in decarboxylation and dehydrogenation)
Fermentation test
Bacteria that catabolize carbohydrate or protein produce acid, causing the pH indicator to change color
Oxidase test
identifies bacteria that have cytochrome oxidase (e.g. pseudomonas)
Light-dependent (light) reactions
Conversion of light energy into chemical energy (ATP and NADPH)
Light-independent (dark) reactions
ATP and NADPH are use dto reduce CO2 to sugar (carbon fixation) via the Calvin-Benson Cycle
Calvin-Benson Cycle
?
Phototrophs
use light energy (like chlorophyll)
Photoautotrophs
use energy in the Calbin-Benson cycle to fix CO2 to sugar
Oxygenic photoautotrophs
produces O2
Anoxygenic photoautotrophs
does not produce O2
Chemoautotrophs
Use energy from inorganic chemicals, CO2 as a carbon source Energy is used in the Calvin-Benson cycle to fix CO2
Chemoheterotrophs
Use energy and carbon from organic materials Medically and economically important
What is the rate of reaction and which factors it depends on?
The frequency of collisions containing enough energy to bring about a reaction - It can be increased by enzymes, or an increase in temperature, pressure, or concentration
What is a catalyst?
A substance that speeds up a chemical reaction without being altered
Enzymes are ________ catalysts.
biological
Name of an enzyme always ends with ______
-ase
Substrates _______ with an enzyme’s __________ to form an ____________. The substrate is ______ and ______ into ________, which are then released from an the enzyme.
connect/contact; active site; enzyme substrate complex transformed; rearranged; products
What is turnover number of enzyme?
The number of substrate molecules an enzyme converts to a product per second
What are the components of an enzyme?
Assist enzymes; electron carriers - NAD+ NADP+ FAD Coenzyme A
What are the factors that affect enzymes and how?
Temperature - raised can increase production, too high can denature proteins; pH - too high or too low can denature proteins of enzymes Substrate concentration - not enough substrates can limit production while too many can max out production
What are metabolic pathways?
Sequence of chemical reactions undergone by a compound or class of compounds in a living organism
What is competitive inhibition and what is noncompetitive inhibition?
Competitive inhibition occurs when substrates which act like isomers compete with other substrates by taking their place on the active sites on enzymes so that the other substrates cannot connect and create products necessary for metabolic processes Noncompetitive inhibition is when a substrate attaches to an enzyme’s allosteric site but does not interrupt or interfere with other substrates attaching to active sites and creating necessary products
Explain the terms oxidation and reduction.
Oxidation occurs when energy production results in the removal of an electron Reduction occurs when energy production results in the gain of electron
What is phosphorylation?
The addition of a phosphate group (po4)3- to a molecule
What are the two important steps in glycolysis
1) Preparatory Stage -2 ATP are used -Glucose is split to form two molecules of glyceraldehyde 3-phosphate 2) Energy-conserving stage -The two glyceraldehyde 3-phosphate molecules are oxidized to 2 pyruvic acid molecules -4ATP are produced -2 NADH are produced
Draw outline of glycolysis. Write all the names of the products and show where the ATP are formed.
[doodle]
The glucose is converted into ___ molecules of ______ in glycolysis.
two; pyruvic acid
Pyruvic acid is converted into _______ before entering in the _______ cycle.
acetyl CoA; Kreb’s
After the end of cellular respiration _____ glucose molecule produces a total of _____ ATP molecules (net gain).
1; 38
At the end of cellular respiration ____ and ____ is produced.
CO2; water
Draw the outline of Kreb’s Cycle/Citric Acid cycle. Include all the steps
[doodle]
The substrate level phosphorylation occurs in _____ and _____ cycles.
Glycolysis; Kreb’s
Oxidative phosphorylation occurs in _________ which is present in the _______.
Electron transport chain; plasma membrane
In ________ lactic acid, alcohol, propionic acid, vinegar, and ascorbic acid are produced.
Fermentation
Biochemical tests identify bacteria by ________.
Detecting enzymes
Photosynthesis is the process of conversion of ________ energy into ______ energy. It is used by many bacteria and plants.
light; chemical
What is the difference between autotroph and heterotroph?
An autotroph is an organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide. A heterotroph is an organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide.
