Cellular Respiration Flashcards
Cellular respiration
an ATP generating process that occurs within cells. Energy is extracted from energy rich glucose to form ATP from ADP and P. The chemical equation is
C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy
Aerobic respiration
cellular respiration in the presence of O2. It is divided into three components: glycolosis, the Krebs cycle and oxidative phosphorylation.
Glycolosis
the decomposition of glucose to pyruvate. Nine intermediate products are formed. and each one is catalyzed by an enzyme. Mg2+ are cofactors that promote enzyme activity.
Glycolosis Steps
1) 2 ATP are added: First several steps require energy input. This changes glucose in preparation for subsequent steps.
2) 2 NADH are produced. NADH, a coenzyme, forms when NAD+ combines with the two energy rich electrons. and H+ (obtained from an intermediate). As a result NADH is an energy rich molecule.
3) 4 ATP are produced
4) 2 pyruvate are formed
Summary: glycolosis takes 1 glucose and turns it into 2 pyruvate, 2 NADH adn a net of 2 ATP. Occurs in cytosol.
The Krebs Cycle
details what happens to pyruvate the end product of glycolosis.
3 NADH, 1 FADH2, 1 ATP AND CO2.
Begins with acetyl CoA combines with OAA to form citrate. There are seven intermediate products along the way. 3 NADH and 1 FADH2 are made and CO2 released.
also known as Citric acid cycle and TCA cycle
occurs in mitochondria
Step leading to Krebs cycle
1) Pyruvate to acetyl CoA.: In a step leading up to the actual Krebs cycle, pyruvate combines with coenzyme A (CoA) to produce acytal CoA. In that reaction 1 NADH and 1 CO2 are also produced.
OAA
oxaloacetate
FADH2
like NADH is a coenzyme, accepting electrons during a reaction
CO2 from Krebs Cycle is
the CO2 animals exhale when they breathe.
Oxidative Phosphorylation
the process of extracting ATP from NADH and FADH2. Electrons from NADH and FADH2 pass along an electron support chain. The final electron acceptor of the ETC is oxygen. The 1/2 O2 accepts the two electrons and together with 2 H+ forms water.
occurs in mitochondria
Electron transport chain
the chain consists of proteins that pass these electrons from one carrier protein to the next. Along each step of the chain the electrons give up energy used to phosphorylate ADP to ATP.
How much ATP can be produced from NADH
it produces enough electrons to produce 3 ATP
FADH2 produces enough electrons to produce __ ATP
2 ATP
Cytochrome C
one of the carrier proteins (includes iron) in the ETC is so ubiquitous among living organisms that approximately 100 amino acid sequence of the protein is often compared among species to access genetic relations
Mitochondria distinct areas
Outer membrane, intermembrane space, inner membrane, matrix
Outer membrane of mitochondria
this membrane is like the plasma membrane consists of a double layer of phospholipids
Intermembrane space of mitochondria
this is the narrow area between the inner and outer membranes. H+ ions (protons) accumulate here
Inner membrane of mitochondria
the second membrane, also a double phospholipid bilayer, has cristae. Oxidative phosphorylation occurs here. Within the membrane and its cristae the electron transport chain removes electrons from NADH and FADh2 and protein complexes transports H+ ions from the matrix to the intermembrane space.
Matrix
the matrix is the fluid material that fills the area inside the inner membrane. the Krebs Cycle and the conversion of pyruvate to acetyl CoA occur here.
-The Krebs cycle produces NADH and FADH2 in addition CO2 is generated and substrate level phosphorylation occurs to produce ATP.
Chemiosmosis
the mechanism of ATP generation occurs when energy is stored in the form of a proton concentration gradient across a membrane
ATP synthase generates ATP in mitochondria explain
ATP synthase a channel protein in the inner membrane, allows the protons in the intermembrane compartment to flow back into the matrix. The protons moving through the channel generate the energy for ATP synthase to produce ATP.
how pH is created in mitochondria
as H+ are transferred from the matrix to the intermembrane space, the concentration of H+ increase (and pH decreases) in the intermembrane space and decreases in the matrix (pH increases)
Two types of phosphorylation
substrate level and oxidative, two metabolic processes for generating ATP occur
Substrate level phosphorylation
occurs when a phosphate group and its associated energy is transferred to ADP to form ATP. the substrate molecule (molecule within the substrate group) donates the high energy phosphate group. Occurs in glycoyisis
Oxidative phosphorylation
occurs when a phosphate group is added to ADP to form ATP but the energy for the bond does not accompany the phosphare group. Instead the ETC supplies the engery.
Anaerobic respiration
the method cells use when there is no oxygen present and no electron acceptor exists to accept electrons at the end of ETC ceasing Krebs cycle and glycolosis. Occurs in the cytosol. two metabolic pathways are alcohol and lactic acid fermentation.
Alcohol fermentation (fermentation)
occurs in plants, fungi (yeasts) and bacteria
1) pyruvate to acetaldehyde. for each pyruvate 1 CO2 and 1 acetalhyde are produced, the CO2 formed is the source of carbonation in fermented drinks like beer and champagne
2) acetaldehyde to ethanol. the important part of this step is the energy in NADH is used to drive this reaction releasing NAD+. For each acetaldehyde, 1 ethanol is made and 1 NAD+ is produced
Lactic Acid fermentation
A pyruvate is converted to lactate, and in the process, NADH gives up its electrons to form NAD+, as in alchohol fermentaion, the NAD+ can now be used as glycolysis. In animals most lactate is transported to the liver where it is converted back to glucose when surplus ATP is available.
