Terms in this set (73)
Equation for Cellular Respiration?
What is cellular respiration?
An ATP-generating process that occurs within cells; energy is extracted from energy rich glucose to form ATP from ADP and Pi
Internal vs external respiration
External is entry of air into lungs and gas exchange between alveoli and blood; internal respiration is exchange of gas between blood and the cells + intracellular respiration processes
Overall, what kind of a process is cellular respiration?
Oxidative, exergonic (∆G = -686 kcal/mole)
The name for ceullular respiration when it occurs in the presence of O2
Three stages of aerobic respiration?
2. Krebs Cycle
3. Oxidative phosphorylation
Decomposition of glucose into pyruvate
(Glyco) - glucose
(lysis) - decomp
Where does glycolysis take place?
Two important enzymes for glycolysis are?
Hexokinase and PFK (phosphofructokinase). Each step here uses phosphate group from the 2 invested ATP's
Phophorylates glucose, and important because it cant diffuse out
Meaning that its adding a phosphate group to a molecule derived from ATP. Hexokinase frequently phosphorylates many six membered rings
What does "kinase" mean?
an enzyme that catalyzes the transfer of a phosphate group from ATP to a specified molecule.
Adds second phosphate, making fructose 1,6-bisphosphate
This is irreversible and commits it to glycolysis, a major regulatory point
Net result of glycolysis
Takes 1 glucose, makes 2 NADH, 2 pyruvate and a net of 2 ATP (but actually made 4, used 2)
What is NADH?
An energy rich molecule; coenzyme that forms when NAD+ combines with two energy rich electrons and H+
What is pyrvuate decarboxylation?
- At this point we are in the mitochondrial matrix
- Pyruvate to Acetyl CoA, producing 1 NADH and 1 CO2
NET: 2 NADH + 2 CO2
Catalyzed by PDC enzyme (pyruvate dehydrogenase complex)
What else is the Krebs cycle known as?
Citric acid cycle and TCA cycle (tricarboxylic acid cycle)
What step happens before the actual Krebs cycle? What's this called, and where does it occur?
Pyruvate combines with coenzyme A to make acetyl coA and 1 NADH and 1 CO2 are produced
Pyruvate decarboxylation, occurs in the mitochondrial matrix
First step of the Krebs cycle?
Acetyl CoA and oxaloacetate acid (OAA) combine to make citrate
Krebs cycle end products?
Citric acid, 3 NADH, 1 FADH2, CO2, 1 ATP
Process of extracting ADP from NADH and FADH2
Carrier proteins that include nonprotein parts containing iron, part of oxidative phosphorylation
They also have nonprotein parts like iron that donate/accept electrons for redox
Coenzyme Q (CoQ) / Ubiquinone
Soluble carrier dissolved in the membrane that can be fully reduced / oxidized, it passes electrons as seen in diagram
How many ATP for each NADH?
How many ATP for each FADH2?
Final electron acceptor for the ETC? What does it form?
Oxygen. Forms water after accepting 2 electrons and adding with 2H+
Ubiquitous among living organisms that approximately 100-amino acid sequence of the protein is often compared among species to assess genetic relatedness
Theoretically, how many ATP?
Around 36, but usually less (in eukaryotes) for prokaryotes (38)
Why is the yield of ATP higher in prokaryotes?
Difference because prokaryotes have no mitochondria so they (unlike eukaryotes) don't need to transfer pyruvate into the mitochondrial matrix (which is done via active transport thus costing ATP), they use cell membrane for respiration.
Where does Krebs cycle occur?
Where does oxidative phosphorylation occur?
Mitochondria, inner membrane
What are the 4 distinct areas of the mitochondria?
1. Outer membrane
2. Intermembrane space
3. Inner membrane
This membrane, like the plasma membrane, consists of a double layer of phospholipids
Outer membrane of the mitochondria
This is the narrow area between the inner and outer membranes, H+ ions (protons) accumulate here
Second membrane is also a double phospholipid bilayer, has convulutions called cristae. Oxidative phosphorylation occurs here. Has protein complexes such as PCI, II, III, IV & ATP synthase
Inner membrane of the mitochondria
The fluid material that fills the area inside the inner membrane and the Krebs cycle & pyruvate decarboxylation occur here
What two things have a double layer of phospholipids?
Plasma membrane and inner and outer membrane of the mitochondria
Where do H+ ions accumulate?
Convolutions in the second membrane (inner membrane)
ATP synthase function?
Phosphorylation of ADP to form ATP
Allows protons to flow from the intermembrane compartment back to the matrix, and the protons moving through the channel generate the energy for ATP synthase to generate ATP
What is the mitochondrial matrix?
It is where Krebs cycle occurs and also is the fluid material that fills the area inside the inner membrane
Mechanism of ATP generation that occurs when energy is stored in the form of proton concentration gradient across a membrane
ATP is a (RNA/DNA) nucleotide? Is ATP stable?
RNA (due to ribose sugar). ATP is unstable because of the 3 phosphates in ATP are negatively charged and repel one another. When one phosphate group removed via hydrolysis, a more stable molecule ADP results and the change is from less stable to more stable always releases energy
What kind of gradients are created during chemiosmosis?
Electrical (voltage) and pH (proton). These are potential energy reserves that act like water in a dam
What are the two types of metabolic processes for generating ATP?
Phosphorylation - substrate level phosphorylation and oxidative phosphorylation
Substrate level phosphorylation
When a phosphate group and its associated energy is transferred to ADP to form ATP, the substrate molecule (the one with the phosphate group) donates the high energy phosphate group and this type occurs during glycolysis
What kind of phosphorylation during glycolysis?
Oxidative phosphorylation - more defined
When a phosphate group is added to ADP to form ATP, but the energy for the bond does not accompany the phosphate group. Instead, electrons in the ETC of oxidative phosphorylation supply the energy and that energy is used to generate the H+ gradient which, in turn, supplis the energy to ATP synthases to generate ATP form ADP and a phosphate group
What happens when there is no oxygen present during cellular respiration?
There is no oxygen, so there is no electron acceptor at the end of ETC and NADH accumulates. After NAD+ has been converted to NADH, the Krebs cycle and glycolysis both stop, because both need NAD+ to accept electrons
This is called anaerobic respiration
How can a cell remedy the lack of oxygen?
Undergo anaerobic respiration, which will replenish NAD+ so that glycolysis can proceed once again
Where does anaerobic respiration occur?
In cytosol alongside glycolysis
Where does alcohol fermentation occur?
Plants, bacteria, and fungi (such as yeasts)
Where does lactic acid fermentation occur?
Humans and other mammals
What is the end result of lactic acid fermentation?
Pyruvate converted to lactate and NADH gives up electrons to form NAD+
What is always the starting material in fermentation?
What is the first step of alcohol fermentation?
Pyruvate converted to acetylaldehyde
What is the second step of alcohol fermentation?
Acetylaldehyde converted to ethanol, and the energy from NADH is used to make NAD+
CO2 from this step is the source of carbonation in drinks like beer and champagne
In alcohol fermentation, when pyruvate is converted into acetylaldehyde
Ethanol produced here is the source of alcohol in beer and wine
In alcohol fermentation, when acetylaldehyde is converted into ethanol
What inhibits hexokinase? What does hexokinase do?
Converts glucose into Glucose-6-phosphate (G6P)
What activates PFK1?
AMP, Fructose-6-phosphate, insulin, and Fructose-2,6-BP
What inhibits PFK1?
ATP, Fructose-1,6,BP, citrate, glucagon
What does PFK1 do?
Converts Fructose-6-phosphate into fructose-1,6-biphosphate
Final electron acceptor in alcohol fermentation
Compare facultative vs obligate anaerobes
Facultative anaerobes can use oxygen when it's present (more efficient) but switch to fermentation/anaerobic respiration if it isn't; obligate anaerobes cannot live in presence of oxygen
When glucose supply is low, what happens?
Body uses other energy sources, in the priority of carbs, fats, and proteins
What is the production of glucose called?
Where does gluconeogenesis occur?
Occurs in the liver and kidney
What is responsible for maintaining glucose concentration in blood?
What is glycogen's relationship to glucose? Where's it stored?
It's a polymer of glucose, stored 2/3 in liver and 1/3 in muscles
NOTE that all cells are capable of producing and storing glycogen, but only liver and muscle cells have large amounts
Disaccharides are hydrolyzed into ____, most of which can be converted to glucose or glycolytic intermediates
What does oxidative deamination do?
Oxidative deamination removes ammonia molecule directly from AA. Ammonia is toxic to vertebrates: fish excrete, insects and birds convert to uric acid, mammals convert to urea for excretion.
What is ammonia converted into in some vertebrates?
Uric acid in fish, insects, birds
Urea in mammals
How are fatty acids broken down for energy?
Fatty acids are broken down for energy via beta oxidation (takes place in mitochondrial matrix)