Unit 2 (Week 6) Cellular Respiration Flashcards
What is the process by which living cells obtain energy from organic molecules and release waste products and was ultimately partly responsible of Carmen running a marathon versus 1 mile?
Cellular respiration
The cells in Carmen’s leg muscles had become more efficient at cellular respiration.
What does metabolism have that fire doesn’t have when using energy or fuel?
Control.
What is the primary aim of cellular respiration?
To make adenosine triphosphate, or ATP.
What is the type of cellular respiration in which O2 is consumed and CO2 is released?
Aerobic respiration
This is completed through the oxidation of organic molecules. Thus, we breath.
What three energy intermediates are created in the oxidation process of glucose within our cells?
ATP
NADH
FADH2
What are the four metabolic pathways involved in breakdown of glucose?
- Glycolysis
- Breakdown of pyruvate
- Citric acid cycle
- Oxidative phosphorylation
What is the metabolic pathway that breaks down glucose (6 carbon atoms) into pyruvate?
Additionally, where does glycolysis occur?
Glycolysis
In eukaryotes, this metabolic pathway occurs in the cytosol.
What are the products of glucose being broken down by glycolysis?
Two molecules of pyruvate (3 carbons each) and 2 molecules of ATP (via substrate-level phosphorylation) and 2 molecules of NADH
Substrate-level phosphorylation, which means the enzyme directly transfers a phosphate from an organic molecule to ADP
Where do the two pyruvate molecules go to be broken down into 2 acetyl groups (two carbons each) and 2 CO2 molecules?
The mitochondrial matrix.
Additionally, two NADH molecule is made by the reduction of NAD+ for each pyruvate broken down via oxidation.
What is the cycle that results in the breakdown of carbohydrates to CO2; also known as the Krebs cycle?
Citric acid cycle; this is where the acetyl groups are completely broken down.
During the citric acid cycle AKA the Krebs cycle, what are the different and total amount of energy intermediates and waste created by the TWO acetyl groups?
Two ATP (via substrate-level phosphorylation), Two FADH2, and six NADH.
Four CO2 molecules
This all occurs in the mitochondrial matrix.
What is present in the six NADH and two FADH2 molecules that is readily transferable in a redox reaction to other molecules?
High-energy electrons
How is the energy harnessed from the high-energy electrons from NADH and FADH2?
Through an electron transport chain producing an H+ electrochemical gradient.
What is the process for harnessed energy to make ATP which is stored in an ion electrochemical gradient (H+) to make ATP from ADP and Pi?
Chemiosmosis
Why do you call the overall process of the electron transport and ATP synthesis, oxidative phosphorylation?
NADH or FADH2 is oxidized (loss of energy)
ADP has become phosphorylated to make ATP
[BONUS] How many ATP molecules can be made via oxidative phosphorylation?
30-34 molecules of ATP via chemiosmosis
Where does the oxidation phosphorylation occur inside the inner mitochondrial membrane or matrix?
The cristae; the projections formed by the invagination of the inner mitochondrial membrane.
Remember: these projections increase surface area and therefore increase the amount of ATP synthesized
[BONUS] Where does oxidative phosphorylation occur in bacteria and archaea?
Along the plasma membrane
[Glycolysis Start] What does the word Glycolysis mean in Greek?
Glykos meaning sweet, lysis meaning splitting.
T/F The metabolic pathway of glycolysis can occur in aerobic and anaerobic conditions.
True
How many steps are involved in glycolysis where different enzymes are needed to catalyze each event in the pathway?
10
An achievement in biochemistry; the study of the chemistry of living things.
[First Phase; Steps 1-3] Energy Investment: What happens in the first three steps of glycolysis?
- Two ATP molecules are hydrolyzed
- Phosphates from ATP are attached to glucose to create fructose-1,6-biphosphate
What does the energy phase raise and thereby allowing?
Raises free energy of glucose allowing future reactions to become exergonic.
[Second Phase; Steps 4-5] Cleavage: What happens to the fructose-1,6-diphosphate molecule?
The six carbon molecule is broken into two molecules of glyceraldehyde-3-phosphate.
[Third Phase; Steps 6-10] Energy Liberation: What is net molecules produced in this phase?
Two ATP, two NADH, and two molecules of pyruvate.
Four molecules are actually produced in this phase but two were used in the energy investment phase.
With regard to oxygen needs, what advantage do glycolytic muscle fibers provide?
Glycolytic muscle fibers rely on glycolysis for their ATP needs. Because glycolysis does not require oxygen, such muscle fibers can function without oxygen.
Why are two NADH molecules formed in the third phase of glycolysis?
Since NAD+ exists, electrons are added through reduction and ADP is phosphorylated into ATP.
Which organic molecules donate a phosphate group to ADP during substrate-level phosphorylation?
The molecules that donate phosphates are 1,3-bisphosphoglycerate and phosphoenolpyruvate.
How is glycolysis regulated?
Availability of substrates, like glucose, and by feedback inhibition of the enzyme, phosphofructokinase.
Phosphofructokinase is the catalyst for the slowest, rate-limiting step in Step 3. When sufficient amount of ATP occurs, feedback inhibition occurs using the allosteric site located on the enzyme causing it to undergo a conformational change rendering the active site inhibited.
What is the Warburg effect in relation to tumors and cancer and is the basis for detection of these disease states via positron-emission tomography (PET)?
The cells use glycolysis for ATP production while healthy cells mainly use oxidative phosphorylation.
How does using fluorodeoxyglucose (FDG) in PET scans help detect cancer cells?
Cancer cells use high amounts of glucose and since these cancer cell’s genome expression involves the encoding of more enzymes involved with glycolysis, high concentrations of the radioactive FDG can be observed.
What percentage of cancers exhibit an overexpression of glycolysis?
Approx 80%
This includes cancers associated with lung, skin, colon, liver, pancreatic, breast, ovarian, and prostate.
All 10 glycolytic enzymes are overexpressed in many of these cases!
Why is FDG radiolabeled?
FDG is radiolabeled so it can be specifically detected by a PET scan.
Why is FDG radiolabeled?
FDG is radiolabeled so it can be specifically detected by a PET scan.
How does the overexpression of glycolytic enzymes affect tumor growth?
The increase in glycolysis favors tumor growth because of the hypoxic , deficient in oxygen, environment within the tumors.
Glycolysis creates ATP without oxygen while oxidative phosphorylation needs oxygen. With this, the increase of glycolytic enzymes is present and favorable to cancer cells since they would have a hard time producing ATP via oxidative phosphorylation.
[Breakdown of Pyruvate] Where is pyruvate produced and where is it transported to?
Made in the cytosol and then sent to the mitochondrial matrix.
What oxidizes pyruvate when it enters the mitochondrial matrix?
Pyruvate hydrogenase
