Lecture 10-11 Flashcards
1
Q
- Cellular respiration:
A
- Cellular respiration:
o Collection of metabolic reactions within cells that break down food molecules and use free energy to synthesize ATP
o Ultimate source for this process: carbohydrates, fats, proteins, photosynthesis
2
Q
- Glucose and gasoline
A
- Glucose = gas of molecules
o Gasoline: Carbon to hydrogen bond when most energy is stored, reformation of other atoms, organic molecule
Electrons are far away from nucleus
o Glucose: OH (less energy than gasoline) since it has oxygen (wishes to hold on to electrons)
Thus electrons are held closer to nucleus of oxygen atom
o Combustion of glucose or gasoline in presence of oxygen releases heat as reactants are converted into CO2 and H2O
o Energy produced during formation of bonds (aka products) is greater than energy required to break bonds in reactants
3
Q
Coupled Oxidation
also see diagram
A
Coupled Oxidation – reduction reactions are central to energy metabolism
- Oxidation: partial or full loss of electrons from a substance
- Reduction: partial or full gain of electrons to a substance
- Redox: coupled reaction between oxidation and reduction
- LEO THE LION SAYS GER
o Losing electrons = oxidation
o Gaining electrons = reduction - Transfer of Hydrogen = transfer of electron (redox)
- When a molecule loses hydrogen, it becomes oxidized
4
Q
Cellular respiration is controlled combustion
A
Cellular respiration is controlled combustion
- Aerobic Respiration Oxidation of Glucose by O2 into CO2 and Water: C6H12O6 + 6O2 6CO2 + 6H2O G = - 686 kcal/mol By Catabolizing (releasing energy by breaking down large organic molecules into smaller ones) glucose in steps, more energy can be harnessed to make ATP
5
Q
- Aerobic Respiration:
A
- Aerobic Respiration:
o Heat energy increase = energy is then released in one big step could denature enzyme
o Solution: stepwise oxidation of glucose in cells, so that you don’t need to spend ATP, can capture most of the energy from glucose captured by cell, AE energy is much lower, reaction cns occur in cell without copious amounts of energy expenditure
6
Q
- Oxidation of glucose occurs through series of…
A
- Oxidation of glucose occurs through series of enzyme-catalyzed reactions with a small activation energy
o Exergonic, same change in free energy (change in G is negative)
7
Q
- Cellular respiration = controlled combustion
A
- Cellular respiration = controlled combustion
o Potential energy of glucose is not liberated suddenly, rather a slow release with energy being transferred to other molecule
o Oxidation of food molecules occurs in presence of group of enzymes called dehydrogenases
Dehydrogenases facilitate transfer of electrons from food to a molecule
• Most common energy carrier = NAD (oxidized) and NADH (reduced)
• NAD: Co-enzyme • Not a protein • Used in the electron transport chain Potential energy carried in NADH is used to synthesize ATP
During respiration, dehydrogenases remove two H atoms from a substrate molecule and transfer two electrons (and only one proton) to NAD, reducing it to NADH
• This enzyme catalyzed transfer = high effiency
8
Q
- NAD
A
- NAD
o It is a carrier, no amino group is not a protein, work with enzyme which is protein, it is rather a co-protein, it takes on electron
o How you capture energy (place on intermediate molecule) for later use
9
Q
- Primary goal of cellular respiration:
A
- Primary goal of cellular respiration: transform potential energy in food molecules into ATP
10
Q
- 3 phases of cellular respiration:
A
- 3 phases of cellular respiration:
1. Glycolysis:
a. enzymes break down food molecules and glucose into two molecules of pyruvate, some ATP and NADH are synthesized
2. Pyruvate oxidation and citric acid cycle:
a. Acetyl coenzyme enters metabolic cycle = completely oxidized to CO2, some ATP and NADH are synthesized
3. Oxidative phosphorylation:
a. NADH synthesized by glycolysis and citric acid cycle = oxidized
b. Liberated electrons = passed along electron chain and transferred to oxygen, producing water
c. Free energy realised during electron transport = used to generate proton gradient across membrane = used to synthesize ATP
11
Q
- Eukaryotic cell =
A
- Eukaryotic cell = citric acid cycle and oxid. Phos. occur in mitochondrion
12
Q
- Mitochondrion = powerhouse of cell
A
- Mitochondrion = powerhouse of cell, largest generator of ATP
o Composed of 2 membranes: outer and inner
Intermembrane space: found between outer and inner membranes
Matrix: interior aqueous environment
13
Q
- Prokaryotic cells:
A
- Prokaryotic cells: electron transfer and oxid. Phos. occur on plasma membrane
14
Q
Glycolysis is also known as
A
splitting of glucose
15
Q
- Glycolysis : 10 sequential enzyme-catalyzed reactions leading to oxidation of 6 carbon sugar glucose
o Produces …
A
- Glycolysis : 10 sequential enzyme-catalyzed reactions leading to oxidation of 6 carbon sugar glucose
o Produces 2 molecules of three carbon compound pyruvate
o Potential energy released in oxidation = synthesis NADH and ATP
o NAD: • Strips TWO H from organic molecules (2 electrons and 2 protons) • Reduces to NADH + H+ • NADH oxidizes (releases H+ plus 2 e-) in electron transport chain to convert back to NAD
16
Q
- ATP production in glycolysis:
A
- ATP production in glycolysis:
o Bond forms due to free energy
o Glucose is – free energy
o ATP is then created
17
Q
- Reactions of glycolysis
o During process no ….
A
- Reactions of glycolysis
o During process no carbon molecules have been lost
o ATP is generated by substrate phosphorylation
o NAD is an oxidizing agent because it is being reduced
18
Q
- Overview Glycolysis:
All organisms can do glycolysis
Happens in the cytosol does not need mitochondria
Means sweet breakdown (universal – which means it is ancient)
Occurs in cytosol
Cells spend 2 ATP and 2 ADP, get 2 (net change of 2 ATP)
A
- Overview Glycolysis:
All organisms can do glycolysis
Happens in the cytosol does not need mitochondria
Means sweet breakdown (universal – which means it is ancient)
Occurs in cytosol
Cells spend 2 ATP and 2 ADP, get 2 (net change of 2 ATP)
19
Q
- Three facts of Glycolysis:
A
- Three facts of Glycolysis:
1. Glycolysis is universal, found in 3 domains of life
2. Does not depend upon presence of O2
3. Occurs in cytosol of cells via soluble enzymes = does not require complicated electron transport chains and internal membrane systems to function
20
Q
- ATP molecules
A
- ATP molecules
o Produced in glycolysis
o Result from substrate-level phosphorylation
21
Q
- Substrate-level phosphorylation
A
- Substrate-level phosphorylation
o Enzyme-catalyzed reaction
o Transfers phosphate group from substrate to ADP
22
Q
3 steps in glycolysis:
A
- Energy investment followed by payoff
- No carbon is lost
- ATP is generated by substrate level phosphorylation
23
Q
- Energy investment followed by payoff
A
a. Glucose has 6 c atoms and O,
b. Spend ATP, adds phosphate group to change structure of glucose
c. Due to physical reactions, it rearranges itself
d. Spend more ATP to take phosphate group to stick at other end of molecule (to balance it out) (total of 2 phosphate groups on glucose) Investment of 2 ATP for each glucose molecules = energy reward (4 ATP and two NADH molecules are produced during energy releasing phase)
e. Enzyme comes into play and molecule splits in two, (1 glucose molecule splits into 2 molecules) 3 carbon and a phosphate and three carbon and a phosphate
24
Q
- No carbon is lost
A
a. Reaction of glycolysis converts glucose into 2 molecules of pyruvate (oxidization results in EP of two molecules of pyruvate less than one molecule of glucose)
b. NAD captures electron and becomes NADH (spent energy)
c. Binds itself to molecule (captures energy)
d. ADP using stored energy of previous molecule to stick phosphate to ATP molecule
e. Recapture 2 ATP
f. Captured more energy than put in
g. Important you get four ATP, and you spend 2 and the result is pyruvate
25
Q
- ATP is generated by substrate level phosphorylation
A
a. During glycolysis= ATP generated by phosphorylation
i. This process involves transfer of high-energy substrate molecule to ADP
