Chapter 9 Flashcards
Formula for photosynthesis
6CO2+H2O+sunlight->C6H12O6+6O2
Formula for respiration
C6H12O6+6O2->6CO2+6H2O+energy
Aerobic respiration
oxygen required
- higher multicellular organisms
- glucose completely broken down
- yields many ATPs
Anaerobic or fermentation
- no oxygen used
- bacteria and other lower forms
- partial degradation of glucose
- yields only 2 ATPs
oxidation
a substance loses electrons, electron acceptor is called the oxidizing agent
reduction
substance gains electrons, electron donor is called reducing agent
Steps of energy investment stage of Glycolysis
- one ATP transfers a phosphate group to glucose – glucose 6 phosphate molecule
- Glucose 6 phosphate is converted into fructose 6 phosphate molecule
3. A second ATP transfers phosphate to
fructose 6 phosphate forming fructose 1,6 bi-phosphate.
4. Fructose 1,6 bi-phosphate splits into
1 G3P and
1 DHAP (gets converted into G3P)
Steps of energy payoff of glycolysis
- The 2 G3P (also known as PGAL) give
up phosphate group to ADP (forming 2 ATPs) - Electrons and H+ ions are donated to
NAD to becomes NADH - The next conversion is from
3-phosphoglycerate 2-phosphoglycerate pyruvate.
(and 2 more ATPs are produced. )
products of Glycolysis
- 2 pyruvates
- 2 net atps (4 made 2 used)
- 2 NADH
- 2 H2O
Before Citric Acid Cycle Begins
- Two pyruvate molecules from glycolysis enter the mitochondrion
- With the help of Coenzyme A, one carbon atom is stripped from each pyruvate forming CO2 and Acetyl- Co A.
- NAD is reduced to NADH
Citric Acid Cycle
4.. Acetyl CoA (2 C) is merged with oxaloacetate (4 C),
to form citrate (6 carbons).
- Citrate is converted back to oxaloacetate
through a series of reactions. - During this process 1 ATP molecule, 3 NADH
and one FADH2 are formed. - 2 more CO2 are formed and released
- The same process repeats for the other
pyruvate molecule
Overview of Electron Transport
- The electron transport chain takes place in the cristae
- chain’s components are proteins, which exist in multiprotein complexes
- Redox reactions happen
- Electrons drop in free energy as they go down the chain and are finally passed to O2, forming H2O
Electron Transport Chain/Phosphorlation
- Electrons and H+ from NADH and FADH2 formed during glycolysis and Citric Acid Cycle enter electron transport chains.
- They give up electrons and H+ ions are pumped from the mitochondrial matrix to the inter membrane space.
- Increases H+ ions within intermembrane
space, creating a steep concentration gradient - H+ want to diffuse back into the matrix, but
cannot cross the mitochondrial membrane. - Must cross through ATP synthase-protein
(which helps in the formation of ATP from ADP
and phosphate.) - ATP synthase uses the exergonic flow of H+ to make ATP from ADP and phosphates
This is an example of chemiosmosis, the use of energy in a H+ gradient to drive cellular work
- Last components of electron transfer
chains pass electrons to oxygen which
combines with hydrogen to form H2O.
Alcoholic Fermentation
1.2 pyruvate molecules are split to form
2 molecules of acetaldehyde and 2 CO2
- Acetaldehyde accepts electrons and H+
from NADH to form ethyl alcohol or ethanol
Lactate Fermentation and applications
NADH gives electrons and H+ to pyruvate
Converts pyruvate to lactate a three carbon compound –lactate.
Applications:
Lactate fermentation by lacto bacillus
cheese, yoghurt, buttermilk
Curing meats, pickling
Obligate anaerobes
carry out fermentation or anaerobic respiration and cannot survive in the presence of O2
facultative anaerobes
using either fermentation or cellular respiration
pyruvate is a fork metabolic road that leads to two alternative catabolic routes
Energy from Fats
When glucose is not available, triglycerides
are trapped as energy source
Stored in fat cells of adipose tissue
Enzymes in fat cells will break down fat-
glycerol and fatty acids (beta oxidation)
Enzymes in liver convert glycerol to PGAL
Fatty acids will be converted to Acetyl-CoA
Energy from proteins
Proteins are digested by enzymes to amino acid subunits
If you eat more protein than your body needs, aminoacids are further degraded
Amino group is pulled out
The remaining backbone is split and Acetyl CoA, pyruvate, or intermediates of Krebs cycle are formed
Feedback Mechanisms
Feedback inhibition is the most common mechanism for control
If ATP concentration begins to drop, respiration speeds up
when there is plenty of ATP, respiration slows down
