Biological Energy Sources Flashcards
Structure of ATP
Adenine + Ribose = nucloeside (adenosine)
3 phosphate groups + Ribose + Adenine = nucleotide (adenosine triphosphate)
Alpha phosphate is directly attached to ribose
There are alpha, beta, and gamma phosphates
Why is the game phosphate highly unstable?
Because of so much negatives
ATP Hydrolysis
High energy phosphodiester bond is broken through hydrolysis to make ADP
*this is favorable and spontaneous
T or F. ADP Phosphorylation is unfavorable and non spontaneous
True
Mechanisms for ATP Formation
Substrate-level phosphorylation
Oxidative phosphorylation
When does substrate-level phosphorylation occurs? Explain the mechanism
It occurs during glycolysis and involves the transfer of a phosphate group from a glycolytic intermediate to ADP, forming ATP (also occurs on citric acid cycle- GTP)
*this is always enzyme catalyze and always coupled with a spontaneous and favorable rxn to help it drive forward
Oxidative Phosphorylation accounts for the formation for most of ATP. Describe it
ATP synthase is used to form ATP when protons are pumped to the mitochondrial matrix. It uses the energy present in the electrochemical gradient.
T or F. Oxidative phosphorylation and substrate level phosphorylation can only occur in the presence of oxygen.
False. Substrate level phosphorylation can occur in the presence or absence of oxygen. For oxidative phosphorylation, oxygen is required. Oxygen is terminal electron acceptor in ETC
This is similar to ATP but powers biological rxns involved in signaling cascades and protein synthesis
GTP- produced using substrate-level phosphorylation in the citric acid cycle
Other high energy bonds
- Thioester bond in acetyl-CoA
- bonds in the reduced conenzymes: FADH2, NADH
What type of bonds do our cells use to store energy for later use and to power non-spontaneous reactions that are necessary for cellular function?
High energy bonds
A molecule of ATP contains 3 phosphate groups attached via the alpha phosphate to which hydroxyl group of ribose?
5’
Which molecules are involved in carrying electrons from substrates in glycolysis and the citric acid cycle to the ETC?
NADH and FADH2
Redox reactions in our cells are used in process that involves?
Energy
Redox reactions play a huge role in?
Cellular metabolism
OIL RIG
Oxidation- loss of electrons
Reduction- gain of electrons
Reduction
- gain of electrons
-fewer bonds to oxygen
-more bonds to hydrogen
Ex. Aldehyde to alcohol
Oxidation
- lose electrons
- more bonds to oxygen
-less bonds to hydrogen
Ex. Alcohol to aldehyde
Alkene is more reduced or oxidized than alkane ?
Oxidized
What molecules play major roles in redox reactions in the cellular metabolism?
NADH and FADH2
NADH
- when NAD+ gains a hydrogen it becomes more reduced and in the process, it oxidized a molecule which lose a hydrogen
- oxidation of NADH is spontaneous as well.
FADH2
- when FAD+ gain 2 e- (2 hydrogens) it becomes reduced to FADH2 and it was also an oxidizing agent for a the other molecule involved in this process
- can be partially oxidized by losing only one 1 electron (FADH) or fully oxidized by losing 2 electrons (FADH2)
NADH and FADH2 are used in which pathways
Glycolysis, citric acid cycle, and beta-oxidation
The pumps use the energy gain from electron transfers to drive what against their concentration gradient?
Hydrogen ions, or protons
The proton gradient powers oxidative phosphorylation via what?
ATP synthase
What is the final acceptor in the ETC?
Diatomic oxygen molecule that is reduced to water
Measure how energetically favorable reduction is
Reduction potential
The more positive the reduction potential is, the more a substance likes to be reduced
Place the following in order of most to least oxidized: ethane, ethane, methane, and ethene
Ethane, ethene, ethane, methane
If. A redox reaction required a biological reducing agent carrying two electrons, which of the following could serve as this reducing agent?
NADH and FADH2
Oxygen is the final acceptor in the ETC, which means it reduction potential must be __________ than the complex immediately before it and it oxidation potential must __________ than the complex immediately before it
Higher; Lower
What is the cell’s predominant source of fuel
Glucose- can be easily stored as glycogen and its catabolism liberates large amounts of ATP via aerobic respiration
Can glucose simply cross the membrane
No. There are special transmembrane glucose transporters
4 most important glucose transporters
GLUT 1-4
How does the body make a smart choice about how to use glucose?
The presence of diverse glucose transporters and their differential expression across cell types
Type of glucose transporter. Location
Nearly all tissue, especially fetal tissues, erythrocytes, and cancer cells
GLUT 1
Type of glucose transporter. Function
- Baseline cellular glucose uptake
- expression increases when glucose is low
GLUT 1
Type of glucose transporter. Location
Liver, kidney, pancreatic beta cells
GLUT 2
type of glucose transporter. Function
- bidirectional transport for glycolysis/ glycogenesis and
- glucose sensor
GLUT 2
Type of glucose transporter: Location
- neurons, placenta
GLUT 3
Type of glucose transporter. Function
- high glucose affinity
- transports glucose into cell even when extracellular concentrations are low
GLUT 3
Type of glucose transport. Location
Skeletal and cardiac muscle, adipose tissue
GLUT 4
Type of glucose transporter. Function
- glucose storage as glycogen or triglycerides
- unregulated by glucose and insulin
- insulin sensitive
GLUT 4- regulated by hormone insulin and primarily expressed after meals when blood glucose levels are high
Type 2 Diabetes. Which glucose transporter becomes insensitive to insulin and stops being expressed with normal insulin levels?
GLUT 4
T or F. A cancer cell from a particular tissue is likely to express more glucose transporters than a healthy cell from the same tissue.
True. Cancer cells are cells in which the regulation of growth and division have been significantly altered. Because cancerous cells grow more quickly and I divided more frequently, their energy demands are higher,
