Bioenergetics 2 Flashcards
What can be used to drive a reaction that requires the input of free energy?
The free energy (/\G) released from an exergonic reaction
Which type of /\G reactions can occur spontaneously?
-ve /\G
What does ATP stand for?
Adenosine triphosphate
In terms of ATP, ADP + AMP what remains constant and what varies?
Constant - total conc
Varies - ratios
What type of reaction is the synthesis of ADP + P –> ATP?
Exergonic
cellular respiration
What does the hydrolysis of ATP –> ADP + P produce?
Fuel for endergonic processes
Define valency
The combining power of an element
- how well it forms bonds
No. of bonds the atoms of an element can form
What does empty space on chemical diagram represent?
C bound to 2 H
What is type of molecule is adenine?
What type of molecule is adenosine?
Base
Nuceloside
What type of molecule is AMP?
What about ADP?
What about ATP?
Nuceleotide
Ns diP (NDP)
Ns triP (NTP)
What is a nucleoside?
Base + sugar
What are the 4 nucleoside examples?
Cytidine
Uridine
Adenosine
Guanosine
What is the function of cytidine?
Lipid biosynthesis
What is the function of uridine?
Carbohydrate
biosynthesis (e.g. glycogen)
What is the function of adenosine?
Energy carrier
What is the function of guanosine?
Transmembrane signalling
Some energetics
Only which type of molecules can diffuse across plasma membranes?
Hydrophobic
What is the free energy of ATP hydrolysis?
/\Go’ = 30.5 kJ/mol
What does /\Go’ mean?
The reactants were 1M + the products were 1M + the pH is 7
How do Na-K transporters work?
3Na+ exit
2K+ enter
Uses ATP
Describe the muscle contraction process.
- Ca2+ binds to troponin
- >active site on actin exposed - myosin head forms crossbridge w/ actin
- power stroke
- myosin head bends & ADP + P released - new ATP attaches to myosin head –> cross bridge breaks
- ATP hydrolysed into ADP + P
- -> returns myosin to original position
How does free energy vary?
> from 1 cell type to another
within the cell when conditions vary
between compartments within a cell
What is the complication with ATP, ADP + Pi?
They can each bind tightly to some cellular proteins
–> affects conc of molecule available to react
Is /\Gp greater or less than /\Go’?
greater than
/\G of ATP –> ADP is large enough for what?
Yet small enough that…?
Driving many reactions for biosynthetic pathways
ATP can be synthesised ready from available nutrients
Although /\G is large and
-ve, ATP is a relatively… what?
How is this?
Stable compound in aqueous solution
(doesn’t spontaneously hydrolyse)
-ve charges on P groups are balanced by Mg
ADP phosphorylation is driven by what?
Energy derived from catabolism
What does ATP hydrolysis drive?
Anabolic processes, mechanical + active transport
What do the adenine + ribosyl groups of ATP, ADP + AMP do?
Provide structures that allow these molecules to bind to enzymes + participate in regulating enzymatic activities
The hydrolysis of which energy carrying compound is linked to ATP synthesis?
Phosphoenolpyruvate
What is the role of phosphocreatine?
Acts as a buffer for ATP production in muscle
What energy-related role does acetyl-coA have?
Energy carrier related to lipid synthesis
What is the name of the high energy bond in acetyl-coA?
Thioester
