Flashcards in Biochemistry Deck (81)
What are the laws of thermodynamics?
1st - energy is neither created or destroyed - just converted from one form to another
2nd - No energy conversion is 100% efficient, some of the produced energy will always be unavailable
What are the principles of the following common reactions;
Esterification - Water is a bi-product
Condensation - Water is removed
Hydolysis - Water is added
what is meant by entropy?
(things tend towards disorder)
What are exergonic and endergonic reactions?
An exergonic reaction is one in which the total free energy of the products is less than the total free energy of the reactants. This is a NEGATIVE change and can occur SPONTANEOUSLY.
An endergonic reaction is one in which the total free energy of the products i s more than the total free energy of the reactants. This is a POSITIVE change which REQUIRES ENERGY to proceed.
What are the standard conditions?
1 Atmosphere pressure
1M concentration of reactants
Are +ve or -ve deltaG changes favourable or unfavourable?
+ve = UNFAVOURABLE
-ve = FAVOURABLE
Define the terms glycolysis and glyconeogenesis
GLYCOLYSIS- The breakdown of glucose to generate ATP
GLYCONEOGENESIS - Making glucose from non-carbohydrate sources
What is meant by an amphipathic molecule?
It is both hydrophilic and hydrophobic
What is Ka
The acid dissociation constant - it measure how readily an acid donates or accepts
The higher the dissociation constant, the stronger the acid
What is a buffer solution?
A solution which resists changes in pH when small amounts of acid or alkali are added
In which direction is the coding strand synthesised in DNA replication? What direction is the template strand synthesised in?
Coding - 5' to 3' direction
Template - 3' to 5'
What are the functions of the following in DNA replication ?
DNA polymerase - elongates both strands
Primase - synthesises a primer
DNA helicase - unwinds the double helix
What is the lagging strand in DNA replication composed of?
What is significant about the 'TATA box'?
This is the point at which transcription is about to start
What is TBP and what is its function?
It is the TATA box binding protein.
It binds DNA and indicates where transcription should start.
What are the 5 important steps during transcription?
RNA polymerase binging
DNA chain separation
To which end of the strand is the poly (A) tail added and what is its purpose?
Added to the 3' end - it is added for stability
What is Vmax?
The maximum velocity that can possibly be obtained by that enzyme
What is Km? What does it mean if this value is high or low?
The amount of substrate that is required for the enzyme to work to 50% of its max
High Km - Lots of substrate is required by the enzyme
Low Km - The enzyme only requires a small amount of substrate
In terms of the Lineweaver- Burk plot, describe the slope of the line and where it intersects the x and y axis
The slope = Km/Vmax
Vmax = The intersection with the y axis
Km = The intersection with the x axis
How does competitive and non-competitive inhibition affect Vmax and Km?
Competitive inhibition does not change Vmax but varies Km
Non-compeitive inhibition causes Vmax to vary but does not affect Km
What is ANABOLISM?
ASSIMILATION OF MOLECULES
= ENDERGONIC AND REDUCTIVE
What is CATABOLISM?
BREAKDOWN OF MOLECULES
=EXERGONIC AND OXIDATIVE
What are the three control points in glycolysis?
Hexokinase - regulates entry of glucose
Phosphofructokinase - regulates rate of flow
Pyruvate kinase - regulates product exit
How many times does the TCA cycle turn for each molecule of glucose consumed?
What effect does a surplus of substrates or products have on the rate of the TCA cycle?
surplus of substrates - accelerated the rate of the TCA cycle
surplus of products - slows the TCA cycle
What does the standard redox potential(E'o) of a reduced substance measure?
How readily that substrate donates an electron in comparison with hydrogen
Would a higher affinity for electrons than H2 suggest a positive or negative E'o?
Would a lower affinity for electrons than H2 suggest a positive or negative E'o?