What is a covalent bond?
The sharing of electron pairs
What is an ionic bond?
Attraction of opposite charges
What is a hydrogen bond?
Sharing of a hydrogen atom
What are Van der Wall interactions?
Electron interactions of non-polar substances
If an atom is more electronegative is it more or less likely to attract bonded electrons towards it?
More likely
What is a condensation reaction?
When water is removed
What is a hydrolysis reaction?
When water is added
What is lactose made up of?
Galactose and glucose
What is sucrose made up of?
Glucose and fructose
Which glucose linkages are found in cellulose?
Beta 1,4
Which glucose linkages are found in glycogen?
Alpha 1,4 and occasionally alpha 1,6
Give examples of a disaccharide
Lactose, maltose, cellobiose, sucrose
Give examples of a polysaccharide
cellulose and glycogen
First law of thermodynamics
Energy is neither created nor destroyed, just converted from one form to another
Second law of thermodynamics
When energy is converted from one form to another, some energy becomes unavailable to do work
What is Gibbs free energy law?
ΔG = ΔH - TΔS
What is the equation for a change in free energy?
ΔG = (Energy of products) - (Energy of reactants)
What is enthalpy?
Heat content
What is entropy?
Disorder
What is an exergonic reaction?
The free energy at the end of the reaction is less than the free energy at the start - energy has left the system
What is an endergonic reaction?
The free energy available at the end of the reaction is more than at the start
Is ΔG in exergonic +ve or -ve?
Negative
Is ΔG in endergonic +ve or -ve?
Positive
Catabolism
Break down of complex molecules
Anabolism
Assembly of complex molecules from smaller ones
Glycolysis
Break down of glucose into pyruvate
Gluconeogynesis
Makes glucose from pyruvate
4 Types of amino acid
Non-polar = hydrophobic
Polar = uncharged
Basic
Acidic
Acids
Proton donators
Bases
Proton acceptors
Zwitterions
Amino acids with no net charge
What are the two forms of tertiary protein structures?
Fibrous - parallel
Globular - spherical shape
Interactions present in a tertiary structure
Covalent disulphide bridges
Hydrophobic interactions
H-Bonds
Van der Val Forces
Which amino acid forms disulphide bridges?
Cystine
Where does DNA replication and transcription take place?
Nucleus
Where does translation take place?
Cytoplasm
Nucleoside
Base + sugar
Nucleotide
Nucleoside + phosphate group
Which carbon is the base and phosphate connected to?
Base = carbon 1 Phosphate = Carbon 5
Purines
Adenine and guanine
Pyridemines
Thymine, uracil and cytosine
How many bonds between A and T?
2
How many bonds between C and G?
3
What is the catalyst for DNA replication?
DNA polymerase
Which direction does DNA polymerase work?
3’ to 5’ direction
What is the most abundant type of RNA?
Ribosomal
What synthesises all RNA?
Pol II
Transcription
Making an RNA molecule from a DNA molecule template i.e. it synthesises mRNA using Pol II
Where is a TATA box usually found?
25 nucleotides before transcription starts
What is the function of a TATA box binding protein?
Provides a landing platform for further transcription factors and RNA polymerase
Translation
Where the anticodons in tRNA form base pairs with the codons in mRNA - both consist of three nucleotides
Degenerate
Many codons code for one amino acid
Unambiguous
Each codon codes for only one amino acid or a stop
Which enzyme binds amino acids to their tRNA molecule?
Aminoacyl-tRNA synthase
What is the initiation tRNA?
UAC
Stop codons
UAA, UAG and UGA
Point mutation
Change in single base in DNA
Silent mutation
No effect on protein function
What do free ribosomes do?
Make proteins for the nucleus, mitochondria, cytosol
What do bound ribosomes do?
Make proteins for the plasma membrane, ER and golgi body
Apoenzyme
An enzyme without a co-factor
Holoenzyme
An enzyme with a co-factor
Example of a co-factor
zinc, ion, copper (in stable transition state)
Isoenzymes
Enzymes which both catalyse the same reaction but do it in a slightly different way from each other
Phosphorylation
Converts enzymes into an active or inactive form
Km
The substrate conc. where the initial reaction rate is half the maximal
Which axis does Km cross?
x axis intersection
Which axis does Vmax cross?
y axis intersection
Vmax
The maximum velocity of a reaction
What does a low Km mean?
The enzyme only needs a little substrate
What does a high Km mean?
The enzyme needs a lot of substrate
Is competitive inhibition reversible or irreversible?
Reversable
What happens to Vmax and Km in competitive inhibition?
Km changes, Vmax doesn’t
What happens to Vmax and Km in non-competitive inhibition?
Vmax changes, Km doesn’t
What kind of curve is formed bye an allosteric enzyme?
Sigmoidal curve - not hyperbola
Anabolism
Oxidised precursor + electrons = reduced biosynthetic product
What are the two qualities of an anabolic reaction?
Endergonic and reductive
Catabolism
Reduced fule - electrons = oxidised product
What are the two qualities of a catabolic reaction?
Exergonic and oxidative
Terminal electron acceptor
Oxygen
What are the four fates of glucose?
Stored as glycogen, starch etc.
Oxidised to pyruvate
Fermented to Lactate
Oxidised via the pentose-phosphate pathway to make ribose-5-phosphate
Where does glycolysis take place?
Cytoplasm
Where does the Kreb’s cycle take place?
Matrix of the mitochondria
Where does the cytochrome system take place?
Cristae of the mitochondria
Which two ways are glucose transported into a cell?
Via an Na+/glucose symporter
Passive facilitated diffusion glucose transporter
Where do GLUT receptors work?
GLUT 1 and 3 = Brain
GLUT 2 = liver
GLUT 4 = Muscle and fat
GLUT 5 = Gut
What are the steps of glycolysis?
Glucose > Fructose-1,6-biophosphate > 2 triode phosphate > 2 pyruvate
What are the control points of glycolysis?
Hectokinase, Phosphofrucktokinase and pyruvate kinase
How does AMP increase glycolysis?
By allosterically increasing phosphofructokinase
What three substances inhibit glycolysis?
ATP, citrate and H+
How is NAD+ regenerated?
Through the metabolism of pyruvate
How does pyruvate enter the matrix?
H+ conc. gradient
H+/pyruvate symport by facilitated diffusion
What catalyses the conversion of pyruvate into Acetly-CoA?
Pyruvate dehydrogenase complex
Which enzyme is not located in the mitochondria matrix for the TCA cycle?
Succinate dehydrogenase
Net yield from each molecule of glucose
4 ATP
10 NADH and H+
2 FADH2
2 CO2
What is the energy from proton flow used for?
Phosphorylation of ADP to ATP
2 transport modes of NADH
Glycerol-3-phosphate
Malate-asparate shuffle
Phosphorylate transfer potential
Free energy change for the hydrolysis of ATP
Electron transfer potential
Redox potential of a compound - how readily it donates an electron
2 stages of oxidative phosphorylation
Electron transport
ATP synthesis
Cytochromes
Proteins which contain a harm group as a functional co-factor
Which complexes pump H+ ions?
I, III and IV
Where is there a higher concentration of protons in the mitochondria?
Inter-membrane space not the matrix
Is the matrix negative or positive?
Negative
Chemicals which inhibit oxidative phosphorylation
Cyanide, CO and azide
P/O ratio
Measurement of the coupling of ATP synthase to electron transport
Yield of ATP from 1 mole of glucose
30-32