Flashcards in Biochemistry Deck (107):
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?
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?
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?
What is entropy?
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?
Is ΔG in endergonic +ve or -ve?
Break down of complex molecules
Assembly of complex molecules from smaller ones
Break down of glucose into pyruvate
Makes glucose from pyruvate
4 Types of amino acid
Non-polar = hydrophobic
Polar = uncharged
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
Van der Val Forces
Which amino acid forms disulphide bridges?
Where does DNA replication and transcription take place?
Where does translation take place?
Base + sugar
Nucleoside + phosphate group
Which carbon is the base and phosphate connected to?
Base = carbon 1
Phosphate = Carbon 5
Adenine and guanine
Thymine, uracil and cytosine
How many bonds between A and T?
How many bonds between C and G?
What is the catalyst for DNA replication?
Which direction does DNA polymerase work?
3' to 5' direction
What is the most abundant type of RNA?
What synthesises all RNA?
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
Where the anticodons in tRNA form base pairs with the codons in mRNA - both consist of three nucleotides
Many codons code for one amino acid
Each codon codes for only one amino acid or a stop
Which enzyme binds amino acids to their tRNA molecule?
What is the initiation tRNA?
UAA, UAG and UGA
Change in single base in DNA
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
An enzyme without a co-factor
An enzyme with a co-factor
Example of a co-factor
zinc, ion, copper (in stable transition state)
Enzymes which both catalyse the same reaction but do it in a slightly different way from each other
Converts enzymes into an active or inactive form
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
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?
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
Oxidised precursor + electrons = reduced biosynthetic product
What are the two qualities of an anabolic reaction?
Endergonic and reductive
Reduced fule - electrons = oxidised product
What are the two qualities of a catabolic reaction?
Exergonic and oxidative
Terminal electron acceptor
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?
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?
Net yield from each molecule of glucose
10 NADH and H+
What is the energy from proton flow used for?
Phosphorylation of ADP to ATP
2 transport modes of NADH
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
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?
Chemicals which inhibit oxidative phosphorylation
Cyanide, CO and azide
Measurement of the coupling of ATP synthase to electron transport