Biochemistry Flashcards
What are nucleotides?
Compound = nitrogen containing base + sugar + phosphate
Which end of DNA are new nucleotides added to?
3”
What are ZDV & AZT?
Retrovirals (used to treat HIV)
What are Okazaki fragments?
Short DNA formed on a lagging strand in DNA replication
What does helicase do?
Unwind DNA strand (stop it rewinding)
In which direction is the leading strand formed in?
3” - 5”
In which direction is the lagging strand formed in?
5” - 3”
What do enzymes do?
Catalyse a reaction so it reaches equilibrium faster
Do enzymes alter the position of equilibrium?
No
What are the 2 types of co factors?
Metal ions
Coenzymes
What is an apoenzyme?
Enzyme without cofactor
What is holoenzyme?
Enzyme with cofactor
Where do substrates bind to enzymes?
Active site
What factors affect enzyme activity?
Temperature
pH
Concentration (enzyme or substrate)
What are isozymes?
Isoforms of enzymes
Catalyse same reaction but have different shape & properties
What does increased CK show?
Muscle damage (skeletal)
What are Zymogens?
Inactive precursors of enzymes
What does the Michaelis-Menten equation show?
Kinetics of an enzyme reaction
What is Vmax?
Maximal rate of reaction (with unlimited substrate)
What is Km?
Michaelis constant
Conc of S when 1/2 Vmax
Mechanisms of enzyme control
Allosteric Regulation of transcription Reversible covalent modification Irreversible covalent modification Degradation
What is Allosteric control?
Altered enzyme activity by means of conformation induced by different molecules
Do Allosteric enzymes follow Michaelis-Menten kinetics?
NO
What shape is the curve of an allosteric enzyme?
Sigmoid
What is cooperativity?
Influence that binding of a ligand to one promoter has on the binding of a ligand to another promoter in an oligomennorhea phase
What are nucleosides?
Compound = nitrogen based base + sugar
E.g. Adenosine
4 types of amino acid
Polar
Non polar
Acidic
Basic
What is the Henderson-Hasselbach equation used for?
Calculate the properties of buffer solutions
What is a buffer solution?
A solution that’s pH remains constant when small amounts of acid or base are added
When does pH = pKa in a titration curve?
Point of inflexion
What is the primary structure of a protein?
Sequence of amino acid residues (held together by covalent peptide bonds)
What is the secondary structure of a protein?
Localised conformation of the polypeptide backbone
What is the tertiary structure of a protein?
3D structure of an entire polypeptide, including all its side chains
What is the quaternary structure of a protein?
Spatial arrangement of polypeptide chains in a protein with multiple subunits (NOT all the time)
3 arrangements of secondary structure protein?
Alpha helix
Beta pleated sheets
Beta strands
Which protein has a triple helix?
Collagen
Why is collagen important?
Influences strength of connective tissue
Important for blood clotting
Symptoms of scurvy?.
Bleeding gums
Skin discolouration
Stages of catabolism
1) macromolecules -> monomeric units
2) monomeric units -> Acetyl-CoA + some ATP
3) Acetyl group -> Kreb cycle -> CO2 + H2O
3 types of protein
Fibrous
Globular
Conjugated
Which forces stabilise tertiary structures?
Covalent disulphide bridges Electrostatic interactions Hydrogen bonds Hydrophobic interactions Complex formation with metal ions
What 4 things can disrupt protein structure?
Heat
Extremes of pH
Detergents (urea, guanidine hydrochloride)
Thiol agents, reducing agents
Where does GLUT1 work?
Brain (low Km)
Where do GLUT2 receptors act?
Liver (high Km) Beta cells (insulin dependent)
Where does the GLUT3 receptor act?
Brain (low Km)
Where does the GLUT4 receptor act?
Muscle (insulin-dependent)
Adipose tissue
Where does the GLUT5 receptor act?
But (fructose transport)
3 enzymes involved in glycolysis?
Hero kinase
Phospofructokinase
Pyruvate kinase
What is the substrate for the TCA cycle?
Acetyl Co-A
What is given off when pyruvate is converted to Acetly Co-A?
CO2
What combines with Acetyl Co-A at the start of the TCA cycle?
Oxaloacetate
How many GTP are produced in the TCA cycle?
1
What are the 2 stages of oxidative phosphorylation?
Electron transport
ATP synthesis
In oxidative phosphorylation what reduces O2 to H2O?
Electrons from NADH & FADH
What does the P/O ratio measure?
The coupling of ATP to synthesis to electron transport
How many ATP are made in total in the complete oxidation of glucose?
30-32 ATP molecules
What type of diseases are OXOPHOS?
Degenerative diseases
Examples of glycogen storage disease
McArdle’s disease
Andersen disease
Pompe disease
Which enzyme marks muscle damage and what is its presentation?
CK
General aches/pains, crush injury, dark urine, poor exercise tolerance
What enzymes indicate liver damage and what is its clinical presentation?
ALT, AST, GGT
Abdominal pain/tenderness, nausea/vomiting, jaundice
What enzymes indicate pancreatic damage and what does it present as?
AMY, LIP
Acute abdominal pain, radiates to back
What enzymes indicate cardiac damage and what is its clinical presentation?
CK, AST, LDH
Central chest pain, acute breathlessness, palpitations, cardiac arrest
What does an increase in ALT usually indicate?
Drug overdose (or liver necrosis) - exclusive to liver
What does GGT increase indicate?
GGT found in biliary tract and in liver
Increase shows alcohol excess
What is lipase a good indicator of?
Pancreatic hepatitis
What does reduced trope in show?
Had an MI
Symptoms of hyperglycaemia?
Extreme thirst Dry mouth Blurred vision Drowsiness Frequent need to pass urine
Symptoms of hypoglycaemia?
Feeling shaky and irritable Sweating Tingling lips Feeling weak Hunger Nausea
Why do hypoglycaemic patients feel sick?
Lack of glucose -> breakdown fats to ketones -> acidosis
What are chylomicrons?
A lipoprotein present in the blood after digested fat has been absorbed from the small intestine
How do statins work?
Inhibit an enzyme involved in cholesterol synthesis in the liver
How is Vmax determined from a Lineweaver-burk plot?
Intersection with the y axis
How is Km determined from a lineweaver-burk plot?
Intersection with x axis
