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Enzymes produced in an inactive form, often needing to undergo a change in tertiary structure (shape)

apoenzyme

holoenzyme

Inactive substances that are converted into an enzyme by another enzyme

• Thymine and Adenine
• Cytosine and Guanine

• Contain 2 carbon rings
• Adenine
• Guanine

• Single carbon ring structure
• Thymine and Cytosine

• Hydrogen Bonding
• Thymine and Adenine form 2 H bonds
• Cytosine and Guanine form 3 H bonds

• Monomer: Nucleotides
• Reaction Type: Condensation
• Bonds produced: Phosphodiester

• Pentose sugar - deoxyribose or ribose
• Phosphate group - PO₄^2-
• Nitrogenous Base

Ribose has an extra OH ) instead of just H on Carbon 2

• CAM 
• Take up CO2 at night and store it to photosynthesize in the day

• Found on T-helper cells surface membrane
• Bind to the surface antigens on antigen presenting cells (APCs)

• CD4 receptors bind to APCs
• Produce Interleukins (type of cytokine) to stimulate:
• B cells
• production of other T cells
• macrophages to ingest pathogens with antigen-antibody complex

• Destroy pathogen with the antigen
• Enzyme Perforin makes holes in their membrane to make them freely permeable

• Immunological memory staying in body for years 
• Divide to form T killer cells in the presence of the antigen

• Suppress the immune system stopping the immune response once the pathogen is destroyed 
• Ensures body recognises self antigens and prevents an autoimmune reponse
• Uses Interleukins

Divide when activated to form plasma cells and B memory cells

Produce 2000 antibodies per second to a particular antigen

• Live for a long time as part of immunological memory
• Remember specific antigen and respond when it is encountered again - making plasma cells

• Bacterial
• Gram Positive bacteria
• Destroys crops and leaves, leaving area unusable for 2 years
• No cure

• Virus
• Infects tobacco plants, tomato etc.
• Damages leaves flower and fruit, stunts growth, reduces yield/total crop loss
• Resistant strains available
• No cure

• Fungus-like protocist oomycyete
• Penetrate host cells destroying leaves/tubers/fruit
• Lots of crop damage
• No cure
• Resistant strains, careful management, chemical treatment reduce risk of infection

• Fungus
• Banana disease
• Destroys leaves, hyphae penetrate and digest cells - black
• Reduction in yield
• Good husbandry and fungicide control spread
• No cure
• Resistant strains being developed

• Bacteria 
• Damages/ destroys lung tissue
• Suppresses immune system
• Curable by antibiotics
• Preventable - vaccination and improving living standards

• Bacteria
• Infection of brain membrane 
• Spread to rest of body causing blood poisoning and death
• Rash
• Immediate attention needed - antibiotics
• Vaccines can prevent some forms

• Virus
• Immunodeficiency virus - syndrome
• Targets T helper cells destroying immune system
• Retrovirus with RNA in genetic material
• enzyme reverse transcriptase transcribes single strand of RNA into strand of DNA to interfere with host cell's genetic material
• No cure, but drugs help slow progress

• Virus
• infection of ciliated epithelial cells - kills them
• can be fatal to young and old often from secondary infection
• Vulnerable groups are given a vaccination annually

• Protoctista spread by bites of infected mosquitoes 
• Life cycle reproducing in female mosquito then passed on to people
• infects RB cells, liver, brain
• No vaccine
• Limited cures
• The vector must be controlled using insecticides, removing standing water, nets, long clothing etc

• Fungus
• Causes grey/white crusty circular areas of skin
• Itchy
• Antifungal creams are effective cure

• fungal
• Grows on and digests warm, moist skin between toes
• Cracking and scaling of skin
• Antifungal creams are effective cure

Fomites - eg bedding, socks...

• Mast cells activated by damaged tissue and release histamines and cytokines
• Histamines: make blood vessels dilate causing heat and redness - help prevent pathogens reproducing
• Histamines: make blood vessel walls more leaky - blood plasma forced out to tissue fluid
• Cytokines: attract WB cells - phagocytes - to site which dispose of pathogens by phagocytosis

• Damaged tissue activates platelets 
• They release Thromboplastin 
• Which in the presence of Ca²⁺ catalyses prothrombin into enzyme Thrombin 
• This catalyses soluble fibrinogen into insoluble fibrin
• Fibrin molecules then polymerise forming mesh forming the clot

• Biurete Test:
• Peptide bonds form violet complexes with Copper ions in alkaline solutions
• Sample mixed with NaOH CaSO4/Biuret reagent solutions
• Left to stand
• Colour change observed

• Benedicts Test
• Grind sample and add to boiling tube
• Add equal volume of Benedict's reagent - Copper II sulphate
• Heat gently for 5 minutes

• Reducing sugars add electrons making Cu2+ ions (blue) go to Cu+ (red)
• Non-reducing sugars means it remains blue eg sucrose

• Iodine Test
• Add iodine dissolved in potassium iodide solution
• Yellow/brown goes purple/black in presence of starch

• Emulsion Test
• Mix with ethanol
• Mix with water and shake
• White emulsion layer on top indicates presence of lipid

• Thin Layer Chromatography 
• Gel applied to surface eg glass
• Amino Acids added to one end
• End submerged in organic solvent
• How far the amino acids move depends on their interactions with the gel (stationary phase) and solvent (mobile phase) - Hydrogen bonds and solubility
• They move at different rates - separating out

• Use biological components to determine presence and concentration of substances eg glucose
• Protein immobilised to a surface eg enzyme, antibody, ssDNA...
• This interacts with substance under investigation
• Causes a change in the transducer 
• Detects change and produces response eg electric current or dye
• Display - visible qualitative or quantitative signal eg particular colour or reading on display