Human health and disease

• Transcription: The DNA helicase breaks the hydrogen bonds between bases in the helix, exposing unpaired bases.
• Translation: contains two attachment sites for tRNA and one attachment site for mRNA, they carry specific amino acids and bind to ribosomes by codon-anticodon interactions.
• DNA- larger than RNA, double stranded, sugar= deoxyribose, bases are G,A,C,T, double helix so strands are antiparallel
• RNA- smaller than DNA, single stranded, sugar= ribose, bases are G,A,C,U, isnt a double helix.
• mRNA- is a single strand wound into a helix, complementary to DNA and carries genetic code to a ribosome.
• rRNA- makes up ribosomes along with proteins, ribosomes are made up of 2 subunits, 1 small and 1 large, the site of translation in protein synthesis.
• tRNA- specific to amino acid, small molecules folded into a clover leaf shape.
• Adenine pairs with thymine in DNA and uracil in RNA
• Guanine pairs with cytosine
• Nucleotides- a 5 carbon sugar (ribose/deoxyribose), a nitrogenous base (thymine, adenine, guanine, cytosine) and a phosphate group
• ATP- formed in an endergonic reaction, reaction takes energy away. energy required to combine ADP and inorganic phosphate to form ATP from exergonic reactions. ATP may be called the 'universal energy currency' in organisms because its a common energy source used in all living organisms.
• Triglyceride- important for insulation, energy store and protects delicate organs

  
• Glycerol- joins via condensation reactions

  
• Phospholipid- hydrophilic head, hydrophobic tail. heads face out and tails face in

  
• steroids- all steroids contain 4 rings, steroids include oestrogen and testosterone, made from cholesterol

  
• Saturated fatty acids- no carbon-carbon double bonds. Unsaturated fatty acids- contains one carbon-carbon double bonds. Polyunsaturated- contains 2 or more carbon-carbon double bonds

  
• Alpha carbon- 4 different chemical groups attached. NH2 amino group- attached to the alpha carbon by a covalent bond, it is attached at one end of the molecule N terminal. COOH carboxyl group- attached at other end of the molecule, the C terminal. R group- variable group with different amino acids, it can be a single hydrogen or a more complex group, can form disulphide bridges.

  A) R group

  B) NH2 amino group

  C) COOH carboxyl group

  D) alpha carbon

  
• Maltose: alpha glucose-alpha glucose-product of starch digestion. Sucrose: alpha glucose-fructose-table sugar. Lactose: galactose-alpha glucose-milk sugar. All disaccharides can be hydrolysed into its monomers by enzymes.
• Primary- sequence of amino acid, a polypeptide chain, amino acids held with peptide bonds. Secondary- folding of polypeptide chains into an alpha helix or beta pleated sheet, with hydrogen bonds. Tertiary- folding of polypeptide chains into a quaternary structure, with hydrogen bonds. Quaternary- two or more polypeptide chains joined, haemoglobin.

  
• Globular protein- soluble spherical molecules with metabolic functions, enzymes. Structural- insoluble molecules with a structural function, keratin.
• DNA replication- DNA helicase breaks the hydrogen bonds between the bases, unwinding the DNA to expose unpaired bases, this then forms bonds between adjacent nucleotides in the new strands of DNA being formed.
• Genetic code- amino acids are coded using triplets of bases in the DNA, its transcripted to produce codons in mRNA and then translated to produce amino acids. genetic= code is a linear, triplet, non-overlapping, universal code for the production of polypeptides in all organisms
• The polarity of protein molecules affects their position in the membrane. Intrinsic proteins include channel proteins and carrier proteins. the extracellular surfaces can be glycosylated have sugar chains attached. The fluid mosaic model is used to show this.

  
• plasma membrane- controls materials that move in and out of cell. Nucleus- contains DNA. Nucleolus- makes ribosomes. Rough ER- contains ribosomes for protein synthesis. Smooth ER- synthesis lipids and carbohydrates. Golgi apparatus- packages proteins into membrane bound sacks. Mitochondria- site of aerobic respiration and ATP. Nuclear envelope- double membrane around nucleus has pores to let mRNA leave.

  
• All have endothelial cells and a lumen. Capillaries are a tissue but artery and vein is a organ. Only veins have valves. Capillaries don't have an outer layer, muscle or elastic. Arteries have a thicker muscle layer and elastic layer. Capillaries have a much narrower lumen.

  
• Atrial systole- the SAN generated an impulse, the impulse spreads along Purkinje fibres to all parts of the atria, the muscle contracts. Atrial systole- impulse is held up at the AVN, lets the atria empty, cardiac muscle contracts, ventricles relaxes and blood continues to be forced.
• Ventricular systole + atrial diastole- impulse is conducted along the bundles through ventricle walls, atria relaxes, ventricles contract and AV valves close. Atrial + ventricular diastole- no impulse, cardiac muscle in atria and ventricles relax. The cardiac muscle is myogenic- naturally contracts and relaxes on its own accord.
• When the atria contracts, pressure increases, moving blood to ventricles. When the ventricle contracts, pressure increases, moving blood to arteries. The valves prevent back flow. Arterioles have high pressure and muscles contract to constrict blood vessels. Capillaries are very thin to maximise the exchange of materials.
• • Erythrocytes- contains haemoglobin and are important for transporting oxygen. Leukocytes- white blood cells that are involved with immunity and engulf pathogens. Thrombocytes form clots when blood vessels are breached to stop bleeding
• Blood is a medium for transporting materials around the body. It transports waste products like urea and carbon dioxide in the form of hydrogen carbonate, electrolytes, amino acids, protein and hormones all within the plasma.
• Blood is grouped depending on the presence/lack of antigens on the erythrocyte surface, this is called ABO blood groups. Blood is grouped according to the presence of the Rhesus D antigen, those who have it are Rhesus positive and those who don't are Rhesus negative.

  
• Breathing in-external muscles contract, internal muscles relax, ribs are pulled up and out to increase thorax volume, diaphragm muscles contract (flattening). Breathing out- internal muscles contract, external muscles relax, ribs are pulled down and in to decrease thorax volume, diaphragm muscles relax (domed shape)
• The alveoli is the site of gas exchange, they need support to prevent the sacks from collapsing during expiration. A pulmonary surfactant is released to reduce surface tension and prevent the collapse.

  
• Collision theory- enzymes work when they collide with substrate. Competitive- inhibitor is a similar shape to substrate, competes with enzyme. Non-competitive- inhibitor is complementary to another site on the enzyme and distorts the active site shape.

  
• Simple diffusion- small lipid soluble molecules from an area of high concentration to low concentration through a bilayer. Facilitated diffusion- the movement of water soluble molecules that move via special proteins. Active transport- movement of substances from a low concentration to a high one carried out by proteins and needs ATP. Osmosis- Movement of water from high to low. Endocytosis and exocytosis- bulk transport of large molecules.
• The right+left atria receive blood from systemic+pulmonary circulation. Both ventricles force blood through both circulations. The right ventricle pumps blood to the lungs and has a thinner muscular wall. The left ventricle has thicker walls to allow pressure to pump blood to the rest of the body.