Cells Nucleus Contains DNA Nucleolus inside Double nuclear

Cells Nucleus • Contains DNA • Nucleolus inside • Double nuclear membrane with nuclear pores • Produces m. RNA for protein synthesis Mitochondria • Double membrane with foldings (cristae) • Kreb’s cycle occurs in matrix • Oxidative phosphorylation occurs in the inner membrane • ATP produced here The Peer Teaching Society is not liable for false or misleading information…

Cells Endoplasmic reticulum (ER) Smooth – lipid synthesis Rough – contains ribosomes for protein synthesis Golgi apparatus • Receives proteins/lipids from ER, then packages them into vesicles for transport Vesicles • Storage and transportation The Peer Teaching Society is not liable for false or misleading information…

Cells Cytoskeleton • 3 D internal scaffold which holds cell structure together • Allows movement e. g. facilitated diffusion Made from • Microfilament (actin) • Intermediate filament • Microtubules (two tubulin proteins) The Peer Teaching Society is not liable for false or misleading information…

Cell membranes • Phospholipid bilayer • “Fluid mosaic model” – due to intrinsic/extrinsic proteins Functions • Acts as semi-permeable membrane • Hosts cell membrane receptors • Regulates what goes in and out of cell • Separates intracellular cell contents from extracellular cell contents Lipid tail = hydrophobic Fatty acid head = hydrophilic The Peer Teaching Society is not liable for false or misleading information…

Cell membranes Contains • Cholesterol – supports fluidity • Proteins – act as transporters • Glycolipids and glycoproteins – involved in cell signalling Lipid groups that make up the plasma membrane: • Phospholipids • Glycolipids • Sphingolipids • Cholesterol The Peer Teaching Society is not liable for false or misleading information…

Cell junctions The Peer Teaching Society is not liable for false or misleading information…

Movement across membrane • Endocytosis Energetic process to absorb/engulf molecules into cell. • Exocytosis Vesicles (from Golgi apparatus) move out of cell • Diffusion Moves across membrane down concentration gradient • Facilitated diffusion Moves across membrane through carrier proteins • Active transport Moves across membrane against concentration gradient (using ATP and a carrier protein) • Osmosis Water movement across membrane down concentration gradient The Peer Teaching Society is not liable for false or misleading information…

Hormones • Peptide vs steroid Peptide hormones (e. g. thyroxine) Steroid hormones (e. g. cortisol) Stored in vesicles ready for release Made and released when needed Made by amino acids (e. g. tyrosine) Made from cholesterol Binds onto cell membrane Binds onto blood protein Fast action Slow action The Peer Teaching Society is not liable for false or misleading information…

Homeostasis Definition: the maintenance of stable internal conditions within the body Positive feedback • rate of a process increases as the concentration of the product increases e. g. Clotting cascade Negative feedback • rate of the process decreases as the concentration of the product increases e. g. Blood glucose regulation/osmoregulation The Peer Teaching Society is not liable for false or misleading information…

Cell signalling The Peer Teaching Society is not liable for false or misleading information…

Water distribution in the body • 2/3 intracellular 28 L 3 L intravascular • 1/3 extracellular 14 L 11 L interstitial fluid ECF: contains glucose, urea, Cl- and HCO 3 - , main cation is Na+ ICF: main cation is K+ The Peer Teaching Society is not liable for false or misleading information…

Osmoregulation • Low water levels (dehydration) detected by osmoreceptors in the hypothalamus of the brain • Osmoreceptors send signals to the posterior pituitary gland, to release anti-diuretic hormone (ADH) • ADH travels to the kidney and allows more water uptake through aquaporins in the collecting duct Fluid loss can be SENSIBLE (can be measured e. g. urine) or INSENSIBLE (cannot be measured e. g. evaporation) The Peer Teaching Society is not liable for false or misleading information…

Definitions - water • Osmolality: concentration of solutes in plasma per KILOGRAM of SOLVENT • Osmolarity: concentration of solutes in plasma per LITRE of SOLUTION • Osmotic pressure: measure of how easily a solution can take in water • Oncotic pressure: specific type of osmotic pressure concerning blood proteins e. g. albumin • Oedema: increased movement of fluid from plasma to interstitial space The Peer Teaching Society is not liable for false or misleading information…

Carbohydrates • Monosaccharide: any sugar that can not be hydrolysed e. g. Glucose • Oligosaccharide: a substance made up of 3 -10 monosaccharides. • Polysaccharide: a complex carbohydrate composed of more than 10 monosaccharides joined by glycosidic bonds • Glycosidic bonds form from a condensation reaction of two monosaccharides. Water is produced as a by product The Peer Teaching Society is not liable for false or misleading information…

Lipids • • • Hydrophobic Made from fatty acids (saturated or unsaturated) Saturated = single bonds Unsaturated = double bonds Ester bond formed in lipids The Peer Teaching Society is not liable for false or misleading information…

Amino acids Central carbon atom attached to • Amine group –NH 2 • Carboxyl group –COOH • Hydrogen group –H • Variable group –R Peptide bonds form between amino acids in condensation reaction The Peer Teaching Society is not liable for false or misleading information…

Proteins • • Primary sequence of amino acids with peptide bonds Secondary alpha helix / beta pleated sheet Tertiary folding into 3 D shape – includes disulphide bridges and hydrogen bonds Quaternary multiple tertiary proteins working together e. g. haemoglobin The Peer Teaching Society is not liable for false or misleading information…

Enzymes Enzyme: a biological catalyst Co-enzymes: form covalent bonds with enzyme to maximise enzyme activity Factors which affect rate of reaction: • Temperature • Surface area • Enzyme • Pressure/concentration The Peer Teaching Society is not liable for false or misleading information…

Forces In order of strength: • Ionic bonding • Covalent bonding • Hydrogen bonding • Van der Waals The Peer Teaching Society is not liable for false or misleading information…

ATP-ADP cycle • ATP + water -> ADP + phosphate + H+ • Energetically favourable • Phosphate and H+ enter other metabolic pathways Common uses of ATP • Muscle contraction • Biosynthesis Production of ATP • Oxidation of lipids/proteins/carbs • • • The ATP molecule has two phosphoanhydride bonds These are RELATIVELY WEAK bonds, hence require relatively less energy to break Overall more energy is released informing the products that used tobreak bonds in the reactants The Peer Teaching Society is not liable for false or misleading information…