Biology - Biochemistry (MYP5)

Intramolecular force

within

Intermolecular force

between

Unequal electron distrubution

results in a permanent dipole

Cohesive properties (water)

water interacts with other water molecules

Adhesive properties (water)

water interacts with polar/ionic molecules

Thermal properties (water)

water can absorb significant amounts of heat energy before changing state, this is due to the extensive hydrogen bonding between water molecules

Solvent properties (water)

water dissolves polar/ionic substances (making it an effective transport medium)

Non-polar molecules

oils and fats

Polar molecules and ions

sugar and salt

Hydrophilic

polar (water-loving)

Hydrophobic

non-polar (water-hating)

Metabolism

the totality of chemical reactions that occur in a cell organism - controlled by enzymes (expression regulated by gene activation)

Metabolic reactions (2 key functions)

1. Provide a source of energy for cellular processes (growth, reproduction) 2. Enable the synthesis and assimilation of new materials for use in the cell

Anabolic reactions

build up complex molecules from simple ones - includes the formation of macromolecules from monomers

Catabolic reactions

breaks complex molecules into simple ones - includes the release of monomers from macromolecules

Organic compounds

carbon-containing molecules found in living things

Four main classes

Carbohydrates, Proteins, Lipids, Nucleic acids

Table sugar (class)

Carbohydrates (sucrose)

Steroids (class)

Lipids

DNA (class)

Nucleic acids

Amino acids (class)

Proteins

Monomer (carbs)

Monosaccharide

Monomer (lipids)

Glycerol and fatty acids

Monomer (proteins)

Amino acids

Monomer (nucleic acids)

Nucleotide

Polymer (carbs)

Polysaccharide

Polymer (lipids)

Triglyceride

Polymer (proteins)

Polypeptide

Polymer (nucleic acids)

DNA and/or RNA

Bond involved (carbs)

Glycosidic link

Bond involved (lipids)

Ester linkage

Bond involved (proteins)

Peptide bond

Bond involved (nucleic acids)

Phosphodiester bond

Amino acids (non-polar)

Glycine, Alanine, Valine, Cysteine

Amino acids (polar)

Serline, Glutamine

Amino acids (positive charge)

Lysine, Arginine

Amino acids (negative charge)

Glutamete

Amino acids (links)

covalently linked together by peptide bonds (polypeptides) - polypeptides are synthesised on ribosomes via the process of translation

Condensation reaction

monomer + monomer ------> dimer + h2o

Protein function (structure)

collagen, spider silk

Protein function (hormones)

insulin, glucagon

Protein function (immunity)

immunoglobulins

Protein function (transport)

haemoglobin

Protein function (sensation)

rhodopsin

Protein function (movement)

actin, myasin

Protein function (enzymes)

rubisco, catalase

Denaturation

the change in protein structure that results in a loss (often permanent) of its biological properties - loss of tertiary structure = loss of biological activity

Denaturation conditions (2 key conditions)

1. Temperature - may disrupt bonds that hold proteins together
2. pH - may alter the charge of the protein thus changing its solubility and shape

Gene

is a sequence of DNA that codes for a polypeptide

2 main processes (gene)

1. Transcription - mRNA transcript made from DNA template
2. Translation - mRNA transcript encodes amino acid sequence

Primary (protein structure)

controls all subsequent levels of protein structure

Secondary (protein structure)

stabilises hydrogen bonds between non-adjacent amino acids

Tertiary (protein structure)

interactions between variable groups (ionic bonds, H bonds)

Quarternary (protein structure)

the presence of more than one polypeptide chain in a biologically active protein

Polysaccharides of Glucose

Cellulose, Starch and Glycogen

Cellulose (Polysaccharides of Glucose)

a structural polysaccharide in plant cell walls
1. composed of b-glucose subunits (linear arrangement)

Starch (Polysaccharides of Glucose)

an energy storage polysaccharide used in plants
1. Amylose - composed of a-glucose subunits (linear)
2. Amylopectin - made of a-glucose subunits (branched)

Glycogen (Polysaccharides of Glucose)

an energy storage polysaccharide in humans
1. composed of a-glucose subunits (branched orientation)

Lipids

are a class of organic molecules that are insoluble in polar solvents - they include triglycerides, phospholipids, steroids, waxes and carotenoids

Lipids perform a variety of functions in the body (SHIPS):

1. Storage of energy (triglycerides)
2. Hormonal roles (steroid hormones)
3. Insulation (sphingolipids)
4. Protection of internal cavities (fats and waxes)
5. Structural components of cells (phospholipids)

Triglycerides

function primarily as a long-term energy source - they are formed via condensation between glycerol and 3 fatty acid chains

SODAS

Storage, Osmotic effect (water pulling capacity), Digestion, ATP yield (energy yield), Solubility

Carbohydrate: glycogen (SODAS)

Short-term storage (S), more effect on cell (O), readily digested (D), lower (A), water soluble (S)

Lipid: triglyceride (SODAS)

Long-term storage (S), less effect on cell (O), less easily digested (D), higher (A), not water soluble (S)

LDL

low density lipoproteins - carries cholesterol from liver to the body (for use by the cells)

HDL

high density lipoproteins - carries the excess cholesterol back to liver (for disposal)