The cell theory
- All organisms are composed of cells (or the products of cells)- All cells come from pre-existing cells- The cell is the smallest living organisational unit.
Include protists, fungi, plants & animals.
Common features shared by all cells
Plasma membraneCytoplasmGenetic material in the form of DNARibosomes.
Simple structureA nucleoid lacking a membraneScattered ribosomesDNA mainly in a single-stranded loop in the nucleoid.
Complex structureMembrane-bound nucleusMany organelles in the cell cytoplasmDNA mainly in chromosomes in the nucleus.
NucleusVacuoleGolgi apparatusRough and smooth endoplasmic reticulumRibosomesPlastidsMitochondriaCell wall
NucleusRibosomesGolgi apparatusRough and smooth endoplasmic reticulumVacuolesMitochondriaLysosomesVesiclesCentrioles
Organic versus Inorganic substances
- Contain carbon & hydrogen
- Are found in living things
- Those that are not organic
- e.g. oxygen, water & carbon dioxide
Main types of Organic Compounds
Large organic moleculesFormed by joining together many smaller units (monomers) Monomers form a chain or polymer. Examples: polysaccharides, nucleic acids and proteins
- are an important source of chemical energy forliving organisms (e.g. glucose)- are used as energy reserves in plants (e.g. starch) and animals (e.g. glycogen) - form structural components such as cell walls (e.g. cellulose in plants).- form part of both DNA and RNA- combine with proteins and lipids to form glycoproteins and glycolipids, as in cell membranes.
Fatty substances that are not soluble in waterRoles: - the main component of cell membranes - store energy - play an important role as hormones
Contain the genetic material of all organisms. There are two types: - DNA-carries the 'instructions' required to assemble proteins - RNA-plays a major role in the manufacture of proteins.
Functions of Proteins
Catalyse cellular reactionsPlay an important role as hormonesAct as carrier moleculesForm structural components in organismsPlay an important role in the immune system (e.g. antibodies and antigens)
Important properties of water
CohesivenessSurface tensionHeat capacity pH
Main source of Carbon?
Atmospheric carbon dioxide
Component of all proteins