1.2 Important principles in biology

Organisms are ‘living’ things• Living things:– Store energy – in cells, tissues and organs– Release energy – cellular respiration, photosynthesis– Use energy – to move, grow, repair structures, reproduce, detect

and respond to changes, keep internal conditions within limits– Exchange matter with their surroundings – waste products exit,

essential materials enter– Are made of cells

*No non-living thing possesses ALL of these attributes.

Waterfall – non living thing

Elephant – living thing

Candelabra tree – living thing

•All organisms are made up of cells (and the products of cells)

•All cells come from pre-existing cells

•The cell is the smallest living organisational unit

Evolution explains diversity:

• Organisms have changed through time – diversity of living things, fossil record, geographic distribution of organisms, DNA information

• Over time, species become structurally, physically, physiologically and behaviourally adapted to the particular environment in which they live.

• Individuals with features most suited to their environment are likely to survive and produce more offspring than those with less favourable features.

• Over many generations, favoured features become more frequent in the population and undesirable features become less frequent.

• Questions 5 – 8

Compounds

• 92 different elements on Earth• Compounds are molecules containing different

different elements • Organisms produce characteristic complex

compounds that contain carbon and hydrogen• These are called organic compounds • All other compounds are called inorganic

compounds (water, oxygen, Carbon Dioxide, Nitrogen & minerals)

water

• Most organisms are usually 70-90% water• Has important properties –

• pH – enzymes• Cohesiveness – “sticky” allows movement of water up

stems• high heat capacity – absorbs heat without a change in

temperature (temperature regulation)

O2 & CO2

• O2 - Used for release of energy from food molecules

• CO2 - Used in photosynthesis

Nitrogen

• Key component of all proteins• Atmosphere is about 78% nitrogen gas

Minerals

• Biologically important minerals• Phosphorous, potassium, calcium, magnesium, iron, sodium,

iodine, sulfur

Organic molecules

• Carbohydrates• Important source of energy for living organisms• Basic subunits is a monosaccharide (‘single sugar’) • Two sugars join to form a disaccaride• Long chains are called polysaccarides

• Lipids• Fats and oils • Energy stores • Phospohlipids make up the cell membrane

• Proteins• More complex, thousands of different ones • Each organisms proteins are unique• Composed of smaller subunits called amino acids• Linked together with a peptide bond• 20 different amino acids

• Nucleic acids• Genetic material of all organisms• Two types - DNA and RNA

– DNA carries the instructions for protein assembly– RNA plays a roll in the manufacture of proteins within cells

Organic molecules

• Vitamins• Required by animals in small amounts for normal

functioning• Some can be synthesised, others must be obtained in

the diet (Vitamin C) • Some are water soluble (not storable), some are lipid

soluble (storable)

Organic molecules

• Q 9 – 11• Chapter Summary • Key terms – cards or list• Chapter review questions 1 - 11