CARBOHYDRATES

• Living things use carbohydrates as a key source

of ENERGY!

• include sugars and complex carbohydrates

(starches)

• contain the elements carbon, hydrogen, and

oxygen in a 1:2:1 ratio

• 4 calories per gram

Monosaccharides (simple sugars)

• all have the formula C6H12O6

• all have a single ring structure

– (glucose is an example)

Disaccharides (double sugars)

• all have the formula C12H22O11

• sucrose (table sugar) is an example

Polysaccharides

• Formed of three or more simple sugar units

• Glycogen - animal starch stored in liver & muscles

• Cellulose – plant starch - indigestible in humans -

forms cell walls

• Starches - used as energy storage

Lipids (Fats)

• Fats, oils, waxes, steroids

• Chiefly function in energy storage, protection,

and insulation

• Contain carbon, hydrogen, and oxygen but they

are not in a 1:2:1 ratio

• Tend to be large molecules -- an example of a

neutral lipid is below

• 9 calories per gram

Lipids - What are they good

for?

• Fats -- found chiefly in animals

• Oils and waxes -- found chiefly in plants

• Oils are liquid at room temperature, waxes are solids

• Lipids along with proteins are key components of cell membranes

• Steroids are special lipids used to build many reproductive hormones and cholesterol

PROTEINS

• Contain the elements carbon, hydrogen, oxygen, and

nitrogen

• 4 calories per gram

• Build & repair tissue

• Movement (actin,myosin)

• Structure (collagen)

• Transport (hemoglobin)

• Defense (antibodies)

• Regulation (enzymes)

NUCLEIC ACIDS aka the building

blocks of DNA and RNA

• composed of NUCLEOTIDES

• store & transmit heredity/genetic information

• a 5- carbon sugar + a nitrogenous base + a phosphate

group

• Contain C, H, O, N & P

• We’ll talk about these later

Enzymes and Enzyme Action

• catalyst: inorganic or organic substance which

speeds up the rate of a chemical reaction without

changing the reaction

• enzymes: organic catalysts made of protein

– most enzyme names end in -ase

– Enzymes lower the energy needed to start a chemical

reaction. (activation energy)

• Substrate = reactant

– reactant + reactant = products

"Lock and Key Theory"

• each enzyme is specific for one and ONLY one

substrate (one lock - one key)

• this theory has some weaknesses, but it

explains some basic things about enzyme

function

Factors Influencing Rate of

Enzyme Action

1. pH - the optimum (best) in most living things is

close to 7 (neutral)

2. Temperature - strongly influences enzyme

activity

3. Concentrations of Enzyme and Substrate

A little more on WATER

• Cohesion – like molecules attracted to each

other

• Surface tension – cohesion of water molecules

that enable it to resist external forces (gravity)

• Adhesion – attraction of different types of

molecules

Hydrolysis

• Hydro = water

• Lysis = break apart

• Chemical process in which a water molecule is

added to a substance resulting in the split of that

substance into two parts

Dehydration

• Chemical process involving the removal of water

to join molecules

• (it’s the opposite of hydrolysis)

Capillary Action

• aka – capillarity

• The ability of a liquid to flow against gravity

• Liquid spontaneously rises in a narrow space

such as a thin tube or paper

Capillarity

• It happens because: the inter-molecular

attractive forces between the liquid and solid

surrounding surfaces

• The combination of surface tension (which is

caused by cohesion within the liquid) and forces

of adhesion between the liquid and container act

to lift the liquid