Ch. 6.4 Life substances Objectives: Classify the variety of organic compounds. Describe how polymers are formed and broken down in organisms. Compare the chemical structures of carbohydrates, lipids, proteins, and nucleic acids, and relate their importance to living things. Identify the effects of enzymes.

The Chemistry of Life What are living creatures made of? Why do we have to eat?

Molecules of Life  Put C, H, O, N together in different ways to build living organisms  What are bodies made of? carbohydrates  sugars & starches proteins fats (lipids) nucleic acids  DNA, RNA

Why do we eat?  We eat to take in more of these chemicals Food for building materials  to make more of us (cells)  for growth  for repair Food to make energy  calories  to make ATP ATP

What do we need to eat?  Foods to give you more building blocks & more energy  for building & running bodies carbohydrates proteins fats nucleic acids vitamins minerals, salts water

 Water 65% of your body is H 2 O water is inorganic  doesn’t contain carbon  Rest of you is made of carbon molecules organic molecules  carbohydrates  proteins  fats  nucleic acids Don’t forget water

The Role of Carbon in Organisms  Organic compounds contain carbon  A carbon atom has four electrons available for bonding in its outer energy level. In order to become stable, a carbon atom forms four covalent bonds that fill its outer energy level.  Carbon compounds vary greatly in size.  When carbon atoms bond to each other, they can form straight chains, branched chains, or rings.

How do we make these molecules? We build them!

Building large molecules of life  Chain together smaller molecules building block molecules = monomers  Big molecules built from little molecules polymers

 Small molecules = building blocks  Bond them together = polymers Building large organic molecules

Making and Breaking of POLYMERS  Cells link monomers to form polymers by dehydration synthesis (building up) Short polymer Unlinked monomer Removal of water molecule Longer polymer

Building important polymers sugar – sugar – sugar – sugar – sugar – sugar nucleotide – nucleotide – nucleotide – nucleotide Carbohydrates = built from sugars Proteins = built from amino acids Nucleic acids (DNA) = built from nucleotides amino acid amino acid – amino acid – amino acid – amino acid – amino acid –

How to build large molecules  Dehydration Synthesis building bigger molecules from smaller molecules building cells & bodies  repair  growth  reproduction + ATP

Example of synthesis amino acidsprotein amino acids = building block protein = polymer  Proteins are synthesized by bonding amino acids

How to take large molecules apart  Hydrolysis (Digestion) taking big molecules apart getting raw materials  for synthesis & growth making energy (ATP)  for synthesis, growth & everyday functions + ATP

Making and Breaking of POLYMERS  Polymers are broken down to monomers by the reverse process, hydrolysis ( hydro ~ add water; lysis ~ to split) Addition of water molecule

Example of digestion starchglucose ATP  Starch is digested to glucose

1. CARBOHYDRATES  composed of carbon, hydrogen, and oxygen with a ratio of about two hydrogen atoms and one oxygen atom for every carbon atom.

Carbohydrates  Building block molecules = sugar sugar - sugar - sugar - sugar - sugar sugars

sucrose Carbohydrates  Function: quick energy energy storage structure  cell wall in plants  Examples sugars starches cellulose (cell wall) glucose C 6 H 12 O 6 starch

Regents Biology Building carbohydrates  Synthesis | glucose | glucose 1 sugar = monosaccharide 2 sugars = disaccharide | maltose mono = one saccharide = sugar di = two

Regents Biology Building carbohydrates  Synthesis | fructose | glucose 1 sugar = monosaccharide | sucrose (table sugar) 2 sugars = disaccharide How sweet it is!

Regents Biology BIG carbohydrates  Polysaccharides  large carbohydrates  starch  energy storage in plants potatoes  glycogen  energy storage in animals in liver & muscles  cellulose  structure in plants cell walls  chitin  structure in arthropods & fungi exoskeleton poly = many

Regents Biology Building BIG carbohydrates glucose + glucose + glucose… = starch (plant) glycogen (animal) energy storage polysaccharide

Regents Biology Digesting starch vs. cellulose starch easy to digest cellulose hard to digest enzyme

Regents Biology Cellulose  Cell walls in plants  herbivores can digest cellulose well  most carnivores cannot digest cellulose  that’s why they eat meat to get their energy & nutrients  cellulose = roughage  stays undigested  keeps material moving in your intestines

Lipids composed largely of carbon and hydrogen They are not true polymers They are grouped together because they do not mix with water (Nonpolar) ( ie. fats, oils, waxes )

Lipids  Examples fats oils waxes Steroid hormones  sex hormones testosterone (male) estrogen (female)

Lipids  Function: energy storage  very concentrated  twice the energy as carbohydrates! cell membrane cushions organs insulates body  think whale blubber!

Structure of Fat not a chain (polymer) = just a “big fat molecule”

Saturated fats  Most animal fats solid at room temperature  Limit the amount in your diet contributes to heart disease deposits in arteries

Lipids include fats,  Fats are lipids whose main function is long term energy storage  Other functions: Insulation in higher vertebrates “shock absorber” for internal organs Fatty acid

Saturated & Unsaturated fats  fatty acids of unsaturated fats (plant oils) contain double bonds These prevent them from solidifying at room temperature  Saturated fats (lard) lack double bonds They are solid at room temperature

Saturated fats  Most animal fats solid at room temperature  Limit the amount in your diet contributes to heart disease deposits in arteries

Unsaturated fats  Plant, vegetable & fish fats liquid at room temperature  the fat molecules don’t stack tightly together  Better choice in your diet

Saturated vs. unsaturated saturatedunsaturated

Other lipids in biology  Cholesterol good molecule in cell membranes make hormones from it  including sex hormones but too much cholesterol in blood may lead to heart disease

Other lipids in biology  Cell membranes are made out of lipids phospholipids heads are on the outside touching water  “like” water tails are on inside away from water  “scared” of water forms a barrier between the cell & the outside