IB Biology Topic 2 : Molecular Biology

How many bonds can carbon make

carbon can make four covalent bonds

Four most common compounds

* carbon
* hydrogen
* nitrogen
* oxygen

what is life based on

carbon compounds

metabolism

chemical processes in the body, synthesis & breakdown of substances in living organisms.

anabolism

the synthesis of complex molecules (condensation reaction)

catabolism

the breakdown of complex molecules into simpler macromolecules (hydrolysis)

Importance of the artificial creation of urea

vitalism - states that organic compounds can come from living things, so the creation on urea in a lab disproved this

international problems with water

Water is not readily available to all countries. And even within countries there are distribution problems

What does polar and non polar mean?

* polar means that there is a positive and negative charge and equal sharing of electrons
* non-polar means that there is an unequal sharing

what kind bonds do water molecules make with each other

hydrogen bonds

Hydrogen Bonds

Hydrogen bonds are the weakest because they are positive

Covalent Bonds

covalent bonds are strongest because they share a pair of electrons.

Properties of Water

Water molecules are polar (forms hydrogen bonds), because of the pull of electrons towards oxygen.

Cohesion

when water sticks to itself. Allows surface tension to occur.

Adhesion

when water sticks to to other substances.

Thermal properties of water (3)

* water has the highest heat capacity
* takes a lot of energy before it will change temperature
* It also has a high boiling point because it takes a lot of energy to break hydrogen bonds.

Hydrophobic (2)

* not attracted to water
* insoluble in water

Hydrophilic (3)

* attracted to water
* dissolves well in water
* form molecular bonds with water molecules

What are the four main macromolecules?

* lipids
* carbohydrates
* nucleic acids
* proteins

Carbohydrates

* Sugars
* Made of of C, H, and O
* Quick energy storage

Monosaccharides

* sugars that consist of a single sub-unit (monomer)
* glucose, fructose, galactose

Disaccharides (2)

* pairs of monosaccharides linked together by condensation
* eg. maltose (glucose +glucose) lactose (glucose + galactose) sucrose (fructose + glucose)

Polysaccharides (4)

* complex carbohydrates
* chain of many monosaccharides
* extremely soluble
* eg starch, glycogen and cellulose

How are sugars classified?

the number of carbons

Lipids

* carbon compounds
* non polar hydrophobic organic molecules

Types of lipids (3):

* triglycerides (fats & oils)
* phospholipids
* steroids (testosterone & estrogen)

Function of lipids

* twice as much energy as carbohydrates but a slower release
* insulation
* framework for cell membrane

Health risks for trans/saturated fat (2)

Trans fats increase the "bad" cholesterol which raises the risks of heat disease.

BMI Equation

bmi = weight of body / (height in meters squared)

Fatty Acids (3)

* Saturated: connected by single bonds
* Unsaturated: one or more double bonds
* Mono-saturated: one double bond

Cis-unsaturated:

H bonded to C on the same side of the double bond

Trans-unsaturated:

H bonded to C on different sides of the double bond.

Polypeptides

* chain of amino acids

Denaturation (2)

* destruction of enzyme characteristics
* caused by heat or change in pH

Enzymes (2)

* biological catalysts
* they speed up chemical reactions and metabolism

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Factors affecting enzymes (3)

* temperature
* pH
* substrate concentration

Production of lactose free milk (for lactose intolerant people)

* lactose is the sugar in milk
* hydrolyzed into glucose by enzyme lactase

DNA

* nucleotide: sugar, phosphate and nitrogenous base

Bases of DNA

adenine, thymine, guanine and cytosine

Structure of DNA

double helix

Structure RNA

single stranded

Base of RNA

thymine is replaced by uracil

Proteome

the combination of all proteins in an organism

bonds that link amino acids to form polypeptides. you take way the OH and one of te H's from the H2 of the amine group

Peptide bonds

primary, secondary, tertiary, and quaternary

the arrangement of the order of amino acids

This group determines the function of the protein and thus instructs how the it will interact with other amino acids ( which instructs how the amino acid chains are folded)

The importance of the R group

Activation energy

the energy it takes to begin a reaction

Active site

the place where the substrate binds to the enzyme; where the reaction occurs