Chemistry• Atoms are the basic units of matter• Cells are the basic units of life

• Cells are made of matter, especially organic matter (contains carbon atoms)

• The principal categories of organic matter are:– Carbohydrates– Lipids– Proteins– Nucleic acids

pH• pH - a measure of the amount of

hydrogen ions in a solution. Concentration of hydrogen [H+].

• The relationship between [H+] and pH is: pH=-log [H+].

• pH varies between 0 and 14, neutral pH =7= pH of water.

• The higher the acidity, the higher the concentration of hydrogen ions is. For every unit of pH, the hydrogen concentration in the solution multiplies by

• This concept of acidity is very important for life

Organic compounds

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Carbohydrates: C6 or C5 ring

* C6 ring: common carbohydrates:

- 1 ring: glucose, fructose, galactose

- 2 rings: sucrose, lactose, maltose

- Many rings: glycogen, starch

- Role: Short term energy storage

Carbohydrates: C6 or C5 ring

• C5 ring: special role

• In ATP, nucleic acids

Organic compounds

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Lipids

• Formed by a glycerol backbone and attached fatty-acids

• Fatty-acids: a string of carbons with hydrogen atoms

• Molecules hydrophobic and rich in energy long term energy storage

Figure 2-8 (3 of 6)

Figure 2-8 (2 of 6)

Phospholipids

• One fatty-acid is replaced by a phosphoric group property of the molecule changes amphipatic molecules (like both water and lipids)

Figure 3-15 - Overview

Lipid: Cholesterol

• Component of cell membrane

• Base for steroid hormones

Organic compounds

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Proteins

• Two basic roles:- Structural: building block of the cell (collagen, elastin..)

- Enzymatic: control metabolism (enzymes)

Proteins: Primary structure

• The primary structure of a proteins is its string of amino acids.

• These a.a. are covalently (strongly) attached

• There are 20 different amino acids that can potentially be found in the proteins

• The order of a.a. varies different sequences

Secondary structure of a protein

• Folding of the a.a. chain - fold as a alpha helix

- or a beta sheet

Tertiary structure of a protein

• Folding of the chain due to hydrogen bonds formed by the various amino acids

** This folding gives the protein its shape the shape of a protein gives it its function

Figure 2-16

Figure 2-9 - Overview (1 of 7)

Figure 2-9 (2 of 7)

So what happens when the pH in the cell changes?

So what happens when the pH in the cell changes?

• The protein changes shape loose its function denaturation

Organic compounds

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Nucleic acid• DNA• RNA• ATP

• Formed by a C5 carbohydrate + phosphate + a base

• Bases: adenine, cytosine, thymine, guanine and uracil

Figure 2-12 - Overview