Lesson 4 (Week 5)4 March 2014

Biochemical molecules and cellular transport

Pop QuizQuestion Bega Cooma Queanbeyan

1 c c c

2 b b b

3 a a a

4 b a a

5 a a c

6 b b b

7 a a b

8 c a a

Bonus

Bonus

Total 5 7 5

Today’s lessonWe will be looking at • Basic chemistry principles• Biochemical molecules– Carbohydrates– Proteins– Lipids

• Passive transport in cells– Diffusion– Osmosis– Facilitated diffusion

Some basic chemistry

• All matter is made up of atoms• Atoms combine to form molecules• Compound- is a molecule with more than

one type of atom.

Basic chemistrySubstance Chemical formula Atomic structureWater H2O

Carbon dioxide

CO2

Oxygen (gas)

O2

Glucose C6H12O6

Urea CO(NH2)2

Table salt NaCl

More basic chem• All particles are in motion (Brownian motion)• Motion of particles depends on energy

available to them (ie heat increases motion)• Atoms stick together due to chemical bonds• Bonds store energy- when a bond is broken,

energy can be released

Organic compounds

• Derive from life and living things• Contain carbon atoms in chains or ring

molecular structures

Carbohydrates• Include substances such as sugars, starches,

cellulose• Are made up of Carbon (C), Hydrogen (H)

and Oxygen (O)• Carbons form chains or rings (rings are more

common)• Often a repeat sequence of a simple

saccharide (or two)

Carbs• Monosaccharides have the simplest molecular structure• Include simple sugars (eg glucose) & taste sweet• 3,5 or 6 carbon atoms

Carbs• Disaccharides are also sugars and include

sucrose (cane sugar)• Made us of 2 monosaccharide subunits

eg sucrose=glucose + fructose subunits

Carbs• Polysaccharides are the most complex carbs

include starch and cellulose• Contain many hundreds of subunits in long

chains eg starch contains many glucose subunits (300-600) in long chains

Lipids• Include fats, waxes, steroids and phospholipids• Usually repel water and form globules

Fats

• Act as an energy store• Have long chains of carbons in their

structure

Phopho lipids• A molecule with a polar head and non polar

tail• Allows formation of the cell membrane- a

phospho lipid bilayer

Proteins• Include enzymes, cell structure, antibodies,

toxins, hormones• Are made up of chains of amino acids in

complex structures

Protein synthesis

DNA and RNA• Made up of chains of nucleotides• Nucleotides are made up of rings if carbon, a

phosphate group and a nitrogenous base

Movement across cell membranes• Substances have to move in and out of cells• Small particles such as O2, CO2, H2O can diffuse

across cell membranes • Larger particles such as glucose need to be facilitated• Membrane impermeable to proteins, nucleotides

Concentration gradients

• These occur when there is a difference between concentrations of solutions between two regions

• Diffusion occurs ‘down’ the conc gradient, from high to low

Diffusion

• Movement of ions down a concentration gradient (ie from high low)

Homework: where does diffusion occur in a biological organism and for what purpose?

Osmosis• Movement of water across a semipermeable

membrane

Homework: can you find examples of osmosis occurring in a biological organism?

Isotonic, hypotonic and hypertonic• Movement of water via osmosis is dependent on

concentration of solutes (dissolved substances) on either side of the membrane. Intercellular fluid can be isotonic (same concentrated), hypotonic (less concentrated) or hypertonic (more concentrated)

Facilitated diffusion

• Movement of molecules across the cell membrane down a concentration gradient, via a specific carrier protein