Aim: What are the compounds important to living things?

The physical and chemical properties of water make it unique and necessary for living things

Water is necessary for all chemical reactions in living systems.

Water's Chemical Properties

Polar molecule

•sticky

•universal solvent

• pH of 7

Water's Physical Properties

• found in all three states of matter -- liquid, solid (ice), and gas (steam)

Water’s Physical Properties

• water's freezing point is 0 degrees on the Celsius scale

• water's boiling point is100 degrees Celsius

• high specific heat index

Physical Property of water

• high surface tension

Other important inorganic compounds found in living things include salt

body fluids contain salt

Halite

The Chemical Evolution occurred in H2O

The molecules we know today are descended from the first molecules that formed life on

Earth.

Earth’s Primordial Environment Present atmosphere First Molecules formed in organic soup

RNA was the first organic molecule to appear in the organic soup (ocean) of

modern Earth

• Read the article – take notes

• share with your group

What is RNA ?

Atom Element Compounds

Living things are made from organic compounds (C, H, O, N, S, P and other elements in minute amounts)

Organic CompoundsCarbohydrates – sugar, starches

Proteins – meat, fish, beans

Nucleic Acids – RNA, DNA

Lipids - fats

RNA is a polymer made up of four repeating subunits called nucleotides. Each nucleotide contains a sugar, a phosphate group and a nitrogenous base.

Aim: What is RNA?

Nucleotides in RNA are made up of a sugar, phosphate and base

The sugar in the nucleotide that makes up RNA is ribose

Types of RNA

• mRNA - carries a message

• tRNA – carries a code from the mRNA

• rRNA – structural RNA that makes up a ribosome

HW 6

• Make templates of the structures on the sheet with the Parts of RNA nucleotides

• Ribose + phosphoric acid – yellow• Uracil – blue• Cytosine – black• Adenine – red• Guanine – green• Cut out the pieces (4 ribose-phosphoric acid)

and one of each of the others.

Messenger RNA

Messenger RNA is transcribed in the nucleus.

Transfer RNA

The mRNA then enters the cytoplasm and attaches to a ribosome. Translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine. The ribosome also binds the next codon and its anticodon.

mRNA Start codon

Ribosome

Methionine

Phenylalanine tRNALysine

Nucleus

Aim: What is the Structure of mRNA ?Section 12-3

mRNA

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