Molecules of Life

Chapter 3

Molecules

Inorganic compound Nonliving matter Salts, water

Organic compound Molecules of life

Contains Carbon (C) and Hydrogen (H) Carbon backbone

Carbon Chemistry

Cell is mostly water The rest of the cell consists mostly of carbon-based molecules

Carbon is a versatile atom four electrons in an outer shell that holds eight can share its electrons with other atoms to form up to four

covalent bonds

Organic Molecules

Many molecules of life are macromolecules(macromolecules contain many molecules joined together)

Monomers: Simple organic molecules that exist individually

Polymers: Large organic molecules form by combining monomers

Polymer Monomer

Carbohydrate Monosaccharide

Protein Amino acid

Lipids Triglycerides

Nucleic acid Nucleotide

Molecules of Life

4 main classes of biological molecules 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic Acids

Carbohydrates

Carbohydrates

Some Functions: Quick fuel Short-term energy storage Structure of organisms Cell to cell recognition

Consist of C, H, and O atoms 1:2:1 ratio

“Saccharides”3 major classes:

Monosaccharides Disaccharides Polysaccharides

Monosaccharides

“simple sugars”; “one monomer of a sugar” Dissolve easily in water

hydrophilic

Glucose C6H12O6

Fructose Form of glucose

Disaccharides

Short chain of two sugar monomers

Two Monosaccharides Lactose, sucrose, maltose Lactose = glucose + galactose

Polysaccharide

“Complex” carbohydrate Composed of many glucose molecules

Glycogen Polysaccharide of glucose Storage form of glucose in animals

Starch Storage form of glucose in plants

Cellulose Found in the cell walls of plants

Lipids

Lipids

Cells use lipids to store energy Hydrophobic Functions:

Energy Storage Cushioning and Insulation Found in the plasma membrane

3 main types: Fats & Oils Phospholipids Steroids

Fats

Dietary fat consists largely of the molecule triglyceride Combination of glycerol and three fatty

acids

Fats

Unsaturated fatty acids Have less than the maximum number of hydrogens

bonded to the carbons

Saturated fatty acids Have the maximum number of hydrogens bonded to the

carbons Most animal fats have a high proportion of saturated fatty

acids, which can be unhealthy Example: butter

Most plant oils tend to be low in saturated fatty acids Example: corn oil

Phospholipids

Glycerol, two fatty acids and a phosphate group

Plasma membrane Nonpolar tail Polar heads

Proteins

Why Proteins??

VERY important functions in cells Keratin and collagen have structural roles Enzymes speed up chemical reactions of

metabolism Responsible for transport of substances within

the body Transport substances across cell membranes Hormones that regulate cellular function

Insulin

Proteins

Made from amino acids 20 various kinds

Amino acids linked to one another by peptide bonds Two amino acids bound

by a peptide bond is a dipeptide

Three or more is a polypeptide chain

Protein

Polypeptide

Peptide / Dipeptide

Amino Acids

Protein Structure

Protein’s final shape and chemical behavior arise from it’s primary structure Chain bends, folds, coils,

etc.

Denaturing When proteins lose their

shape

Nucleic Acids

Nucleotides and Nucleic Acids

Nucleic acids Can be single stranded or double stranded

DNA Deoxyribonucleic acid genetic information

RNA Ribonucleic acid used to build proteins

Nucleotides and Nucleic Acids

Nucleic acids Built by nucleotides

Phosphate Pentose sugar Nitrogen-containing base

DNA Composition

DNA is built from four different kinds of nucleotides One of four bases determines the

nucleotide: A - Adenine G - Guanine T - Thymine C – Cytosine

DNA consists of two strands of nucleotides twisted into a double helix

GAGA….a nucleotide repeat!!

Base pairs Bases can only pair up with their corresponding “mate” 2 kinds:

A – T G – C

Amount of A = T Amount of G = C Can line up in any order

DNA Composition

Nucleotides linked together by covalent bonds

Bases of one strand linked to the other by hydrogen bonds

The two strands run in opposite directions

DNA into RNA

RNA a big player!! Single strand Sugar, phosphate group,

and a N-containing base Bases are:

A, C, G, and URACIL (U)