Molecules of Life Matter is anything that occupies

Molecules of Life Matter is anything that occupies space or has mass • Mass – quantity of matter an object has • Weight – pull of gravity on an object Can you think of something that has neither mass nor weight?

Elements • Pure substances that cannot be broken down chemically into simpler kinds of matter • More than 100 elements (92 naturally occurring)

Atoms • The simplest particle of an element that retains all the properties of that element • Properties of atoms determine the structure and properties of the matter they compose

The Nucleus • Central core • Consists of positive charged protons and neutral neutrons • Positively charged • Contains most of the mass of the atom

The Neutrons • The number varies slightly among atoms of the same element • Different number of neutrons produces isotopes of the same element

The Protons • All atoms of a given element have the same number of protons • Number of protons called the atomic number • Number of protons balanced by an equal number of negatively charged electrons

The Electrons • Negatively charged high energy particles with little or no mass • Travel at very high speeds at various distances (energy levels) from the nucleus • Are located around the nucleus

Atomic Mass • The atomic mass of an atom is found by adding the number of protons & neutrons in an atom • # of protons + # of neutrons =atomic mass What is the Atomic Mass of the following element?

90% of the mass of an organism is composed of 4 elements 1. 2. 3. 4. oxygen carbon hydrogen nitrogen

____ ATOMS MOLECULES _____ ORGANELLES ______

CELLS TISSUES ____________ Similar cells working together IMAGE SOURCES: see last slide

ORGANS SYSTEMS ______ Different tissues working together Different organs working together ORGANISM ______

Compounds • Most elements do not exist by themselves but as compounds. • A compound is a pure substance made up of atoms of two or more elements.

Is H 20 an element or a compound? Why?

Carbon Compounds • Contain carbon atoms, an element with four valence electrons • The most common biomolecule or basic building blocks of cells.

Carbohydrates • One of the four main carbon molecules • Made of carbon, hydrogen, and oxygen in a 1: 2: 1 ratio

Carbohydrates • Monosaccharide (single sugar) • Disaccharide (double sugars) table sugar • Polysaccharide (many sugars) starch

Carbohydrates Cells use carbohydrates for: structural support energy supply cell recognition

Lipids • Consist of chains of carbon atoms bonded to each other and to hydrogen atoms.

Lipids include: fats phospholipids steriods waxes

Lipids The main purpose of lipids: Store Energy Control Water Movement

Proteins Made of Amino Acids There are 20 different amino acids Every amino acid has an amino group (-NH 2) and a carboxyl group (-COOH) with a varying side group.

Proteins They are the workhorse molecules of all living things. Proteins: Provide structure / support Enable movement Carry out chemical reactions Aid in transportation / movement

Nucleic Acids Composed of a chain of nucleotides. Nucleotides are made of three parts: a sugar, a base, and a phosphate group.

Nucleic Acids include DNA stores genetic information RNA responsible for protein synthesis ATP main energy source for cells