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Chemistry of Life

All biology is based on chemistry

Let’s start: Everything is built from atoms

Elements necessary for life

Atoms versus ions (and why this matters)

Oxygen in atoms and molecules

Example of water and hydrogen peroxide (for now, see below)

Chemistry of carbon atoms (for now, see below)

What is metabolism? (anabolic and catabolic)

Organic molecules

Synthesizing organic molecules


Cellular respiration (intro)

Cellular respiration (honors)

Photosynthesis (intro)

Photosynthesis (honors)

How does fat get made? What happens to it when it is broken down?

And although some people consider this next idea an “honors” topic, in some ways it is the most basic: X-ray crystallography. How we know how atoms are really arranged in proteins, enzymes, DNA, etc.?

Inorganic chemistry

Chlorine and bleach terminology

Sample MCAS questions

Biology and Particle Physics: The Particle Physics of You

The chemistry of water

Water is the basis of all life on Earth.

H2O    dihydrogen monoxide , or just dihydrogen oxide

H2O2   hydrogen peroxide

Pure H2O2 is rocket fuel. It would burn through your skin.

H2O2 that you buy in the store is weak – It’s only 3% . The rest is water.

H2O2 is not stable – it eventually breaks down into regular water and oxygen gas bubbles.

You see those oxygen bubbles fizzing when you put H2O2 on a wound.

Chemistry of carbon atoms

Atoms of the same element will have totally different properties, depending on how they are arranged. Consider how the same carbons act in

(a) coal           (b) graphite – used in pencils, or golf clubs

(c) diamond   (d) buckyball

(e) nanotube  (f) graphene

Carbon forms of

Carbon with oxygen

What happens when carbon bonds with oxygen?

CO    carbon monoxide    

It prevents your red blood cells from carrying oxygen

Extremely tiny amounts of CO exist naturally and safely.
But when larger amounts form they quickly become deadly.

CO forms when we burn fuel, but there is not enough oxygen to produce carbon dioxide (CO2). That can happen when we use a stove or internal combustion engine, in an enclosed space.

CO2  carbon dioxide

Forms during cellular respiration, the process by which cells get energy from burning sugar.

CO2 is a waste product made by animal life. We excrete it through our lungs.

Organic molecules

are based on Carbon and Hydrogen (with a few other atoms)

C = Carbon                           H = Hydrogen

O = Oxygen                            N = Nitrogen

S = Sulfur                              P = Phosphorus

Glucose – a simple sugar

Glucose is the most common source of energy for animals. It is made by plants during photosynthesis.

Chemical formula for glucose:   C6H12O6

This is a simple way to show the glucose molecule

This is a ball-and-stick model of the same molecule

Sample questions

Feb 2016 MCAS.

ATP molecules in cells undergo a process called hydrolysis. The equation below represents this process.

ATP + H2O → ADP + Pi

( Pi = inorganic phosphate)

What always happens within cells as a result of ATP hydrolysis?

A. Water is produced.
B. Chemical energy is released.
C. Phosphorus atoms are used up.
D. Carbohydrate building blocks are formed.


Feb 2017 MCAS.

Some bacteria produce cellulase, a substance that speeds up the breakdown
of cellulose in plant cell walls. Cellulase is an example of which of the following?
A. a carbohydrate .    B. an enzyme .     C. a hormone .     D. an organelle


Feb 2017 MCAS.  Protein pumps actively transport ions across a cell’s plasma membrane. What molecule directly supplies the energy required for this transport?

A. ATP .       B. cholesterol .       C. oxygen .       D. tRNA


Learning Standards

Massachusetts Curriculum Frameworks: Biology

8.MS-PS1-1. Develop a model to describe that (a) atoms combine in a multitude of ways to
produce pure substances which make up all of the living and nonliving things that we
encounter, (b) atoms form molecules and compounds that range in size from two to
thousands of atoms, and (c) mixtures are composed of different proportions of pure

Clarification Statement: Examples of molecular-level models could include drawings, three-dimensional ball and stick structures, and computer representations showing different molecules with different types of atoms.

HS-LS1-6. Construct an explanation based on evidence that organic molecules are primarily composed of six elements, where carbon, hydrogen, and oxygen atoms may combine with nitrogen, sulfur, and phosphorus to form monomers that can further combine to form large carbon-based macromolecules.
Clarification Statements:
• Monomers include amino acids, mono- and disaccharides, nucleotides, and fatty acids.
• Organic macromolecules include proteins, carbohydrates (polysaccharides), nucleic acids, and lipids.

Disciplinary Core Idea Progression Matrix: PS1.A Structure of matter

That matter is composed of atoms and molecules can be used to explain the properties of substances, diversity of materials, how mixtures will interact, states of matter, phase changes, and conservation of matter.

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