WHAT MOLECULES ARE THE BUILDING BLOCKS FOR LIFE?

Macromolecules

Organic vs. Inorganic

- Organic Compounds contain carbon and are in living things

- Inorganic compounds generally don’t contain carbon atoms Carbon can combine to form 4 covalent

bonds; can create a wide variety of many simple or complex compounds

-Functional Groups are groups of atoms that influence the properties of their molecules and the chemical reactions in which they participate.

- Polymers are repeated, linked units of a molecule

- Monomers are simple molecules formed by hydrolysis

Cellular Currency

ATP- (Adenosine Triphosphate) is the energy currency of the cell, Ex) Debit card not useful in school building but cash is, much like glucose isn’t useful to cell until it is broken down into ATP through cellular respiration

4 Classes of Organic Compounds

-Carbohydrates

- Lipids

-Proteins

- Nucleic Acids

I. Carbohydrates – organic compounds

Made of carbon, hydrogen and oxygen in a 1:2:1 ratio

A) Monosaccharide – simple sugar a. Examples are fructose, glucose, galactose b. Molecular formula is same (C6H12O6) but

structures are different, called isomers

Carbohydrates – organic compounds, con’t

B) Disaccharide- double sugars a. Example is sucrose- made of fructose and

glucose b. Complex molecule

C) Polysaccharide- 3+ monosaccharide a. Examples are glycogen, starch and cellulose b. Very complex strands of sugar molecules tied

together to form long chains

II. Protein- organic compounds

organic compounds made of carbon, hydrogen, oxygen and nitrogen; formed from amino acids linked together

A) Amino Acids- 20 different ones a. Share same basic structure and bond with

a peptide bond (covalent) b. Polypeptides are long chains of Amino

Acids (building blocks of life)B) Enzymes- biological catalysts that

speed up or slow down chemical reactions a. Environmentally sensitive – temperature,

pH, etc.

III. Lipids- large, nonpolar molecules

Include: triglycerides, phospholipids, steroids, waxes, and pigments

A) Fatty Acids- unbranched carbon chains a. Has polar and nonpolar end b. Saturated fats have all carbons fully bonded to

four atoms c. Unsaturated fats may contain at least one or

more double bond

III. Lipids, con’t

B) Triglycerides – fats, phospholipids and waxes a. Have high melting point and are hard

when saturated b. Unsaturated are soft and usually liquids

C) Phospholipids- have a phosphate attached to a glycerol which has two fatty acids a. Polar and nonpolar ends form

‘phospholipid bilayer’ of the cell membrane

III. Lipids, con’t

D) Waxes- long fatty acid chain with alcohol chain hanging a. Waterproof, form barriers in animals and

coatings on plantsE) Steroids- 4 fused carbon rings with

different functional groups a. Examples- testosterone, cholesterol

IV. Nucleic Acids

A) DNA- Deoxyribonucleic Acid a. Large, complex molecule that determine all the

traits of an organism b. Contains nucleotides- 3 parts; a phosphate

group, a 5-carbon sugar and a ring shaped nitrogen base (A-T-G-C-and U in RNA)

B) RNA- Ribonucleic Acid a. Stores and transfers information from DNA b. Acts as enzymes

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Importance of water

• Overview: The Molecule That Supports All of Life

• Water is the biological medium here on Earth

• All living organisms require water more than any other substance

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Water Facts• Three-quarters of the Earth’s

surface is submerged in water• The abundance of water is the

main reason the Earth is habitable

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Water’s Polarity• The polarity of water molecules

– Allows them to form hydrogen bonds with each other

– Contributes to the various properties water exhibits

Hydrogenbonds

+

+

H

H+

+

–

–

– –

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Properties of water• Six emergent properties of water

contribute to Earth’s fitness for life1.Cohesion/Adhesion2.Surface tension3.Temperature Moderation4.High specific heat5.Evaporative cooling6.Universal solvent

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Cohesion• Water molecules exhibit cohesion• Cohesion

– Is the bonding of a high percentage of the molecules to neighboring water molecules

– Is due to hydrogen bonding– Like molecules bonding to each

other (water attracting other water molecules)

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Cohesion• Cohesion

– Helps pull water up through the microscopic vessels of plants (capillarity)

Water conducting cells

100 µm

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Surface Tension• Surface tension

– Is a measure of how hard it is to break the surface of a liquid

– Is related to cohesion

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Moderation of Temperature• Water moderates air temperature• By absorbing heat from air that

is warmer and releasing the stored heat to air that is cooler

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Heat and Temperature• Kinetic energy

– Is the energy of motion• Heat

– Is a measure of the total amount of kinetic energy due to molecular motion

• Temperature– Measures the intensity of heat

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Water’s High Specific Heat• The specific heat of a substance

– Is the amount of heat that must be absorbed or lost for 1 gram of that substance to change its temperature by 1ºC

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Specific Heat• Water has a high specific heat

which allows it to minimize temperature fluctuations to within limits that permit life– Heat is absorbed when

hydrogen bonds break– Heat is released when

hydrogen bonds form

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Evaporative Cooling• Evaporation

– Is the transformation of a substance from a liquid to a gas

– Requires energy• Heat of vaporization

– Is the quantity of heat a liquid must absorb for 1 gram of it to be converted from a liquid to a gas

– 100oC steam has MORE HEAT than 100oC boiling water (540 calories)

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Evaporative Cooling

• Is due to water’s high heat of vaporization

• Allows water to cool a surface• Sweating cools the body as

heat energy from the body changes sweat into a gas

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Insulation of Bodies of Water by Floating Ice

• Solid water, or ice–Is less dense than liquid water

–Floats in liquid water–Insulates water & organisms below ice layer