Biology I Notes
Chapter 2—Chemistry of Life
Name___________________
Atoms/Elements
•All matter is made of ___________
- # Protons—_________________
- # Electrons—_____________________
- # Neutrons—mass number ________ atomic number
Elements:
•are substances made of one kind of ________and are therefore the simplest
•differ in the number of ____________ they contain
•Represented by alphabetic symbols: _______________
Compounds-Covalent bonding
–Compound-bonded atoms of 2 or more different ____________
•Covalent bonds ____________electrons and form molecules
•Hydrogen bonds are weak attractions between polar molecules
–Example: ________________
–shared electrons are attracted more strongly by the oxygen than the
hydrogen
–results in partially ____________and ____________ ends or poles
Compounds-Ionic bonding
•Ionic bonds form when atoms or pairs of molecules lose or gain
an electron.
–loss of an electron forms a cation
(+ charge)
–gain of an electron forms an anion
(- charge)
________bonding
______bonding
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The number of times an atom can bond to another atom is determined by the number of
________________ in the __________________________.
•The first shell can hold _________
•The second shell can hold __________
•The third shell can hold _________
Water and Solutions
Properties of Water
•______ of the body is water
•______of the molecules in the body are water molecules
•assists in temperature regulation—maintaining _______________
–Cohesion is an attraction between substances of the ___________________
•the _________bonds between water molecules cause the cohesion of liquid
water
•Molecules at the surface of water link together to create __________________
•Ex: water molecules to ________________________
–Adhesion is an attraction between ______________ substances
•Seen in plants as capillary action as water is attracted to the _________________ more
strongly than __________ pulls it down, allowing stems and leaves to acquire the water
they need.
•Ex: water molecule to glass surface on side of ____________________
The Universal Solvent-_______________
•Water’s ___________ permits it to dissolve many substances
•__________-polar substances like ______ do NOT dissolve well in water
pH
•indicates the number of charged_____________ atoms in a solution
•acids have a pH ___________ 7 and form ________________when dissolved in water
•bases have a pH ___________ 7 and form ________________when dissolved in water
•water is considered _________________
•pH scale (p.33)
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Organic CompoundsCARBOHYDRATES
-Made of ___________ in a ratio of ____________
-____________, galactose, fructose
-Common processes involving organic compounds
 _________________________—combines 2 sugar
molecules (monosaccharide) to form a disaccharide or a
polysaccharide made of many _________________________
– ____________________—occurs when carbohydrates
consumed as food are broken apart to form simple sugars
» requires one _______________________________
» opposite of __________________________
LIPIDS




Made of ____________but in a much greater ratio than carbohydrates
Store more energy than _________________________
Contained in _________________ cell membranes
Saturated vs. Unsaturated
o saturated fats are solid at ____________________________
o unsaturated fats are generally ___________at room temperature
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PROTEINS
•
•
•
•
A chain of molecules called _________________
___________ different amino acids
builds muscle, skin, ligaments, bones, hair, etc.
Made of _______________________
NUCLEIC ACIDS
• Made of C, H, O, N, ________
• __________
• __________
CHEMICAL REACTIONS
– Absorb or release energy when
• Chemical bonds are _____________
• Chemical bonds are _____________
– Need energy to begin—called _________________________
ENZYMES
– Most are _________________
– Increase the speed of chemical reactions in __________________
– Very specific
• Act on substances called ______________________
• The active site of the enzyme determines which substrate it can
act on
• Fig. 2-15 (p 41)
– Affected by
• _______________
• __________
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