Download Biology 30 The Chemistry of Living Things

Biology 30
The Chemistry of Living Things
Hierarchy of organization:
Chemistry:
MATTER:
Periodic Table:
ELEMENT:
Ex. oxygen, gold, copper, carbon
COMPOUND:
Ex. salt (NaCl), H2O
ELEMENTS ESSENTIAL TO LIFE:
25 of all elements are essential to life:
4 of these make up 96% of all living matter:
1.
2.
3.
4.
The remaining 4% include:
1. Phosphorus (P)
2. Sulfur (S)
3. Calcium (Ca)
4. Potassium (K)
The human body:
O, C, H, N, Ca, P, K, S, Na, Cl, Mg
Trace elements:
Ex. Iron (Fe), iodine (I)
Fortified Foods:
ATOMS:
Atoms consists of subatomic particles:
Particle
Found
~ Weight (Daltons)
Charge
atomic # 6 C
mass # 12.
Atomic Number:
Atomic weight (or mass number):
Ex. 612C = At. wt => 12 = 6p + 6n
Biology 30
The Chemistry of Living Things
Page 1 of 10
Electrons are found in orbitals around the nucleus
SHELLS: 1st = -.
2nd and subsequent shells =
OCTET Rule: exception H/He
Noble Gases:
Isotope:
Ex. Carbon: 12, 13 & 14
6
13C => How many neutrons?
Proton?
Electrons?
Radioactive isotope (p. 21, Fig 2.5 A&B)
14
6C
=
=> 14 = 6p + 8n => Radioactive isotope
Usefulness in science?
How do the elements stay together?
Chemical bonds:
Three types of chemical bonds:
1. Covalent Bond (between elements)
2. Ionic Bond (between elements)
3. Hydrogen Bond (between molecules)
COVALENT BOND:
Types of covalents bonds:
H-H => single covalent bond
O=O => double covalent bond
N = N => triple covalent bond
H2O => compound
How are electrons attracted to another?
Electronegativity:
Non-Polar covalent bond:
Ex. Oxygen (O2), Methane (CH4)
Polar covalent bond:
Occurs when:
Ex. Water (H2O)
Biology 30
The Chemistry of Living Things
Page 2 of 10
IONIC BOND
ION:
CATION:
ANION:
Electrolyte:
Ex. table salt (NaCl)
Na+
cation
+
Clanion
<--->
NaCl
HYDROGEN BOND
Living cells: electronegative atom => O or N
Are weak bonds, therefore easy to break
IMPORTANCE:
WATER AND ITS UNUSUAL PROPETIES:
Note: Understand these 5 properties & their significance to life.
H-bond
Water:
Polar molecule
Hydrogen bonding BETWEEN each water molecule
a) Cohesiveness
cohesion:
adhesion:
surface tension
b) High specific heat
c) High heat of vaporization
Evaporative cooling:
d) Density of water
e) Versatile solvent
Biology 30
The Chemistry of Living Things
Page 3 of 10
pH, acids, bases & buffers
Terms:
Solution:
Solvent:
Solute:
aqueous solution:
Dissociation of H2O (refers to the separation of H2O)
H2O <--> H+ + OH-
or
H2O + H2O <--> H3O+ + OH-.
Chemical equilibrium = the amount of H+ is equal to the amount of OH.
pH scale: (p. 27; Fig. 2.15)
range:
log based scale pH = -log[H+]
= - log [10-5]
= - (-5)
=5
0.00001M
Inverse relationship:
• Increase [H+] When:
pH = 7 pH < 7 pH > 7 •
Decrease [H+] Most biological systems:
Exception:
(a)
<--------
(b)
---------->
(c)
-------->
(d)
<--------
0
(e)
7
(f)
1. pH values of acidic solutions
2. pH values of basic (alkaline) solutions
3. point at which H+ equal OH-.
4. progressing from a weak to strong acid
5. progressing from a weak to a strong base
6. results of adding more hydrogen to a solution
14
(g)
ACIDS:
BASES:
BUFFERS:
Biology 30
The Chemistry of Living Things
Page 4 of 10
Ex. Carbonic acid - bicarbonate buffer system (2nd most important body buffering system)
If pH rises ...
H2CO3 -------> HCO3- + H+.
(acid)
(base)
+
H donor H+ acceptor
If pH drops ... H2CO3 <------- HCO3- + H+.
releases H+.
absorbs H+.
helps to maintain your blood pH at ~ 7.35 - 7.45
If blood pH:
falls below 7.35 => acidosis => needs to absorb H+.
rises above 7.45 => alkalosis => needs to release H+.
Is this system involved in positive or negative feedback?
Organic chemistry:
CARBON:
- Atomic # =
, therefore has
- Forms covalent bonds with:
valence (outer shell) electrons
Hydrocarbons
Ex.
6 FUNCTIONAL GROUPS:
1. HYDROXYL GROUP
2. CARBONYL GROUP
ALDEHYDES (C dbl bond O at the end)
KETONES (C dbl bond O in middle)
3. CARBOXYL GROUP
carboxylic acids.
4. AMINo GROUP
amines
5. PHOSPHATE GROUP
Ex. ATP ---> ADP + Pi
6. METHYL GROUP
Biology 30
The Chemistry of Living Things
Page 5 of 10
Biological Molecules:
4 classes of large biological molecules in living organisms:
1. Carbohydrates
2. Proteins
3. Nucleic acids
4. Lipids (not a true macromolecule)
Classifying organic compounds:
Monomers:
Polymers:
Formation of polymers: Fig 2.13
Dehydration reactions (synthesis):
Ex. glucose + glucose = maltose
Breaking of polymers:
Hydrolysis (water;loosening or splitting)
Ex. digestive enzymes
Types of Macromolecules:
CARBOHYDRATES:
Classified by:
1. Monosaccharides = (mono = single; sacchar = sugar)
Simple sugar composed of:
2. Disaccharides =(Di = two; saccharide = sugar) Fig. 2.13b
Results from the removal of:
Disaccharide
Maltose
Lactose
Sucrose
Monomers
Usage
3. Polysaccharide fig.2.15
-2 important biological functions:
1. Energy storage (starch & glycogen)
a) Starch:
b) Glycogen:
Biology 30
The Chemistry of Living Things
Page 6 of 10
2. Structural support (cellulose & chitin)
a) Cellulose:
b) Chitin:
LIPIDS: (Fig. 2.16)
1. Fats:
macromolecules constructed from:
a) glycerol = 3C -OH
b) Fatty acid (carboxylic acid)
carboxyl:
hydrocarbon tail:
Formation of fats
Triglycerides:
SATURATED
UNSATURATED
Ex.
Ex.
2. Phospholipids Fig. 2.17
Composed of:
Hydrophilic heads & Hydrophobic tails
Micelles:
Surfactant (surface active agent):
3. Steroids (Fig 2.18)
Functions of lipids:
1.
2.
3.
4.
5.
6.
PROTEINS: (Fig 2.20)
Peptide bond
Biology 30
The Chemistry of Living Things
Page 7 of 10
-N-C-C-N-C-C- = backbone
Polypeptide chain =
There are 20 amino acids which make up proteins (Fig 2.19)
Amino acids contain both carboxyl and amino functional groups.
Levels of protein structure (Fig 2.21):
a) Primary structure (1˚):
b) Secondary structure (2˚):
2 types of secondary structure:
α helix
ß pleated sheet
c) Tertiary structure (3˚):
d) Quaternary structure (4˚):
Ex. Hemogoblin = 4 subunits
Denaturation:
Causes of denaturation:
1.
2.
3.
4.
8 Functions of proteins:
1. structural support
2. storage
3. transport
4. hormonal
5. receptor
6. contractile
7. defense
8. enzymatic
Enzymes: Fig. 2.22
•
• Catalysts:
•
How enzymes work?
•
Specificity:
•
Recycled (reusable)
Biology 30
The Chemistry of Living Things
Page 8 of 10
Catalytic cycle: E + S --> ES complex --> E + P
Substrate:
Active site:
Induced fit model:
Factors that affect enzyme activity:
1. Environmental conditions (optimum conditions)
a)
b)
c)
2. Cofactors and coenzymes:
• cofactors = inorganic (zinc, iron)
• coenzymes = organic (vitamins)
3. Enzyme inhibitors (p.85, Fig. 5.16)
• competitive inhibitors:
non-competitive inhibitors:
NUCLEIC ACIDS:
Nucleotide = building block of a nucleic acid; composed of:
a) Pentose (5-C sugar)
b) Nitrogeneous bases:
c) Phosphate Group:
3 Examples of Nucleotide based molecules:
1. DNA = deoxyribonucleic acid (Fig 2.24)
DNA: the double helix = 3-D shape = Watson & Crick => 1953
Contains:
Biology 30
The Chemistry of Living Things
Page 9 of 10
2. RNA = ribonucleic acid (Fig 2.24)
Contains:
3. ATP = adenosine triphosphate (Fig 2.26)
Functions of Nucleotide based molecules
a)
b)
c)
d)
Biology 30
The Chemistry of Living Things
Page 10 of 10