Transcript Chapter 2

LE 2-2
Sodium
Chlorine
Sodium chloride
Table 2-1
LE 2-3
Nitrogen deficiency
Iodine deficiency
Review of Chemistry
LE 2-8
Hydrogen
1H
2
Atomic number
He
Atomic mass
First
shell
4.00
Helium
2He
Element symbol
Electron-shell
diagram
Lithium
3Li
Beryllium
4Be
Boron
5B
Carbon
6C
Nitrogen
7N
Oxygen
8O
Fluorine
9F
Neon
10Ne
Sodium
11Na
Magnesium
12Mg
Aluminum
12Al
Silicon
14Si
Phosphorus
15P
Sulfur
16S
Chlorine
17Cl
Argon
18Ar
Second
shell
Third
shell
LE 2-4
Cloud of negative
charge (2 electrons)
Electrons
Nucleus
LE 2-7a
A ball bouncing down a flight
of stairs provides an analogy for
energy levels of electrons.
LE 2-7b
Third energy level (shell)
Second energy level (shell)
Energy
absorbed
First energy level (shell)
Energy
lost
Atomic
nucleus
LE 2-10
Hydrogen atoms (2 H)
Hydrogen
molecule (H2)
Ionic Bond Example
• Take NaCl as example
• Sodium: loses one electron
• Chlorine: Gains one electron
Formation of Sodium
Chloride
Covalent Bonds
• No gain or loss of electrons
• Only shared electrons
• Electrons can be shared equally or
unequally
Covalently Bonded
Molecules
Name
(molecular
formula)
Hydrogen (H2)
Oxygen (O2)
Water (H2O)
Methane (CH4)
Electronshell
diagram
Structural
formula
Spacefilling
model
Nonpolar Covalent Bonds
• Share e- equally
• The non-polar compounds can NOT
be dissolved in water
Polar Covalent Bonds
• Share e- unequally
• The polar compounds can EASILY be
dissolved in water
Hydrogen Bonds
• Water (H2O or H–O–H) is a polar molecule
– H’s become slightly +, O slightly –
• When polar molecules are dissolved in water
– The H’s of water molecules are attracted to the
negative parts of the solute molecules
• Weak bond, easily broken
Water Molecule
Animation
pH Scale
• pH scale used to indicate acidity and
alkalinity of a solution.
– Values range from 0-14
• 0 to <7 = Acidic
• 7 = Neutral
• >7 to 14 = Basic (or alkaline)
• pH = -log10 [H+]
pH Scale
0
Increasingly Acidic
[H+] > [OH–]
1
Neutral
[H+] = [OH–]
Battery acid
2 Digestive (stomach)
juice, lemon juice
3 Vinegar, beer, wine,
cola
4 Tomato juice
5 Black coffee
Rainwater
6 Urine
7 Pure water
Human blood
8
Increasingly Basic
[H+] < [OH–]
Seawater
9
10
Milk of magnesia
11
Household ammonia
12
Household bleach
13
Oven cleaner
14
Buffers in Biology
• Human blood normally 7.4
• Many foods and metabolic processes add
or subtract H+ or OH- ions
• Reducing blood pH to 7.0 results in acidosis
• Increasing blood pH to 7.8 results in alkalosis
• Both life threatening situations
• Bicarbonate ion (-HCO3) and proteins in
the blood buffers pH to 7.4
Biological Molecules
• Macromolecules
– Carbohydrates
– Lipids
– Proteins
– Nucleic Acids
• Functional Groups and Isomers
Short polymer
Unlinked monomer
Dehydration removes a water
molecule, forming a new bond
Longer polymer
Dehydration reaction in the synthesis of a polymer
Hydrolysis adds a water
molecule, breaking a bond
Hydrolysis of a polymer
Macromolecules
• large size
• Consist of many repeating units
– polymer
– Repeating units are called monomers
•Category
•Example
•Subunit(s)
•Lipids
•Fat
•Glycerol & fatty acids
•Carbohydrates •Polysaccharide
•Monosaccharide
•Proteins
•Polypeptide
•Amino acid
•Nucleic Acids
•DNA, RNA
•Nucleotide
Common Foods
a Glucose
a and b glucose ring structures
b Glucose
Glucose in medicine
• Blood glucose levels:
–
–
–
–
–
Fasting normal serum 60-115 mg/dl
Hyper-glycemia >140 mg/dl
Hypo-glycemia: man < 50 mg/dl; woman < 40
Panic < 40 mg/dl or > 500 mg/dl
Extracellular levels are closely regulated, which is
called glucose homeostasis
• Factors controlling blood glucose levels: intake,
storage and utilization.
• Type I and type II diabetes: insulin deficiency
and receptor deficiency.
a Glucose
a and b glucose ring structures
b Glucose
Starch: 1–4 linkage of a glucose monomers.
Chloroplast
Starch
1 µm
Amylose
Amylopectin
Starch: a plant polysaccharide
Mitochondria Glycogen granules
0.5 µm
Glycogen
Glycogen: an animal polysaccharide
Cellulose microfibrils
in a plant cell wall
Cell walls
Microfibril
0.5 µm
Plant cells
Cellulose
molecules
b Glucose
monomer
The structure of chitin.
Chitin forms the exoskeleton of arthropods.
This cicada is molting, shedding its old
exoskeleton and emerging in adult form.
Chitin is used to make a strong and
flexible surgical thread that decomposes
after the wound or incision heals.
Types of Lipids:
Triglycerides
CH2—R1
CH—R2
CH2—R3
R=
R=
Fatty acid
(palmitic acid)
Dehydration reaction in the synthesis of a fat
Ester linkage
Fat molecule (triacylglycerol)
Stearic acid
Saturated fat and fatty acid.
Oleic acid
cis double bond
causes bending
Unsaturated fat and fatty acid.
Video
Protein: Levels of Structure
• Primary:
– the sequence of amino acids
– A string of beads of 20 different colors with
direction
• Secondary:
a-helix or b-sheets
• Tertiary: Further folding
• Quaternary:
Subunits
The spiral strands
(capture strands) are
elastic, stretching in
response to wind,
rain, and the touch
of insects.
Abdominal glands
of the spider
secrete silk
fibers that form
the web.
The radiating
strands, made
of dry silk fibers,
maintain the
shape of the web.
Spider silk: a structural protein
Containing b pleated sheets
Hydrophobic
interactions and
van der Waals
interactions
Polypeptide
backbone
Hydrogen
bond
Disulfide bridge
Ionic bond
5 end
Nucleoside
Nitrogenous
base
Phosphate
group
Nucleotide
3 end
Polynucleotide, or
nucleic acid
Pentose
sugar
Nitrogenous bases
Pyrimidines
Cytosine
C
Thymine (in DNA) Uracil (in RNA)
U
T
Purines
Adenine
A
Guanine
G
Pentose sugars
Deoxyribose (in DNA)
Nucleoside components
Ribose (in RNA)
ATP