Download Covalent Reactions Atoms SHARE electrons

Unit 1: Cell Biology
Chapter 2: The Molecules of Cells
Covalent Reactions
Atoms SHARE electrons
More Covalent Reactions
Ionic Reactions
Atoms GAIN or LOSE electrons
Ionic bond= attraction between oppositely charged ions
Hydrogen Bonds
• Hydrogen bond = covalently bonded
hydrogen is positive and attracted to a
negatively charged atom
Polarity of H20
Hydrogen bonds
Cohesive
Note to self:
[H+] = hydrogen ions
[OH-]= hyrdoxide ions
Acidic: pH <7
[H+] > [OH-]
Neutral: pH = 7
[H+] = [OH-]
Basic: pH >7
[H+] < [OH-]
pH Scale
Synthesis (dehydration) & Hydrolysis
Monomer= simple organic
molecule, exists
individually
Polymer/Macromolecule=
many monomers linked
together
Examples of Monomers and Polymers
Polymer
carbohydrate
protein
Nucleic acid
lipids
See page 31 in Inquiry into Life text
Monomer
monosaccharide
Amino acids
nucleotides
Fatty acids
Carbohydrates (CH2O)n
Functions: a) quick & short term energy storage
b) structural role in plants, bacteria, insects
Types:
Monosaccharide= simple sugar, 3-7 carbon atoms
ex. Glucose, fructose, galactose
Disaccharide= two monosaccharides joined by dehydration
ex. Maltose, sucrose, lactose
Polysaccharide= long polymers of many glucose subunits
ex. Starch, glycogen, cellulose
Synthesis and Degradation
of Maltose, a disaccharide
Lipids
Functions: energy storage
Types:
• Fats (triglyceride) and Oils
– Saturated Fatty Acid= no double covalent bonds
between carbon atoms (saturated)
– Unsaturated Fatty Acid= has double bonds between
carbon atoms
• Phospholipids- like fats but has phosphate group
instead of third fatty acid
• Steroids- has a backbone of 4 fused carbon rings
(Cholesterol is a type of steroid)
Synthesis and Degradation
of a Fat molecule
Structure of a
phospholipid and
steroid
See Figures 2.22 and 2.23 in Inquiry into
Life textbook
Proteins
Proteins= polymers of amino acid monomers
Many functions! Some examples:
• Keratin- skin and nails
• Collagen- ligaments, tendons, skin
• Many hormones
• Actin and Myosin- allow muscles to contract
• Hemoglobin- transport oxygen in blood
• Antibodies in the blood
• Allow movement through cell membrane
• Enzymes (speed up chemical reactions)
Representative Amino Acids
Synthesis and Degradation of
a dipeptide
Amino acids
Polypeptides
Proteins
Levels of Protein Organization
• Primary: linear sequence of amino acids joined
by a peptide bond
• Secondary: polypeptides take on a certain
orientation in space (alpha helix or pleated sheet)
due to hydrogen bonding between peptides
• Tertiary: final 3D shape maintained by various
bonding (covalent, ionic and hydrogen)
• Quaternary: only in some protein, due to
polypeptide arrangements
Levels of Protein Organization
Nucleic Acids
Two Types:
DNA
Sugar
Bases
Strands
Helix
Functions
RNA
Deoxyribose
A,G,T,C
Double
Yes
Ribose
A,G,U,C
Single
No
Genetic
material that
specifies
protein
synthesis
mRNA, rRNA,
or tRNA
Function in
protein
synthesis
Overview of DNA structure
ATP (Adenosine Triphosphate)
• Energy carrier in cells
• High energy molecule because last two
phosphate bonds are unstable and easily
broken