2 chemical principles
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Medical Technology Department, Faculty of Science, Islamic University-Gaza M MICRO B BIOLOGY Dr. Abdelraouf A. Elmanama Dr. Abdelraouf A. Elmanama Ph. D Microbiology Ph. D Microbiology 2008 Chapter 2 Chapter 2 Chemical Principles Chemical Principles
Transcript of 2 chemical principles
Medical Technology Department, Faculty of Science, Islamic University-Gaza
MMICROBBIOLOGY
Dr. Abdelraouf A. ElmanamaDr. Abdelraouf A. ElmanamaPh. D MicrobiologyPh. D Microbiology
2008
Chapter 2Chapter 2Chemical PrinciplesChemical Principles
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Chemistry
• Chemistry is the study of interactions between atoms and molecules.
• The atom is the smallest unit of matter that enters into chemical reactions.
• Atoms interact to form molecules.
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Atoms are composed of
• Electrons: negatively charged particles
• Protons: positively charged particles
• Neutrons: uncharged particles
The Study of Atoms
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• Protons and neutrons are in the nucleus.
• Electrons move around the nucleus.
The Study of Atoms
Figure 2.1
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• Each chemical element has a different number of protons.
• Isotopes of an element are atoms with different numbers of neutrons. Isotopes of oxygen are:
Chemical Elements
168 O 17
8 O 188 O
2008Table 2.1
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• Electrons are arranged in electron shells corresponding to different energy levels.
Electronic Configurations
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Electronic Configurations
Table 2.2.1
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Electronic Configurations
Table 2.2.2
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• Atoms combine to complete the outermost shell.
• The number of missing or extra electrons in this shell is the valence.
How Atoms Form Molecules: Chemical Bonds
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• A compound contains different kinds of atoms.
H2O
• The forces holding atoms in a compound are chemical bonds.
How Atoms Form Molecules: Chemical Bonds
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• The number of protons and electrons is equal in an atom.
• Ions are atoms that have gained or lost electrons and are charged.
How Atoms Form Molecules: Chemical Bonds
Figure 2.2a
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• Ionic bonds are attractions between ions of opposite charge. One atom loses electrons and another gains electrons.
Ionic Bonds
Figure 2.2b
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• Covalent bonds form when two atoms share one or more pairs of electrons.
Covalent Bonds
Figure 2.3a
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• Hydrogen bonds form when a hydrogen atom covalently bonded to an O or N atom in another molecule.
Hydrogen Bonds
Figure 2.4
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• The sum of the atomic weights in a molecule is the molecular weight.
• One mole of a substance is its molecular weight in grams.
Molecular Weight and Moles
H2O
2H = 2 1 = 2
O = 16
MW = 18
1 mole weighs 18 g
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• Chemical reactions involve the making or breaking of bonds between atoms.
• A change in chemical energy occurs during a chemical reaction.
• Endergonic reactions absorb energy.
• Exergonic reactions release energy.
Chemical Reactions
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• Occur when atoms, ions, or molecules combine to form new, larger molecules
• Anabolism is the synthesis of molecules in a cell.
Synthesis Reactions
A + B ABAtom, ion,
or molecule A
Atom, ion,
or molecule BNew molecule
AB
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• Occur when a molecule is split into smaller molecules, ions, or atoms.
• Catabolism is the decomposition reactions in a cell.
Decomposition Reactions
A + BABAtom, ion,
or molecule A
Atom, ion,
or molecule BNew molecule
AB
Breaksdown into
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• Are part synthesis and part decomposition.
Exchange Reactions
NaCl + H2ONaOH + HCl
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• Can readily go in either direction.
• Each direction may need special conditions.
Reversible Reactions
A + BWater
AB
Heat
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Important Biological Molecules
• Organic compounds always contain carbon and hydrogen.
• Inorganic compounds typically lack carbon.
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• Polar molecule
Inorganic Compounds: Water
Figure 2.4a
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• Solvent
• Polar substances dissociate, forming solutes
Inorganic Compounds: Water
Figure 2.5
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• H+ and OH participate in chemical reactions
Inorganic Compounds: Water
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• Hydrogen bonding between water molecules makes water a temperature buffer.
Inorganic Compounds: Water
Figure 2.4b
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• An acid is a substance that dissociates into one or more H+.
HCl H+ + Cl
Acids, Bases, and Salts
Figure 2.6a
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• A base is a substance that dissociates into one or more OH.
NaOH Na+ + OH
Acids, Bases, and Salts
Figure 2.6b
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• A salt is a substance that dissociates into cations and anions, neither of which is H+
or OH.
NaCl Na+ + Cl
Acids, Bases, and Salts
Figure 2.6c
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• The amount of H+ in a solution is expressed as pH.
• pH = log[H+]
• Increasing [H+], increases acidity.
• Increasing [OH] increases alkalinity.
• Most organisms grow best between pH 6.5 and 8.5.
Acid-Base Balance
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Acid-Base Balance
Figure 2.7
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• The chain of carbon atoms in an organic molecule is the carbon skeleton.
• Functional groups are responsible for most of the chemical properties of a particular organic compound.
Organic Compounds
2008Table 2.3.1
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• Small organic molecules can combine into large macromolecules.
• Macromolecules are polymers consisting of many small repeating molecules.
• The smaller molecules are called monomers.
Organic Compounds
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• Monomers join by dehydration synthesis or condensation reactions.
Organic Compounds
Figure 2.8
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• Are important for structure and as energy sources.
• Consist of C, H, and O with the formula (CH2O)n
Carbohydrates
Figure 2.8
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• Monosaccharides are simple sugars with 3 to 7 carbon atoms.
Carbohydrates
Figure 2.8
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• Disaccharides are formed when two monosaccharides are joined in a dehydration synthesis.
• Disaccharides can be broken down by hydrolysis.
Carbohydrates
Figure 2.8
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• Oligosaccharides consist of 2 to 20 monosaccharides.
• Polysaccharides consist of tens or hundreds of monosaccharides joined through dehydration synthesis.
• Starch, glycogen, dextran, and cellulose are polymers of glucose that are covalently bonded differently.
• Chitin is a polymer of two sugars repeating many times.
Carbohydrates
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• Are the primary components of cell membranes.
• Consist of C, H, and O.
• Are nonpolar and insoluble in water.
Lipids
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• Called fats or triglycerides contain glycerol and fatty acids; formed by dehydration synthesis.
• Unsaturated fats have one or more double bonds in the fatty acids.
Simple lipids
Figure 2.9c
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• Contain C, H, and O + P, N, or S.
• Membranes are made of phospholipids
Complex lipids
Figure 2.10a
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• Consist of four carbon rings, with an –OH group attached to one ring.
• Are part of membranes.
Steroids
Figure 2.11
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• Are essential in cell structure and function.
• Enzymes are proteins that speed chemical reactions.
• Transporter proteins move chemicals across membranes.
• Flagella are made of proteins.
• Some bacterial toxins are proteins.
Proteins
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• Consist of subunits called amino acids.
Proteins
Table 2.4.1
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Proteins
Table 2.4.2
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• Exist in either of two stereoisomers, D or L.
• L-forms are most often found in nature.
Amino Acids
Figure 2.13
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• Peptide bonds between amino acids are formed by dehydration synthesis.
Peptide Bonds
Figure 2.14
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• The primary structure is a polypeptide chain
Levels of Protein Structure
Figure 2.15a
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• The secondary structure occurs when the amino acid chain folds and coils in a regular helix or pleats.
Levels of Protein Structure
Figure 2.15b
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• The tertiary structure occurs when the helix folds irregularly, forming disulfide bonds, hydrogen bonds, and ionic bonds between amino acids in the chain.
Levels of Protein Structure
Figure 2.15c
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• The quaternary structure consists of two or more polypeptides.
Levels of Protein Structure
Figure 2.15d
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• Conjugated proteins consist of amino acids and other organic molecules:
• Glycoproteins
• Nucleoproteins
• Lipoproteins
Level of Protein Structure
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• Consist of nucleotides.
• Nucleotides consist of a:• Pentose• Phosphate group• Nitrogen-containing (purine or pyrimidine) base
Nucleic Acids
Figure 2.16
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• Has deoxyribose
• Exists as a double helix
• A hydrogen bonds with T
• C hydrogen bonds with G
DNA
Figure 2.16
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• Has ribose
• Is single-stranded
• A hydrogen bonds with U
• C hydrogen bonds with G
RNA
Figure 2.17
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• Has ribose, adenine, and 3 phosphate groups
ATP
Figure 2.18
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• Is made by dehydration synthesis.
• Is broken by hydrolysis to liberate useful energy for the cell.
ATP
