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Chemistry Review
• Chemistry– Atoms, molecules, &
compounds– Inorganic Molecules– Organic Molecules
• Biological Macromolecues
– Lipids– Carbohydrates– ___________– Nucleic Acids
Chemical Principles
• What is the smallest unit of matter that enters into chemical reactions?
• Chemistry = interactions between ____ and molecules
H H
O
Atomic Structure• Electrons – negatively charged subatomic particles
circling a nucleus• Nucleus – contains neutrons and protons
– Neutrons – uncharged particles– Protons – positively charged particles
Atomic Structure• Element = single type
of atom• Atomic Number =
number of protons in nucleus
• Atomic Mass (atomic weight) = sum of masses of protons, neutrons, and electrons
Isotopes
• Isotopes - differ in number of ________ in their nuclei
• Stable isotopes• Unstable isotopes
–Release energy during radioactive decay
168 O 17
8 O 188 O
Will this effect the overall charge?
Electron Configurations• Electrons determine
an atom’s chemical behavior
• Occupy electron shells• Valance electrons –
the missing or extra electrons in this shell.
• Atoms combine to complete the outermost shell.
Electronic Configurations
Table 2.2.1
Electron Configurations
Figure 2.3
Electron Configurations
• How many valance electrons does this atom want to give up or acquire?
Chemical Bonds
• A compound contains different kinds of atoms.
H2O
• The forces holding atoms in a compound are chemical bonds.
Name the different types of chemical bonds.
Chemical Bonds
• Ionic Bonds• ________ Bonds
–Nonpolar –Polar
• Hydrogen bonds – weak forces that combine with polar covalent bonds
Ionic Bonds• Two atoms with vastly different electronegativities.• Atoms give or receive electrons to form IONS
– positively (cation) charged– or negatively (anion) charged
Ionic Bonds• Ionic bonds are attractions between ions of
opposite charge. • One atom loses electrons and another
gains electrons.
Figure 2.2b
Covalent Bonds
• Covalent bond – sharing of a pair of electrons by two atoms
Covalent Bonds
Nonpolar Covalent Bonds
• Atoms with similar electronegativities• Equal sharing of electrons• No poles exist
Polar Covalent Bonds
• Unequal sharing of electrons– due to significantly different electronegativities
• Most important polar covalent bonds involve hydrogen
–Allows for hydrogen bonding
Polar Covalent Bonds
Figure 2.7a
Hydrogen Bonds
• Electrical attraction between –partially charged H+ & full or partial negative
charged molecule• Weaker than covalent bonds but ________ for life
–Many help to stabilize 3-D shapes of large molecules
Hydrogen Bonds
Chemical Reactions• The making or breaking of chemical bonds• Involve reactants and products• Three categories of chemical reactions
–Synthesis reactions–Decomposition reactions–Exchange reactions
Synthesis Reactions
• Formation of larger, more complex molecules• Important type – dehydration synthesis
–Water molecule formed• Require energy (endothermic)• All the synthesis reactions in an organism are called anabolism
A + B ABAtom, ion,
or molecule A
→Atom, ion,
or molecule BNew molecule
AB
Decomposition Reactions
• Break bonds within larger molecules to form smaller atoms, ions, and molecules
• Release energy (exothermic)• Common type – hydrolysis• All the decomposition reactions in an organism are
called catabolism
A + BABAtom, ion,
or molecule A
→Atom, ion,
or molecule BNew molecule
AB
Breaksdown into
Chemical Reactions
The sum total of all chemical reactions is an organism is called _______?
Exchange Reactions
• Part synthesis and part decompositionreactions
• Involve endothermic and exothermic steps• Atoms moved from one molecule to another
NaCl + H2O→NaOH + HCl
Reversible Reactions
• Can readily go in either direction.• Each direction may need special conditions.
←→
Heat
A + B ABWater
Inorganic Compounds: Water
• Polar molecule– Remains liquid across wide
range of temperatures– Water molecules are cohesive →
surface tension
Figure 2.4a
• Excellent Solvent– Polar
substances dissociate, forming solutes
Inorganic Compounds: Water
Figure 2.5
Inorganic Compounds: Water
• Participates in many chemical reactions
• H+ and OH−
Inorganic Compounds: Water
• Hydrogen bonding between water molecules makes water a temperature ______.– Can absorb significant
amounts of energy without changing temperature
Figure 2.4b
Acids and BasesAn acid is a substance that dissociates into one or more H+.
HCl → H+ + Cl−
A base is a substance that dissociates into one or more OH−.
NaOH → Na+ + OH−
Salts
• A salt is a substance that dissociates into cations and anions, neither of which is H+
or OH−.
NaCl → Na+ + Cl−
Acid-Base Balance
• 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
Figure 2.7
• Carbon skeleton = chain of carbon atoms in an organic molecule.
• Functional groups give an organic compound its chemical properties.
Organic Compounds
Table 2.3.1
Organic Compounds
• Small organic molecules can combine into large macromolecules.
• Basic subunit = monomer• Chain of monomers = polymer• Macromolecules are polymers consisting
of many small repeating molecules.
Organic Compounds
• Monomers join by dehydration synthesis or (condensation reactions).
Figure 2.8
Important Biological Molecules
• Organic compounds - always contain carbon and hydrogen.
• Inorganic compounds typically lack carbon. • Macromolecules in a cell
– Lipids– Carbohydrates– ________– Nucleic Acids
• Monomers – basic building blocks of macromolecules
• Not composed of monomers • All are hydrophobic (non polar)
–Insoluble in water• Are the primary components of cell membranes.
• Consist of C, H, and O.• Four groups
–Fats–Phospholipids–Waxes–Steroids
Lipids
Fats
Figure 2.15
Figure 2.16
Phospholipids
Figure 2.16
Phospholipids
Major membrane component
Waxes
• Contain one long-chain fatty acid covalently linked to long-chain alcohol by ester bond
• Completely ________ in water; lack hydrophilic head
Figure 2.17
Steroids
Part of cell membraneUsed for signaling
Carbohydrates
• Organic molecules • Composed of carbon, hydrogen, and oxygen
(CH2O)n
• Important for structure and as an energy source
Carbohydrates
• Types–Monosaccharides–Disaccharides–Polysaccharides
Monosaccharides
= simple sugars
Figure 2.18a
Monosaccharides
Figure 2.18b
Monosaccharides
Figure 2.18c
Disaccharides
•Disaccharides = two monosaccharides joined in a dehydration reaction.
•Disaccharides can be broken down by ___?_____.
Figure 2.19
Disaccharides
Figure 2.19
Carbohydrates• 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.
Polysaccharides
Figure 2.20
Polysaccharides
Figure 2.20
• Mostly composed of carbon, hydrogen, oxygen, nitrogen, and sulfur
• Functions–Structure–Enzymatic catalysis–Regulation–Transportation–Defense and offense
Proteins
Amino Acids• The monomers that make up proteins• Most organisms use only 21 amino acids to build proteins
• Side groups affect interactions• A covalent bond (peptide bond) formed between amino acids by dehydration synthesis reaction
Amino Acids
Figure 2.21
Protein Structure•The primary structure is a polypeptide chain
•The secondary structure occurs when the amino acid chain folds and coils in a regular helix or pleats.
Figure 2.24
Figure 2.24
Protein Structure
•The tertiary structure from disulfide bonds, hydrogen bonds, and ionic bonds between amino acids in the chain.
•The quaternary structure consists of two or more polypeptides.
Proteins – Form follows Function
Modified Proteins
• Conjugated proteins consist of amino acids and other organic molecules:• Glycoproteins = proteins + sugars• Nucleoproteins = proteins + nucleic acids• Lipoproteins = proteins + lipids
Nucleic Acids
• DNA and RNA vital as genetic material of organisms
• RNA helps form polypeptides
Nucleotides
• The monomers that make up nucleic acids• Composed of three parts
–Phosphate group–Pentose sugar – deoxyribose or ribose–One of five cyclic nitrogenous bases
• Adenine (A)• Guanine (G)• Cytosine (C)• Thymine (T)• Uracil (U)
Nucleic Acid Structure
Figure 2.26
Nucleic Acid Structure• H bonds form between C and G and between T and A in DNA
–U and A in RNA• DNA is double stranded in most cells and viruses
–Two strands are complementary–Two strands are antiparallel
Nucleic Acid Function
• DNA is genetic material of all organisms and of many viruses
• Carries instructions for synthesis of RNA and proteins → controls synthesis of all molecules in an organism
Figure 2.27
ATP
ATP• Is made by dehydration synthesis.• Is broken by hydrolysis to liberate useful
energy for the cell.
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