Transcript Chemistry of Life

Chemistry of Life
Objectives
• Define the terms atom, element,
molecule, and compound.
• Describe the structure of an atom.
• Compare and contrast ionic and
covalent types of chemical bonding.
• Distinguish between organic and
inorganic chemical compounds.
Objectives
• Discuss the chemical characteristics of
water.
• Explain the concept of PH.
• Discuss the structure and function of the
following types of organic molecules:
– Carbs
– Lipids
– Proteins
– Nucleic acid
Levels of Chemical
Organization
• Matter
– Anything that occupies space and
has mass.
• Molecules are particles of matter,
made up of atoms.
Atoms
• Nucleus
– Central core of the atom
– Contains subatomic particles:
• Protons = positively charged
–Number of protons determines
type of atom. (atomic number)
• Neutrons = no charge
Atoms
• Orbiting around the nucleus are negatively
charged particles called electrons.
– Energy levels (shells)
– Outer level may hold up to 8 electrons.
– Energy increases with distance from the
nucleus.
– Number of electrons in the outer shell
affects the atoms ability to unite with
other atoms.
Elements, Molecules,
and Compounds
• Element
– Pure substance; made up of only
one kind of atom.
• Molecule
– Group of atoms bound together.
• Compound
– Substances whose molecules have
more than one kind of atom.
Elements, Molecules,
and Compounds
• Compounds are written in formulas
containing symbols and number of
atoms in subscript.
• Example: Carbon Dioxide
–CO2
Elements, Molecules,
and Compounds
• Four kinds of atoms make up approx.
96% of the human body.
– Oxygen
– Carbon
– Hydrogen
– Nitrogen
• 20 or more trace elements.
Chemical Bonding
• Chemical bonds form to make atoms
more stable.
– Considered stable when the outer
energy level is full. (8 electrons)
• Atoms will share, donate, or borrow
electrons to fill the outermost energy
level.
Ionic Bonds
• Ions form when atoms gain or lose
electrons in the outer energy levels.
• Positive Ions
– Have lost electrons becoming
positively charged.
• Negative Ions
– Have gained electrons becoming
negatively charged.
Ionic Bonds
• Example: (Fig 2-2)
– Sodium – Na
• Containing 1 electron in outer shell.
– Chlorine – Cl
• Contains 7 electrons in outer shell.
• Donating or borrowing electrons make
sodium positively charged and chlorine
negatively charged forming a bond NaCl
or Sodium Cloride.
Electrolytes
• Ionic molecules dissociate easily in
water forming electrolytes.
• Examples:
– Sodium – Na+
– Chloride – Cl– Calcium – Ca++
– Potassium – K+
Covalent Bonds
• Atoms that share electrons, rather
than donate or receive them form
covalent bonds.
• Bonds are not easily broken and do
not break apart in water.
Organic/Inorganic
Compounds
• Living organisms contain both
organic and inorganic compounds.
• Organic compounds contain:
– Carbon to Carbon covalent bonds
And/Or
– Carbon to Hydrogen covalent
bonds
• Inorganic compounds lack these
bonds.
Inorganic Compounds
• Water
– Most abundant compound in the
body.
– Solvent that other solutes are
dissolved.
• Aqueous solution
– Essential in many important
chemical reactions.
Chemical Reactions
Fig 2-4
• Dehydration synthesis
– Water is removed from smaller
molecules so larger ones can be
created.
• Hydrolysis
– Water is added to larger molecules
to break them apart into smaller
ones.
Chemical Reactions
• Chemical reactions involve energy
transfers.
• Some of the energy used to build the
molecules are stored as potential
energy and released when broken
apart.
• Example:
– Adenosine Triphosphate (ATP)
– Needed for muscle contraction.
Chemical Reactions
• Chemical equations show how
reactants interact to form products.
• Written with “arrows” to separate
and show products.
• Example:
– K+ + ClKCL
The pH Scale
Acids, Bases, and Salts
• Water molecules dissociate to form
equal amounts of Hydrogen
Ions/Hydroxide Ions.
– Neutral pH 7.0
• Acids are higher in Hydrogen Ions (<
7.0)
• Bases/Alkalines are lower in
Hydrogen Ions (>7.0)
Acids, Bases, and Salts
• Strong acids or strong bases are
neutralized when mixed with each
other and form salts.
• Buffers are chemical systems that
absorb excess acids or bases and
thus maintain a relatively stable pH.
Organic Compounds
• More complex than inorganic
compounds.
– Carbohydrates
– Lipids
– Proteins
– Nucleic acids
Organic Compounds
• Carbohydrates
– Sugars and complex
carbohydrates
• Monosaccharide
(Glucose/Dextrose)
• Disaccharide (Sucrose/Lactose)
• Polysaccharides
(Glycogen/Starches)
– Contains Carbon, Hydrogen,
Organic Compounds
• Lipids - Fats and oils
– Triglycerides
• Glycerol and 3 fatty acids.
• Stores energy.
– Phospholipids
• Phosphorus unit with 2 fatty acids
• Forms cell membranes
– Cholesterol
• Transports lipids
• Basis for making steroid hormones
Organic Compounds
• Proteins
– Very large molecules composed of
amino acids held together in long
folded chains by peptide bonds.
• Structural proteins
• Functional proteins
– Can bond with other compounds to
form mixed molecules:
• Glycoproteins
• Lipoproteins
Organic Compounds
• Structural Proteins
– Form structures in the body.
– Collagen is a fibrous protein that
holds many tissues together.
– Keratin forms tough, waterproof
fibers in the outer layer of the skin.
Organic Compounds
• Functional Proteins
– Participate in chemical processes.
– Examples:
• Hormones
• Cell membrane
channels/receptors
• Enzymes
Organic Compounds
• Enzymes
– Catalysts
• Assist with chemical reactions
– Lock and Key model
• Each enzyme fits a particular
molecule that it acts on as a key
fits into a lock.
Organic Compounds
• Nucleic acids
– Direct proteins for overall body
structure and function.
– Basic building blocks are called
nucleotides.
• Phosphate, sugar, and nitrogen
base.
– Deoxyribonucleic Acid (DNA)
– Ribonucleic Acid (RNA)
Nucleic Acids
• Deoxyribonucleic Acid (DNA)
• Nucleotide bases:
– Adensine
– Thymine
– Guanine
– Cytosine
• Used as a master code for
assembling proteins.
Nucleic Acids
• Ribonucleic Acid (RNA)
• Nucleotide bases:
– Adensine
– Uracil
– Guanine
– Cytosine
• Used as a temporary working copy of a
gene.
• Portion of DNA code
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