Download The Molecules of Cells

The Molecules of
Cells
Organic Compounds
• Are carbon containing compounds
• Carbon has the ability to form covalent
bonds that are strong and stable
Carbohydrates
• CHO-means that the compound contains
carbon, hydrogen, and oxygen in a ratio of
1:2:1; is also the abbreviation for
carbohydrates
• The primary function of carbohydrates is to
store and release energy
• There are three categories of CHO, mono,
di, and polysaccharides
Monosaccharides
*are the simplest carbohydrates; contain one sugar
Ex. Glucose-sugar green plants produce
and most living organisms use as
their
energy source
• Ex. Galactose; found in milk
• Ex. Fructose; found in fruits
• Chemical formula for each monosaccharide is C6H12O6
The arrangement of the atoms makes each compound
different. Therefore, they are isomers of each other.
Structural Formulas of Simple
Sugars
Disaccharides
*Composed of two simple sugars or
monosaccharides
– Ex. Sucrose (glucose + fructose); table sugar
– Ex. Maltose (glucose + glucose); malt sugar
– Ex. Lactose (glucose + galactose); milk sugar
– Molecular formula C12H22O11
• can derive the formula by dehydration synthesis
Polysaccharides
• Are the largest carbohydrate molecule
• Composed of at least three
monosaccharides
• Is the form in which living things store
excess sugar
• Ex. Starch, cellulose, and glycogen
– Molecular formula is (C6H10O5)n
– n=the # of repeating units
• Starch consists of highly branched chains of glucose
units and is used as food storage by plants; potatoes
and grains
• Cellulose another glucose polymer that forms the cell
walls of plants and gives structural support (strength and
rigidity); made of glucose units hooked together like a
chain-link fence; found in plants and is a major
component of wood
• Glycogen-animals store food in this form; is another
polymer, but is more highly branched than starch; found
in the liver and muscles of animals
The Structure of Lipids
• Are organic compounds with a large proportion
of C-H bonds and less O2 than CHO
• Commonly called fats, oils, and waxes; fats and
waxes are usually solids at room temp., oils are
liquids; waxes consist of one fatty acid linked to
an alcohol
• Are insoluble in water because their molecules
are non-polar (not attracted by H2O)
• Most common type consists of 3 fatty
acids bonded to a molecule of glycerol;
triglyceride
• Lipids have various functions
– Can be used to store energy
– Used to form biological membranes
– Act as chemical messengers (use it as a starting
material for making other steroids, including male and
female sex hormones)
– Steroids are lipids; cholesterol is an example
– Too much cholesterol may lead to artherosclerosis
Types of Lipids or Fats
• Saturated fats occur when every carbon (C)
atom in a fatty acid chain is joined to another C
by a single bond; found in meats, most dairy
products
• Unsaturated fats occur when a pair of C atoms is
joined by a double bond
• Polyunsaturated fats occur when a fatty acid
contains several double bonds; tend to be
liquids at room temp; Ex. Cooking oils such as
olive, corn, canola, and peanut oils
• Sterols (Steroids) play a number of important
roles in building cells and carrying messages
from one part of the body to another: Ex.
Cholesterol
• used for vitamin D synthesis
• Used for bile salts
• Membrane structure
• Steroid hormone synthesis
• Phospholipids are molecules that consist of
parts that dissolve well in water and parts that do
not; play key roles in forming cell membranes
from their ability to form bilayers
Proteins
• Are essential to all life
• Are composed of nitrogen in addition to
CHO
• Are polymers of amino acids (aa) (building
blocks of proteins); long chains of aa
produces a protein
• Has an amino group on one end and a
carboxyl group on the other end
Protein Structure
Four Levels of Protein Structure
Descriptions of 4 Protein Levels
• Primary (1st)-linear sequence of amino acids
• Secondary (2nd)-part of the polypeptide coils or
folds into alpha helices and pleated sheets;
twisted or folded
• Tertiary (3rd)-overall 3D shape of the
polypeptide; fibrous or globular
• Quaternary (4th)-consists of 2 or more
polypeptide chains or subunits
• Van der Waals forces and hydrogen bonds help
maintain a protein’s shape
Seven Classes of Proteins
• Structural-silk of spiders and hair fibers
• Contractile-muscle movement
• Storage-ovalbumin (egg white); source of amino
acids for developing embryos
• Defensive-antibodies fight infection
• Transport-hemoglobin transports oxygen in the
bloodstream
• Signal-hormones help coordinate body activities
(sending messages)
• Enzymes-serve as chemical catalysts to speed
up reactions
Nucleic Acids
• Large, organic molecules (macromolecules) composed
of CHONP atoms
• Stores information in cells in the form of a code
• Are polymers of individual monomers known as
nucleotides
• Nucleotides are composed of a 5C sugar, a nitrogenous
base, and a phosphate (PO4 group)
• Are two types; DNA and RNA
• DNA is the master copy of an organism’s information
code; it forms the genetic code
• RNA forms a copy of DNA for use in protein synthesis
DNA vs RNA
• DNA consists of a double helical structure; it contains the
sugar deoxyribose, and the bases adenine, thymine,
cytosine, guanine
• RNA consists of a single strand; it contains the sugar
ribose, and the bases adenine, uracil, cytosine, and
guanine
Enzymes
Enzymes
• Are proteins
• Speed up a reaction by binding to the
reactants (substrates).
• Substrates bind to enzymes at a region
known as the active site.
• Are very specific; a particular enzyme can
catalyze only one particular chemical
reaction involving specific substrates.
Enzymes
• Are important in regulating chemical
pathways, synthesizing materials, needed
by cells, releasing energy and transferring
information.
• Are involved in digestion, respiration,
reproduction, vision, movement, thought,
and in the making of other enzymes.
Enzymes
• Are catalysts that work by lowering the
”start-up” energy of a reaction.
• Every enzyme has conditions for which it
is most effective.
• Temperature affects molecular motion.
• Optimal temperature produces the highest
rate of contact between reactant
molecules and the enzyme's active site.
Enzymes
• Higher temperature denatures the
enzymes, altering it’s specific 3-D shape
and destroying it’s function.
• Salt concentration and pH also influence
enzyme activity.
• Optimal pH is between 6-8.
• Outside this range, enzyme action and
normal chemical functioning of cells
maybe impaired.
The Effect of an Enzyme on EA
Enzyme Substrate Complex
Competitive Inhibition
Noncompetitive Inhibitors
Properties of WATER
Properties of Water
• Serves as a means of transport of materials in
organisms; ex. Plant sap and blood are mostly
water
• Is a polar molecule (a molecule that has an
unequal distribution of charges); it also easily
attracts other H2O molecules
• Makes up about 70-95% of most organisms
• Composed of 2 atoms of H+ linked by covalent
bonds to 1 atom of O2
Structural Formulas of Water
• Water is the most abundant compound in nearly
all living organisms
• Water is slightly charged on each end; makes it
good at forming mixtures (solutions and
suspensions)
Solutions-the molecules are uniformly spread
throughout the water
• Solvent does the dissolving; solute is the substance that is
dissolved
• Water is the universal solvent
Suspensions are mixtures of water and non
dissolved materials
The Uniqueness of Water
• Has a high surface tension; ex. H2O skier, water strider
• Cohesion-attraction between molecules of the same
substance
• Adhesion-attraction between molecules of different
substances
• Water creeps up in thin tubes; capillary action Ex. Plants
get H2O from the ground
• Has a high heat of vaporization; Ex. Helps cool the body
when sweating
• Resists temperature change; water must lose a lot of
heat when it cools; requires more heat to increase the
temperature than do most other common substances
• Water expands when it freezes; Ex. If H2O
freezes inside the cracks of rocks, it often
breaks apart the rocks forming soil over a
long period of time.
Acids, Bases, and pH
• pH scale-indicates the concentration of H+ ions
in solutions
• Acids-any compound that forms H+ ions in
solution; acidic solutions contain a higher
concentration of these ions than pure water and
have pH values below 7
• Bases-a compound that produces OH- ions in
solution; basic or alkaline solutions contain lower
concentrations of H+ ions that pure water and
has pH values above 7
• Buffers-dissolved compounds; weak acids or
bases that can react with strong acids or bases
to prevent sharp, sudden change in pH