Transcript The Molecules of Cells

The Building Blocks of
Life
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
Common name: sugars & starches
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
Structural Formulas of SimpleSugars
The arrangement of the atoms makes each
compound different. Therefore, they are isomers
of each other.
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
Lipids
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(hardening of the
arteries)
The Structure of Lipids
Contain the elements carbon,
hydrogen, & oxygen
Are organic compounds with a large
proportion of C-H bonds and less O2
than carbohydrates
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
Types of Lipids or Fats
Saturated fats occur when every carbon
(C) atom in a fatty acid chain is joined to
another carbon by a single bond; found
in meats, most dairy products; contain the
maximum # of hydrogen atoms; usually
solids at room temperature.
Unsaturated fats occur when a pair of C
atoms is joined by a double bond; usually
liquids at room temperature.
Polyunsaturated fats occur when a fatty
acid contains several double bonds but
have at least two double bonds.
– Cooking oils such as olive, corn, canola, and peanut
oils are examples.
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 carbon, hydrogen, oxygen;CHON
Are made of amino acids (aa)
(building blocks of proteins); long
chains of amino acids produce
proteins
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
Are two types; DNA and RNA
Large, organic molecules (macromolecules)
composed of carbon, hydrogen, oxygen,
nitrogen, and phosphorus atoms (CHONP)
Stores information in cells in the form of a code
(store & transmit genetic information)
Are polymers of individual monomers known as
nucleotides (subunits)
Nucleotides are composed of a 5C sugar, a
nitrogenous base, and a phosphate (PO4⁻3)
group
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
DNA vs RNA
DNA consists of a double helical structure; it
contains the sugar deoxyribose, and the bases
adenine, thymine, cytosine, guanine (ATCG)
RNA consists of a single strand; it contains the
sugar ribose, and the bases adenine, uracil,
cytosine, and guanine (AUCG)
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