Transcript Macromolecules and Enzymes final draft

Macromolecules Goal
• Know the structure and function of all 4
macromolecules
Macromolecules : The
Molecules of Life
• Within cells, small organic molecules called
monomers are joined together to form
larger molecules, known as
Macromolecules.
• Each cell has thousands of different kinds of
macromolecules.
• Macromolecules vary among cells of an
organism, vary more within a species, and
vary even more between species.
Function: What do macromolecules do?
• Carbohydrates - short term energy storage;
structure of some organisms
• Lipids - (also known as fats) - long term
energy storage
• Nucleic Acids (DNA and RNA) - the
instructions the cell uses to build proteins
• Proteins (Polypeptides): The highly
variable macromolecules that make each
organism unique
Carbohydrates
Sugars & Starches
Used for energy in all organisms
and for structure in plants.
Sugars
• Function: Monosaccharides serve as a major fuel
for cells and as raw material for building molecules
• Monosaccharides have molecular formulas that
are usually multiples of CH2O – 1:2:1 ratio
• Glucose is the most common monosaccharide
• Structure: though often drawn as a linear
skeleton, in aqueous solutions they form rings
LE 5-4
Linear and
ring forms
Abbreviated ring
structure
Monosaccharides (simple sugars)=
monomer of carbohydrates
• Mono- = one
• Glucose (C6H12O6) =
sugar used as an energy
source in all cells.
• Other Examples:
Fructose (Fruit sugar) &
Galactose (Milk sugar)
Disaccharides (sugars) =
2 monosaccharides linked together.
• Di- = two
• Examples: Lactose (milk
sugar) & Sucrose
• (table sugar)
Storage and Structure Polysaccharides
3 or more monosaccharides linked.
• Poly- = Many
• Glycogen = Used as energy
storage in animals.
• Cellulose = Used to form the
cell wall of plants.
• Chitin- is found in the
exoskeleton of arthropods and
the cell walls of many fungi
Storage Polysaccharides
• Starch, a storage polysaccharide of plants,
consists entirely of glucose monomers
• Plants store surplus starch as granules within
chloroplasts and other plastids
Chloroplast
Starch
LE 5-6a
1 µm
Amylose
Amylopectin
Starch: a plant polysaccharide
LE 5-8
Cellulose microfibrils
in a plant cell wall
Cell walls
Microfibril
0.5 µm
Plant cells
Cellulose
molecules
b Glucose
monomer
• Enzymes that digest starch by hydrolyzing alpha
linkages can’t hydrolyze beta linkages in cellulose
• Cellulose in human food passes through the
digestive tract as insoluble fiber
• Some microbes use enzymes to digest cellulose
• Many herbivores, from cows to termites, have
symbiotic relationships with these microbes
Lipids (fats)
Steriods
Used for long-term energy storage.
Lipids are a diverse group of
hydrophobic molecules
• Lipids are the one class of large biological
molecules that do not form polymers
• The unifying feature of lipids is having little or no
affinity for water
• Lipids are hydrophobic because they consist
mostly of hydrocarbons, which form nonpolar
covalent bonds
• The most biologically important lipids are fats,
sterols and phospholipids.
• When phospholipids are added to water, they selfassemble into a bilayer, with the hydrophobic tails
pointing toward the interior
• The structure of phospholipids results in a bilayer
arrangement found in cell membranes
• Phospholipids are the major component of all cell
membranes
LE 5-14
Hydrophilic
head
Hydrophobic
tails
WATER
WATER
Steroids
• Considered lipids because they are
hydrophobic!!
• Consist of 4 fused rings
• Cholesterol is a steroid
Nucleic Acids
DNA – your genetic code
RNA – used to make proteins
Nucleotide = monomer of nucleic
acids.
• Nucleotide has 3
parts:
- phosphate
- 5-carbon sugar
- nitrogen base.
DNA & RNA = Polymers of nucleic
acids
• DNA – di=2 (α-helix) carries the information on how to make
proteins. Mostly 2 strands. (1-strand DNA (ssDNA) found in
viruses)
• RNA is directly involved in making proteins. Mostly 1 strand. (2strand RNA (dsRNA) found in viruses )
Proteins
The major building block in living things.
Muscles, enzymes, antibodies, cell structure
Proteins have many structures, resulting in a
wide range of functions
• Proteins account for more than 50% of the dry
mass of most cells
• Protein functions include enzymes*,structural
support, storage, transport, cellular
communications, movement, and defense against
foreign substances
• Different functions=different shapes
Structure of Proteins
• Protein = Polypeptide (polymer)
comprised of monomers (amino acids).
There are 20 different amino acids.
• Amine Group (NH2)-Basic
• Carboxylic Acid Group (COOH) –
Acidic
• The center asymmetrical carbon is
called the alpha carbon.
• The R group (think random) is variable
for each amino acid! Also called the
side chain.
Four Levels of Protein Structure
Primary structure of a protein is its unique sequence of
amino acids.
Secondary structure, found in most proteins, consists of
coils and folds in the polypeptide chain. The sequence of
amino acids converts into 1 of 2 forms
» α-helix
» β-pleated sheets
1’ and 2’ Levels Protein Structure
Tertiary structure is determined by interactions among
various side chains (R groups)
Quaternary structure results when a protein consists of
multiple polypeptide chains
Not found in all proteins
Same bonds/interactions as tertiary level
Tertiary & Quaternary Levels
Protein Denaturation
Protein Denaturation
• Denaturation
• Protein unravels and loses its native conformation
• Structure & Function
• Change in the protein’s structure = loss of function
• Denaturation occurs:
– Organic solvent
– Any chemical that disrupts the tertiary
structure
– Heat (excessive)
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Macromolecules
Macromolecule Function
Carbohydrate
Lipid
Nucleic Acids
Proteins
Structure
Sample MC
• Which molecule stores the largest amount of
energy?
• A. Fat
• B. Starch
• C. Protein
• D. Glycogen
Sample Question
A molecule with the chemical formula
C16H32O16 is probably a
A) carbohydrate.
B) lipid.
C) protein.
D) nucleic acid.
E) hydrocarbon.
Sample MC
Amino acids are the building blocks of
A.
B.
C.
D.
Proteins
Lipids
Carbohydrates
Nucleic Acids
Sample MC
Which polymer carries genetic information?
A.
B.
C.
D.
Protein
Lipid
Carbohydrate
Nucleic Acid
Sample MC
• Unlike carbohydrates and fats, proteins
contain _____.
•
•
•
•
A) nitrogen
B) carbon
C) hydrogen
D) oxygen
Sample MC
• .
Which of these elements is NOT part of a
carbohydrate molecule?
•
•
•
•
A) hydrogen
B) oxygen
C) carbon
D) magnesium
SC.L 18.11
Reaction Rates & Enzymes
o The rates of reaction among atoms and
molecules depends on many factors. We will
review the effects of temperature,
concentration, and pH, and the presence or
absence of catalysts
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What Determines the
Speed of a Reaction?
• Speed of reaction, or “reaction rate”
depends on how many collisions occur
between reactants.
• The more collisions, the faster the reaction
occurs.
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Activation Energy
• The greater the required activation energy
of a reaction, the slower the reaction will
proceed.
• If the required activation energy is
lowered, a reaction will proceed faster.
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Some Chemical Reactions are
VERY FAST
Reaction between chlorine, Cl2 (green gas) and sodium metal, produces NaCl, salt
2 Na  Cl2  2 NaCl
Some Chemical Reactions Are
VERY Slow
This piece of metal has been reacting with oxygen in
the air (rusting) for many years. This is a VERY slow
reaction which will keep on going for a long time. Where
would rust occur more quickly Florida or Arizona?
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What are some factors that
affect reaction rates?
• Temperature:
more collisions means faster reaction rate
• Concentration:
more reactants means faster reaction rate
• pH and solubility
Optimal pH means faster rate of reaction
• Catalyst:
lower activation energy means faster reaction rate
Temperature
• Particles are Always Moving
Atoms of a solid
Atoms of a gas in a container
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How fast the particles are
moving is measured by
Temperature
Longer arrows show
that at a higher
temperature the
particles are moving
faster.
Shorter arrows show
that at a lower
temperature the
particles are moving
slower.
Collision theory
•
Speed of reaction, or “reaction rate” depends on how many collisions
occur between reactants.
The more collisions, the faster the reaction occurs
The rearranging of the atoms happen
ONLY after they collide against each
other.
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Temperature
• The higher the temperature, the
more motion in the particles.
• This means there will be more
collisions, and therefore, the
reaction rate will be faster.
• However , prolonged temperature will
result in denaturing the enzyme.
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Concentration
Two Containers Filled with CH4 And O2
The container above has 40 particles
of O2 and 5 particles of CH4.
The container above has 40 particles
of O2 but 20 particles of CH4.
What can you say about the rate of reaction in these two containers?
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Concentration of the
Reactants
• The container with more reactants
will react faster.
• More reactants means more
collisions and faster reaction rate.
• Because the second container has
more CH4, we can say it has a
higher concentration of CH4.
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Effect of Concentration of
Oxygen
When heated, steel wool reacts with oxygen in the
air. The concentration of oxygen in the air is 21%.
If the same steel wool is placed in a flask containing
100% oxygen, the reaction occurs much faster.
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pH (Concentration of H+)
• pH is a measure of the Hydrogen Ion
(H+) concentration in a solution.
• The rate of certain reactions is affected
by the pH of the solution.
• Most enzymes (which are catalyst)
have an optimum pH of between 4 and
9, and quite frequently near the neutral
point of 7.
• The activity of enzymes is strongly
affected by changes in pH and
temperature.
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Catalysts
• A catalyst is a substance that
makes a reaction go faster by
lowering the required activation
energy.
• A catalyst IS NOT changed or used
up in a reaction.
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Biological Catalysts Enzymes
• Living organisms also have catalysts that
speed up reactions.
• These catalysts are called enzymes.
• Enzymes in the blood catalyze the
decomposition of hydrogen peroxide.
That is why applying hydrogen peroxide
on a wound makes it foamy.
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Effect of a Catalyst
The blue line represents a
reaction without a catalyst.
The red line represents a
reaction where a catalyst
was added.
The activation energy is
lower so the reaction will go
faster.
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1. Which of the following is a way to
slow a reaction?
A placing the reactants under bright light
B placing the reactants in a tightly sealed container
C filtering out some of the reactants
D moving the reaction to a warmer room
2.
In the collision theory to explain chemical
reactions, what must happen for a
reaction to take place?
A Reactants must collide with the surface of the
container
B Reactants must collide and have the same energy
C Reactants must collide and have enough energy to
react
D Reactants must collide and have very little energy
3. A carbohydrate is an organic compound that
is composed of carbon, hydrogen, and
oxygen. The unique structure of
carbohydrates makes them useful material for
building cell walls in plants. Which of the
following is a function of carbohydrates in
animals?
A. digesting food
B. fighting disease
C. storing long-term energy
D. providing skeletal structure
4. Raising the temperature usually
speeds up the rate of a chemical
reaction. Which statement below
explains how increasing temperature
increases the reaction rate?
a. It prevents inhibitors form slowing down the reaction among
particles.
b. It acts as a catalyst to make reactions among particles occur
more frequently.
c. It causes particles to break apart, which makes it easier for
chemical reactions to occur.
d. It increases the number of particles that have enough kinetic
energy to react when they collide.
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5. Metabolism is generally referred to as the
chemical processes that allow the body to
function. Which of the following molecules
allow a metabolic chemical reaction to
proceed more quickly?
A.
B.
C.
D.
Buffers
Carbohydrates
Enzymes
vitamins