Download Enzymes

CHARACTERISTICS OF
LIVING THINGS &
BIOCHEMISTRY
Workbook Topic 1
Textbook Chapters 5 & 6
Characteristics of Life
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Organism: a living thing
All organisms have similar life functions
Life function: the activities carried out
by living things
Metabolism: all the chemical reactions
that occur within a living thing
Homeostasis: the maintenance of a
stable internal environment
Life Functions
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1. Nutrition: obtaining materials from
the environment and processing them for
use
2. Transport: absorption and movement
of materials in an organism
3. Respiration: processes that provide
the energy needed for life
4. Excretion: removal of waste products
Life Functions, cont’d
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5. Synthesis: formation of large
molecules from smaller ones
6. Regulation: the control and
coordination of an organism’s activities
7. Growth: an increase in size and/or cell
number
Life Functions, cont’d
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8. Reproduction: the production of new
individuals to allow the species to
survive
Tip: If organisms don’t carry out
these life functions, they die. If
organisms don’t reproduce, their
species goes extinct.
Matter and Atoms
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Matter: anything that has mass and
takes up space
All matter is made up of units called
atoms
Atoms are the smallest parts of matter
Tip: Everything on Earth is made of
matter and atoms.
Elements and Compounds
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Elements: different types of atoms
◦ 118 elements
◦ Cannot be broken down into smaller parts
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The 6 most important elements for
organisms:
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◦
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Carbon (C)
Oxygen (O)
Hydrogen (H)
Nitrogen (N)
Phosphorus (P)
Sulfur (S)
You are 96% carbon,
oxygen, hydrogen, and
nitrogen
Elements and Compounds, cont’d
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Elements combine with each other to
form new substances called compounds
Compounds are held together by
chemical bonds
Examples of compounds:
◦ Water (H2O) is two hydrogen atoms bonded to
one oxygen atom
◦ Carbon dioxide (CO2) is one carbon atom
bonded to two oxygen atoms
Chemical
bond
H
O
H
Organic Compounds
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Organic compounds contain carbon
Our bodies use organic compounds to:
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1. make energy
2. build new structures
3. store materials
4. repair existing structures
5. keep all chemical activities working
properly
These reactions are all part of
metabolism
Organic Molecules, cont’d
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Polymers: large organic molecules made
by linking smaller parts together
Monomers: smaller parts (subunits) of
molecules
◦ Monomer + Monomer = Polymer
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Condensation synthesis: the process of
linking monomers together to make
polymers
Hydrolysis: the process of breaking
down polymers into monomers
Building
blocks
Large
molecule
Carbohydrates
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Carbohydrates are sugars
Made of the elements carbon, hydrogen,
and oxygen
The functions of carbohydrates are:
◦ 1. to store energy
◦ 2. to provide building materials for the body
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The monomers of carbohydrates are
simple sugars or monosaccharides
Examples: glucose and fructose
Carbohydrates, cont’d
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When two simple sugars are linked
together, they form a disaccharide
Example: glucose + fructose = sucrose
◦ Sucrose is table sugar
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Lactose, the sugar found in milk, is also
a disaccharide
Tip: Notice that the sugars’ names all end
in –ose.
Glucose
C6H12O6
CH2OH
C
O
H
H
H
C
OH
C
OH
H
C
C
H
OH
OH
Carbohydrates, cont’d
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When many simple sugars are linked
together, they form a polysaccharide
Polysaccharides store large amounts of
energy
Humans use the polysaccharide glycogen
Plants use the polysaccharide starch
Lipids
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Fats and oils are lipids
Lipids are made of long chains of carbon
and hydrogen atoms
Lipids store energy more efficiently than
carbohydrates do
The energy stored in lipids is for longterm use and is not used up quickly
◦ It takes a lot of exercise to burn fat
Lipids, cont’d
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Lipids are made of two different parts:
one glycerol molecule and three fatty
acid molecules
The fatty acids can be very long
Tip: Make sure you know
the monomers for each
type of large polymer.
Glycerol
3 Fatty Acids
H
H
H
H
C
C
C
H
O
O
O
O
H
H
H
H
C
C
C
C
C
H
H
H
H
O
H
H
H
H
C
C
C
C
C
H
H
H
H
O
H
H
H
H
C
C
C
C
C
H
H
H
H
H
H
H
Lipids, cont’d
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There are two types of fats: saturated
and unsaturated
Saturated fats contain as many
hydrogen atoms as they can
◦ Solid at room temperature
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Unsaturated fats are missing some
hydrogen atoms
◦ Liquid at room temperature
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When a fat is missing many hydrogen
atoms, it is polyunsaturated
Saturated fat
Glycerol
O
H
H
H
H
C
C
C
C
C
H
H
H
H
H
Unsaturated fat
Glycerol
O
H
C
C
H
C
H
C
C
H
H
Lipids, cont’d
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Polyunsaturated fats are less likely to
cause heart disease than saturated fats
Vegetable oils contain polyunsaturated
fats; meats and dairy contain saturated
fats
Lipids, cont’d
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Steroids are also lipids
Made of carbon atoms arranged in a ring
Cholesterol is a steroid that is found in food
and is also made in the body
High levels of cholesterol can lead to
hardening of the arteries (atherosclerosis)
which can cause heart disease
The male hormone testosterone and the
female hormone estrogen are also steroids
cholesterol
testosterone
estrogen
Proteins
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Proteins are much more diverse than the
other macromolecules
No two people except for identical twins
have exactly the same proteins
Proteins have many functions:
◦ 1. building materials (collagen and elastin)
◦ 2. transport other materials (hemoglobin in the
blood)
◦ 3. send signals (insulin and other hormones)
◦ 4. defense against disease (antibodies)
◦ 5. control metabolism (enzymes)
Proteins, cont’d
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Proteins are large polymers made of amino
acid monomers
There are 20 different amino acids
The order of the amino acids determines the
protein’s properties
Some amino acids are attracted to each
other and others are repelled
This makes the protein fold up in unique
ways
Each protein has its own specific shape
called its conformation
Basic Amino Acid Structure
Amine
group
H
O
C
C
Carboxyl
group
H
H
N
OH
R
Side chain
(different in every
amino acid)
Nucleic Acids
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Nucleic acids consist of
deoxyribonucleic acid (DNA) and
ribonucleic acid (RNA)
DNA and RNA store genetic information
DNA and RNA are made up of many
nucleotide monomers linked together
Tip: Your DNA is unique, and it is what
makes all your proteins unique as well.
Nucleic Acids, cont’d
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Nucleotides consist of a sugar, a
phosphate, and a nitrogenous base
Phosphate
P
5-Carbon
sugar
Nitrogenous base
Nucleic Acids, cont’d
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The sequence of nucleotides in DNA
determines the sequence of nucleotides
in RNA
The sequence of nucleotides in RNA
determines the sequence of amino acids
in a protein
DNA  RNA  Protein
Enzymes
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Enzymes: proteins that speed up
reactions in organisms
Organic catalysts
Enzymes work on substances called
substrates
Substrates are turned into products
Enzymes have an area called the active
site that matches the shape of the
substrate
Enzymes are specific for their substrates
Enzymes, cont’d
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The names of enzymes usually end in
―ase and refer to their substrate
◦ Ex: maltase breaks down the disaccharide
maltose
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Lipases break down lipids
Proteases break down proteins
How Enzymes Work
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Old model: lock and key model
◦ The active site and substrate are said to fit
together just as a key fits in a lock
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New model: induced-fit model
◦ The active site changes shape slightly to
better fit the substrate
Tip: The induced fit model is the result of
many scientists completing experiments
with enzymes.
How Enzymes Work, cont’d
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The substrate fits into the active site of
the enzyme to make an enzymesubstrate complex
Enzymes change the substrate, but the
enzyme itself is not changed
The same enzyme can be reused many
times
1
2
Enzyme-substrate
complex
Products
4
3
Enzyme breaks the
bond holding the
substrate together
How Enzymes Work, cont’d
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An enzyme works by lowering the energy
a reaction needs to change a substrate
All reactions require a “push” to get
started
This push is called the activation
energy
The more activation energy a reaction
needs, the slower the reaction
Enzymes lower the amount of activation
energy needed
Activation energy
without an enzyme
ENERGY
Activation energy
with an enzyme
REACTION
Enzymes and Temperature
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All enzymes have a temperature at
which they work best
◦ This is called its optimum temperature
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Enzymes that function in humans will
have optimum temperatures close to
normal body temperature (37°C)
If the temperature gets too high, the
enzyme can denature
When an enzyme denatures, its active
site loses its shape it cannot do its job
Optimum
temperature =
highest activity
ENZYME
ACTIVITY
Enzyme is
denatured
TEMPERATURE
Enzymes and pH
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pH is a measure of how acidic or basic a
substance is
The pH scale ranges from 0 to 14
◦ 0-6 = acidic
◦ 7 = neutral
◦ 8-14 = basic
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For most enzymes in humans, the
optimum pH is around neutral because
most of the body is neutral
Enzymes and pH, cont’d
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Salivary amylase, which breaks down
sugars as we chew, works best around
pH 7
Pepsin, an enzyme that works in the
stomach, has an optimum pH around 2
◦ The stomach is an acidic environment
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If the pH becomes too low or too high, the
enzyme will denature
Salivary
amylase
Pepsin
ENZYME
ACTIVITY
0
1
2
3
4
pH
5
6
7
8
9