Transcript Biochemistry of life

Biochemistry of
Life
Matter and Atoms
 Everything
on Earth is made up of matter
 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
Elements and Compounds
 There
are 118 different types of atoms called
elements
 The six most important elements for living things
(organisms) are :
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Carbon (C)
Oxygen (O)
Hydrogen (H)
Nitrogen (N)
Phosphorus (P)
Sulfur (S)
 Elements
cannot be broken down into smaller
parts
 Elements can combine with other elements to
form a new substance called a compound
 Compounds are held together by chemical
bonds
 Examples of compounds:
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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
 Our
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1.
2.
3.
4.
5.
bodies use organic compounds to:
make energy
build new structures
store materials
repair existing structures
keep all chemical activities working properly
 These
reactions are all part of metabolism
 Organic
compounds are usually very large and
are called polymers
 Polymers are made by linking smaller parts
together
 The smaller parts are called monomers
 Monomer + Monomer = Polymer
 The process of linking monomers together to
make polymers is called condensation
synthesis by removing a water (dehydration
synthesis)
 The process of breaking down polymers into
monomers is hydrolysis by adding water
Carbohydrates
 Carbohydrates
are sugars
 Made of the elements carbon, hydrogen, and
oxygen
 The functions of carbohydrates are:
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1. to store energy
2. to provide building materials for the body
 The
monomers of carbohydrates are simple
sugars or monosaccharides
 Examples: glucose and fructose
 When
two simple sugars are linked together,
they form a disaccharide
 Example: glucose + fructose = sucrose

Sucrose is table sugar
 Lactose,
the sugar found in milk, is also a
disaccharide
Glucose
C6H12O6
CH2OH
C
O
H
H
H
C
OH
C
OH
H
C
C
H
OH
OH
 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
 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 long-term use
and is not used up quickly

It takes a lot of exercise to burn fat
 Lipids
are made of two different parts: one
glycerol molecule and three fatty acid molecules
 The fatty acids can be very long
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
 There
are two types of fats: saturated and
unsaturated
 Saturated fats contain as many hydrogen atoms
as they can (all single bonds between the C
atome)
 Unsaturated fats are missing some hydrogen
atoms (double or triple bond between the c
atome)
 When a fat is missing many hydrogen atoms, it is
polyunsaturated
 Polyunsaturated fats are less likely to cause
heart disease than saturated fats
 Vegetable oils contain polyunsaturated fats;
meats and dairy contain saturated fats
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
 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
Proteins (Polypeptide)
 Proteins
are much more diverse than the other
macromolecules Nitrogen containing compounds
 No two people except for identical twins have
exactly the same proteins
 Proteins have many functions:
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1.
2.
3.
4.
5.
building materials (collagen and elastin)
transport other materials (hemoglobin in the blood)
send signals (insulin and other hormones)
defense against disease (antibodies)
control metabolism (enzymes)
 Proteins
are large polymers made of amino acid
monomers
 There are 20 different amino acids (9 essentials)
 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
Essential Amino Acids
 An
essential amino acid may also be called an
indispensable amino acid. (9) (peptide)
 This is an amino acid that the body cannot
synthesize on its own, so it must be obtained
from the diet.
 Because each has its own physiology, the list of
essential amino acids is different for humans
than it is for other organisms.
Basic Amino Acid Structure
Amine
group
H
O
C
C
Carboxyl
group
H
N
OH
H
R
Side chain
(different in every
amino acid)
Nucleic Acids
 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
 Nucleotides consist of a sugar, a phosphate, and
a nitrogenous base
 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
Phosphate
P
5-Carbon
sugar
Nitrogenous base
Building Blocks and polymer
Building blocks
Structure
Amino acids
Proteins, enzymes, hormones
Sugars
Starches carbohydrates
Glycerol and fatty acids
Lipid
Nucleotides(phosphate, sugar, base)
Nucleic acids DNA :RNA
Differences between DNA and
RNA
DNA
RNA
Deoxyribose
Ribose
A;T;C;G
A;U;C;G
Double stranded for cell reproduction
Single stranded for protein synthesis
Enzymes
 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
names of enzymes usually end in –ase and
refer to their substrate
 The
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Ex: maltase breaks down the disaccharide maltose
 Lipases
break down lipids
 Proteases break down proteins
 Co-Enzyme
is a vitamin they are sometimes
needed by the enzyme to complete the job.
Lock and Key Model
 The
active site and substrate are said to fit
together just as a key fits in a lock
 In reality, the active site changes shape slightly
to accommodate the substrate
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Like a glove molding to a hand
Called the induced-fit model
 The
substrate fits into the active site of the
enzyme to make an enzyme-substrate 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
 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
 All
enzymes have a temperature at which they
work best
 This is called its optimum temperature
 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
 Sometimes,
the active site will go back to its
normal shape if the temperature is lowered
 Denaturation can be permanent
Optimum
temperature =
highest activity
ENZYME
ACTIVITY
Enzyme is
denatured
TEMPERATURE
Enzymes and pH
 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
 For most enzymes in humans, the optimum pH is
around neutral because most of the body is
neutral
 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
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 If
The stomach is an acidic environment
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
Substrate Concentration
 Increasing
the substrate’s concentration makes
the enzyme’s rate increase
 After a point, the enzyme is working as fast as it
can
 Adding more substrate at this point will not
increase the rate any more.
 The enzyme can be reused. It will complete its
function and attach to another substrate.
Enzyme is working as fast
as it can
ENZYME
ACTIVITY
SUBSTRATE CONCENTRATION