Transcript Biochemistry of Cells

Biochemistry of Cells
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What you need to learn…
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Why carbon?
Name the 4 macromolecules
Know the building block or monomer of each.
Know their functions
Know examples of each.
Know what dehydration synthesis and hydrolysis are.
Understand some properties of these molecules
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Water
About 60-90 percent
of an organism is
water
Water is used in
most reactions in
the body
Water is called
the universal
solvent
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Water Properties
Polarity
Cohesiveness
Adhesiveness
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The Water Molecule
Polarity
A water molecule is polar because there is an
uneven distribution of electrons between
the oxygen and hydrogen atoms.
(+)
(—)
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Hydrogen Bonds
Polar water molecules act like magnets and
attract each other
Hydrogen Bonds
The attraction of the Hydrogen end (+) of
one molecule for the Oxygen end (-) of
another water molecule.
They are the strongest bonds that can form
between molecules
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Hydrogen Bonds
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Cohesion
The attraction between
molecules of the same
substance (e.g. water).
Allows some insects and
spiders to walk on
water.
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Adhesion
Attraction between molecules of
different substances
Responsible for Capillary forces in plants
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Carbon-based Molecules
Although a cell is
mostly water, the
rest of the cell
consists mostly of
carbon-based
molecules
Organic chemistry
is the study of
carbon compounds
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Carbon is a Versatile Atom
It has four electrons
in an outer shell that
holds eight
Carbon can
share its
electrons with
other atoms to
form up to four
covalent bonds
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Carbon can use its bonds to::
Attach to other
carbons
Form an
endless
diversity of
carbon
skeletons
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Shape of Organic Molecules
Each type of
organic molecule
has a unique
three-dimensional
shape
The shape
determines its
function in an
organism
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Giant Molecules - Polymers
Large molecules
are called polymers
Polymers are built
from smaller
molecules called
monomers
Biologists call
them
macromolecules
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Most Macromolecules are Polymers
Polymers are made by stringing together
many smaller molecules called monomers
Nucleic Acid
Monomer
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Linking Monomers
Cells link monomers by a process
called dehydration synthesis
(removing a molecule of water)
Remove
H
H2O Forms
Remove OH
This process joins two sugar monomers
to make a double sugar
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Breaking Down Polymers
Cells break down
macromolecules
by a process
called
hydrolysis
(adding a
molecule of
water)
Water added to split a double sugar
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Macromolecules in Organisms
There are four categories of large
molecules in cells:
Carbohydrates
Lipids
Proteins
Nucleic Acids
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Monosaccharides:
Called simple sugars
Include glucose,
fructose, & galactose
Have the same
chemical, but
different structural
formulas called an
isomer.
C6H12O6
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Monosaccharides
Glucose is found in
sports drinks
Fructose is found
in fruits
Honey contains
both glucose &
fructose
Galactose is called
“milk sugar”
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Carbohydrates
Carbohydrates include:
Small sugar molecules
in soft drinks
Long starch molecules
in pasta and potatoes
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Rings
In aqueous (watery) solutions,
monosaccharides form ring structures
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Cellular Fuel
Monosaccharides
are the main
fuel that cells
use for cellular
work
ATP
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Disaccharides
A disaccharide is a
double sugar
They’re made by
joining two
monosaccharides
Involves removing
a water molecule
(dehydration)
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Disaccharides
Common disaccharides include:
Sucrose (table sugar)
Lactose (Milk Sugar)
Maltose (Grain sugar)
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Polysaccharides
Complex
carbohydrates
Composed of many
sugar monomers
linked together
Polymers of
monosaccharide
chains
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Examples of Polysaccharides
Glucose Monomer
Starch
Glycogen
Cellulose
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Sugars in Water
Simple sugars and double sugars dissolve
WATER
readily in water
MOLECULE
They are
hydrophilic,
or “waterloving”
SUGAR
MOLECULE
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Lipids
Lipids are hydrophobic –”water fearing”
Do NOT mix with water
Includes
fats,
waxes,
steroids,
& oils
FAT MOLECULE
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Function of Lipids
Fats store energy, help to insulate the
body, and cushion and protect organs
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Types of Fatty Acids
Unsaturated fatty acids have less than
the maximum number of hydrogens
bonded to the carbons (a double bond
between carbons)
Saturated fatty acids have the
maximum number of hydrogens bonded
to the carbons (all single bonds
between carbons)
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Types of Fatty Acids
Single
Bonds in
Carbon
chain
Double bond in carbon chain
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Triglyceride
Monomer of lipids
Composed of
Glycerol & 3
fatty acid chains
Glycerol forms
the “backbone”
of the fat
Organic Alcohol
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Triglyceride
Glycerol
Fatty Acid Chains
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Fats in Organisms
Most animal fats have a high proportion
of saturated fatty acids & exist as
solids at room temperature (butter,
margarine, shortening)
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Fats in Organisms
Most plant oils tend to be low in
saturated fatty acids & exist as
liquids at room temperature (oils)
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Steroids
The carbon skeleton
of steroids is bent
to form 4 fused
rings
Cholesterol is
the “base
steroid” from
which your body
produces other
steroids
Cholesterol
Estrogen
Testosterone
Estrogen & testosterone are also steroids
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Synthetic Anabolic Steroids
They are variants
of testosterone
Some athletes use
them to build up
their muscles quickly
They can pose
serious health risks
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Proteins
Proteins are polymers made of
monomers called amino acids
All proteins are made of 20 different
amino acids linked in different orders
Proteins are used to build cells, act
as hormones & enzymes, and do much
of the work in a cell
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Four Types of Proteins
Storage
Structural
Contractile
Transport
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20 Amino Acid Monomers
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Linking Amino Acids
Carboxyl
Cells link amino
acids together to Amino
Side
make proteins
The process is
called dehydration
synthesis
Peptide bonds
form to hold the
amino acids
together
Group
Dehydration
Synthesis
Peptide Bond
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Proteins as Enzymes
Many proteins act as biological catalysts
or enzymes
Thousands of different enzymes exist
in the body
Enzymes control the rate of chemical
reactions by weakening bonds, thus
lowering the amount of activation
energy needed for the reaction
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Protein Structures
Secondary protein structures occur
when protein chains coil or fold
When protein chains called polypeptides
join together, the tertiary structure
forms
In the watery environment of a cell,
proteins become globular in their
quaternary structure
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Denaturating Proteins
Changes in temperature & pH can
denature (unfold) a protein so it no
longer works
Cooking denatures
protein in eggs
Milk protein separates into
curds & whey when it
denatures
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Nucleic Acids
Store hereditary information
Contain information for making all
the body’s proteins
Two types exist --- DNA &
RNA
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Nucleic Acids
Nitrogenous base
(A,G,C, or T)
Nucleic
acids are
polymers of
nucleotides
Phosphate
group
Thymine (T)
Sugar
(deoxyribose)
Phosphate
Base
Sugar
Nucleotide
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Bases
Each DNA
nucleotide has one
of the following
bases:
–Adenine (A)
Thymine (T)
Cytosine (C)
–Guanine (G)
–Thymine (T)
–Cytosine (C)
Adenine (A)
Guanine (G)
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End
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