Transcript water

Biochemistry: Chemical Reactions in Living Cells
Chemical Reactions in Living Cells
• Chemical Reaction
– Involves the making and breaking of chemical
bonds
– Represented as a “short statement”:
2 H2 O
2 H 2 + O2
How would you balance this?
Does this happen on its own?
• Activation Energy: The amount of
energy needed to initiate a reaction
Biochemistry: The unique properties of water
δ+
δ-
δ+
Water molecules are polar covalent bonds.
They are attracted to other water
molecules through relatively weak
Hydrogen bonds.
Biochemistry: The unique properties of water
Can water form ions?
Yes, at a very small rate
(1 out of 500,000,000!)
+
H2O
+
H
-
+
OH
How would you quantify (count) this ionic
disassociation? The pH scale
The “power of Hydrogen” scale
Increasingly Acidic 
 Increasingly Basic
Neutral
Stomach Acid,
lemon juice
Vinegar, cola
+
<[H ]
>[OH ]
Tomato juice
Black coffee;
Rainwater
Urine
Pure water;
Human blood
[H+] = [OH-]
Seawater
Milk of magnesia
Household ammonia
Household bleach
Oven cleaner
+
>[H ]
<[OH ]
Organic Compounds: An Overview
Besides water, what elements and
compounds are essential to life?
Organic compounds
1. Mostly contain Carbon,
Carbon Hydrogen, Oxygen,
Nitrogen, Phosphorus and Sulfur*
H
H H
H H H
O
H C C C C C C
O O O H O
H H H
H
*For Homework: Left Side IntNB Assignment: Write an Acrostic Poem for the six
elements often found in organic compounds
Organic Compounds: Carbohydrates
Can you believe that each
of your cells contains
about 2 meters of me?
Hurry up,
HiSugar,
there! IMy
Hey
Lipids!
You
name
is
Polly
sure
am happy
should
have
Peptide.
Four categories
of
organic
that
you’re
a
more
energy
Carbohydrate
stored up than
a. Carbohydrates
likethis!
me.
Organic compounds (continued…)
2.
b. Lipids
c. Proteins
d. Nucleic Acids
compounds:
Awww, how
Does this bond
sweet!
structure make
me look fat?
3. All formed and separated in similar ways
a. Formation (Polymerization): Dehydration
Synthesis
b. Separation: Hydrolysis
Bonding: Polymerization
Polymerization
• Polymerization (definition):
– Forming of large organic macromolecules by
the joining of smaller repeating units called
monomers
Bonding: Polymerization: Dehydration Synthesis
Dehydration Synthesis
• Dehydration Synthesis is the removal of a
water molecule to form a new bond.
HO
1
2
3
H
HO
Short Polymer
Monomer
H2O
Dehydration removes a water
molecule forming a new bond
HO
1
2
H
3
4
H
Bonding: Polymerization: Hydrolysis
Hydrolysis
• Polymers are broken by adding water.
HO
• Literally, “Water Splitting”
2
HO
1
2
3
4
H
HO
H
Hydrolysis adds a water
molecule to break a bond
HO
1
2
3
Short Polymer
H
Monomer
Bonding: Carbon
Carbon = The element of life
• Carbon’s Valence has ____
4 electrons
4 elements
• Can bond with ____
• Can form chains, rings, branches, &
isomers
What biological
do C
you think
C C impact
C C C
isomers have on living systems?
HO
H
HO
OH
C C
C C
H
H
H
OH
Bonding: The importance of chemical structure
Thalidomide: an optical isomer
Bonding: Bond Energy
Bond energy
• When bonds are broken,
made, energy
energy(E)
(E)isis
stored. for use.
released
Glucose: A Monosaccharide
Fructose: A Monosaccharide
Sucrose: A Disaccharide
Organic Compounds: Carbohydrates
Carbohydrates
• Carbohydrates are:
– an important energy (E) source
– Cellular structures
• Carbon, Hydrogen and Oxygen in a ratio
of 1:2:1
• General Formula (CH
CH2O)n
O
Carbon
Water = hydrate
Organic Compounds: Carbohydrates: Monomers
Carbohydrates
• Monosaccharides (simple sugars)
– Contain 3-7 Carbons each
• Examples: Glucose
Glucose, Galactose, Fructose
Organic Compounds: Carbohydrates: Dimers
Carbohydrates
• Disaccharides (two sugars)
• Examples: Sucrose
Sucrose, Maltose, Lactose
– Maltose = Glucose + Glucose
– Lactose = Glucose + Galactose
Glucose
Fructose
Organic Compounds: Carbohydrates: Polymers
Carbohydrates
• Polysaccharides (many sugars)
• Examples: Starch
Starch, Glycogen, Cellulose
Chloroplast
Starch
Liver Cell
Cellulose
Plant Cells
Glycogen
Plant Cells
Organic Compounds: Lipids
Lipids
• Lipids function in:
– Energy (E) storage,
– forming cell membranes,
– and as chemical messengers
(e.g., hormones)
• Nonpolar (hydrophobic)
• Made up mostly of Carbon and Hydrogen
(with a few Oxygen)
Organic Compounds: Lipids: Fats
Lipids
1. Fats (Triglycerides)
– Glycerol + 3 Fatty Acids
– Saturated = No Double Bonds (solid)
– Unsaturated = Double Bonds (liquid)
OH
OH
OH
OH
OH
Ester Bonds
OH
Organic Compounds: Lipids: Phospholipids
Lipids
2. Phospholipids
– Glycerol with Phosphate Head +
2 Fatty Acid Chains
– Amphiphilic (“Both” “lover”)
•
•
Hydrophilic headPhosphate
Hydrophobic tail
Glycerol
– Forms 2 layers in water
– Makes up cell membranes
Fatty Acids
Organic Compounds: Lipids: Sterols
Lipids
3. Sterols
OH
– Lipids whose Carbon Skeleton
consists of 4
fused rings
O
OH
O
– Includes:
•
•
•
HO
Hormones
Cholesterol
Cortisol
– Makes up cell membranes
HO
O
Testosterone
Estrogen
OH
Organic Compounds: Proteins
Proteins
•
•
Made up of Carbon, Hydrogen, Oxygen
and Nitrogen (and some Sulfur)
Many functions represented through
different types of proteins
Organic Compounds: Proteins: Functions
Proteins
I am completely
ICatalysts
am an enzyme.
• Enzymes:
that speed up the
unchanged,
and
Hi
sweeties,
Do
am
the
active
site.
I am
going
tomore
try
for
some
rate ofI you
aready
chemical
reaction
rememberbindsI am a product, too.
The substrate
tosucrose!
convert you.
– Build up orme?
tobreak
me. down Isubstrate
am a fructose now.
• Fit a
together
like a “lock” and a “key”
I am now
product.
In addition
what
– Not
used
up
in thetoreaction
I am
a glucose
now.
know.
I am biological
a
– Work inyou
a very
specific
range
substrate.
– Usually end with “-ase”
Organic Compounds: Proteins: Functions
Proteins
•
Structural Proteins
– Provides mechanical support to cells and
tissues
•
Transport Proteins
– Transports small ions or molecules
•
Motor Proteins
– Enables structures to move
Organic Compounds: Proteins: Functions
Proteins
•
Hormones (signaling proteins)
– Carries signals from cell-to-cell
– e.g., insulin
•
Storage
– Stores small molecules or ions
– e.g., iron is stored in the liver in ferritin
•
Other specialized functions
– Defense (antibodies),
– Receptor proteins (in eyes and muscles to
detect stimulus)
Organic Compounds: Proteins: Monomers
Proteins
•
Monomers: Amino Acids
– Peptide Bond:
Bond between 2 Amino Acids:
Amino end (NH2) and the Carboxyl end (COOH)
R Group =
Side
Chains
H2O
Backbone
Organic Compounds: Proteins: Monomers
Proteins
• R Groups (Side chains)
– Differ in:
• Size
• Charge
• Polarity
• There are 20 protein-building Amino Acids
– 9 Essential Amino Acids
• Can’t be synthesized by the body, but are
necessary
forAmino
life Acid
Hydrophilic
Hydrophobic Amino Acid
Organic Compounds: Proteins: Polymers
Proteins
•
•
Polymers: Polypeptides
“Many Peptides”
Four Levels of Structure
–
–
–
–
•
Primary (1°)
Secondary (2°) – H bonds
Tertiary (3°)
Quaternary (4°) – several
polypeptides
These specific shapes
allow proteins to function
Organic Compounds: Proteins: Denaturation
Proteins
• Denaturation
– When the protein loses its
shape, and becomes nonfunctional due to:
– Changes in
•
•
•
•
temperature
pH
salinity (salt concentration)
alcohol concentration
Organic Compounds: Nucleic Acids
Nucleic Acids
• Nucleic Acids
– Informational Polymers: Code for all of the
proteins in an organism
– Monomers: Nucleotides
• Phosphate Group
• 5-Carbon Sugar
• Nitrogenous base
Organic Compounds: Nucleic Acids
Nucleic Acids
• DNA (Deoxyribonucleic
Acid)
Deoxyribo
– Backbone sugar: Deoxyribose
– Four Bases
•
•
•
•
Cytosine
Thymine
Uracil
Adenine (A)
Guanine (G)
Thymine (T)
Cytosine (C)
• RNA (Ribonucleic Acid)
Adenine
– Messenger RNA: mRNA conveys the
instructions to build proteins from the
genetic information in DNA
– Differences from DNA:
• Backbone sugar: Ribose
• Uracil in place of Thymine
Guanine
Organic Compounds: Nucleic Acids and Proteins
Flow of Information
DNA
RNA
Protein