Title: The Chemical Building Blocks of Life
1The Chemical Building Blocks of Life
2Comparison of Molecules
- Inorganic Chemistry of elements other than
carbon - Organic Carbon-based chemistry
- Always containcarbon and hydrogen
- Often quite large, withmany atoms
- Usually associatedliving systems
- Often associated with nonliving matter
3- All living things are mostly composed of 4
elements H, O, N, C "honk" - Compounds are broken down into 2 general
categories - Inorganic Compounds
- Do not contain carbon
- Organic compounds
- Contain significant amounts of carbon.
- Often found with common "functional groups"
more on this in a minute!
4Why Carbon?
- Carbon is essential to life for several reasons
- It can form strong stable (usually nonpolar)
covalent bonds - It can form up to 4 chemical bonds due to 4
valence electrons - It can form multiple bonds
5More on the Carbon Atom
- Carbon atoms
- Contain a total of 6 electrons
- Often bonds with other carbon atoms to make
hydrocarbons - Can produce long carbon chains like octane
- Can produce ring forms like cyclohexane
6- Carbon skeletons vary in many ways
Ethane
Propane
Carbon skeletons vary in length.
Isobutane
Butane
Skeletons may be unbranched or branched.
1-Butene
2-Butene
Skeletons may have double bonds, which can vary
in location.
Cyclohexane
Benzene
Figure 3.1, bottom part
Skeletons may be arranged in rings.
7 Functional groups help determine the properties
of organic compounds
- Functional groups
- specific groups of atoms attached to carbon
backbones - retain definite chemical properties
- Functional groups are the groups of atoms that
participate in chemical reactions - Ex. Hydroxyl groups are characteristic of
alcohols - Ex. The carboxyl group acts as an acid
8Table 3.2
9Macromolecules
- Some molecules called macromolecules because of
their large size - Usually consist of many repeating units
- Resulting molecule is a polymer (many parts)
- Repeating units are called monomers
- Some examples
10 Cells make a huge number of large molecules
from a small set of small molecules
- Most of the large molecules in living things are
macromolecules called polymers - Polymers are long chains of smaller molecular
units called monomers (building blocks) - A huge number of different polymers can be made
from a small number of monomers
11Dehydration and Hydrolysis
- Dehydration - Removal of water molecule
- Used to connect monomers together to make
polymers - Polymerization of glucose monomers to make starch
- Hydrolysis - Addition of water molecule
- Used to disassemble polymers into monomer parts
- Digestion of starch into glucose monomers
- Specific enzymes required for each reaction
- Accelerate reaction
- Are not used in the reaction
12- Cells link monomers to form polymers by
dehydration synthesis, removes OH and H during
synthesis of a new molecule.
1
2
3
Unlinked monomer
Short polymer
Removal ofwater molecule
1
2
3
4
Longer polymer
Figure 3.3A
13- Polymers are broken down to monomers by the
reverse process, hydrolysis. (Breaks a covalent
bond by adding OH and H.)
1
2
3
4
Addition ofwater molecule
1
2
3
Figure 3.3B
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15The Major Organic Groups
16What you need to know
- The monomer of each group
- The function of each group
- The characteristics of each group
- Unique properties of each group
17Carbohydrates
- Carbohydrates are loosely defined as molecules
that contain carbon, hydrogen, and oxygen in a
121 ratio. - monosaccharides - simple sugars
- disaccharides - two monosaccharides joined by a
covalent bond - polysaccharides
- made of many
- monosaccharide
- subunits
18Function
- Primary Function Quick Energy!
19 Monosaccharides are the simplest carbohydrates
- Monosaccharides are single-unit sugars
- These molecules typically have a formula that is
a multiple of CH2O - Hydrogen to oxygen ratio is 21.
- Monosaccharides are the fuels for cellular work
Hi Honey Im home!
Youre so sweet!
Figure 3.4A
20- The monosaccharides glucose and fructose are
isomers
- They contain the same atoms but in different
arrangements
Glucose
Fructose
Figure 3.4B
21Isomers
- isomers - alternative forms of the same substance
- ex. 8 isomers of glucose
22 Cells link single sugars to form disaccharides
- Monosaccharides can join to form disaccharides,
such as sucrose (table sugar) and
maltose (brewing sugar) - Which type of reaction forms
a disaccharide?
Glucose
Glucose
Sucrose
Figure 3.5
Maltose
23- Polysaccharides are long chains of sugar units.
These large molecules are polymers of hundreds or
thousands of monosaccharides linked by
dehydration synthesis.
Starch granules in potato tuber cells
Glucosemonomer
STARCH
Glycogen granules in muscle tissue
GLYCOGEN
Cellulose fibrils ina plant cell wall
CELLULOSE
Cellulosemolecules
Figure 3.7
24Storage polysaccharides.
- Starch - plant storage
- Glycogen - animal storage
- stored in the liver
Electron micrograph of a section of a liver cell
showing glycogen deposits as accumulations of
electron dense particles (arrows). Mitochondria
are also shown. x30,000.
25Structural Carbohydrates
- Cellulose - plants
- alpha form or beta form of ring
- animals can not digest cellulose - fiber
- most abundant form of living terrestrial biomass.
- Chitin - exoskeleton of
arthropods and in fungi
cell walls - modified form of
cellulose
26Lipids Basic Information
- Lipids are loosely defined as groups of molecules
that are insoluble in water. - Fats (triglycerides), oils, waxes, and steroids.
- Phospholipids ( a special category) form the core
of all biological membranes.
27Lipids
- Insoluble in water
- Long chains of repeating CH2 units
- Renders molecule nonpolar
- Types of Lipids
- Long-term energy storage thermal insulation in
animals
- Long-term energy storage in plants and their seeds
- Component of plasma membrane
- Component of plasma membrane hormones
- Wear resistance retain water
28Lipids are hydrophobic
- Lipids repel water.
- Ex. The cuticle of plants is waxy. The waxy
covering makes the plant water proof and
minimizes water loss.
29Building Blocks of Lipids
- One glycerol
- Three fatty acids
-
30Fats and Oils (triglycerides)
- Fats and oils consist of a glycerol molecule with
three attached fatty acids (triglyceride /
triglycerol). - Saturated fats - all internal carbon atoms are
bonded to at least two hydrogen atoms - usually a solid at room temperature
- Unsaturated fats - at least one double bond
between successive carbon atoms - Polyunsaturated - contains more than one double
bond - usually liquid at room
temperature
31Fats as Energy Storage Molecules
- Fats, on average, yield about 9 kcal per gram
versus 4 kcal per gram for carbohydrates. - Animal fats are saturated while most plant fats
are unsaturated. - Consumption of excess carbohydrates leads to
conversion into starch, glycogen, or fats for
future use.
32Triglycerides
33Saturated vs. unsaturated fatty acids
34Hydrogenated Fats
- Hydrogenation is used to add hydrogens to
unsaturated fats and make them more solid. If a
fat is FULLY saturated, it becomes solid, like
candle wax. If it is PARTIALLY saturated (the
same as partially hydrogenated) the result is a
semi-solid, like margarine.
35Steroids
- Steroid hormones are crucial substances for the
proper function of the body. They mediate a wide
variety of vital physiological functions ranging
from anti-inflammatory agents to regulating
events during pregnancy. - They are synthesized and secreted into the
bloodstream by endocrine glands such as the
adrenal cortex and the gonads (ovary and testis).
- Skeleton made of four fused carbon rings
- Cholesterol is a steroid
as well as the foundation
for other steroids.
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37Waxes
- Long-chain fatty acid bonded to a long-chain
alcohol - High melting point
- Waterproof
- Resistant to degradation
- Why do you wax a car?
38Waxes
39Phospholipids
40Phospholipids
- Derived from triglycerides
- Glycerol backbone
- Two fatty acids attached instead of three
- Third fatty acid replaced by phosphate group
- The fatty acids are nonpolar and hydrophobic
- The phosphate group is polar and hydrophilic
- Molecules self arrange when
placed in water - Polar phosphate heads
next to water - Nonpolar fatty acid
tails overlap and
exclude
water - Spontaneously form double
layer a sphere
41Phospholipid Structure
- Phospholipid molecules have one end which is
attracted to water while the other is repelled by
it. The fatty acid end is not attracted to water
and is called hydrophobic. At the other end of
the molecule the phosphate group is attracted to
water, it is said to be hydrophilic.
Hydrophilic Head
Hydrophobic Tail
42Phospholipids Form Membranes
43Proteins
- Protein functions
- enzyme (catalyst)
- defense
- transport
- support
- motion
- regulation
- storage
447 Classes of Proteins
- Structural
- Spider silk
- Mammal hair
- Fibers of tendons and lipids
- Contractile
- Muscular movement
- Storage
- Egg white
- Defense
- Antibodies
- Transport
- Hemoglobin
- Signal
- Some hormones
- Chemical catalyst
- Enzymes
45Structure is related to function!
- Structurally sophisticated.
- Shape determines function and is crucial to the
job of a protein. - Composed of amino acids joined together by
peptide bonds. - 20 types of amino acids
- Made at the ribosomes in a cell.
46Monomer Amino Acids (AA)
- contain an amino group (-NH2), a carboxyl group
(-COOH) and a hydrogen atom, all bonded to a
central carbon atom - twenty common AA grouped
into five classes based on
side groups - nonpolar AA
- polar uncharged AA
- charged AA
- aromatic AA
- special-function AA
47Structural Formulas for the 20 Amino Acids
48Amino Acids
- Peptide bond links two amino acids.
- A protein is composed of one or more long chains
of amino acids linked by peptide bonds (dipetide
and polypeptides).
49The Polypeptide Backbone
- Amino acids joined together end-to-end
- COOH of one AA covalently bonds to the NH2 of the
next AA - Special name for this bond - Peptide Bond
- Two AAs bonded together Dipeptide
- Three AAs bonded together Tripeptide
- Many AAs bonded together Polypeptide
- Characteristics of a protein determined by
composition and sequence of AAs - Virtually unlimited number of proteins
50Protein Structure
- Protein function is determined by its shape.
- The shape is driven by a number of noncovalent
interactions such as hydrogen bonding. - Protein structure
- primary - specific amino acid sequence
- secondary - folding of amino acid chains
51Protein Structure
- tertiary - final folded shape of globular protein
- quaternary - forms when two or more polypeptide
chains associate to form a functional protein
52Summary Levels of Structure
- Primary
- Literally, the sequence of amino acids
- A string of beads (up to 20 different colors)
- Secondary
- The way the amino acid chain coils or folds
- Describing the way a knot is tied
- Tertiary
- Overall three-dimensional shape of a polypeptide
- Describing what a knot looks like from the
outside - Quaternary
- Consists of more than one polypeptide
- Like several completed knots glued together
53Levels of Protein Organization
54Examples of Fibrous Proteins
55How enzymes workInduced Fit Model
- The substrate (what the enzyme is going to work
upon) comes into contact with the active site of
the enzyme. - The enzyme wraps around the substrate breaking
or forming bonds. - The product is released.
56Enzyme at work
57 Unfolding Proteins
- Denaturation refers to
the process of changing
a proteins shape. - usually rendered
biologically inactive - salt-curing and pickling used to preserve food
- temperature - high temperatures break bonds.
- pH - designed to work at a specific pH!
58Examples
- You can not use fresh pineapple in jello but you
can used canned! Why? - Pepsin is an enzyme that helps break down
proteins in the stomach during digestion. It
works at a pH of 2! - Trypsin is an enzyme that helps break down
proteins as well. It works in the intestines with
a pH of 8. - Many snake venoms are enzymes that work when
directly injected into blood or tissue (pH
7.4). If swallowed, they are denatured by the
acidity of the stomach! (Dont try it, just take
my word for it!) - Why do people without refrigeration salt their
food for long term storage?
59Nucleic Acids
60Nucleic Acids
- Deoxyribonucleic Acid (DNA)
- Encodes information used to assemble proteins.
- Ribonucleic Acid (RNA)
- Reads DNA-encoded information to direct protein
synthesis. - Adenosine triphosphate (ATP)
- Provides energy
61Nucleic Acid Structure
- Nucleic acids are composed of long polymers of
repeating subunits, nucleotides - the monomer. - five-carbon sugar
- phosphate
- nitrogenous base
- purines
- adenine and guanine
- pyrimidines
- cytosine, thymine, and uracil
62Nucleic Acid Structure
- DNA exists as double-stranded molecules.
- Genetic info. - coded for by the order of the
nucleotides. - double helix
- complementary base pairing
- hydrogen bonding
- base pairing A-T, C-G
- RNA exists as a single stand.
- contains ribose instead of deoxyribose
- contains uracil in place of thymine
63Nucleotides
64Comparison of DNA RNA
- Cytosine, guanine
- adenine, uracil
- Cytosine, guanineadenine, thymine
- Double-stranded Pairing across strands
- Interprets genetic info protein synthesis
- Heredity cellular control center
- Cell nucleus and cytoplasm
- Chromosomes of cell nucleus
65Structure of DNA
66RNA Structure
67DNA ? RNA? Protein
68Other Nucleic Acids
- ATP (adenosine triphosphate) is composed of
adenine, ribose, and three phosphates - In cells, one phosphate bond is hydrolyzed
Yields - The molecule ADP (adenosine diphosphate)
- An inorganic phosphate molecule pi
- Energy
- Other energy sources used to put ADP and pi back
together again
69ATP
70Summary
- Biological Molecules (contain Carbon)
- Macromolecules (polymers made of monomers)
- Proteins (amino acids)
- Polypeptides
- Enzymes
- Nucleic Acids (nucleotides)
- DNA and RNA
- Lipids (glycerol 3 fatty acids)
- Fats, Oils, Waxes, Steroids, and Phospholipids
- Carbohydrates (monosaccharides)
- Monosaccharides, Disaccharides, and
Polysaccharides (Starch, Glycogen, Cellulose, and
Chitin)
71Summary
and
Phosphate group
Enzymes
Not all inclusive!