Transcript Molecules of Life - CCRI Faculty Web

Molecules of Life
Chapter 3
Molecules
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Inorganic compound
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Nonliving matter
Salts, water
Organic compound
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Molecules of life
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Contains Carbon (C) and Hydrogen (H)
Carbon backbone
Carbon Chemistry
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Cell is mostly water
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Carbon is a versatile atom
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The rest of the cell consists mostly of carbon-based molecules
four electrons in an outer shell that holds eight
can share its electrons with other atoms to form up to four
covalent bonds
Structures may vary
Organic Molecules
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Many molecules of life are macromolecules
(macromolecules contain many molecules joined together)
Monomers: Simple organic molecules that exist individually
Polymers: Large organic molecules form by combining
monomers
Polymer
Monomer
Carbohydrate
Monosaccharide
Protein
Amino acid
Lipids
Triglycerides
Nucleic acid
Nucleotide
Polymers Are Built of Monomers
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All polymers are assembled the same way
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Covalent bond is formed by removing an hydroxyl
group (OH) from one subunit and a hydrogen (H)
from another subunit
Amounts to the removal of a molecule of water
(H2O)
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Dehydration synthesis
Polymers Are Built of Monomers
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Process of disassembling polymers into
component monomers is essentially the
reverse of dehydration synthesis
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Molecule of water is added to break the covalent
bond between the monomers
Hydrolysis
Molecules of Life
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4 main classes of biological molecules
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1.
2.
3.
4.
Carbohydrates
Lipids
Proteins
Nucleic Acids
Carbohydrates
Carbohydrates
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Some Functions:
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Quick fuel
Short-term energy storage
Structure of organisms
Cell to cell recognition
Consist of C, H, and O atoms
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1:2:1 ratio
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“Saccharides”
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3 major classes:
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Monosaccharides
Disaccharides
Polysaccharides
Monosaccharides
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“simple sugars”; “one monomer of a sugar”
Dissolve easily in water
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hydrophilic
Glucose C6H12O6
Fructose
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Form of glucose
Disaccharides
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Short chain of two sugar
monomers
Two Monosaccharides
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Lactose, sucrose, maltose
Lactose = glucose + galactose
Polysaccharide
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“Complex” carbohydrate
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Contain many C-H bonds
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Glycogen
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Polysaccharide of glucose
Storage form of glucose in animals
Starch
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Good for storing energy
These bond types are the ones most often broken by
organisms to obtain energy
Storage form of glucose in plants
Cellulose
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Found in the cell walls of plants
Lipids
Lipids
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Cells use lipids to store energy
Hydrophobic
Functions:
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Energy Storage
Cushioning and Insulation
Found in the plasma membrane
3 main types:
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Fats & Oils
Phospholipids
Steroids
Fats
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Dietary fat consists largely of the
molecule triglyceride
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Combination of glycerol and three fatty
acids
Fats
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Unsaturated fatty acids
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Have less than the maximum number
of hydrogens bonded to the carbons
Saturated fatty acids
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Have the maximum number of
hydrogens bonded to the carbons
Most animal fats have a high
proportion of saturated fatty acids,
which can be unhealthy
 Example: butter
Most plant oils tend to be low in
saturated fatty acids
 Example: corn oil
Phospholipids
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Glycerol, two fatty
acids and a phosphate
group
Plasma membrane
Nonpolar tail
Polar heads
Proteins
Why Proteins??
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VERY important functions in cells
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Keratin and collagen have structural roles
Enzymes speed up chemical reactions of
metabolism
Responsible for transport of substances within
the body
Transport substances across cell membranes
Hormones that regulate cellular function
 Insulin
Proteins
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Made from amino acids
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20 various kinds
Amino acids linked to
one another by peptide
bonds
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Two amino acids bound
by a peptide bond is a
dipeptide
Three or more is a
polypeptide chain
Amino Acids
Peptide / Dipeptide
Polypeptide
Protein
Proteins
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Amino acids are small molecules with a simple basic
structure, a carbon atom to which three groups are
added
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an amino group (-NH2)
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a carboxyl group (-COOH)
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a functional group (R)
The functional group gives amino acids their chemical
identity
Protein Structure
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Protein’s final shape
and chemical behavior
arise from:
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Chain bends, folds,
coils, etc.
Proteins
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Primary structure
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sequence of amino
acids in the
polypeptide chain
determines all other
levels of protein
structure
Proteins
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Secondary
structure
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Forms because
regions of the
polypeptide that are
non-polar are forced
together
folded structure may
resemble coils,
helices, or sheets
Proteins
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Tertiary structure
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final 3-D shape of
the protein
final twists and folds
that lead to this
shape are the result
of polarity
differences in
regions of the
polypeptide
Proteins
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Quaternary
structure
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spatial arrangement
of proteins
comprised of more
than one polypeptide
chain
Protein
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The shape of a protein affects its function
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Changes to the environment of the protein may
cause it to unfold or denature
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Increased temperature or lower pH affects hydrogen
bonding, which is involved in the folding process
Denatured protein is inactive
Nucleic Acids
Proteins
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Denaturing
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When proteins lose their shape
Nucleotides and Nucleic Acids
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Nucleic acids
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Can be single stranded or double stranded
 DNA
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Deoxyribonucleic acid
genetic information
RNA
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Ribonucleic acid
used to build proteins
Nucleotides and Nucleic Acids
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Nucleic acids
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Built by nucleotides
 Phosphate
 Pentose sugar
 Nitrogen-containing base
DNA Composition
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DNA is built from four different
kinds of nucleotides
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One of four bases determines the
nucleotide:
 A - Adenine
 G - Guanine
 T - Thymine
 C – Cytosine
DNA consists of two strands of
nucleotides twisted into a double
helix
GAGA….a nucleotide repeat!!
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Base pairs
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Bases can only pair up with their corresponding “mate”
2 kinds:
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A–T
G–C
Amount of A = T
Amount of G = C
Can line up in any order
DNA Composition
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Nucleotides linked together by
covalent bonds
Bases of one strand linked to the
other by hydrogen bonds
The two strands run in opposite
directions
DNA into RNA
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RNA a big player!!
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Single strand
Sugar, phosphate group,
and a N-containing base
Bases are:
 A, C, G, and URACIL (U)