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The Molecules of Cells
 Always
contain carbon
 Always have covalent bonds (not ionic)
 Usually associated with large numbers of
atoms
 Commonly associated with living things
 Can
covalently bond with as many as 4 other
atoms

4 valence electrons
 Can

form many shapes
3-Dimensional shape is very important to function
 Carbohydrates
 Lipids
 Proteins
 Nucleic
Acids
 Monomer—individual




Carbohydrates—monosaccharides
Lipids—fatty acids
Proteins—amino acids
Nucleic acids—nucleotides
 Polymer—many

building unit
units covalently bonded
Each monomer is like a pearl on a necklace
 Functional
groups—atoms or clusters of
atoms covalently bonded to organic
compounds that affect the compound’s
structure and function
 Fuctional-group

Changes the chemical reactivity
 Electron

transfer
transfer
Transfers energy
 Rearrangement

Changes internal bonds, changing 3D structure
 Condensation


Combines two compounds by removing water
Dehydration synthesis
 Cleavage


Splits compounds with water
Hydrolysis
 Split
OH- from one molecule
 Split H+ from another molecule
 Bonds form at exposed sites
 Water is byproduct
 “Dehydration Synthesis”—Remove water
(dehydrate) to combine/create (synthesize)
 Reverse
of
condensation
 Split molecules
 Add OH- and H+
from water
 Literally “water
splitting”


Hydro = water
Lysis = break,
destroy
 Contain
C, H, and O in 1:2:1 ratio
 Hydrophilic
 Used for energy storage, structure
 Monosaccharides





Single sugar unit
Glucose, fructose, galactose
Hydroxyl group (OH-)
Isomers—same molecular formula (C6H12O6),
different structure
Used to assemble larger carbohydrates
 Disaccharide

Short chain of two sugar monomers




Formed by dehydration synthesis
Maltose—Glucose + Glucose
Sucrose—Glucose + Fructose
Lactose—Glucose + Galactose
 Polysaccharide—chain
of hundreds or
thousands of monomers

Straight or branched
 “Complex”

Starch—plant energy storage




Cell wall
Insoluble in water, indigestible
Glycogen—animal energy storage



Easily converted to glucose
Slightly- or unbranched
Cellulose—plant structural


carbohydrates
Stored in muscle & liver
Highly branched
Chitin—structural component of insects
 Greasy
or oily compounds
 Non-polar, hydrophobic
 Energy storage, membrane structure,
coatings, insulation
 Fatty
acids—long chain of mostly C and H with a
carboxyl group (-COOH) at the end
 Saturated—single Carbon bonds

“Saturated” with hydrogen (H+ everywhere possible)
 Unsaturated—double

Carbon bonds
Some carbons don’t have max possible H+
 Fat—one
or more fatty acids attached to
glycerol
 Twice the energy of carbohydrates
 Triglycerides—95% of all fats


Glycerol + 3 Fatty Acid side chains
Combined through dehydration synthesis
 Phospolipid

2 Fatty Acids + Phosphate Group + Glycerol



Similar to triglyceride but with phosphate group
replacing a fatty acid chain
Main structural material of membranes
Hydrophilic “head”, hydrophobic “tail”
 Sterols




4 carbon rings, no fatty acid tails
Cholesterol, testosterone, estrogen, other hormones
Some regulate vitamin D function
Regulate cell membrane fluidity
 Waxes


Long-chain fatty acids + alcohols or carbon rings
Coatings for plant parts or animal coverings
 Most
diverse of all biological molecules
 Enzymes
 Cell movement
 Cell signaling
 Storage & transport
 Hormones
 Antibodies
 Structure
 Amino
acid—monomer unit
 Three groups covalently bonded to central C
 Same backbone, vary only in R group
 20 amino acids necessary for life
 Polypeptides—polymer

of proteins
Peptide bond, between C and N
 Formed
by dehydration synthesis
 Structure


Primary
Secondary




b Pleated Sheet
Alpha Helix
Tertiary
Quaternary
 The
shape of the structure
determines function
 Shape is determined by
amino acids & hydrogen
bonds
 A single amino acid change
will affect all the way to the
quaternary structure
 Why
is structure important?
 Change in shape is VERY important to function

Sickle cell anemia due to a single amino acid difference
 Denaturation—unraveling

of polypeptide chains
Loose shape, therefore also function
 Lipoproteins

Bonded to fats
 Glycoproteins

Bonded to carbohydrates
 Important
to metabolism & heredity
 Nucleotide—monomer unit


5-carbon sugar (ribose or deoxyribose)
Nitrogen base


Adenine, thymine, guanine, cytosine, uracil
Phosphate group
 DNA—double-stranded
helix, carries
hereditary information
 RNA—single-stranded helix, translates code
to build proteins
 ATP—single nucleotide, releases energy for
cells to work