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Biochemistry
biochemistry: where chemistry and biology meet head-on
living things require millions of chemical reactions within the body, just to survive
metabolism: all the chemical reactions occurring in the body
most important chemical compounds besides water for life to exist are organic compounds
carbon atoms are combined with oxygen and usually hydrogen, and also nitrogen, sulfur, phosphorus
a few carbon compounds that aren’t included with organic compounds: carbon dioxide (CO2), carbon
monoxide (CO), and carbonic acid (H2CO3)
organic molecules:
are usually associated with living things
always contain carbon
are “large” molecules, many atoms
always have covalent bonds
Macromolecules
“macro” – large
Macromolecules are polymers of smaller molecules called monomers
carbon atoms combine in long chains that form the backbone of macromolecules
the backbone of carbon atoms is called the carbon skeleton, giving each macromolecule a particular
structure, and a particular function
four types of macromolecules in cellular biology: carbohydrates, lipids, proteins, and nucleic acids
Building Macromolecules
Dehydration Synthesis
large molecules are built by chemically joining 2 or more monomers
one water molecule must be removed each time a new bond is formed
this process is called dehydration
C6H12O6 + C6H12O6  C12H22O11 + H2O
Breaking Down Macromolecules
Hydrolysis
water must be added to break the bonds between monomers
the amount of water molecules needed is always one less than the total number of molecules in the
macromolecules
this process is called hydrolysis – literally means breaking apart water
C12H22O11 + H2O  C6H12O6 + C6H12O6
Carbohydrates
sugars and groups of sugars
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purposes: energy and structure
the largest volume of our daily food
the component of our food that supplies energy
elements- carbon, hydrogen, oxygen
come mainly from plant sources, although milk and milk products contain some carbohydrates in the form
of lactose
if we take in more carbohydrates than is needed for energy, the unused portion is stored in the liver or the
tissues as glycogen
complex carbohydrates often supply energy and other nutrients and fiber that the body needs and are a
better choice for long-term energy needs
energy: 4-5 cal/g *except for cellulose which is 0 cal/g
Monosaccharide – 1 sugar; simplest sugar  may contain 3-7 carbon atoms in carbon skeleton
glucose
fructose
isomers- same molecular formula, different structural formula
galactose
C6H12O6 – molecular formula
CH2O – empirical formula
structural formulas (arrangement)
glucose and galactose- hexagon
fructose- pentagon
are monomers of macromolecules
provide quick energy (used directly by our cells)
most organisms use glucose as source of energy
glucose is the only one that can be used directly by your cells
are found in:
glucose- also known as blood or grape sugar
nearly all plant foods
trees: sap = sugar
pine trees = turpentine
flowers: nectar  honey
fructose:
fruits- bananas, apples, etc
galactose:
never found by itself
always with another sugar molecule
Disaccharide – 2 sugar molecules linked
C12H22O11 + H2O
sucrose = glucose + fructose
maltose = glucose + glucose
lactose = glucose + galactose
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all have alpha linkages
provide fast energy
for hypoglycemic and diabetic people with a low blood sugar: apple or orange juice (monosaccharide) is
better than candy (disaccharide) because monosaccharides provide quicker energy than disaccharides
are found in:
lactose:
milk
maltose:
malt: wheat grain  milkshakes, whoppers
used as flavor
sucrose:
sugar cane
sugar beets
cookies, candies
table sugar
fruits and vegetables
Polysaccharide – many sugar molecules linked together for energy storage or plant structure
amylose (starch)
cellulose
glycogen
All polymers of glucose
amylose/starch- energy-storage and carbon-reserve in many plants and important food source for humans
glycogen- also known as animal starch
starch and glycogen:
long term energy storage  athletes and exercise
stored for future energy use (glycogen)
4-5 cal/g
alpha linkages- can be digested
straight chain in picture
cellulose:
forms fibers for plant structures
plant cell walls
0 cal/g
beta linkages – we don’t have the enzymes to digest it
provides fiber in the diet- it makes the going great and its chewy  makes you think you ate a lot
are found in:
glycogen:
muscle tissue
liver
cellulose:
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plant cell walls
starch:
potatoes, grains
wheat, barley, rice, oats, corn, pasta, breads, cereals
Lipids
insoluble in water (think oil and water)
multipurpose molecules: long term energy storage, structural purposes within the cell, cell signaling
purposes, protection, insulation, prevention of water loss
elements: carbon, hydrogen, oxygen
a more effective energy storage than carbohydrates because they contain lots of hydrogen and less oxygen
4 types: triglycerides, phospholipids, steroids, and waxes
Triglycerides = fats and oils
3 fatty acids + glycerol  triglyceride + 3H2O
triglyceride + 3H2O  3 fatty acids + glycerol
all nonpolar  hydrophobic
purpose: long term energy storage, insulation
pack away lots of energy for animals like squirrels to escape quickly
9-10 cal/g
saturated fats (fats)
single bonds ( C–C)
unhealthy
solids at room temperature
found in animals
lard (animal fat), margarine, butter, yogurt, cheese, tropical oils like palm and kernel oil
chains are straight  fixed, locked in place – solid
unsaturated fats (oils)
double bonds (C=C)
healthy
liquids at room temperature
found in plants
corn oil, peanut oil, vegetable oil, olive oil, canola oil, sesame seed oil
chains have kinks where double bonds are  more fluid – liquid
Phospholipids
phosphate group + glycerol + 2 fatty acid chains
usually one of the fatty acid chains is saturated
– phosphate “head”  hydrophilic
– fatty acid “tails”  hydrophobic
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phosphate: polar  hydrophilic
glycerol and fatty acids: nonpolar  hydrophobic
purpose: STRUCTURE – they are the primary component of the cell’s membranes
regulates the types of material that move in and out of cells
present in cell membranes: keeps animal cells flexible
nucleus
cell membrane
H20 outside of cell
cytoplasm
H20 inside of cell
Steroids
four fused rings with attached groups
totally different structure
classified as lipids because of their insolubility
examples: cholesterol, sex hormones (estrogen/testosterone)
purpose:
too much cholesterol can block blood vessels causing heart disease and atherosclerosis
structure: cholesterol – increase the fluidity of cell membranes
signaling: act as chemical messengers (hormones)  cholesterol molecules are modified to form
sex hormones (like testosterone, estrogen)
are found in:
cholesterol- cell membranes
hormones- reproductive organs
Waxes
solid at room temperature
used mainly by plants, but also bees, some furry animals and humans
purpose: protection, prevents water loss
Protein
Greek “proteios” = first place  are very important
probably the most complicated of all biological molecules
proteins (polymers) are composed of chains of amino acids (monomers)
contain hydrogen, oxygen, and carbon and nitrogen (*lipids and carbohydrates don’t*)
amino acid:
amino
group
H
H
H
N–C–C
R
O
OH
carboxylic acid
group
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variable group
amino acids- the building blocks of proteins
there are 20 different kinds of amino acids
there are millions of different proteins, all built from different combinations of the 20 amino acids
bonds between amino acids are called peptide bonds which form peptides
many peptides linked together form polypeptides
proteins can be made of one or more polypeptide chains
there are 4 levels of protein structure
the function of a protein is largely determined by its shape
the primary structure of a protein determines its 3D shape (secondary or tertiary)
the tertiary structure determines a protein’s function
a few proteins become active only when two or more tertiary combine to make quaternary
primary structure: the amino acid sequence of the polypeptide
secondary structure: hydrogen bonding between amino acids causes the polypeptide to form an
alpha helix or beta sheet
tertiary structure: further twisting and folding that results in the final 3D shape of the
polypeptide
usually globular or spherical partly due to covalent bonding between R groups
quaternary structure: some proteins (but not all) are formed from 2 or more polypeptide chains
interacting
occurs when 2 or more polypeptides join to form a single protein
each of them has its own 1, 2, and 3 structure (like Hb)
protein folding diseases: mad cow, alzheimer’s, cystic fibrosis, cancer
Purposes:
Importance
Description
Example
structural features
present in hair, fur, nails, hooves, claws, and beaks
kerotin, collagen
enzymes
regulate chemical reactions
lactose, cellulose
energy
4-5 cal/g
casein (milk), albumin (egg
whites)
transportation
carries oxygen (O2) in the blood moves materials in hemoglobin, carrier proteins
and out of the cell
antibodies
provide protection against foreign substances
(viruses, bacteria)
immunoglobulins
hormones
carry chemical “messages” throughout the body
insulin, somatotropin (HGH)
*meat, fish, beans, nuts, milk, eggs
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toxins
poison, venom from snakes, bees, jellyfish
neurotoxin
movement
muscle tissue (heart, digestive system, skeleton)
actin, myosin
Key Terms
macromolecules: large complex molecules
isomers: have the same molecular formula, but different structural formulas
polysaccharide: many sugar molecules linked together for energy storage or structure
amino acids- the building blocks of proteins
peptide bonds: bonds between amino acids
polypeptide: many peptides linked together
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