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BSC 2010 - Exam I Lectures and Text Pages
• I. Intro to Biology (2-29)
• II. Chemistry of Life
–
Chemistry review (30-46)
–
Water (47-57)
–
Carbon (58-67)
–
Macromolecules (68-91)
• III. Cells and Membranes
–
Cell structure (92-123)
–
Membranes (124-140)
• IV. Introductory Biochemistry
–
Energy and Metabolism (141-159)
–
Cellular Respiration (160-180)
–
Photosynthesis (181-200)
The Chemistry of Carbon (Ch. 4)
• Carbon can bond to carbon: and form long
chains or ring structures
• Carbon can bond: to many different
functional groups.
Carbon—The Backbone of Biological Molecules
• All living organisms
– Are made up of chemicals based mostly on the
element carbon
Figure 4.1
Carbon atoms can bond to four other atoms
• Carbon has four valence electrons
• This allows it to form four covalent bonds with a
variety of atoms, and to form large complex
molecules.
Molecular Diversity Arising from Carbon Skeleton Variation
• Carbon chains
– Form the skeletons of most organic molecules
– Vary in length and shape
H H H
H C C C H
H H H
Propane
H
H C H
H
H
H H H H
(b) Branching
H C C C C H
H C C C H
H H H
H H H H
2-methylpropane
Butane
(commonly called isobutane)
H H H H
H H H H
(c) Double bonds H
H C C C C H
C C C C H
H
H
H H
1-Butene
2-Butene
H
H
H
H
C
H
H
C C H
C H
(d) Rings
H C
C
H
H C
C
H
H
C
C
C
(a) Length
Figure 4.5 A-D
H H
H C C H
H H
Ethane
Cyclohexane
Benzene
The electron configuration of carbon
Gives it covalent compatibility with many different
elements
Figure 4.4
Hydrogen
Oxygen
Nitrogen
Carbon
(valence = 1)
(valence = 2)
(valence = 3)
(valence = 4)
H
O
N
C
Hydrocarbons are molecules consisting of only carbon and hydrogen
• Hydrocarbons
– Are found in many of a cell’s organic
molecules
Fat droplets (stained red)
Figure 4.6 A, B
(a) A fat molecule
100 µm
(b) Mammalian adipose cells
Functional groups = chemically reactive groups of atoms within a molecule
– Give organic molecules distinctive chemical
properties
Estradiol
OH
CH3
HO
Female lion
OH
CH3
CH3
O
Figure 4.9
Male lion
Testosterone
Functional Groups Engage in Chemical Reactions
• Six functional groups are important in the
chemistry of life
– Hydroxyl -OH; alcohols
– Carbonyl >CO; aldehydes and ketones
– Carboxyl -COOH; carboxylic (organic) acids
– Amino –NH2; amines
– Sulfhydryl -SH; thiols
– Phosphate –OPO32-; organic phosphates
BSC 2010 - Exam I Lectures and Text Pages
• I. Intro to Biology (2-29)
• II. Chemistry of Life
–
Chemistry review (30-46)
–
Water (47-57)
–
Carbon (58-67)
–
Macromolecules (68-91)
• III. Cells and Membranes
–
Cell structure (92-123)
–
Membranes (124-140)
• IV. Introductory Biochemistry
–
Energy and Metabolism (141-159)
–
Cellular Respiration (160-180)
–
Photosynthesis (181-200)
Macromolecules – Structure and Function (Ch. 5)
Another level in the hierarchy of biological organization is reached
when small organic molecules are joined together.
Macromolecules are large molecules composed of smaller
molecules, and they can be very complex in structure.
Figure 5.1
Macromolecules – Structure and Function (Ch. 5)
4 main classes of carbon-based molecules necessary to
life
1. Carbohydrates – sugars and their polymers
2. Lipids – diverse group of nonpolar molecules
3. Proteins – polymers of amino acids
4. Nucleic Acids –polymers of nucleotides
Most macromolecules are polymers, built from monomers
Three of the classes of life’s organic
molecules are polymers
– Carbohydrates
– Proteins
– Nucleic acids
A polymer is a long molecule consisting of many
similar building blocks called monomers
The Synthesis of Polymers
• Monomers form larger molecules by
condensation reactions called dehydration
reactions
HO
1
3
2
H
Unlinked monomer
Short polymer
Dehydration removes a water
molecule, forming a new bond
HO
Figure 5.2A
1
2
H
HO
3
H2O
4
H
Longer polymer
(a) Dehydration reaction in the synthesis of a polymer
The Breakdown of Polymers
• Polymers can disassemble by
– Hydrolysis
HO
1
2
3
4
Hydrolysis adds a water
molecule, breaking a bond
HO
1
2
3
H
Figure 5.2B (b) Hydrolysis of a polymer
H
H2O
HO
H
Carbohydrates
Carbohydrates include both sugars and their
polymers
Carbohydrates serve as immediate fuel, energy
storage, and building material.
Sugars
• Monosaccharides – the monomers of
carbohydrates
– Are the simplest sugars
– Can be used for fuel
– Can be converted into other organic molecules
– Can be combined into polymers
Examples of monosaccharides
Triose sugars Pentose sugars
(C3H6O3)
(C5H10O5)
H
O
H
Aldoses
C
O
H
O
C
C
OH
H
C
OH
H
C
OH
H
C
OH
H
C
OH
HO
C
H
C
OH
H
H
C
OH
H
H
H
H
C
H
C
OH
H
HO
C
H
C
OH
HO
C
H
H
C
OH
H
C
OH
H
C
OH
H
C
OH
H
H
Glucose
Galactose
H
C OH
H
C
O
H
C OH
H
C OH
C
O
O
C OH
H
C OH
HO
H
H
C OH
H
C OH
Dihydroxyacetone
H
C OH
H
C OH
H
H
C OH
H
Ribulose
O
C
H
Ribose
Ketoses
H
C
Glyceraldehyde
Figure 5.3
Hexose sugars
(C6H12O6)
C H
H
Fructose
Monosaccharides
May be linear, or can form rings
O
H
1C
H
HO
2
3
C
6CH OH
2
OH
H
C
H
4
H
H
H
C
5
5C
6
C
H
OH
4C
OH
OH
OH
O
5C
H
H
OH
C
6CH OH
2
3
C
H
2C
O
H
H
4C
1C
CH2OH
O
OH
H
OH
3C
6
H
1C
H
2C
4
HO
H
OH
3
OH
H
H
1
2
OH
OH
H
H
O
5
OH
OH
H
Figure 5.4 (a) Linear and ring forms. Chemical equilibrium between the linear and ring
structures greatly favors the formation of rings. To form the glucose ring,
carbon 1 bonds to the oxygen attached to carbon 5.
Disaccharides = dimers
• Disaccharides
– Consist of two monosaccharides
– Are joined by a glycosidic linkage
Examples of disaccharides
(a) Dehydration reaction
in the synthesis of
maltose. The bonding
of two glucose units
forms maltose. The
glycosidic link joins
the number 1 carbon
of one glucose to the
number 4 carbon of
the second glucose.
Joining the glucose
monomers in a
different way would
result in a different
disaccharide.
CH2OH
CH2OH
H
O
H
OH H
OH
HO
H
H
H
HO
H
OH
H
OH
H
H
OHOH
H
O
H
OH H
CH2OH
H
1–4
1 glycosidic
linkage
HO
4
O
H
H
OH H
OH
O
H
OH
H
H
OH
OH
H2O
Glucose
Glucose
CH2OH
H
(b) Dehydration reaction
in the synthesis of
HO
sucrose. Sucrose is
a disaccharide formed
from glucose and fructose.
Notice that fructose,
though a hexose like
glucose, forms a
five-sided ring.
Figure 5.5
O
CH2OH
O
H
OH
H
H
CH2OH
H
OH
HO
CH2OH
O
H
H
H
HO
CH2OH
OH
OH
Maltose
H
O
H
OH
H
1–2
glycosidic
1
linkage
H
Fructose
2
H
H
CH2OH
OH H
OH
Sucrose
H
HO
O
HO
H2O
Glucose
CH2OH
O
Polysaccharides – polymers
• Polysaccharides
– Are polymers of sugars
– Serve many roles in organisms
– May be 100s to 1000s of monomers
Storage Polysaccharides
• Starch
Chloroplast
–
Is the major storage form of
glucose in plants
–
Is a polymer consisting entirely
of glucose monomers
Starch
1 m
Amylose
Amylopectin
Figure 5.6 (a) Starch: a plant polysaccharide
Storage Polysaccharides
• Glycogen
– Consists of glucose monomers
– Is the major storage form of glucose in animals
Mitochondria
Giycogen
granules
0.5 m
Glycogen
Figure 5.6 (b) Glycogen: an animal polysaccharide
Structural Polysaccharides - Cellulose
H
– Is a polymer of
glucose
CH2O
H
O
H
OH H
H
4
H
– Has different
glycosidic linkages
than starch
CH2O
H
H
O OH
H
4
1
OH H
HO
H
C
H
OH
HO
O
OH
 glucose
H
C
OH
HO
C
H
H
C
OH
H
C
OH
H
C
OH
H
OH
 glucose
(a)  and  glucose ring structures
CH2O
H
O
CH2O
H
O
HO
4
1
OH
O
1
OH
4
O
1
OH
OH
OH
CH2O
H
O
CH2O
H
O
O
4
1
OH
O
OH
OH
(b) Starch: 1– 4 linkage of  glucose monomers
CH2O
H
O
HO
Figure 5.7 A–C
OH
CH2O
H
O
OH
O
1
4
OH
O
OH
OH
O
OH
O
O
CH2O
CH2O
OH
OH
H
H
(c) Cellulose: 1– 4 linkage of  glucose monomers
OH
Cellulose
– Is a major component of the tough walls that
enclose plant cells
Cell walls
Cellulose microfibrils
in a plant cell wall
Microfibril
About 80 cellulose
molecules associate
to form a microfibril, the
main architectural unit
of the plant cell wall.
0.5 m
Plant cells
Parallel cellulose molecules are
held together by hydrogen
bonds between hydroxyl
groups attached to carbon
atoms 3 and 6.
Figure 5.8
OH CH2OH
OH
CH2OH
O O
O O
OH
OH
OH
OH
O
O O
O O
O CH OH
OH
CH2OH
2
H
CH2OH
OH CH2OH
OH
O O
O O
OH
OH
OH
OH
O
O O
O O
O CH OH
OH CH2OH
2
H
CH2OH
OH
OH CH2OH
O O
O O
OH
OH
OH O
O OH
O O
O
O CH OH
OH CH2OH
2
H
 Glucose
monomer
Cellulose
molecules
A cellulose molecule
is an unbranched 
glucose polymer.
Cellulose
• Cellulose is difficult to digest
– Cows have microbes in their stomachs to
facilitate this process
Figure 5.9
Chitin – an animal structural polysaccharide
– Is found in the exoskeleton of arthropods
– Can be used as surgical thread
CH2O
H
O OH
H
H
OH H
OH
H
H
NH
C
O
CH3
(a) The structure of the (b) Chitin forms the exoskeleton
of arthropods. This cicada
chitin monomer.
is molting, shedding its old
exoskeleton and emerging
Figure 5.10 A–C
in adult form.
(c) Chitin is used to make a
strong and flexible surgical
thread that decomposes after
the wound or incision heals.
Lipids
• Lipids, a diverse group of hydrophobic molecules
– Are the one class of large biological molecules
that do not consist of polymers
– Share the common trait of being hydrophobic
– Are fats, oils, waxes and other biologically
important molecules
Fats
• Fats, oils and waxes
– Are constructed from two types of smaller
molecules, a single glycerol and usually three
fatty acids
H
H
C
O
C
OH
HO
H
C
OH
H
C
OH
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
Fatty acid
(palmitic acid)
H
Glycerol
(a) Dehydration reaction in the synthesis of a fat
Ester linkage
O
H
H
C
O
C
H
C
H
O
H
C
O
C
O
H
C
H
Figure 5.11
O
C
H
C
H
H
C
H
C
H
H
H
C
H
C
H
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
(b) Fat molecule (triacylglycerol)
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
H
C
C
H
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
H
C
H
H
H
C
H
H
H
C
H
H
• Fatty acids
– Can be saturated or unsaturated
– Vary in the length and number and locations of
double bonds they contain
Saturated fatty acids
– Have the maximum number of hydrogen atoms
possible
– Have no double bonds
Stearic acid
Figure 5.12 (a) Saturated fat and fatty acid
Unsaturated fatty acids
- Have one or more double bonds
- and are thus not “saturated” with the maximum
number of hydrogens
Oleic acid
Figure 5.12
(b) Unsaturated fat and fatty acid
cis double bond
causes bending
Phospholipids
• Phospholipids (major part of membranes)
– Have only two fatty acids
– Have a phosphate group instead of a third
fatty acid
Phospholipid structure
– Consists of a hydrophilic “head” and
hydrophobic “tails” (amphipathic)
CH2
+
N(CH )
3 3
Choline
CH2
O
O
P
O–
Phosphate
O
CH2
CH
O
O
C
O C
CH2
Glycerol
O
Fatty acids
Hydrophilic
head
Hydrophobic
tails
Figure 5.13
(a) Structural formula
(b) Space-filling model
(c) Phospholipid
symbol
Cell Membranes
• The structure of phospholipids
– Results in a bilayer arrangement found in cell
membranes
WATER
Hydrophilic
head
WATER
Hydrophobic
tail
Figure 5.14
Steroids – lipids characterized by four fused carbon rings
• One steroid, cholesterol
– Is found in cell membranes
– Is a precursor for some hormones
H3C
CH3
CH3
Figure 5.15
HO
CH3
CH3
Steroid Hormones – important chemical messengers
• Cholesterol is the precursor to many important
hormones: estrogen, testosterone, and
progesterone.
• Testosterone is the major anabolic steroid,
leads to muscle formation, plays a role in
sexual drive in the brain. Testosterone can be
converted to estrogen, which signals cells to
divide.
Steroids are also important in bile acids.
Prostaglandins
• non-steroid lipid-based hormones
• important to the inflammatory response and
pain.
• important in the birth process.
• precursor- arachidonic acid.