Download 04b Carbohydrates-student note

Carbohydrates

An immense variety of polymers can be built from a small set of ___________________.
Carbohydrates
 Organic molecules made of _____________ (carbon, hydrogen and oxygen) and their
polymers
 Classified by the type and number of simple sugars
 major source of ENERGY and CARBON!
1. Monosaccharides
 simple sugars in which C, H, and O occur in ratio = __________________
 major nutrients for cells; glucose is most common
 can be produced by __________________________ organisms from CO2, H2O, sunlight
 store ____________ in chemical bonds, which is released during cellular respiration
Characteristics of a sugar:
 An _____________________ attached to each carbon except one, which double
bonded to an oxygen (_________________________)
 Size of carbon skeleton – commonly 3 (triose), 5 (pentose), or 6 (hexose)
 In aqueous solutions, many simple sugars form rings
a) Glucose C6H12O6 (two forms)
b) Galactose
 ________________________________________________
 ________________________________________________
 ________________________________________________
c) Fructose
 ________________________________________________
 ________________________________________________
2. Disaccharides
 “double” sugar that consists of 2 monosaccharides joined by a
______________________________________
 glycosidic linkage = covalent bond formed by condensation reaction between
two sugar monomers, for example, maltose.
(see next page)
a)
Maltose C12H22O11
α glucose + α glucose  maltose + H2O
(C6H12O6)
(C6H12O6)
(C12H22O11)
Disaccharide
Monomers
(H2O)
General Comments
Maltose
Lactose
Sucrose
 NOTE: Disaccharides can be broken down into simple sugars again through a
hydrolysis reaction
3. Polysaccharides
 “many” sugars
 complex carbohydrates composed of many simple sugars (1000’s) synthesized
by condensation rxns
 have ____________________ and ___________________________ roles
 connected via alpha (α) or beta (β) glycosidic linkages
Energy Storage polysaccharides:
a) Starch
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1000’s of units of α glucose; helical; α 1-4 linkages
the main storage product in most plants
when energy is needed, the enzyme amylase assists in
the breakdown
made of 2 types of polysaccharides: Amylopectin
Amylose
(p.31)
(branched)
(unbranched)
b) Glycogen (p.32)
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the polysaccharide that vertebrates use to store glucose
(in muscle and liver tissue)
lots of branching (α 1-4 and α 1-6 links) of α-glucose
units
Structural polysaccharides:
a) Cellulose (p.33)
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b) Chintin (p.33)
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an insoluble linear polysaccharide of D-glucose, used
for support in plants
joined by β 1-4 linkages
its bonds are resistant to hydrolysis
important in our diet as fiber
Cellulose like polymer used in the exoskeletons of bugs
and lobsters and the cell wall of some fungi
Monomer = “amino sugar “N-acetylglucosamine (glucose
with a nitrogen group)
Lipids

Types of lips include ____________________________ (fats and oils),_______________________
and sterols (aka steroids)

Will not dissolve in water  _________________________________________
1. Triglycerides
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_________________________________________________________________________
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_________________________________________________________________________
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_________________________________________________________________________
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_________________________________________________________________________
Formation of Fats:
 Enzyme catalyzed condensation reactions link fatty acid to glycerol molecule by a
_____________________________ = bond between hydroxyl group and carboxyl group)
Saturated Fats
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Unsaturated Fats (i.e. oils)
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2. Phospholipids
 Make up _____________________________________________
 Glycerol molecule is attached to only two fatty acids and 1 phosphate group
 Phosphate head =”_________________________”, while fatty acid tail is
”___________________________”
3. Sterols (steroids)
 Lipids which have characteristic 4 _________________________________ with
various functional groups attached

_____________________ is an important steroid
o Acts as a cell membrane stabilizer
o Precursor to many sex hormones – estrogen/testosterone
o parts of nerve cells
o access amount in blood = atherosclerosis

cells convert cholesterol to ________________________ (bones and teeth) and
__________________________ (digestion of fats)
Proteins

Proteins makeup 50% -60% of your dry weight

Composed of C H O N (and sometimes S and P)

They are very large molecules
ex. β- lactoglobulin – C1642H2652O550N420S18
Insulin – C254H227O75N65S6
Functions of Proteins
1.
2.
3.
4.
5.
6.
7.
8.
enzymes
oxygen transport (haemoglobin)
blood clotting (fibrin)
immunological defense (antibodies)
food reserves (albumin, casein in milk)
hormones
structural (hair, nails, skin)
muscular movement (actin/myosin)
Composition of Proteins
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Proteins are composed of amino acids = monomer
General structure  note
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For each AA there is a different ‘R’ group which lends that AA certain ______________
properties
ex. Glycine – R = H
Alanine – R = CH3
Serine – R= CH2OH
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In solution, the carboxyl group acts as a _______________________, and the amino
group acts as a __________________________.
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Thus, amino acids can exist in three different ________________________ depending on
the pH. (varied properties)
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There are 20 common types of AA’s can be grouped by properties of side chains:
1. nonpolar side groups (________________________) – less soluble in water
2. polar side groups (________________________) –soluble in water; grouped
further into:
a. charged
b. uncharged

There are ____________________________AA’s in human adults (9 in children) and the
body must get these in the diet  the others can be synthesized
Protein Structure

Polypeptide chains = polymers of ________________________, linked by
_______________________, arranged in a specific linear sequence.
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________________________ = covalent bond formed by condensation reaction that links
carboxyl group of one amino acid to amino group of another.

Peptides = are folded and coiled into ____________________________________ structures
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Polypeptide chains range in _____________ and have unique linear __________________.
3D Conformation = Protein Function
A protein’s 3D structure:

enables a protein to _________________ and _________ specifically to another molecule
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is a consequence of the specific linear sequence of amino acids in the polypeptide
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is produced as a result of the ____________________________________ of peptide
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is stabilized by _________________________________ and ______________________________
between neighboring regions of folded protein
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The properties of _________________ influence the folding and coiling of peptide.
Primary (1o) Structure
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Secondary (2o) Structure
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H-H bonds along the backbone of the protein
Types of 2o structure:
i) α helix  hair, wool
ii) sheets  silk, spider webs
iii) “seemingly” random coils
Tertiary (3o) Structure

further chemical interactions between ________________ of certain AA’s lend
further 3D shape:
1) weak interactions stabilize protein:
i.
ii.
iii.
2) covalent linkages:
i.
_______________________ form between 2 cysteine AA’s  these ‘hold’ the
3D structure together Very Important
Quaternary (4o) Structure
 Interactions between polypeptide chains to form larger protein molecules
 Not all proteins undergo 4o structure
ex. Haemoglobin
Collagen (triple helix)
Protein Function

‘Shape determines function’  a proteins function id determined by it’s
configuration

_________________________ (destruction of shape) will result in a loss of function

denatured proteins will halt the biochemical pathways they catalyze
Factors which will Denature Proteins
 pH change
 salt concentration
 various chemicals (organic
solvents)
 temp change
 digestive system (ex. gastrin)
Enzymes
Enzymes are biological catalysts
The rates of reaction depends on:
 concentration of enzymes
 concentration of substrate
 presence of
coenzymes/cofactors/inhibitors
 temperature
 pH
Nucleic Acids

Molecules that enable living organisms to reproduce their complex structures
from one generation to the next
DNA – deoxyribonucleic acid
RNA – ribonucleic acid
DNA Structure

DNA is a polymer composed of many monomers called nucleotides
A nucleotide has 3 parts
1. phosphate group – acts a part of the ‘backbone’  PO4
2. deoxyribose sugar – this bonds with the phosphate group to add to the
‘backbone’. RNA had a ribose sugar instead.
Compare:
3. nitrogenous base – these act as the ‘rungs’ of the ladder that is DNA. In
DNA there are 4 different kinds:
How it all fits together
a) RNA
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is single stranded and it looks like this:
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the N-bases can occur in any combination
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is double stranded and forms a double helix. The two chains form
rings in the middle as the N Bases bond. The bases bond in a
certain way: G-C A-T
b) DNA
A - T 2 H bonds
G - C 3 H bonds
5’ end terminates with PO4 group
3’ end terminates with OH- group of deoxyribose sugar
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There is one full twist every 10 base pairs (3.4 nm). This is what forms the
double helix.
In 1953, Dr, James Watson and Dr. Francis Crick discovered all of this. The also
noted that this structure allowed a repeatable copying mechanism  the ability
to pass on this pattern.
“It has not escaped our notice that the specific
paring we have postulated immediately suggests a
possible copying mechanism for genetic material.”
This is perhaps the single most important sentence in the entire history of
science.
** see journal article (1953)