lecture 2 cell biology
TRANSCRIPT
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222Cell Bilogy 1
Lecture (2)Lipid
Carbohydrates
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222Cell Biolgy 2
Lipid categories
Lipids may be divided into the following categories:
fatty acyls
Glycerophospholipids
sphingolipids
Neutral fats
Plasmalogens
Steroids Waxes
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fatty acyls = fatty acid
They are made of a hydrocarbon chain
It terminates with a carboxylic acid group
It has a polar (hydrophilic end) and a non polar(hydrophobic end)
The carbon chain, typically between four to 24
carbons long (saturated or unsaturated)
The fatty acid is commonly used as abuilding block of more structurally complexlipids.
222Cell Bilogy 3
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222Cell Bilogy 4
Glycerophospholipids= phospholipid
One of components of the lipid bilayer of
cells
Play a role in metabolism and cell signaling
Neural tissue (including the brain) contains
relatively high amounts of
glycerophospholipids, and alterations in their
composition could lead to neurologicaldisorder
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Gglycerophospholipids
in biological membranes
222Cell Bilogy 5
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222Cell Bilogy 6
Steroids Asteroid is a type of organic compound that contains a
specific arrangement of four rings that are joined to
each other.
Examples of steroids include cholesterol, the sex
hormones estradiol and testosterone
Cholesterol is an example of a steroid that plays asignificant role in the structure of the cell membrane
Cholesterol is the compound from which wesynthesize sex hormones and vitamin D2
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222Cell Bilogy 7
Consist of two hydrocarbon chains linked to polar
head groups that contains carbohydrate (Glucose
or galactose or2-10 oligosaccharides )
play an important role in Cell-cell recognition
Glycolipids
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222Cell Bilogy 9
Lipids in water can generate three most commonconfigurations:
(1) liposome or lipid vesicles (a lipid bilayer surrounding
water ): water surrounding the bilayer and containedinternally
(2) a micelle (polar heads in contact with water andhydrophobic tails clustered centrally).
(3) Bilayer sheet
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222Cell Bilogy 10
CARBOHYDRATESCARBOHYDRATESO
rganic compounds that contain carbon, hydrogen, andoxygen at a ratio of1:2:1
Carbohydrates range from small sugar molecules
(monomers) to large polysaccharides
Sugar monomers are monosaccharides, such as glucose
and fructose, mannoseImportance of carbohydrates:
- The major nutrient of cells,- They are energy-storage molecules, Plants store starch
while animals store glycogen.- Their breakdown provide both cellular energy and the
starting material for the synthesis of other cell constituents
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222Cell Bilogy 11
Monosaccharides are the simplest
carbohydrates The carbon skeletons of monosaccharides vary
in length
Glucose and fructose are six carbons long
Others have three to seven carbon atoms
((TriosesTrioses,, TetrosesTetroses ,, PentosesPentoses,, HexosesHexosesHeptoses)Heptoses)
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222Cell Bilogy 12
Structural Formulas of a FewCommon SugarsStructural Formulas of a FewCommon Sugars
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222Cell Bilogy 13
Structural Formulas of a FewCommon SugarsStructural Formulas of a FewCommon Sugars
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222Cell Bilogy 14
Disaccharides-2
- Two monosaccharides
(monomers) can bond to
form a disaccharide byglycosidic bonds in a
dehydration reaction
An example
Two glucose monomers
bonding together to
form maltose
Glucose Glucose
Maltose
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222Cell Bilogy 15
H
2
OH
OHOH
OH
OH
H
H
H
H
H
O
C
CH2OH CH
2OH
HHO
OH
OHH
H
+
H
2
O
C C
C
O
C
CH2OH
H
OH
OHH
H
C C
C
OC
C
CH2OH
OHOH
OH
H
H
H
H
H
O
CH2
OH
Glucose Fructose Sucrose (glucose E1,2
fructose)
+
glycosidicbond
Glucose monomer can bond to a fructose monomer
to form sucrose, a common disaccharide.
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222Cell Bilogy 16
sPolysaccharide-3
Polysaccharides are polymers of monosaccharides bondedtogether by glycosidic bonds
Polysaccharides are divided into two groups depending onits cellular function
1-Structural Polysaccharides:
Found inside and outside cells
Play critical roles in cell-cell recognition, cell protection andcell supporting
Example: Cellulose, Chitin, Hyaluronic acid
2- Nutrient Polysaccharides As storage molecules (starch, glycogen)
Foods high in carbohydrates include breads, pastas, beans,potatoes, bran, rice, and cereals
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222Cell Bilogy 17
The carbohydrates (saccharides) are
divided into four chemical groupings Monosaccharides: only one molecule of sugar (monomer)
Disaccharides: carbohydrates containing two
monosaccharides Oligosaccharides: carbohydrates containing several
monosaccharides
Polysaccharides: extremely long-chain carbohydrates, it
contains many monomeric units (monosaccharides)
connected by glycosidic bonds
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222Cell Bilogy 18
The Glycosidic Bond and Polysaccharides
Glycosidic bonds: covalentbonds linking sugars together in
a polysaccharide
Two possible geometric
orientations: alpha (E) and
beta (F) Configuration of
bond
The principle linkage is 1-4glycosidic bond
1-6 glycosidic bond leads to the
formation of branches joining two
separated 1-4 linkage chains
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222Cell Bilogy 19
The Glycosidic Bond and PolysaccharidesThe Glycosidic Bond and Polysaccharides
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222Cell Biology 20
Cellulose It is a polymer of glucose that forms plant cell walls
cellulose is the most abundant organic molecule on
Earth
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222Cell Biology 21
Chitin
Is a polysaccharide used by insects and crustaceans tobuild an exoskeleton
Found in cell wall of fungi
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222Cell Biology 22
Glycogen
Is energy storage polysaccharide composed ofglucose, which is hydrolyzed by animals whenglucose is needed
Highly branched molecules
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222Cell Biology 23
Starch
Is energy storagepolysaccharide
composed of
glucose monomers
Ti is found in plants
Starch helix may be
unbranched or
branched
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222Cell Biology 24
Paramylum
Homopolsaccharides, found inE
uglina
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222Cell Biology 25
Dextrin
It is a branched polysaccharides , produced bysome bacteria
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222Cell Biology 26
Complex polysaccharides
Polysaccharides can combine with otherclasses of
macromolecules to form complex polysaccharides:
- Glycoproteins: polysaccharides + proteins
Glycolipids:
polysaccharides + lipids
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Good Luck
Dr Mona