1 biology presentations for a-level, in multimedia james bowles, 2001 biology presentations for...
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1BIOLOGY PRESENTATIONS
FOR A-LEVEL, IN MULTIMEDIAJAMES BOWLES, 2001
BIOLOGY PRESENTATIONSFOR A-LEVEL, IN MULTIMEDIA
JAMES BOWLES, 2001
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‘A’ Level Biology
‘A’ Level Biology
CarbohydratesCarbohydrates
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CarbonCarbonNucleus contains 6 Nucleus contains 6 protons and 6 protons and 6 neutrons.neutrons.
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Nucleus contains 6 Nucleus contains 6 protons and 6 protons and 6 neutrons.neutrons.Surrounded by 6 Surrounded by 6 electrons (4 in outer electrons (4 in outer shell)shell)It is, therefore capable It is, therefore capable of forming 4 stable of forming 4 stable covalent bonds covalent bonds (Tetravalent)(Tetravalent)
CarbonCarbon
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Nucleus contains 6 Nucleus contains 6 protons and 6 protons and 6 neutrons.neutrons.
It is, therefore capable It is, therefore capable of forming 4 stable of forming 4 stable covalent bonds covalent bonds (Tetravalent)(Tetravalent)
It is able to form covalent It is able to form covalent bonds with other carbon bonds with other carbon atoms, allowing it to form the atoms, allowing it to form the backbone of biomoleculesbackbone of biomolecules
CarbonCarbon
Surrounded by 6 Surrounded by 6 electrons (4 in outer electrons (4 in outer shell)shell)
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Nucleus contains 6 Nucleus contains 6 protons and 6 protons and 6 neutrons.neutrons.
It is, therefore capable It is, therefore capable of forming 4 stable of forming 4 stable covalent bonds covalent bonds (Tetravalent)(Tetravalent)
It is able to form covalent It is able to form covalent bonds with other carbon bonds with other carbon atoms, allowing it to form the atoms, allowing it to form the backbone of biomoleculesbackbone of biomolecules
CarbonCarbon
Surrounded by 6 Surrounded by 6 electrons (4 in outer electrons (4 in outer shell)shell)
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CarbohydratesCarbohydrates
Most abundant (by Most abundant (by mass) biomolecule in mass) biomolecule in naturenature
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CarbohydratesCarbohydrates
Most abundant (by Most abundant (by mass) biomolecule in mass) biomolecule in naturenatureContain:Contain: CarbonCarbon
OxygenOxygen
HydrogenHydrogen
Simplest formula is Simplest formula is (CH(CH22O)nO)n
9GlucoseGlucose
6 6 CarbonsCarbons6 6 OxygensOxygens12 Hydrogens12 Hydrogens
CC66HH1212OO66
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1
2
3
4
5
6
(C(C66HH1212OO66))
For For convenience convenience carbons are carbons are numbered, numbered, starting withstarting withthe one with the one with the aldehyde the aldehyde groupgroup
GlucoseGlucose
11(C(C66HH1212OO66))GlucoseGlucose
This is This is optical optical isomerismisomerism
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Carbons are Carbons are asymmetric asymmetric since OH and since OH and H and can be H and can be on either sideon either side
22222
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Ring Ring FormationFormationAldehyde Aldehyde
group on group on carbon 1carbon 1
bonds bonds with with
hydroxylhydroxylgroup on group on carbon 5carbon 5
(C(C66HH1212OO66))
1
2
3
4
5
6
GlucoseGlucose
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1
23
4
5
6
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Carbon 1 is now
asymmetrical
1
23
4
5
6
15Gluc
oseGluc
ose
1
23
4
5
6
There are There are two forms of two forms of glucose in glucose in
ring structurering structure
16Gluc
ose
1
23
4
5
6
There are two forms of glucose in
ring structure
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6
3 2
4 1
5
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CHCH22OHOH
33 22
44 11
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For simplicity For simplicity not all the not all the
components components are shownare shown
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Glycosidic BondGlycosidic Bond
CH2OH
3 2
4 1
5
CH2OH
3 2
4 1
5
Monosaccharides join via an Monosaccharides join via an oxygen bridge between carbon 1 oxygen bridge between carbon 1 and carbon 4 of adjacent sugarsand carbon 4 of adjacent sugars
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Glycosidic BondGlycosidic Bond
CH2OH
3 2
4 1
5
CH2OH
3 2
4 1
5
The bond involves the two The bond involves the two hydroxyl groupshydroxyl groups
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CH2OH
3 2
4 1
5
CH2OH
3 2
4 1
5
Glycosidic BondGlycosidic BondWater is produced - Water is produced - this is a this is a CONDENSATION CONDENSATION reactionreaction
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CH2OH
3 2
4 1
5
CH2OH
3 2
4 1
5
Glycosidic BondGlycosidic Bond
The reverse of The reverse of this is this is
HYDROLYSISHYDROLYSIS
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CH2OH
3 2
4 1
5
CH2OH
3 2
4 1
5
The reverse of The reverse of this is this is
HYDROLYSISHYDROLYSIS
Glycosidic BondGlycosidic Bond
24DisaccharidesDisaccharides
1 4
CH2OH
3 2
4
5
CH2OH
3 2
1
5
1 4
MaltoseMaltose
Found in germinating seeds and the Found in germinating seeds and the alimentary canal – breakdown of alimentary canal – breakdown of
starchstarch
GlucosGlucosee
GlucosGlucosee
1-4 1-4 GlycosidiGlycosidic bondc bond
25DisaccharidesDisaccharides
SucroseSucrose
Found in sugar beet and sugar
cane
GlucosGlucosee
FructoseFructose
1-2 1-2 Glycosidic Glycosidic
bondbond
1
CH2OH
3 2
4
5
1
CH2OH
5
4 3
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CH2OH
26DisaccharidesDisaccharides
1 4
CH2OH
3 2
4
5
CH2OH
3 2
1
5
1 4
LactoseLactose
Found in MilkFound in Milk
GalactoGalactosese
GlucosGlucosee
1-4 Glycosidic 1-4 Glycosidic bondbond
27Testing for Reducing SugarsTesting for Reducing Sugars
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1. Combine equal 1. Combine equal quantities of test quantities of test solution and solution and Benedict’s Benedict’s reagent in a test reagent in a test tubetube
Testing for Reducing SugarsTesting for Reducing Sugars
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2. Warm in a water 2. Warm in a water bathbath
Testing for Reducing SugarsTesting for Reducing Sugars
30Testing for Reducing SugarsTesting for Reducing Sugars
3. Change in colour 3. Change in colour and opacity and opacity indicate the indicate the reducing sugar reducing sugar concentrationconcentration
31Testing for Non-Reducing SugarsTesting for Non-Reducing Sugars
CH2OH
3 2
4 1
5
CH2OH
3 2
4 1
5
1. Hydrolyse 1. Hydrolyse the glycosidic the glycosidic bond with bond with warm dilute warm dilute HClHCl
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2. Neutralise with 2. Neutralise with NaHCONaHCO33
Testing for Non-Reducing SugarsTesting for Non-Reducing Sugars
3. Perform a 3. Perform a Benedict’s testBenedict’s test
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Polysaccharides - StarchPolysaccharides - Starch
CH2OH CH2OH CH2OH CH2OH CH2OH
2 components to starch : Amylose 2 components to starch : Amylose and and AmylopectinAmylopectinAmylose is an unbranched molecule Amylose is an unbranched molecule
of glucose units bound by of glucose units bound by 1 – 4 1 – 4 glycosidic bondsglycosidic bonds
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Polysaccharides - StarchPolysaccharides - Starch
The chain of The chain of glucose glucose molecules molecules arranges itself as arranges itself as a helixa helix
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Polysaccharides - StarchPolysaccharides - Starch
The chain of The chain of glucose glucose molecules molecules arranges itself as arranges itself as a helixa helixThe bore of The bore of which is the which is the same size as a same size as a molecule of molecule of iodine in KIiodine in KI
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Polysaccharides - StarchPolysaccharides - Starch
Amylopectin is a Amylopectin is a branched molecule branched molecule with with 1-4 glycosidic 1-4 glycosidic bonds,bonds,And occasional And occasional 1-6 1-6 bonds forming bonds forming branchesbranches
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Polysaccharides - StarchPolysaccharides - Starch
Branches Branches arise every arise every 2525thth or so or so glucose glucose moleculemolecule
38Polysaccharides - GlycogenPolysaccharides - Glycogen
30 000 30 000 glucose units glucose units joined by joined by 1-4 and 1-4 and 1- 1-6 glycosidic 6 glycosidic bondsbonds
Similar structure Similar structure to amylopectin, to amylopectin, but with more but with more frequent frequent branchingbranching
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4 5
6 glucoseglucose
Polysaccharides - CellulosePolysaccharides - Cellulose
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123
4 5
6
Polysaccharides - CellulosePolysaccharides - CelluloseStraight chain molecule of Straight chain molecule of 1-4 1-4 glycosidic bonds,glycosidic bonds,
stabilised by hydrogen bonds stabilised by hydrogen bonds between adjacent glucosesbetween adjacent glucoses
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Hydrogen bonds also exist Hydrogen bonds also exist between adjacent chains – between adjacent chains –
molecule of high tensile strengthmolecule of high tensile strength
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4 5
6
Polysaccharides - CellulosePolysaccharides - Cellulose
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