Flashcards in Lipids, membranes, metabolism Deck (50)
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1
Compare a soap bubble with a cell membrane:
- Both have a hydrophilic head that attracts water and a hydrophobic tail which repels water
- Soap bubble has tail pointing out
- Lipid vesicles have tail pointing in
2
How cholesterol is a bidirectional regulator of membrane fluidity…
Adds strength
At high temps - stabilises membrane and raises its melting point
At low temps - prevents phospholipids from clustering together and stiffening
3
Catabolic =
Breakdown of complex molecule to produce energy using oxidation
4
Anabolic =
Formation of complex molecules from simple ones utilising energy, using reduction
5
Exergonic =
Reactions are spontaneous and release energy
DG = negative
6
Endergonic =
Reactions are non-spontaneous and require energy to occur
DG = positive
7
Energy of a reaction:
DG = DH -TDS
Gibbs free energy change of reaction =
Heat exchange with surroundings - (temperature in K x measure of disorder)
8
Measure of disorder (S)…Increase=
Decrease=
Increase in disorder = positive DS
Decrease in disorder = negative DS
9
Heat exchange with surroundings (H)…
Heat released=
Heat absorbed=
Heat released = exothermic = negative DH
Heat absorbed = endothermic = positive DH
10
Standard conditions -
1M concentrations
25 degrees Celsius
PH 7
11
Energy broken down from food is used for…
Synthetic processes
Mechanical work
Active transport
12
Sources of energy -
Carbohydrates
Lipids
Proteins
13
ATP =
Adenosine triphosphate
Energy currency
Contains an adenine base, a ribose sugar and 3 phosphate groups
14
The hydrolysis of phosphoanhydride bonds in ATP release energy because…
Resonance stabilisation of orthophosphate favours ATP hydrolysis
Electrostatic repulsion created by 4 negative charges, is reduced when ATP is hydrolysed
Stabilisation due to hydration, water binds more effectively to ADP and Pi
15
Carrier molecules =
Small molecules that have important roles in passing electrons
E.g. NAD+, NADP, FAD, FMN
16
During catabolic processes…
Intermediates are oxidised and coenzyme (NAD) is reduced, ATP is produced when NADH is reoxidised in oxidative phosphorylation
17
During anabolic processes…
Intermediates are reduced and coenzyme is oxidised
18
Catabolism: stage 1 -
-extracellular
-building block molecules absorbed into circulation
-no energy produced
19
Catabolism: stage 2 -
-many pathways
-intracellular
-building block molecules are even simpler molecules
-oxidative
20
Catabolism: stage 3-
-mitochondrial
-a single pathway - citric acid cycle
-oxidative
-acetyl precursors for biosynthesis
-oxidative phosphorylation
-NADH + FAD2H reoxidised
-O2 required (reduced to H2O
21
Carbohydrates:
General formula = (CH2O)n
Contain aldehyde or ketone groups
Multiple -OH groups
Monosaccharide - Single sugar units
Monosaccharides are linked by alpha - 1,4 - glycosidic bonds to form complex carbohydrates
22
Maltose =
Glucose + glucose
23
Lactose =
Galactose + glucose
24
Sucrose =
Fructose + glucose
25
Glycogen
Alpha - 1,4 and alpha -1,6 glycosidic bonds
Highly branched
Storage in animal cells
26
Cellulose
Beta -1,4-glycosidic bonds only
Unbranched
Plants cell wall
27
Starch
Alpha-1,4 and alpha-1,6 glycosidic bonds
Less branched
Plant storage molecule
28
Glycolysis :
- central pathway of sugar metabolism
- present in all cell types
- takes place in the cytoplasm
29
Glycolysis step 1
Input of some energy
ATP used to phosphorylate intermediates
30
