Lipids, membranes, metabolism Flashcards Preview

Biochemistry > Lipids, membranes, metabolism > Flashcards

Flashcards in Lipids, membranes, metabolism Deck (50)
Loading flashcards...
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

Glycolysis stage 2

Carbon-6 converted to 2x carbon-3
ATP produced
NADH produced