0212 - Concept of Metabolism - RM

Question 1

Catabolism

Answer 1

Reactions for using energy. The breaking of large molecules and fuels (food), together with O2 and H2O to produce CO2 and intermediates. Intermediates can then convert ADP and NAD into ATP and NADH.

Question 2

Anabolism

Answer 2

Reactions for storing energy.Small molecules and toxins are ‘burned’ with energy from ATP, and with NADH, to create macromolecules and eliminate toxins. This also creates ADP and NAD.

Question 3

Why is the Liver important in metabolism

Answer 3

Key organ for synthesising molecules for all tissues in the body, and storing key compounds such as glycogen. Self sacrificing.

Question 4

Role of Adipose Tissue

Answer 4

Fat Cells - storing lipids, and mobilising fatty acids when energy is required.

Question 5

Role of Kidneys

Answer 5

Can metabolise several toxins into inert substances that can be eliminated.

Question 6

Role of Muscles

Answer 6

The movers. Can store glycogen, and use whatever fuel is available (fat, ketones, protein, or glucose)

Question 7

Role of cytoplasm/cytosol in Metabolism

Answer 7

Soup of the cell, conducts non-oxidative catabolism, synthesis of molecules, and stores fuels (glycogen and TAGs)

Question 8

Role of Endoplasmic Reticulum and Golgi Apparatus

Answer 8

Synthesise and process proteins and complex lipids, modifying their structure to ensure they fulfil their function in the right place.

Question 9

Role of Lysosomes

Answer 9

Garbage dump of the cell, pH of 5.5 enables the hydrolysis (destruction) of external compounds

Question 10

Role of Peroxisomes

Answer 10

Conduct initial breakdown (oxidation) of very long-chain fatty acids (24-26 carbons) before they enter the mitochondria.

Question 11

Role of Mitochondria

Answer 11

Responsible for many metabolic reactions, including 90% of ATP synthesis, providing lots of energy.

Question 12

How are hydrophobic molecules transported between organs

Answer 12

Either on albumin protein (can carry 7 FA’s at one time), or inside lipoproteins.

Question 13

How is Glucose absorbed in the cell

Answer 13

Primarily through the GLUT family, a widespread group of passive transporters that allow hydrophilic glucose to cross the cell membrane.

Question 14

How are Amino Acids absorbed into the cell

Answer 14

Most commonly linked with sodium, but through a number of different paths, including Excitatory Amino Acid Transporters.

Question 15

Why are compartments important in cells

Answer 15

Allow molecules and/or enzymes for a particular reaction to be grouped together and controlled by a transporter.

Question 16

What are Enzymes

Answer 16

Specialised proteins that serve as a catalyst for reactions. They do not change equilibrium, but can lower the rate of reaction or the activation energy.

Question 17

How do enzymes play their role

Answer 17

Acid-Base provision (supplying or removing proton to increase the electrophilic or nucleophilic character of the groups).Promote Transition State Formation - change shape of molecule or distribution of charge to allow extra proton or electron in.Proximity - holding reactants together at an appropriate orientation.Manipulating protein structure - to increase the likelihood of a reaction.

Question 18

What is the enzyme’s Active Site

Answer 18

A small site that is very attractive to the substate, and instantly commits the substrate to the reaction.

Question 19

How does short-term metabolic regulation occur

Answer 19

Almost instantaneously within a cell or group of cells, using specialised hormones that can affect a cell’s redox state (ADP/ATP supply or necessary cofactors).

Question 20

How does longer-term metabolic regulation occur

Answer 20

Hormones are released by organs or glands that monitor the system. These hormones use signal transduction pathways to change the behaviour of an enzyme. Much more complex than short-term ATP/ADP binding.

Question 21

What is Phosphorylation

Answer 21

The addition of a Phosphate group to a protein, changing its electrochemical profile (phosphate is very negative). This changes the shape and behaviour of the protein. It is conducted by Kinases.

Question 22

What is dephosphorylation

Answer 22

The removal of a phosphate group from a protein, changing its electrochemical profile, and thus its shape and behaviour. It is conducted by phosphatases.

Question 23

Why is phosphorylation important

Answer 23

Phosphate has a very negative charge, so can easily change the shape and behaviour of a protein - it is thus a key regulation, acting as a trigger to about 30% of our protein. Around 2% of our genome is devoted to phosphorylation and dephosphorylation.