Introduction to Metabolism Flashcards
1) Define metabolism
All chemical reactions and physical changes that can occur in living organisms (incl. anabolism and catabolism)
2) Define catabolism and give two examples
Metabolic breakdown of substances into smaller products (glycolysis, lipolysis)
3) Define anabolism and give two examples
Simpler substances are transformed into more complex ones, requiring energy (gluconeogenesis, lipogenesis)
4) Why do metabolic pathways have stepwise breakdown?
So energy is released in small, usable packages rather than released in one go (none is stored)
5) Advantage to different forward and reverse pathways?
Separate regulation prevents a futile cycle
6) Where is the energy released at each step stored?
Activated carrier molecules (a.c ATP)
7) How can an energetically unfavorable reaction occur?
Using a coupled reaction where an energetically favorable reaction drives and energetically unfavorable reaction (e.g. oxidation of a food molecule producing an activated carrier molecule that provides energy to the unfavorable reaction)
8) give examples of activated carrier molecules (6)
ATP NADH, NADPH, FADH2 Acetyl CoA Carboxylated biotin S-adenosylmethionine Uridine diphosphate glucose
9) for each activated carrier molecule, which group is carried in the high energy linkage?
ATP - phosphate NADH/NADPH/FADH2 - electrons and H+ Acetyl CoA - acetyl group Carboxylated biotin - carboxyl group S-adenosylmethionine - methyl group Uridine diphosphate glucose - glucose
10) Why is ATP hydrolysis so energetically favorable?
Relieves electrostatic repulsion between phosphate groups and the released phosphate ion’s resonance is stabilised (increase in entropy means positive delta S value)
11) Which ATP hydrolysis produces the most energy?
ATP –> AMP + 2Pi
12) 2 examples of when ATP –> AMP + 2Pi occurs?
In DNA replication and when tRNA binds to an amino acid during translation
13) Explain the function of ATP as ‘the energy currency of living cells’ (4)
- Used directly in cell motility and muscle contraction
(Motor proteins dynein and myosin carry cargoes) - Used in active transport systems (e.g. moving charged particles against the concentration gradient)
- Used in metabolic control - regulation of enzyme activity
- Used in metabolism to add Pi to metabolic intermediates (glucose + ATP –> G-6-P + ADP)
14) Explain the significance of the thioester linkage in Acteyl CoA
Thioester linkage is a ‘high energy bond’
Coenzyme A forms a thioester linkage with carboxylic acids to form acetyl CoA
15) State subcellular locations for each of the processes: glycolysis, link reaction, TCA cycle, oxidative phosphorylation
Glycolysis - cytosol/cytoplasm
Link reaction - mitochondria matrix
TCA - mitochondria matrix
Oxidative phosphorylation - inner membrane of mitochondria