Metabolism

Question 1

4 things metabolism must do to build a cell

Answer 1

1. Baer est energy from environment and transduce to a usable form
2. Harvest electrons from environment
3. Use energy and electrons to convert simple carbon molecules —> complex molecules (monomers)
4. Use energy and electrons to join monomers (to make RNA, DNA, polypeptides, carbohydrate polymers etc)

Question 2

What is an important use of electrons in metabolism?

Answer 2

Electrons drive protons across a membrane to create and electrochemical gradient

Question 3

Why do we need to put energy into our system?

Answer 3

To resist the pull of entropy that wants to break things down

Question 4

Formation of a peptide bond where does the energy come from?

Answer 4

Hydrolysis of GTP to produce GDP and Pi

Question 5

Amylopectin

Answer 5

Dense packing

Get crystalline regions

Question 6

Glycogen

Answer 6

So stored slightly differently to amylopectin’s so it doesn’t crystallise
Needs to be a more rapidly accessible store

Question 7

Cellulose

Answer 7

X

Question 8

Why do we add ATP to molecules?

Answer 8

T o activate them to to make it easier to join them to things

Question 9

What’s used instead of ATP I’m cellulase formation?

Answer 9

UTP used

Question 10

How do cells get H+ when there aren’t any floating around because H2 is the more stable form?

Answer 10

They have acids which donate H+ (can be easily done in an aq environment)

Question 11

If you want to make a H+ what do you need?

Answer 11

H+
AND
and an e-

Question 12

Going from Simple inorganic precursor molecules (eg. Carbon dioxide, nitrate ions etc) to organic building blocks (glucose etc) requires

Answer 12

An abundance of sections

Question 13

Protons in water —-> biomass

Quick recap

Answer 13

Photosynthesis splits water
Electrons captured as NADPH
NADPH used to form GAP (electrons now on GAP)
Photosynthetic organisms turn GAP into biomass

Question 14

Pentode phosphate pathway

Answer 14

NADPH produced by oxidising glucose phosphate

Question 15

How can amino acids be synthesised?

Answer 15

Using carbon skeletons (molecules) from the central metabolic pathway (the kerbs cycle).
Eg. 2-oxoglutarate similar structure to glutamate so side in glutamate synthesis

Question 16

Once one amino acid is synthesises what’s another way that other AAs can be formed?

Answer 16

Transmamination (swapping amine from one AA to another)

Question 17

Where do all the carbon precursors used to make amino acids come from?

Answer 17

Glycolysis
Pentode phosphate pathway
Kerbs cycle (TCA cycle)

Question 18

How many reactions does the complete model of E. Coli metabolism include?

Answer 18

2251

Question 19

In a single celled organism there are more than

Answer 19

1000 chemical reactions that make up the metabolic network

Question 20

Brief logic of metabolic pathways

Answer 20

Central backbone of system where most of the carbon is flowing (Kreb’s cycle, pentode phosphate pathway, glycolysis etc)

This generates ATP and NADPH

Branching off of it are the withdrawal of certain carbon intermediates which provide carbon skeletons for biosynthesis

Question 21

Why must glucose be phosphorylated early in a metabolic pathway?

Answer 21

Important to our a charge on it ASAP so it doesn’t exit the cell through them membrane after you’ve just taken it in AND used energy to do this

Question 22

Three things that limit the metabolic pathway of glycolysis

Answer 22

1. Must generate intermediate molecules that provide the specific carbon skeletons need for biosynthesis of carbohydrates, amino acids etc
2. Must use chemistry that avoids highly reactive intermediates that would be toxic to the cell
3. Must involve early addition of phosphate and therefore negative charge to glucose to prevent loss through cell membrane