glucose and glycogen metabolism

Where is glycogen found?

Primarily in muscle, some in liver and small amount in kidney. 

Draw alpha glucose.

Where does glycolysis occur?

in all tissues in the cytosol ( fluid part of cytoplasm)

How much ATP is made at each step of glycolysis and what is the net yield

• 2 ATP used in activation

• 4 ATP made 

• 2 ATP overall made

What happens to glucose in and after anaerobic glycolysis

glucose -> pyruvate -> lactate 

pyruvate changes to lactate so that it can change NADH back to NAD+

pyruvate + NADH + H+ → NAD+ + lactate

What is the net yield of ATP from glycolysis?

+2 ATP

What molecule is a source for immediate access to energy and how

glucose, through glycolysis 

How does the liver maintain blood glucose levels when it’s low and high

low:  through glycogenolysis: glucagon binds to receptors on the liver cell which makes the liver break down stored glycogen into glucose 

high: through glycogenesis: it stores excess glucose as glycogen 

What is glycogen used for in the liver

to regulate blood glucose levels 

- high: glucose is stored as glycogen in the liver
- low : glycogen broken down into glucose

What is the role of glycogen in muscles and what makes it specialised to do this

 energy store for the muscles
branches mean it can store alot of energy 

What are the 4 steps of glycolysis

1. Activation (using ATP)  ( need to know ) 

2. Splitting the 6C sugar in half 9 

3. Oxidation (removing 2H) ( need to know simple)

4. Synthesis of ATP - substrate level phosphorylation

In detail, what are the 4 steps of anaerobic (normal) glycolysis

1. activation:  

- adding 2 phosphate to glucose making fructose bisphosphate 

- reaction 3 is the rate limiting step as its irreversible, its controlled by ATP if theres high ATP then it inhibits the reaction as there is already enough ATP no need for glycolysis if high ADP they will allow it to happen so more ATP made 

2. splitting 

- 6 carbon sugar splits into 2, 3 carbon sugars

3. oxidation 

- the 3 carbon sugar is ocidised making an aldehyde 

- it looses 2 hydrogens and it reduces NAD+ to NADH

energy from this reaction is used to make ATP

4. ATP synthesis - substrate level phosphrylation

- 1 ATP made in reaction 7 from 1,3 bisphosphoglycerate to 3-phosphoglycerate 
- another made in reaction 10 from phosphoenolypyruvate to pyruvate

What enzyme is needed to make and break bonds between glucose molecules in glycogen

branching enzyme: make 
debranching enzyme: break 

What are the 3 steps of phosphorylation for glycogen breakdown (including extra step for kidneys and why)

• debranching enzyme is also needed to break the a-1,6 bonds

• the last step only happens in liver and kidney as thier th eonly one that has the G6Pase enzme and is the only plaace the glycogen is broken down into glucose to be released into the blood

What are the 2 metabolic fates for pyruvate in aerobic and anaerobic conditions

What are 3 sources of glucose for glycolysis

1. sugars and starch from food 

2. breakdown of glycoegn in liver 

3. recycled glucose ( e.g from lactic acids, amino acids, glycerol) 

Fill in the blanks

 

How is a glycogen chain formed

1. the glucose is activated ( making it more reactive) by being phosphorylated and trapped in a cell making UDP-glucose 

2. the UDP glucose removes the phosphate group added and joins the glycogen primer ( made of a number of glucose units )

3. joined with alpha 1-6 bonds catalysed by branching enzyme 

( dont neeed ot memorise this diagram) 

Why is glucose needed for development

1. growth in the embryo 

•  if low, it can lead to placental failure and faliure of implantation of the embryo to attach to the lining of the uterous

   2.  development of nervous system

• specialisign of cells is regulated by metabolism if not enough glucose these clls wont be able to differntiate 

What enzyme regulates specifically anaerobic glycolysis,

• what are the different types,

• what type is found in liver and which in muscle,

• how is it activated

• lactate dehydrogenase (1-5)

• what determins the type is the amount of alpha/beta lactate dehydrogenase subunits 

• it is activated in anearobic conditions

• LDH5 - liver ( think 5 letters)

• LDH1 - muscle 

What is the overall A → B in glycolysis and what is its functions

Glucose ( 6 C ) -->  2 pyruvate ( 3 C )

ATP synthesis

What are the 2 ways glycolysis is controlled

allosteric 
hormonal 

What is the allosteric control of glycolysis in general

• which enzyme

• how does it control

• allosteric control means Control of rate of reaction using enzymes.

• in activation phase: the enzyme is PFK ( phosphofructokinase)- regulates step 3 in glycolyiss which is the rate limiting step

• if you have high level of ATP or Citrate, it signals to the PFK enzyme to slow down glycolysis, if low then oppposite it modifies glyclysis to speed it up 

• it does it by ATP binding to PFK which changes its structure

What is the specialised function for glycolysis in skeletal muscle, RBC, brain

skeltal muscle: atp for intense exercise 

RBC: they dont have mitchondria so glycolyiss is the only way to make ATP 

Brain: main source of ATP as glucose is the main energy source not fats

What is the link between glycolysis and cancer cells

increase in glycolysis inreases the rate of division 

differnce is that cancer cells convert glucose to to lactate even when theres oxygen