quiz 5 Flashcards
what is the net amount of ATP produced in glycolysis? how is that number determined
7 ATP total
2 ATP are used, 4 are created, and 5 are created from NADH H+
when can glycolysis begin
when glucose enters the cell
what are the two main regulations of glycolysis
glucose transport, regulated molecules
describe GLUT 1&3 for glucose transport
found on erythrocytes and neurons
both have a high affinity, so glycolysis occurs easily
describe GLUT 2 for glucose transport
needs a lot of glucose to move it to the blood
can only occur when there is high blood glucose
describe GLUT 4 with glucose transport
can regulate glycolysis
only transports glucose when insulin is present
what are the 3 regulated molecules
glucokinase
phosphofructokinase-1
pyruvate kinase
describe the regulated molecule glucokinase
low affinity (similar to glut 2)
needs high intercellular glucose concentration to be active
occurs only in liver
describe the regulated molecule phosphofructokinase-1
inhibited by high concentrations of ATP
insulin activates phosphofructokinase-2
results in production of phosphofructokinase-1
signals to the body there is an excess of glucose
describe the regulated molecule pyruvate kinase
activated by presence of 1-6bisphosphate
commits to glycolysis
inhibited by glycogen
what does the glycolysis pathway need to continue
glucose
define glycogen
the storage form of glucose, complex polymer made up of glucose molecules
what is glycogenin
it is the middle portion of glycogen with glucose chains attached.
define a1,4-linkage
bonds between glucose in straight chains
define a1.6-linkage
bond between glucose at branching points
where does glycogenesis occur
cytosolic (liquid portion of cell)
what are the four steps of glycogenesis
- glucose is converted to glucose 6-phosphate via ATP to ADP, glucokinase, and hexokinase
- glucose 6-phosphate is converted to glucose 1-phosphate via phosphoglucomutase
- glucose 1-phosphate is converted to UDP-phosphate via UTP which is converted to PPi, UDP-glucose, and pyrophosphorylase
- UDP-phosphate is converted to (Glucose)n+1 via (Glucose)n to UDP, and glycogensythase
define branching enzyme
removes 7 glucose from an 11+ chain and moves it to an a1-6 linkage position
what do GLUT 2 and 4 do?
store glucose when there is enough
what is regulated in glycogenesis? why?
phosphorylation because it can be reversed
what needs to happen to glycogen synthesis for it to be active
diphosphorylation
what is protein-phosphate-1 need to be activated
insulin
what does protein-kinase-a do
reverses the glycogenesis pathway
what does glucogenolysis do
the reverse of glycogenesis
where does glycogenolysis occur
cytosolic
where does the liver stop breaking down? muscle?
glucose
glycogen
how many steps are in glycogenolysis
2-3
what is glycogenolysis regulated by
glycogen phosphorylase
what are the four steps of glycogenolysis
- (Glucose)n goes to glucose 1-phosphate via phosphorylation and glycogenphosphorylase
- glucose 1-phosphate goes to glucose 6-phosphate via phosphoglucomutase
- glucose 6-phosphate goes to glucose via H2O and glucose 6-phosphotase
- glucose enters bloodstream
define debranching enzyme
begins when only 4 glucose are left on a chain; 3 are removed and added to another chain at a-1,4 linkage and the last glucose will be released as free
which step of glycogenolysis is regulated
the first step
what is protein phosphate-1 activated by
insulin
how many pathways can occur at once
only one
what is glycogenesis stimulated by
insulin
what is glycogenolysis stimulated by
glucagon and epinephrine
define gluconeogenesis
synthesis of glucose; reverse of glycolysis
where does gluconegoensis occur
mostly in the liver, but will occur in the kidneys if starving
describe lactate
pyruvate is changed during anaerobic conditions
released into bloodstream where liver uses it
produced by muscles and erythrocytes (rbc)
describe glycerol
comes from fat and provides energy
main precursor in fasted state
describe amino acid
breakdown of protein from the muscles
maintains blood glucose
last resort for starved state but depletes after many days of fasting
