Biochemistry 2 Flashcards
Define cellular respiration
series of metabolic reactions that convert stored energy in nutrinets into usuable energy for biological proccesses
give some main points of glycolysis
-anaerobic
-short term energy system
-substrate= glucose
-ineffcient-low yield of ATP
Give some main points of the oxidative system
-aerobic
-long-term energy system
-substrate= glucose, fats
-highly efficient-high yield of ATP
list the steps for the metabolism of fatty acids
-lipase
-beta oxidation spiral
-krebs cycle
-ETC
What is the absorptive state ?
in the fed state- following digestion when nutrients are being absorbed into the blood stream
whats the difference between anabolism vs catabolism?
A-storing
C-breaking down
How long does a meal typically take to digest?
4 hours to completly digest and absorb
whats the key hormone in the absorptive state?
insulin
describe the absorptive state at rest
-free glucose used to produce ATP via oxidative pathways
-lipids used for synthesis
-AA for protein synthesis
-excess blood glucose stored as glycogen
What happens to excess FAs and AAs and glucose once glycogen stores are full?
converted and stored as fat- adipose and triglycerides via lipogenesis
Define post absorptive state
in the fasting state-following absorption- when nutrients have been stored and or are being used for biological proccesses in the body
describe the post absorptive state at rest
-glycogenolysis
-lipolysis
-once glycogen stores are depleted alternate substrates can be used to produce glucose-gluconeogenesis
-free glucose used to produce ATP via oxidative pathways
-FA oxidation occurs
What is the key hormone in the post absorptive state?
glucagon
define muscle glyocgen and liver glycogen
MG-on site source of glucose for contracting muscles
LG-systemic control-maintains blood glucose
Describe glycogenesis
-glucose molecules are linked together in long chains forming glycogen
anabolic pathway requiring ATP
absorptive state
influenced by insulin
describe glycogenolysis
-glycogen splitting
-post absorptive state
-in muscles and other cells glucose is trapped inside as glucose-6-phosphate
-in the liver hepatocytes contain the enzyme needed to remove phosphate-releases free glucose
influenced by glucagon,epinephrine,cortisol
Name the other non-CHO sources that create new glucose
lactic acid-by product of anaerobic glycolysis
glycerol from lipolysis or digestion of dietary fats and oils
AA from dietary protein or body protein stores
give a few facts about lipids
-most conc energy source
-energy yield from fat much higher than carbs or protein
-50% fat store
-balance of storage
Describe lipogenesis-absorptive state
multiple pathways where glucose in ingested, FAs and AAs are converted to fat
-influenced by the presence of insulin
describe lipolysis-post absorptive state
-stored triglycerides in adipose are broken down to glycerol and FAs
FAs- used for energy in most cells- B oxidation, krebs, ETC
glycerol-converted to Pyruvic acid for ATP production, or undergo gluconeogenesis
influenced by glucagon, epinephrine, cortisol, thyroid hormones
describe protein catabolism
-surplus proteins are catabolised for energy or converted to fat
-AA are deaminated
-remainder of molecule is ketoacid
Describe ketoacids
-may enter krebs cycle and be fully catabolised for energy
-may be converted to glucose
-may be converted to fat
Describe hormonal control using anabolic hormones
-insulin
-promotes glucose uptake into cells by binding with insulin receptors on the cell surface
- stimulates GLUT-4
-inhibits glycogenolysis
-promotes glucose conversion to triglycerides-lipogenesis
-promotes protein synthesis
What are two key functions of insulin?
promotes glycogenesis and at the same time inhibits glycogenolysis
promotes lipogenesis and protein synthesis
WHere are glut 4 transporters found?
adipose tissue and skeletal and cardiac muscle
Where are glut 3 transporters found?
neurons and placental tissues
Where are glut 2 transporters found?
liver and pancreas
Where are glut 1 transporters found?
brain/ brain-blood barrier
placenta
erythrocytes
Whats the major difference in these glut transporters?
glut-4 is insulin dependent
glut 2 and 1 are NOT insulin dependent
Describe hormonal control using catabolic hormones
-glucagon
-promotes glycogenolysis
-inhibits glycogenesis
-promotes lipolysis
-promotes protein catabolism
Functions of glucagon
-promotes glycogenolysis
-inhibits glycogenesis
-promotes lipolysis
-promotes protein catabolism
Name some catabolic hormones
-epinephrine
-cortisol
-thyroid hormone
Describe the effects of epinephrine
-released in response to stress and excersise
-increases glycogenolysis, lipolysis
Describe the effects of cortisol
-released in response to long term stress and prolonged excersise
-increases gluconeogenesis,protein catabolism,lipolysis
Describe the effect of thyroid hormones
-changes in response to excersise
-increases lipolysis and enhances B-oxidation
-increases glycogenolysis and gluconeogenesis
Whats the overall metabolic effect of catabolic hormones?
raises blood glucose, increases availability and use fo FAs by tissues, glucose conserved for brain and RBCs
What happens if you have low insulin levels?
-reduced glucose uptake-increased use of fats for energy
-no glycogen storgae-reduced glycogenesis
-reduced protein synthesis
-increased hepatic glucoe release
What happens if you have elevated levels of glucagon or cortisol?
-increased lipolysis
-increased AA catabolism and gluconeogenesis
-start to break down body proteins
