Metabolism Flashcards
What is metabolism?
Metabolism: All the chemical reactions that occur in an organism.
Catabolism: Breaking down organic molecules thus releasing energy.
Anabolism: Building of organic molecules thus, consuming energy.
Why do cells require energy?
1) Cellular maintenance/repair
2) Growth & Division
3) Special Processes (Active transport, secretion, contraction etc)
4) Storage of nutrients
Equations for Photosynthesis + Glucose metabolism
Photosynthesis:
6H2O + 6CO2 + Light energy –> C6H12O6 + 6O2
Glucose Metabolism:
C6H12O6 + 6O2 –> 6H2O + 6CO2 + Chemical/Heat energy
Systematic breakdown of glucose (ATP Production) and where they occur
Glycolysis (Cytosol of cell) –> Pyruvate (cytosol of cell) –> Pyruvate converts to acetyl group (Mitochondrial Matrix) –>
acetyl-CoA formation (Mitochondrial Matrix) –> Citric Acid Cycle (Mitochondrial Matrix)–> Electron Transport Chain (Mitochondrial inner membrane)
What is the role of NADH and FADH2 and how are they produced?
NADH is produced by glycolysis, Pyruvate conversion, and the citric acid cycle. FADH2 is produced from the citric acid cycle. They are charged electron carriers that create a H+ gradient. This gradient moves the H+ from the mitochondrial matrix into the intermembrane compartment and eventually back into the matrix. This movement provides energy for ATP synthase to combine ADP + P to create ATP.
Why is O2 required for glucose metabolism?
(Why is this an anaerobic process?)
O2 acts as the final e- acceptor and combines with H+ at the end of Oxidative Phosphorylation to produce water.
If there is no oxygen present, what process occurs after Glycolysis?
Fermentation occurs if cellular respiration cannot. Pyruvate is converted to Lactate which is used to regenerate NAD+ which perpetuates Glycolysis. This creates an acidic environment in muscle tissue, thus decreasing Hb affinity for O2.
How can lipids be used as an energy source?
Fat is stored in adipose tissues as triglycerides. Triglycerides can be broken down into fatty acids and glycerol. Glycerol ultimately can be converted into pyruvate and free fatty acids can ultimately be broken down into acetyl-CoA. Both are then used in the citric acid cycle.
How can Lipolysis result in Ketosis? (And possibly Ketoacidosis?)
During the breakdown of lipids the liver simultaneously produces acetyl-CoA and ketone bodies which travels through the blood to skeletal muscle. Because ketones are acidic, producing an excess can result in ketoacidosis if the buffers in your blood can’t compete. These excess ketone bodies end up in urine and breath.
What is an essential amino acid?
There are 9 amino acids that the body cannot synthesize and therefore must be consumed dietarily.
Protein metabolism: How are amino acids used?
Normally, Amino acids are used immediately to make new proteins but may be “remodeled” to form different AA’s via TRANSAMINATION.
When needed, AA’s can be used for energy by undergoing DEAMINATION to form a different organic acid –> pyruvate or actyle-CoA.
Hormone regulation of blood glucose levels
Insulin: Beta cells from the pancreas lower blood glucose levels via
-increased cell glucose uptake
-accelerated conversion of glucose –> glycogen.
Glucagon: Alpha cells from pancreas raise blood glucose levels via
-accelerated breakdown of glycogen –> glucose.
Methods of glucose conversion
If a cell needs glucose, generally called GLUCOGENESIS, it can:
-Break down glycogen (glycogenolysis)
-Convert non-carb molecules into glucose (gluconeogenesis)
If a cell needs to store Glucose, it can:
-Convert it to glycogen (Glycogenesis)
-Convert it to a lipid (Lipogenesis)
During ketosis it can break down stored fats into fatty acids via Lipolysis.
Absorptive V post-absorptive states
Absorptive state:
-Nutrient absoprtion occurs up to 4 hours post meal
-Insulin is main hormone utilized to balance incoming glucose.
-Other important hormones are: gastrin, secretin, CCK, GH, androgens and estrogens.
Post-Absorptive State:
-No nutrient absorption
-Relies on stored energy reserves (carbs then lipids, then proteins)
-Glucagon is main hormone used to increase blood glucose levels
-Other important hormones are: epinephrine, GH and glucocorticoids.
Why is Thyroid hormone important in regulating metabolism?
- Increases O2 consumption
- Increases heat production (by creating more Na+/K+ pumps & making ATP production less efficient via smaller H+ gradient)
