Biological energy Flashcards
what is biological energy?
the ability of a biological organism or a biological object to do some work
Biological energy is generated from solar energy and humans derive it via food chain
Define the principal energy stores in human body
3 main systems for energy storage :
Glycogen 1g= 4kcal; stored in liver; muscles also store some incase we run out of it in liver
Fat
Phosphocreatine muscle and brain have a lot of them (holds onto extra phosphate so u have more energy) natural source: meat has a lot of creatine
* Aka quickest form of regeneration, by creatine kinase - primary function is to act as temporal energy buffer
* Mostly occurs in muscle and brain
* 43.3kJ (10.3kcal) per mole
* Can store ~ 120g in body
Max effort 5-8s
define 1 kcal
1 kcal - amount of energy required to warm 1kg of air-free water by 1oC at standard atmospheric pressure
what is facilitated diffusion
substances move from high to low conc aka down their concentration gradient; through a transport protein. Does not require energy from ATP
There are 2 regions in the brain that require insulin; what are they
GLUT1 doesn’t require insulin to uptake glucose but there are 2 regions in the brain that do (the other regions don’t): hippocampus (memory) and some cells of** prefrontal cortex** (decision/discipline)
what does GLUT1 do in the brain and where else is it an important transporter of glucose
GLUT1 (glucose transporter 1) protein is embedded in the outer membrane surrounding cells , where it transports glucose(simple sugar) into cells from the blood or from other cells for use as fuel. In the brain, the GLUT1 protein is involved in moving glucose, which is the brain’s main energy source, across the blood-brain barrier.
GLUT1 is insulin-independent
its a transporter in the
*blood
*BBB
*heart (lesser extent)
where does GLUT2 function as a glucose transporter; is it glucose dependent?
GLUT2:
*liver
*pancreas
*small intestine
GLUT2 is:
**Insulin-independent **
High Km
Low affinity
where does GLUT3 function as a glucose transporter
GLUT3:
* Brain
* Neurons
* Sperm
GLUT3:
**Insulin-independent **
Low Km
High affinity
where does GLUT4 function as a glucose transporter
GLUT4:
* Skeletal muscle
* Adipose tissue
* Heart
GLUT 4 is insulin-dependent
what is the function of GLUT5?
GLUT5 allows for **fructose to be transported **from the intestinal lumen into the enterocyte by facilitated diffusion due to fructose’s high concentration in the intestinal lumen. GLUT5 is also expressed in skeletal muscle, testis, kidney, fat tissue (adipocytes), and brain.
what is ATP
ATP= Adenosine triphosphate
- 3 phosphate groups connected via 2 high-energy phosphoanhydride bonds - bonds store substantial amount of energy due to repulsion between -vely charged phosphate groups
- When these high-energy bonds are broken via hydrolysis, energy stored in bonds is released - can be harnessed to power cellular processes requiring energy input, like muscle contraction, active transport of molecules across cell membranes, and molecule synthesis
Describe how energy is generated in the cells/ how is ATP produced in animal cells
Most of ATP produced by metabolising glucose in process of cellular respiration - multistep chain of events
Step 1) **glycolysis in cytoplasm **
* Glucose converted to pyruvate
* Glucose, using 2 ATP converted to fructose diphosphate - converted into 2 glyceraldehyde 3-phosphate - converted into 2x pyruvate (produces 4x ATP and 2x NADH)
* So net gain of 2x ATP
Step 2)** pyruvate oxidation - mitochondrion**
* Pyruvate (aka pyruvic acid) goes into mitochondria and gets decarboxylated into acetate - produces CO2
* Coenzyme A helps transform acetate into acetyl-CoA - produces NADH
Step 3) Krebs cycle - mitochondrion
* Acetyl-CoA joins citric acid cycle (aka Krebs cycle) - chain of steps in a circle
* Oxaloacetate can get converted to citrate and loop is closed so cycle repeats
* During cycle - NADH is produced, captures H+ - succinate to fumarate produces coenzyme Q (QH2)
Step 4) oxidative phosphorylation - mitochondrion
* 5 complexes - NADH feeds H+ into chain of complexes
* This is reason we need to breathe (‘oxidative’)
* Coenzyme Q needed for complex II
Step 5) ATP production - proton motive force, chemiosmosis
=ATP synthase will produce ATP by pumping H+ back into mitochondrial matrix and phosphorylates ATP ;
what is chemiosmosis
Chemiosmosis is the movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient
what enzyme converts glucose to glucose-6-phosphate?
Conversion of glucose-6-phosphate (G6P):
glucose converted to glucose-6-phosphate (G6P) via hexokinase - traps glucose in cell since G6P cannot easily cross plasma membrane
what enzyme converts glucose-6-phosphate into glucose-1-phosphate
Formation of glucose-1-phosphate (G1P):
G6P converted to G1P by **phosphoglucomutase **
