Biological energy Flashcards

1
Q

what is biological energy?

A

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

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2
Q

Define the principal energy stores in human body

A

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

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3
Q

define 1 kcal

A

1 kcal - amount of energy required to warm 1kg of air-free water by 1oC at standard atmospheric pressure

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4
Q

what is facilitated diffusion

A

substances move from high to low conc aka down their concentration gradient; through a transport protein. Does not require energy from ATP

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5
Q

There are 2 regions in the brain that require insulin; what are they

A

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)

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6
Q

what does GLUT1 do in the brain and where else is it an important transporter of glucose

A

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)

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7
Q

where does GLUT2 function as a glucose transporter; is it glucose dependent?

A

GLUT2:
*liver
*pancreas
*small intestine

GLUT2 is:
**Insulin-independent **
High Km
Low affinity

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8
Q

where does GLUT3 function as a glucose transporter

A

GLUT3:
* Brain
* Neurons
* Sperm

GLUT3:
**Insulin-independent **
Low Km
High affinity

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9
Q

where does GLUT4 function as a glucose transporter

A

GLUT4:
* Skeletal muscle
* Adipose tissue
* Heart

GLUT 4 is insulin-dependent

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10
Q

what is the function of GLUT5?

A

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.

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11
Q

what is ATP

A

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
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12
Q

Describe how energy is generated in the cells/ how is ATP produced in animal cells

A

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 ;

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13
Q

what is chemiosmosis

A

Chemiosmosis is the movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient

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14
Q

what enzyme converts glucose to glucose-6-phosphate?

A

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

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15
Q

what enzyme converts glucose-6-phosphate into glucose-1-phosphate

A

Formation of glucose-1-phosphate (G1P):

G6P converted to G1P by **phosphoglucomutase **

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16
Q

how is glucose-1-phosphate activated

A

*Activation of G1P *

G1P activated by conversion into uridine diphosphate glucose (UDP-glucose) via UDP-glucose pyrophosphorylase (UGP2)

UDP-glucose serves as precursor for glycogen synthesis

17
Q

what molecule acts as a primer for glycogen chain initiation

A

Glycogen chain initiation - glycogenin acts as primer by catalysing attachment of short chain of glucose molecules (8-10) to itself - forms nucleus of new glycogen molecule

18
Q

what elongates glycogen chain

A

Elongation of glycogen chains - glycogen synthase extends glycogen chains by adding glucose 1 at time to growing glycogen - requires presence of pre-existing glycogen primer/seed

19
Q

What are the key energy demands of a cell

A

key energy demands of the cell :

  • Synthesis of macromolecules (lipids, proteins, nucleic acids)
  • Active transport
  • Nerve impulse transmission - ANS doing stuff all the time
  • Muscle contraction
  • Cell signalling
  • Temp regulation
20
Q

what is brown fat; difference between white and brown fat

A

brown fat has less lipid content its function is to produce heat (brown fat in rich mitochondria)
* the protein expressed in brown fat is ‘mitochondrial uncoupling protein ‘
-(mitochondrial uncoupling protein 1) induces leak of protons (H+) through membrane and “uncouples” free energy stores in electrochemical gradient from ATP synthesis - dissipates it as heat

white fat is storage its not full of mitochondria

21
Q

Caffeine blocks ________ receptor which make u feel tired

A

Caffeine blocks adenosine receptor which make u feel tired

22
Q

what is glycolysis? where does it occur?

A

Breakdown of glucose into pyruvate - from 6C to 2x 3C molecules

glycolysis occurs in cytoplasm

23
Q

During which process does oxidative phosphorylation take place?

A

Electron transport chain