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Hsf > 5: How do we fuel our body? > Flashcards

5: How do we fuel our body? Flashcards

1
Q

Define glycolysis.

A

First stage of ATP synthesis.

Series of chemical reactions occuring in the cytosol, converting glucose into 2 pyruvic acid molecules, and 2 ATP molecules.

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2
Q

Define citric acid cycle

A

Series of chemical reactions occuring in the mitochondria, converting pyruvic acid into ATP and electron carrier molecules

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3
Q

Define oxidative phosphorylation

A

Last phase of the ATP synthesis. Series of chemical reactions occuring on the inner mitochondrial membrane, converting electron carrier molecules to ATP.

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4
Q

Define glucose

A

Simple sugar molecule (monosaccharide).

Used by thebody to make ATP or stored as glycogen for future use.

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5
Q

Define ATP

A

Adenosine Triphosphate. An adenosine molecule with 3 attached phosphate molecules.

When ATP is broken down, ‘energy’ is released and used by cells and tissues to function.

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6
Q

Define mitochondria

A

An organelle in the cell where ATP is produced

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7
Q

Define lipid bi-layer

A

The head to tail arrangement of phospholipid molecules in the cell plasma membrane

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8
Q

Define selectively permeable membrane

A

Plasma membrane strucutred specific to cells to only let some substances pass through

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9
Q

Define osmosis

A

Movement (diffusion) of water across a selectively permeable membrane. Moving from high concentration to low concentration.

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10
Q

Define hypertonic

A

A hypertonic solution has more solutes than water molecules, comparing to intracellular fluid. >290 m0smol/L

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11
Q

Define hypotonic

A

A hypotonic solution has more water molecules than solutes compared to the intracellular fluid. <290m0smol/L

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12
Q

Define isotonic

A

Isotonic solution has the same total concentration of solutes (osmolarity) as intracellular fluid. Approx 290 m0smol/L

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13
Q

Define diffusion

A

Movement of solutes from area of high concentration to area of low concentration without the use of ATP

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14
Q

Define facilitated diffusion

A

Movement of solute across a plasma membrane via the use of a carrier/channel protein without the use of ATP

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15
Q

Define symport

A

Movement of 2 different ions or molecules in the same direction across a plasma membrane via acarrier/channel protein

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16
Q

Define antiport

A

movement of 2 different ions or molecules in the opposite direction across a plasma membrane, via a carrier/channel protein

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17
Q

What is plasma membrane composed of? (3)

A

Phosholipids, proteins, cholesterol

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18
Q

Bi-molecular layer of ________________ forms the basic structure

A

Phospholipid molecules

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19
Q

_____________ are inserted between the phospholipid molecules at regular intervals

A

Cholesterol molecules

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20
Q

_________ and _________ proteins incorporates in plasma membrane like icebergs floating in a sea of phospholipids

A

Integral, peripheral

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21
Q

Lipid bilayer serves as a highly impermeable barrier to most _____________ and ________substances.

A

Charged (polar), non-lipid soluble

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22
Q

_____________ acting as pores/channels/carriers to allow these substances to cross the membrane

A

Integral proteins

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23
Q

Factors of permeability of plasma membrane (name 3)

A
  1. solubility in lipids
  2. driving forces (up or down gradient)
  3. molecular size
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24
Q

Transport of substances across plasma membrane can either be active or ________

A

passive

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25
Q

Water-soluble substances require specialised ___________ proteins to function as channels or carriers

A

transmembrane

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26
Q

What are the 3 types of passive transport across membrane?

A
  1. Diffusion through the lipid bilayer (lipid soluble substances)
  2. diffusion through ion channels (water soluble subtances)
  3. facilitated diffusion using a carrier (water soluble substances)
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27
Q

What does active transportation through the cell membrane require?

A

Cellular energy (ATP)

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28
Q

Examples of lipid-soluble substances that can diffuse directly through the plasma membrane

A

Respiratory gases, lipids, small alcohols, urea

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29
Q

What is the driving force for a diffusion through the lipid bilayer?

A

Concentration gradient

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30
Q

What water soluble substances diffuses through the plasma membrane through channels?

A

ions, water

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31
Q

What water soluble substances diffuses through the plasma membrane through facilitated diffusion?

A

Sugars and amino acids

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32
Q

What is the driving force for channel and carrier mediated passive ransport of water soluble substances?

A

Concentration gradient or electrical gradient

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33
Q

What substances require facilitated diffusion to travel pass plasma membrane?

A

glucose (out of the cell), fructose (into the cell)

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34
Q

What is the driving force of facilitated diffusion that control the rate of movement?

A

Steepness of concentration gradient; the number of transporter proteins in the membrane

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35
Q

What is the driving force of transportation via ion channels (that is also a membrane proteins)

A

Electrochemical gradient

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36
Q

Why do we call some channels formed by the transport proteins to be “gated”?

A

because they open transiently, some are continuously open

37
Q

Which channels transport at a faster rate? “Gated” ion protein channels, or facilitated diffusion?

A

“Gated” ion protein channels

38
Q

Why does active transport require energy for the process?

A

Because it goes against a concentration gradient

39
Q

What are the 2 types of active transport? Describe them.

A
  1. primary active transport: energy derived directly from ATP via metabolic ATP hydrolysis
  2. Secondary active transport: energy derived indirectly from ATP via cotransport of Na+ or H+, it drives other substances against their own concentration gradients. The plasma membranes contain several antiporters and symporters powered by the sodium ion gradient.
40
Q

What is the most primary transport mechanism for primary active transport?

A

Sodium-potassium ion pump.

It requires 40% of cellular ATP; all cells have 1000s of them; it maintains low concentration of NA+ and a high concentration of K+ in the cytosol; and it operates continually

41
Q

What is exocytosis? Describe the process.

A

Movement of large molecules out of the cell.

Secretory vesicle contains the substance, then the vesicle moves towards and fuses with the plasma membrane, and release the contents into the extracellular fluid.

42
Q

Where does exocytosis occur?

A

In secretory cells

43
Q

Example of exocytosis process.

A

neurotransmitter secretion at the synapse

44
Q

What is endocytosis? Desscribe the process.

A

Movement of large molecules and particles into the cell.

Substances get bound to the receptor molecules on the plasma membrane. Then the recepters molecules start forming a vesicle and fuses into one, separating from the plasma membrane into the intracellular fluid.

45
Q

What are the 3 types of endocytosis? Explain.

A
  1. Pinocytosis: engulfing small particles and fluids
  2. Phagocytosis: engulfing large particles
  3. Receptor-mediated endocytosis: movement of specific substances involving caveolae regions of the cell membrane.
46
Q

What are the 3 major destinations for the nutrients we eat?

A
  1. Energy
  2. Structural or functional molecules
  3. Storage compounds
47
Q

Most energy is derived from the oxidation of ___, _____ and ____

A

CHO, fat and protein

48
Q

About ______ of energy released is lost as _____. The remainder of the energy is stored as ________.

A

60-70%, heat, chemical energy (ATP)

49
Q

Define metabolism

A

all chemical reactions in the body

50
Q

Defien catabolism

A

chemical reactions that break down complex organic molecules

51
Q

Define anabolism

A

Chemical reactions that build-up simple molecules into complex molecules

52
Q

All molecules have energy stored in the ______ between their atoms

A

Bonds

53
Q

What is the chemical compound of an adenosine triphosphate (ATP)?

A

3 phosphate groups attached to an adenine base and a 5c sugar (ribose)

54
Q

What are the functions of ATP?

A

Temporary storage of energy, used for muscle contraction, active transport, movement of structures within the cells

55
Q

How does an ATP release large amount of energy?

A

When terminal phosphate bond is hydrolysed (broken). I.e. ATP -> ADP + iP

56
Q

Describe the stages in energy generation.

A

Fist stage:
Large molecules broken down to smaller units.
- proteins > peptides and amino acids
- fats > glycerol and fatty acids
- polysaccs > simple sugars

Second stage:
Smaller units degraded to a few simple key compounds, playing a central role in metabolism

Third stage:
Citric acid (Krebs) cycle and oxidative phosphorylation

57
Q

What is the chemical reaction of the oxidation of glucose?

A

C6H12O6 -> 6H2O + 6CO2 + 36 ATP + heat

58
Q

What are the 3 pathways that glucose is catabolised?

A
  1. Glycolysis
  2. krebs cycle
  3. electron transport chain and oxidative phosphorylation
59
Q

When does polysaccs and disaccs are converted to monosaccs?

A

During digestion

60
Q

What are the 2 metabolic pathways that synthesise ATP?

A

Anaerobic:
ATP produced in absence of O2 (glycolysis).
Formation of acetyl CoA as a transitional step.

Aerobic:
ATP produced using O2 (oxidative phosphorylation, krebs cycle). Fuel + o2 -> CO2 + H2O + energy (ATP + heat), electron transport chain.

61
Q

What are the 3 phases of glycolysis?

A
  1. sugar activation
  2. sugar cleavage
  3. sugar oxidation and ATP formation
62
Q

Describe glycolysis phase 1, sugar activation.

A

2 ATP molecules are used to activate lucose (fructose-1, 6-bisphosphate)

63
Q

Describe glycolysis phase 2, sugar cleavage.

A

6C sugar is split into two 3C sugars. Each 3C sugar has a phosphate group. inorganic phosphate groups Pi are attached to each oxidised sugar fragment.

64
Q

Describe glycolysis phase 3, oxidation and ATP formation

A

The phosphates are split from the sugar and captured by ADP to form 4 ATP molecules.

The remaining 3C sugars are pyruvic acid.

The final products are 2 pyruvic acid molecules, 2 NADH and H+ molecules (reduced NAD+), a net gain of 2 ATP molecules.

If O2 is available, pyruvic acid prepares to enter Kreb’s cycle.

If O2 is not available, PA accepts H2 from NADH2 to form lactic acid (maintains supplies of NAD+ for glycolysis to continue)

65
Q

Describe the fate of pyruvic acid if there’s O2 or not.

A

When O2 is not available,
it is reduced o lactic acid tha tis rapidly diffuses out of cell into the blood. The liver cells remove lactic acid from blood and convert it back to pyruvic acid.

When O2 is available,
pyruvic acid proceeds to the Krebs Cycle in the mitochondrion.

66
Q

What does pyruvete dehydrogenase do?

A

Convert 3C pyruvic acid to 2C acetyl group plus CO2

67
Q

2C acetyl group is attached to ______________ to form ________________, which enter the Krebs cycle

A

Coenzyme A, acetyl coenzyme A

68
Q

Where does coenzyme A derived from?

A

Vitamin B

69
Q

What is the process called when pyruvic acid enters the mitochondria and remove CO2?

A

Decarboxylation

70
Q

What are the other two names of Krebs cycle?

A

Citric acid cycle, tricarboxylic acid (TCA) cycle

71
Q

What is a krebs cycle?

A

A series of biochemical reactions that occur in the matrix of mitochondria.

The 2C component of acetyl CoA is pulled apart bit-by-bit to release CO2 and H+

Then H+ are sent to the Electron Transport Chain (ETC) as NADH2 and FADH2 to be converted into energy (ATP)

72
Q

NAD+ and FAD+ are ____ carriers

A

H2

73
Q

Each acetyl CoA molecule that enters the Krebs cycle produces:

A

2 molecules of CO2, 3 molecules of NADH2, 1 molecule of ATP, 1 molecule of FADH

74
Q

Each glucose produced #___ acetyl CoA molecules

A

2

75
Q

Where does the ETS located at?

A

Mitochondria

76
Q

ETC is a series of integral membrane proteins (cytochromes) located in the ______ mitochondrial _________

A

Inner, membrane

77
Q

_________________ produces the vast majority of ATP in the cell

A

Oxidative phosphorylation

78
Q

hydrogens delivered to the chain are split into ____ and ________

A

Protons (H+) and electrons

79
Q

What are the water channels that help penetrate water molecules through the lipid bilayer called?

A

Aquaporins (transmembrane proteins)

80
Q

Define osmosis

A

Movement of water from a low solute concentration to a high solute concentration across a semi-permeable membrane

81
Q

Driving forces of osmosis is based on _____________________

A

Concentration of solutes dissolved in it, not about the water concentration. (osmotic pressure)

Because water is the solvent for all solutes, and is present at a very high concentration: 56 molar. Meaning when solutes are dissolved in water, its concentration changes very little.

82
Q

Describe osmotic pressure

A

It’s when solution exerts is proportional to the number of “osmotically-active particles” in solution.

83
Q

What does tonicity measure?

A

the solution’s ability to change the volume of cells by altering their water content (amount/volume)

84
Q

Describe an isotonic solution

A

no net movement of water, so cells maintain their normal shapeD

85
Q

Describe a hypotonic solution

A

cells gain water so are in danger of swelling and bursting

86
Q

Describe a hypertonic solution

A

Cells lose water so are in danger of shrinking and become dehydrated

87
Q

What happens to a red blood cell when it’s in a hypotonic solution?

A

It undergoes haemolysis

88
Q

What happens to a red blood cells when it’s in a hypertonic solution

A

It undergoes crenation.

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