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FHS > Biochemistry & metabolism > Flashcards

Biochemistry & metabolism Flashcards

1
Q

Biochemistry basic facts:

A
  • Chemicals are either organic (anything that contains carbon as part of its chemical makeup) or inorganic (anything that generally lacks carbon)
  • Salts, acids and bases are all electrolytes
  • Acids release hydrogen (H+) ions; Bases take up H+. The more H+ ions in a solution (i.e., blood), the more acidic that solution is, but the lower the concentration of H+, the more basic, or alkaline, the solution is.
    ions
  • Bicarbonate (HCO3-) and Ammonia (NH3) are important in reducing blood acidity (by helping to remove excess H+).
  • Our renal and respiratory systems are incredibly important at maintaining blood pH homeostasis, via the use of chemical buffers.
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2
Q

Macronutrients=

A

Are a big group of specific molecules:
1. Carbohydrates
2. Lipids
3. Proteins

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3
Q

Carbohydrates=

A

a group of molecules which include sugars and starches. They are made up chemically of carbon, hydrogen and oxygen atoms.
Carbohydrates are like building blocks of sugar. They are grouped by how many sugar units they have:
1. Monosaccharides (means one, smallest and simplest sugars)
2. Disacccharides (di means two, made by joining two blocks together)
3. Polysaccharides (poly means many, big chains of sugar blocks linked together)

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4
Q

Lipids=

A

are insoluble in water.
Lipids are also made up of carbon, hydrogen and oxygen.
They include triglycerides, phospholipids, and steroids. The building blocks of lipids are Fatty acids and Glycerol

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5
Q

Proteins=

A

Protein is the basic structural material of the body, accounting for 10-30% of cell mass, and they also make up enzymes, haemoglobin in blood, and the functional contractile proteins of muscle.
The building blocks of proteins are amino acids.

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6
Q

What is the chemical make-up of the macronutrients?

A

Each molecule is made up of atoms connected by bonds.
Carbohydrate –>glucose- C6 H12 O6
Lipids –> Triglycerides- 3 x Fatty acids & 1x Glycerol
Proteins –> Amino acids-
So, breaking bonds of a glucose molecule, or a triglyceride molecule, or an amino acid will release energy. This energy is harnessed and used to produce ATP, which is the body main energy source.

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7
Q

Metabolism=

A

All biochemical reactions occurring in the body. We are extracting nutrients from the food that we’re consuming and we’re using this energy that is provided to drive numerous activities and body processes:
- Muscle contraction
- Nerve impulse conduction
- Active transport
- Digestion
- Biosynthesis
- Storage of nutrients
- Maintenance of body temperature etc
Metabolic pathways are either catabolic or anabolic.

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8
Q

Catabolic Vs Anabolic pathways=

A

Catabolic:
- Break down complex molecules to simpler ones e.g., cellular respiration
- They are exothermic reactions because they release energy as heat + ATP
Anabolic:
- Build up of the complex molecules of life e.g., biosynthetic reactions (protein synthesis)
- They are endothermic reactions because they require energy input in the form of ATP

= all reactions are dependant on the actions of enzymes

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9
Q

Metabolic pathways=

A

Chains or reactions. Each step catalysed by specific enzymes. Some reactions are reversible, others irreversible.
The start of any reaction is known as the substrate, e.g., in carbohydrate metabolism, glucose is our substrate that is going to be broken down to release energy. Each step thereafter releases a new metabolite; that is a new substance that is a derivative of the substrate.
Different metabolic pathways link up via common metabolites.

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10
Q

Adenosine triphosphate (ATP)=

A

We us use ATP that is generated by differing energy systems in the body to drive our metabolic work.
ATP is the only form of energy that can be used to power the cells activities.
It is a temporary store of energy and is able to release energy in a one-step chemicals; reaction
ATP –> ADP + P
(ATP breaks down into ADP and phosphate group, example of reversible reaction)

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11
Q

Stored ATP=

A
  • ATP is stored in very small amounts in the body (80-100g).
  • It is an immediate energy source & enough to supply energy for the first 2-6 seconds of physical activity.
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12
Q

Creatine phosphate=

A
  • CP is an energy rich molecule but can’t be used directly.
  • It is used to quickly convert ADP back to ATP by direct phosphorylation (donating a phosphate group)
  • Immediate energy store in muscles (first 10s of physical activity)
  • Creatine phosphate stores are limited and not an efficient way of providing enough ATP to continually fuel the body’s activities
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13
Q

Creatine Kinase=

A
  • Is an enzyme that catalyses direct phosphorylation
  • Normally found inside healthy muscle, muscle damage causes CK to be lost into the blood stream
  • Damaging exercise/ trauma/ etc., cause increase in blood ck
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14
Q

Glucose=

A

Glucose is our predominant substrate for cellular respiration.
Glucose can be obtained from:
- Free blood glucose (e.g., after a meal)
- Glycogenolysis= (breakdown of glycogen stores in muscle or liver)
- Gluconeogensis= formation of glucose from other nutrients in the liver
Glucose can be catabolised completely:
C6H12O6 + 6O2 → 6H2O + 6CO2 + 38 ATP + heat
Glucose = C6H12O6
Oxygen = O2
Water = H2O
Carbon Dioxide = CO2

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15
Q

Catabolism of glucose has three linked metabolic pathways:

A
  1. Glycolysis (‘anaerobic pathway’)
  2. Krebs cycle
  3. Electron transport chain (‘aerobic pathway’)
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16
Q

Glycolysis=

A
  • Glucose (6C) is broken down to 2 pyretic acid (3C) molecules in the cytoplasm
  • Uses 2 ATP to ‘activate the glucose’ then forms 4 ATP through the pathway (net gain of 2 ATP)
  • Intermediate metabolites are ‘oxidised’, hydrogens and their electrons are removed and picked up by a carrier NAD+ which is converted (reduced) to 2 NADH + H+
17
Q

What are the two possible outcomes of glycolysis?

A
  1. If little oxygen is available pyruvic acid is converted to lactic acid. NADH + H+ converted back to NAD+ (anaerobic pathway)
  2. If enough oxygen is available, pyruvic acid enters mitochondria for the Krebs cycle (aerobic pathway)
    Potential for production of 38 ATP per molecule of glucose
18
Q

Krebs cycle=

A
  • Occurs in the mitochondria
  • Involves building/ breaking bonds
  • During the cycle, carbon atoms are removed as CO2 waste- this depends n acetyl-CoA entering the cycle
19
Q

Oxidation reactions=

A

Glycolysis and the Krebs cycle include oxidation reactions.
Oxidation= addition of oxygen, removal of hydrogens & removal of electrons

20
Q

Catabolism of fat/ lipids=

A

129 ATP’s
- The use of lipids/ triglycerides
- Process of beta-oxidation will break down triglyceride into 2 carbon molecules (2C).
- These 2 carbon molecules (2C) is converted into acetyl-CoA
- If enough O2, full catabolism of fat will occur through Kreb’s cycle and electron transport chain (ETC).
- With very high fat use, Acetyl-CoA is connected to ketones –>ketoacids.
- Blood then becomes very acidic due to reduced availability of carbohydrates

21
Q

When does catabolism of fats/ lipids happen and what are the effects?

A

When does it happen:
- Low CHO diet
- Starvation
- Uncontrolled diabetes mellitus
What are the effects:
- Kussmaul’s respiration= deep & fast
- Ketone breath= smells like pear
- Ketones in urine
- Eventually coma= death

22
Q

Overall cellular respiration=

A

Glucose/ fats + O2 –> ATP + CO2 + H2O

23
Q

Catabolism of protein=

A

Used when other sources are unavailable (e.g., starvation) or during prolonged exercise (e.g., the end of a marathon).
1. In the liver, the amine group (NH2) is removed from amino acids= deamination.
- Amine group converted to ammonia (NH3) then to urea (excreted in urine).
2. Remaining part of molecules may be converted to pyruvic acid or Acetyl-CoA.
- Carry on to the Kreb’s cycle

24
Q

Cellular respiration=

A

Series of metabolic reactions that convert stored energy in nutrients (food) into usable energy- ATP- for biological processes

25
Q

Absorptive state=

A

In the fed state- following digestion- when nutrients are being absorbed into the blood stream. Key hormone in the absorptive state is insulin.
So, at rest:
- Free glucose can be used to produce ATP via oxidative pathways
- Lipids are used for synthesis
- Amino acids may be used for protein synthesis
- Excess blood glucose is stored via glycogenesis as glycogen
- Excess FAs, AAs and glucose, once glycogen stores are full, are converted and stored as fat (i.e., adipose tissue & triglycerides) via lipogenesis

26
Q

Post- absorptive state=

A

In the fasting state, following absorption, when nutrients have been stored and/ or are being used for biological processes in the body. Key hormone in post-absorptive state is glucagon.
So, at rest:
- Stored glycogen is broken down via glycogenolysis to produce free glucose
- Stored triglycerides are broken down via lipolysis to produce FAs and glycerol
- During a prolonged fast or increased demand, alternative substrates can be used to produce glucose via gluconeogensis
- Free glucose can be used to produce ATP via oxidative pathways.
- Fatty acid oxidation occurs

27
Q

What is the normal blood glucose range?

A

= 4-7 mol/L
If blood glucose drops below 4mmol/L–> hypoglycaemia

28
Q

Glycogenesis =

A
  • Glucose molecules are linked together in long chains to form glycogen
  • It occurs in absorptive state (when blood glucose levels are surplus to energy requirements)
  • Can only happen in presence of insulin
29
Q

Glycogenolysis=

A
  • Is glycogen splitting, happens in stressful situations
  • Happens in the post-absorptive state
  • Influenced by glucagon, epinephrine and cortisol
30
Q

Gluconeogenesis=

A

The creation of new glucose from other non CHO (carbohydrate) sources through:
1. lactic acid= by product of anaerobic glycolysis
2. Glycerol= from lipolysis or digestion of dietary fats & oils
3. Amino acids= from dietary protein or body protein stores
So, provides glucose when dietary intake is insufficient or absent.

31
Q

Fats (lipids)=

A
  • The most concentrated energy store
  • Energy yield from fat is much higher than from carbohydrate or protein
  • 50% of fat storage is in subcutaneous adipose tissue
  • Balance of storage is on other fat depots around the body
32
Q

Lipogenesis=

A
  • Storing fat in absorptive state
  • Is multiple pathways whereby ingested glucose, FAs and AAs are converted to fat
  • Influenced by the presence of insulin
33
Q

Lipolysis=

A
  • In post absorptive state
  • Stored triglycerides in adipose are broken down to Glycerol & FAs.
    Fatty acids:
  • Can be used for energy in most cells (β-oxidation; Krebs; ETC).

Glycerol:
- Can be converted to Pyruvic Acid for ATP production (Krebs; ETC).
- Or undergo gluconeogenesis (liver) for maintaining blood glucose.
Influenced by Glucagon; Epinephrine; Cortisol; Thyroid hormones.

34
Q

Ketoacids=

A
  1. May enter Kreb’s cycle and be fully catabolised for energy.
  2. May be converted to glucose.
  3. May be converted to fat.
35
Q

What do physiological responses to change in metabolic states involve?

A

Neurohormonal Regulation

FHS (31 decks)

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