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Medical Cell Biology And Genetics > Topic 5: Energy Reactions in cells > Flashcards

Topic 5: Energy Reactions in cells Flashcards

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1
Q

What is cell metabolism

A

The set of processes which derive energy and raw materials from food stuffs and use them to support repair, growth, and activity of the tissues of the body to sustain life
By making small chemical changes of few types
Reactions are organised into metabolic pathways - some are in all, or multiple cells or restricted to compartments

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2
Q

What are the functions of metabolism

A

Conversion of food to energy to run cellular processes
Conversion of food to cellular blocks for proteins, lipids, nuclei acids and carbs
Elimination of metabolic waste

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3
Q

Describe the relationship between catabolism and anabolism

A

Catabolic - break down larger molecules to smaller, releasing free energy. It is oxidative so releases hydrogen atoms - ‘reducing power’
Anabolic - synthesise larger components from intermediary metabolites with the use of energy released from catabolism (atp). Reductive - use H released in catabolism

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4
Q

Why do cells need a continuous supply of energy

A
  1. Bio synthetic work (anabolism ) - synthesise components
  2. Transport - maintain ion gradients, nutrient uptake
  3. Mechanical - muscle contraction
  4. Electric - nervous impulse
  5. Osmotic - kidney
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5
Q

What is a redox reaction

A

Both oxidation and reduction

Oxidation - removal of electrons or H atoms
Accompanied by reduction
Reduction - gain
OILRIG

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6
Q

What is the the role of redox reactions and H carrier molecules in metabolism

A

When undergoing redox, electrons and protons are transferred to carrier molecules
Include: NAD+, NADP+, FAD
In reduced form: NADH +H+, NADPH + H+, FADH2
concentration of opposing forms of carriers constant - cycle between oxidative and reductive processes

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7
Q

What are the roles of ATP?

A

Must be recycled as limited
It is stable in the absence of specific catalysts - Enables flow of energy to be controlled, when energy levels high, negative feedback, so stop

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8
Q

What are the roles of other molecules containing high energy

A

Energy is melt often stored in form of glycogen or triglyceride
Creating phosphate is used when cells undergo increased metabolic activity and this reserve of energy is used - creatine kinase - phosphocreatine + ATP
When ATP - creatine phosphate is formed + ADP
If low ATP - reaction reversed to form creatine + ATP

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9
Q

Explain the role of high and low energy signals in the regulation of metabolism

A 
When there is lots of ATP = anabolic pathways are activated
When there is little ATP, ADP high, AMP high = catabolic pathways activated 
Adenylate kinase(myokinase): 2ATP -> ATP + AMP
AMP = lower energy signal
High energy(energy levels high) - anabolic pathways so ATP, NADH, NADPH, FADH2
Low energy - catabolic pathways (energy used up) so ADP, AMP, NAD+, NADP+, FAD
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10
Q

What is a metabolic pathway

A 
Start pointe
Intermediates (metabolites)
End points
Interconnections between different pathways
Two types - catabolic and anabolic
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11
Q

What are the waste products of cell metabolism

A

Carbon dioxide
Water
Urea

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12
Q

What are the products of catabolic metabolism

A
  1. Building block materials (sugars, amino acids)- allow fo cell growth, division and repair
    BREAKDOWN INTO
  2. Organic precursors (acetyl coA) - allow for inter conversion of building block material
  3. Bio synthetic reducing power (NADH, NADPH)
  4. Energy for cell function (ATP)
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13
Q

What are the energy contents of food

A

Fat - 37g-1
Carb - 17
Protein - 16
Alcohol - 29

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14
Q

What does the body need energy for

A
  1. Basal metabolic rate - 1700/1400kcal- awake, sitting
  2. Activity - 1000-3000
  3. Specific dynamic action of food - 150 - ingestion, digestion etc

Energy is lost as heat

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15
Q

What happens if energy intake > energy required

A

Excess energy stored for growth such as synthesis of new tissue
And production of adipose tissue

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16
Q

What happens if energy intake< energy requirement

A

Tissue is lost

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17
Q

What forms do energy exist in

A

Heat, light, mechanical, electrical, osmotic, chemical bond

Biology uses chemical bond energy predominately without producing heat as can not use that

18
Q

Describe chemical bond energy

A

All cellular activities involve chemical bonds being broken or formed
If exergonic - release energy
Endergonic - require energy

19
Q

Which reactions can only occur spontaneously

A

Exergonic
Useful energy = free energy, G (gibbs)
Delta G = negative = exergonic

20
Q

What is an exergonic reaction

A

Spontaneous
Reactants of a higher energy level that products
DeltaG is negative

21
Q

What is an endergonic reaction

A

Not spontaneous
Reactants of lower energy level than products so energy needed to put into the system
Delta G = positive

22
Q

What are the standard conditions for free energy

A

25 degrees
1atm
1 mol
pH= 7

23
Q

What are the standard conditions fo free energy in the cell

A

Change in G = change in G in standard conditions + RT x logn(products)/(reactants)

Value indicates ether spontaneous or not
Not rate

24
Q

What processes are H carrier molecules used for

A

ATP production - (NADH + H+)

Biosynthesis (NADPH)

25
Q

What happens to H carrier molecules

A

Contain components from B vitamins

Converted to reduced form by adding two H atoms
One - h+ dissociates into solution
One - present in the molecule

26
Q

How can energy released during oxidative metabolism be used to drive processes?

A

Energy released by oxidation of food - exergonic

Directly - use of NADPH in biosynthesis, oxidised back, substrate reduced by H (bio synthetic Reduction)
Indirectly - mitochondrial system to couple NADH to form ATP(ATP synthesis)

27
Q

What is the structure of ATP

A

Adenine
Ribose
Triophosphate

28
Q

How can ATP release energy

A 
The phosphate bond can be hydrolysed to release an inorganic phosphate and ADP
ATP + H2O -> ADP + Pi
-31kjmol-1
ADP can then hydrolysed to AMP 
ADP + H2O -> AMP + Pi
-31kjmol-1
29
Q

Catabolism involves the breakdown of chemicals to release..

A

Reducing power

Energy (ATP)

30
Q

Reducing,power is converted to ATP by

A

Oxidative phosphorylation

31
Q

Clinical markers related to creatine metabolism

A

Creatine kinase is a marker of myocardial infarcation
One subunit is made of CK-MM and other is CK-MB - specific to heart
CK is released from cardiac cells when damaged in heart attack, present in blood, diagnosed if in correct combination

32
Q

Creatine and phosphocreatine can randomly break down to form

A

Creatinine

Constant formation

33
Q

How is creatinine used as a clinical marker

A

Excreted via kidneys
Creatinine excretion per 24hr = muscle mass
Creatinine concentration in urine = urine dilution (high creatinine - urine concentrated)
Can be used to estimate urinary loss of many substances such as hormones in pregnancy

34
Q

Which phosphate group on ATP is hydrolyzed when energy is needed to drive cellular work?

A

Gamma phosphate

35
Q

Which substance is used to supply the electron transport chain with high-energy electrons derived from metabolic substrates?

A

NADH

36
Q

When ATP levels are high in skeletal muscle, energy may be temporarily stored in which substance?

A

Phosphocreatine

37
Q

How much atp is produced by glycolysis

A

2

38
Q

Exergonic reactions,

A

Delta g less than 0
Spontaneous
Catabolism - oxidation

39
Q

Endergonic reactions

A

Delta G more than 0
Not spontaneous
Requires energy

40
Q

Catabolism

A

NAD+ -> NADH

41
Q

Low creatinine

A

Lots of urine formed

Medical Cell Biology And Genetics (36 decks)

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