Energy Reactions In Cells Flashcards
Define metabolism.
-the set of processes which derive energy & raw materials from foodstuffs and use them to support repair, growth and activity of the tissues of the body to sustain life.
Give features of a metabolic pathway.
- many reactions but few reaction types
- distinct reactions but integrated
- some happen in all cells, others restricted to some cell types
- have start,intermediates,end, interconnections
Define:
- Catabolic pathway
- Anabolic pathway
- catabolic=breakdown of molecules, release large amounts of energy,oxidative(release H)
- anabolic=synthesis of larger components, REQUIRE ATP, reductive(uses H released by catabolism)
What are the products of catabolic metabolism?
- smaller components e.g sugars, amino acids, fatty acids
- organic precursors e.g acetyl CoA
- reducing powers e.g NADH, NADPH
- energy for cell function i.e ATP
Define energy.
What type of work does the body carry out?
- the capacity to do work
- biosynthetic (anabolism- synthesis), transport (maintenance of ion gradients, nutrient uptake), specialised functions (muscle contraction, kidney-osmotic work)
What type of energy do cells use?
Can man use heat for energy?
- chemical bond energy
- No, man is isothermal (cannot use heat energy for work)
Define an exergonic reaction.
- basically means exothermic, releases heat.
- only reaction that can happen spontaneously
- delta G is negative
- reactants more energy than products
Define an endergonic reaction.
- requires energy (endothermic)
- cannot happen spontaneously
- delta G is positive
- products more energy than reactants
What are standard conditions?
What are conditions like in the cell?
- standard= 25 degrees Celsius, 1 mol conc, 1 atm pressure, pH= 7
- cell= non standard
Give some examples of fuel molecules.
What chemical changes do they undergo in the cell?
- NAD+, FAD+, NADP+
- they undergo redox reactions. They undergo oxidation to their reduced form (NAD+ TO NADH+ *remember x2 Hs are added, one gets lost in solution)
- contain components from B vitamins
How can energy released during oxidative metabolism be used?
How can energy released as reducing equivalents be used to drive energy requiring reactions?
*energy released from food-exergonic
Coupling systems
-directly- eg use of NADPH in biosynthesis
-indirectly-eg mitochondrial system to couple NADH to the production of an intermediate energy currency molecule
Why must ATP be continually synthesised?
- There is a limited amount of ATP, only enough for a few seconds
- therefore it must cycle; it is only a carrier not a store
- ATP is stable in the absence of specific catalysts this enables energy flow to be controlled.
- Define high and low energy signals
- give examples for each
- High energy signals are activated when [ATP] is high; anabolic pathways are activated
- signals include ATP,NADH,NADPH
- Low energy signals are activated when [ATP] is low; catabolic pathways are activated
- signals include AMP,ADO,NAD,NADP,FAD
What is creatine phosphate and when is it used?
Give the reaction including the enzyme needed
Creatine phosphate + ADP = ATP + creatine
- enzyme for reaction= creatine kinase
- when ATP levels are high, phosphate bond energy is stored in phosphocreatine
- if there’s a sudden fall in [ATP] bond is broken to release ATP.
How is creatine kinase a marker of myocardial infarction?
-Creatine kinase is made up of two subunits
-different isoform combinations are found in different tissues
CK-MM @70% / CK-MB @ 25-30% in heart muscle.
CK-MB specific to heart muscle, if MI it’s released from cells into other cells.
