ch 3 cell metabolism

Question 1

reactions

Answer 1

• A + B -> C + D
• or A + B <–> C + D (bidirectional)
• C6H12O66O2->6CO2+6H2O is cellular respiration
• –> forward
• <– reverse
• whichever reaction is happening faster will determine if you are making more A and B or more C and D

Question 2

catabolic vs anabolic reactions

Answer 2

• catabolic: breakdown of larger molecules into smaller. releases energy
• anabolic: production of smaller. requires energy

Question 3

bioenergetics: laws of thermodynamics

Answer 3

• first law: energy cannot be destroyed or created, only transformed
• second law: with every transfer or transformation of energy, some useable energy is released as heat

Question 4

first and second law of thermodynamics

Answer 4

• first: conversion of light energy into glucose by plants
• second: with every transfer or transformation, some energy that could have been used to do work escapes as heat
• heat is the cost of every reaction

Question 5

endergonic vs exergonic

Answer 5

endo: chemical reactions that require an input of energy. products contain more free energy than the reactants. energetically uphill. the products have more energy than the reactants.
exo: chemical reactions that release energy. products will have less free energy. energetically downhill. the reactants have more energy than the products.

Question 6

how do eno reactions occur?

Answer 6

• energy from the environment (food) is broken down in exergonic reactions to drive the endo reactions
• for endo to happen exo needs to happen nearby to release energy for endo

Question 7

activation energy

Answer 7

• the energy required for the reactants to engage in a reaction
• most molecules lack the activation energy needed for a reaction to occur
• all reactions require activation energy
  ex: pool ball deep side, pool ball shallow side: they will eventually touch but if you go in and MAKE them touch it speeds up (catalyst = how quickly it happens)
• enzymes speed up chemical reactions by lowering activation energy

Question 8

enzymes

Answer 8

• a class of proteins that serve as biological catalysts (increase reaction rate, are not changed by the reaction so can be used repeatedly, have no effect on free energy of reactants or products, in enzymatic reactions reactants are substrates)

Question 9

catalyzed vs noncatalyzed reactions

Answer 9

• the energy of both the reactants and the products is not affected by the presence of an enzyme. only thing that changes is the activation energy
• lowers amount of time/energy it takes for reaction to reach its peak

Question 10

ligand - receptor interactions

Answer 10

• ligand is anything that binds to a receptor (protein)
• specificity is based on shape
• based on affinity for the protein bc it can make more bonds with the protein

Question 11

naming enzymes

Answer 11

• all enzymes end with -ase and first part applies to the function
• phosphatases: removes phosphate groups
• synthetases: catalyze dehydration synthesis

Question 12

enzyme activity

Answer 12

• measured by the rate at which substrate is converted to product
• influenced by: concentration of enzyme and substrate, enzyme-substrate affinity, temp, pH, regulation by modulators (allosteric regulation), covalent regulation (regulation by chemical groups), feedback inhibition, feedforward activation)

Question 13

regulation of enzymatic reaction rates

Answer 13

• how to speed up reaction?
• add more enzyme but once the enzyme concentration is all binded to the substrate the concentration doesnt matter (affinity)
• temp: increase in temp will increase the rate of reactions until it gets too hot then enzyme is denatured
• pH: function at specific pH. if they’re in the wrong area, they will denature

Question 14

regulation of enzyme reaction rate: covalent regulation

Answer 14

• certain enzymes in the body whose sole function is to activate or inactivate other enzymes

Question 15

phosphorylation and de-phosphorylation

Answer 15

• kinases add a phosphate group to another enzyme and turns these enzymes ON
• phosphates remove a phosphate group from an enzyme and turn these enzymes OFF

Question 16

metabolic pathways

Answer 16

• most reactions are linked together in a chain or web
• these begin with an initial substrate and end with a final product with many along the way
• assembly line fashion with several different enzymes involved

Question 17

feedback inhibition

Answer 17

• C is an allosteric inhibitor of E2
• shuts itself off

Question 18

end product inhibition

Answer 18

• some metabolic pathways have more than one possible end product
• if F begins to build up in the cell, enzyme 3 will be inhibited and the pathway will make more F’
• if F’ begins to accumulate, enzyme 3’ will be inhibited and the pathway will make more F

Question 19

ATP: the medium of energy exchange

Answer 19

• ATP is universal battery that can power a lot of ender reactions
• our cells break down ATP through ATP hydrolysis
• when water gets added to ATP, a phosphate group gets removed, this is very exergonic
• our food gets broken down during cellular respiration and the energy released is used to make ATP
• ATP then gets broken down to provide energy for ender reactions like cellular movement, synthesis, and activation transport