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Life Sciences 141 > Chapter Four > Flashcards

Chapter Four Flashcards

1
Q

What is energy

A

The ability to do work

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2
Q

What is work

A

Done when a force moves on an object

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3
Q

What do all living things require

A

Energy to do work necessary for survival and reproduction

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4
Q

Where does energy come from

A
  • The sun
  • Plants use energy to make sugar and oxygen from CO2 and H2O ( photosynthesis )
  • Organisms eat plants to obtain this energy and use this sugar as a source of energy to do work
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5
Q

The total amount of energy in any object is the sum of energy 2 forms…

A
  1. Kinetic energy
  2. Potential energy
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6
Q

Explain Potential energy fully

A
  • Stored energy available to do work
  • Covalent bonds of molecules like ingredients in energy bars contain a form of potential energy known as chemical energy
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7
Q

Explain kinetic energy fully

A
  • Energy which is being used to do work, any moving object posses it
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8
Q

Explain calories fully

A
  • Are units used to measure energy
  • 1 Calorie is the amount of energy required to raise the temperature of 1 gram of water by 1 degree
  • Common unit for measuring food energy is kilocalories
  • 1 Kilocalorie = 1000 cal
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9
Q

Explain energy conversions in plants

A
  • Photosynthesis
  • Kinetic energy in sunlight is transformed into potential energy and stored in the chemical bonds of other molecules
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10
Q

Explain the energy conversion in respiration

A
  • Releases potential energy and heat is lost to the enviro in each and every step of the way
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11
Q

What is thermodynamics

A

The study of energy transformations

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12
Q

What does the 1st and 2nd law of thermodynamics describe

A

The energy conversions that are vital for life as well as those that occur in the non-living world

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13
Q

What is the 1st Law of Thermodynamics

A
  • AKA the law of energy conversion
  • Energy cannot be created or destroyed, although energy can be converted to other forms
  • Total amount of energy in the universe doesn’t change
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14
Q

Where is the most important energy transformation

A
  1. Photosynthesis
  2. Respiration
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15
Q

Explain the energy transformation in photosynthesis

A
  • Plants and some microbes use CO2; H2O and kinetic energy in the sun to produce sugars that are assembled into glucose and other carbs
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16
Q

Explain the energy conversion in respiration

A
  • Energy - rush glucose molecule changes back to CO2 and H2O liberating the energy necessary to power life
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17
Q

What is the 2nd Law of Thermodynamics

A

All energy transformations are inefficient because every reaction loses some energy to the surroundings as heat

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18
Q

Explain the 2nd Law of thermodynamics fully

A
  • Process of losing some energy as heat is irreversible as cells cannot use the energy that’s been converted to heat
  • This is due to heat being disordered and all the energy transformations become heat, it follows that all energy transformations must head towards incr disorder
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19
Q

Explain entropy fully

A
  • The measure of this randomness
  • The more disorganised a system is the higher the entropy
  • Because organisms are highly organised they may seem to defy Law 2
    - but they aren’t isolated from their surroundings
  • Instead a constant stream of incoming energy and matter allow organisms to maintain their organisation and stay alive using the info in DNA

( ultimately life remains ordered and complex because the sun is constantly supplying energy to the earth )

20
Q

Explain metabolism fully

A
  • Encompasses all the chemical reactions in cells, including those that build new molecules and those that break down the existing

-Photosynthesis and respiration are part of metabolism of the grass

  • Each reaction rearranges atoms into new compounds and each reaction either absorbs to releases energy
21
Q

What is catabolism

A

The process of breaking down materials within the body

22
Q

What is anabolism

A

The process of making larger substances from smaller substances

23
Q

What are the factors affecting metabolism

A
  • Amount and type of food consumed
  • Age and gender affect the speed of it within body
  • Temperature or disease can also incr or decr speed of it
24
Q

What are the groups of metabolic reactions

A
  • Endergonic reactions
  • Exergonic reactions
25
Q

Explain endergonic reactions fully

A
  • Requires an input of energy
  • Products contain more energy than reactants
  • Build complex molecules from simpler components
  • Energy source = sunlight

eg. photosynthesis in which glucose product contains more potential energy than CO2 and H2O

26
Q

Explain exergonic reactions fully

A
  • Releases energy
  • Products contain less energy than reactants
  • Breaks large, complex molecules into their smaller, simpler components
  • Products contain less energy than glucose

eg. cellular respiration in which glucose is broken down into CO2 and H2O

27
Q

What can electrons carry

A

Energy

28
Q

Where do most energy transformations occur

A

Oxidation - Reduction ( Redox )

29
Q

Explain oxidation and reduction fully

A
  • Oxidation = loss of electrons from a molecule; atom or ion
    - are exergonic as they release energy as the go from complex to simpler products
  • Reduction = gain of electrons plus any energy contained in the electrons
    - endergonic as they require a net input of energy
30
Q

Explain the electron donor and reduction half

A
  1. Has more potential before its oxidised than it does after the reaction is complete
  2. Is endergonic as the acceptor molecule has gained the energy rich electrons so it ends up with more potential energy than it had before
31
Q

Explain electron transport chains fully

A
  • Each protein accepts an electron from the molecule before it and passes it to the next
  • Small amounts of energy are released at each step
  • Cell uses this energy in other reactions
  • Each protein is first reduced and then oxidised
  • Both photosynthesis and respiration depend on it
32
Q

Some proteins are…

A

Electron shuttling specialists and groups of electron carriers often align in membranes

33
Q

What does ATP stand for and do

A
  • Adenosine Triphosphate
  • Temporarily stores energy
34
Q

Explain ATP fully

A
  • Cellular Energy Currency
  • Is a nucleotide with an adenine bases, 5 carbon sugar and 3 phosphate gras
  • Phosphate grps place 3 negative charges very close to on another
  • Eukaryotic cells = mitochondria produces most of ATP during CR
  • Energy released from it in exergonic reactions is where the endmost phosphate group is removed through hydrolysis to yield Adenosine diphosphate, a free phosphate group, and a burst of energy
35
Q

Explain ATP usage

A
  • Required in large amounts and can be recycled at a furious pace
  • Essential to life but organisms don’t stockpile it in large quantities

BUT cells store energy rich molecules like fats; starch and glucose

  • ATP is low = cells divert some of their lipid and carb reserves to the pathways of CR
  • For animals that hibernate, stored fat and glycogen are crucial for winter
36
Q

Explain enzymes speeding biochemical reactions up

A
  • Are organic molecules that catalyse chemical reactions without being consumed
  • Among the most important biological molecules
  • Most = proteins but some may be made up of RNA
  • Functions = vary and many organelle mitochondria; chloroplasts; lysosomes )
  • Speed up reactions by lowering the activation energy which is the amount of energy required to start a reaction
37
Q

Explain enzymes and substrates fully

A
  • Bring reactants ( substrates ) into contact with one another so that less energy is required for the reaction to proceed
  • Active site shape ( the region to which the substrates bind ) is the key to picking up substrates
  • Fit like puzzle pieces and once the reaction occurs the enzymes release the products
38
Q

The enzyme substrate complex is…

A

A temporary molecule formed when an enzymes comes into perfect contact with its substrate

39
Q

What conditions are enzymes very sensitive to in the cell

A
  1. pH changes = mostly between 6&8 and pepsin in stomach ( 2&4 )
  2. Salt concentrations becoming too high or low
  3. Temperature = each has an optimum temp at which it functions best thus too high temps cause denaturing
  4. Pharmaceutical drugs can also inhibit enzyme function
40
Q

Examples of enzyme names

A
  • Protease = protein and polypeptide breakdown
  • Lipase = lipids and fats breakdown
  • Transferase = transfer functional gaps from 1 molecule to the other
  • Dehydrogenase = removes hydrogen atoms from molecule
  • Amlyse = breaks down starch into simple sugars
  • Oxidoreductase = catalyses oxi-red reactions
41
Q

Explain the positive feedback

A
  • Reinforces an existing condition

eg. blood clotting = once clot starts forming the reaction accelerates which further stimulates clotting

42
Q

Explain co-factors fully

A
  • Non - protein helpers
  • Substances that must be present for an enzymes to catalyse a chemical reaction
  • Are often oxidised or reduces but aren’t consumed instead are returned to original state once reaction is completed
  • Some are metal and others are organic molecules called coenzymes
43
Q

What happens if a diet lacks vitamins

A

Can lead to a reduced enzyme function and eventually serious illness or even death

44
Q

Explain cells controlling reaction rates fully

A
  • Precisely control reaction rates
  • If they don’t, some important compounds would be in short supply and some would be wasteful
  • Do this through negative and positive feedback
45
Q

Explain the negative feedback fully

A
  • Slows down the synthesis of a chemical products
  • Inhibits enzymes that catalyses the initial reaction and the entire pathway slows down
46
Q

Explain the 2 ways in which negative feedback works fully

A
  1. Competitive inhibition = inhibitor attaches to active site preventing it from binding to substrate
  2. Noncompetitive inhibition = inhibitor binds enzyme at a location other than active site ( Allosteric site ) changing the shape of the enzymes so it can’t fit substrate

Life Sciences 141 (22 decks)

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