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Biology > Topic 5 - Energy for Biological Processes > Flashcards

Topic 5 - Energy for Biological Processes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is energy

A

The ability to do work

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2
Q

Why do we need energy

A
  • Metabolism
  • Movement
  • Active transport
  • Maintenance, repair and division of cells
  • Production of substances
  • Maintenance of body temperature
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3
Q

Structure of ATP

A
  • Mononucleotide (nucleotide occurs singly)
  • x3 phosphates
  • Adenine
  • Ribose sugar
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4
Q

ATPase ?

A

The enzyme that catalyses the breakdown of ATP (ATP synthase catalyses the synthesis of ATP)

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5
Q

Redox reactions?

A

Reduction and oxidation reactions in which one reactant loses electrons (is oxidised) and another gains electrons (is reduced)

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6
Q

Where does the energy to produce ATP usually come from?

A

Usually from breakdown ~(catabolic) or redox reactions

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7
Q

Advantages of ATP

A
  • Instant source of energy
  • Releases energy in small amounts as needed
  • Resynthesized
  • It is mobile and transports chemical energy to where it is needed in the cell
  • Universal energy carrier and can be used in many different chemical reactions
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7
Q

What is respiration

A
  • The process by which energy in organic molecules is made available for an organism to do biological work
  • Cellular respiration occurs in every living cell to produce ATP
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7
Q

Uses of ATP

A
  • Muscle contraction
  • Control of cytoskeleton
  • Active transport
  • Photosynthesis
  • RNA synthesis
  • Protein synthesis
  • DNA synthesis
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7
Q

Aerobic respiration

A

Refers to the cellular respiration that depends on oxygen

Glucose + oxygen > carbon dioxide + water + ATP

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8
Q

Why doesn’t respiration produce flames like combustion?

A
  • Cells have to oxidise glucose in a much more controlled way so that the heat generated does not destroy them
  • The heat is spread over many biochemical reactions which occue in a series of steps
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9
Q

What are some features of the structure of mitochondria?

A
  • Outer membrane
  • Inner membrane
  • Compartment between inner and outer membrane
  • Mitochondrial matrix
  • Stalked particles
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10
Q

Summary of glycolysis

A
  • Occurs in the cytoplasm and does not require oxygen
    1) Glucose (6 carbon sugar) phosphorylated by 2 molecules of ATP
    2) This molecule is unstable and immediately breaks down into 2 molecules of glycerate 3-phosphate (2 x 3 carbon molecules)
    3) 2 Glycerate 3-phosphate oxidised into 2 pyruvate (3 carbon molecules)
    4) 2 NAD coenzymes are oxidised into 2 reduced NAD (NADH)
    5) 2 molecules of ADP are phosphorylated to 2 molecules of ATP
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11
Q

What is the link reaction?

A

It links glycolysis in the cytoplasm with the krebs cycle in the mitochondria (matrix of mitochondria)
Glucose is too large and there’s no transport proteins to allow it to enter the mitochondria (link reaction allows this)

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12
Q

Describe process of link reaction

A

Pyruvate converted into acetyl coenzyme A with help of NADH (dehydrogenation), loss of carbon dioxide (decarboxylation) and addition of CoA

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12
Q

Describe process of Krebs cycle

A
  • Consists of a series of enzyme-controlled reactions
  • 2 carbon (2C) Acetyl CoA enters the circular pathway from the link reaction
  • 4 carbon (4C) oxaloacetate accepts the 2C acetyl fragment from acetyl CoA to form the 6 carbon (6C) citrate (coenzyme A is released in this reaction)
  • Citrate is then converted back to oxaloacetate through a series of oxidation-reduction (redox) reactions
13
Q

Regeneration of oxaloacetate

A

Oxaloacetate regenerated through redox reactions
- Decarboxylation of citrate (6C) , releasing 2 CO2 as waste gas
- Oxidation (dehydrogenation) of citrate
- Releasing H+ that reduce coenzymes NAD and FAD
- 3 NAD and 1 FAD & H+ > 3NADH and 1FADH2 substrate-level phosphorylation
- Phosphate transferred from one of the intermediates to ADP forming 1 ATP

14
Q

Products of Krebs cycle

A
  • ATP
  • 3 NADH
  • 1 FADH2
  • CO2

(for each glucose molecule there are 2 turns of the krebs cycle)

15
Q

Electron Transport Chain (oxidative phosphorylation) requires:

A
  • In presence of oxygen, energy is released to allow phosphorylation of ADP
  • Oxygen (to accept the electrons and hydrogen at the end)
  • Reduced NAD and FAD which are carrying hydrogen
  • Electron carriers (cytochromes)
16
Q

Describe oxidative phosphorylation

A
  • Reduced NAD/FAD, transfer H+ ions/electrons
  • From coenzyme to coenzyme/ carrier to carrier/ along an electron transport chain by series of redox reactions
  • driven by oxygen as terminal acceptor pf electrons
  • H+/protons passed into intermembrane space
  • H+/protons flow back through stalked particles/ ATP synthase
  • by chemiosmosis this energy used to synthesise ATP from ADP and inorganic phosphate by condensation reaction
17
Q

Products of the electron transport chain

A
  • ATP
  • Water
  • NAD
  • FAD
18
Q

Chemiosmosis

A

Process that moves hydrogen ions through the membrane along a concentration gradient. It links the electron transport chain with production of ATP

19
Q

What’s oxygen used for in electron transport chain?

A

Acts as terminal electron/proton acceptor to form the safe by-product water.

20
Q

Anerobic respiration

A

Takes place in the absence of oxygen
It involves glycolysis and generates ATP and NADH.
Because of lack of oxygen NADH is oxidised by fermentation a process in which no more ATP molecules generated

21
Q

2 types of anerobic fermentation

A

1) Alcoholic fermentation (2CO2 released)
2) Lactate fermentaion

22
Q

Ethanol fermentation

A
  • Reduced NAD transfers its hydrogens to ethanol to form ethanal
  • First step of the pathway pyruvate is decarboxylated to ethanol producing CO2
  • Then ethanal reduced to ethanol by enzyme alcohol dehydrogenase
  • Ethanal is hydrogen acceptor
  • Ethanol cannot be further metabolised - waste product
23
Q

Lactate fermentation

A
  • reduced NAD transfers its hydrogen to pyruvate to form lactate
  • Pyruvate reduced to lactate by enzyme lactate dehydrogenase
  • Pyruvate is a hydrogen acceptor
  • Final product lactate can be further metabolised
24
Q

Autotroph

A

An organism which makes complex organic compounds e.g. glucose from simple inorganic compounds

25
Q

Heterotroph

A

An organism that obtains complex organic compounds e.g. glucose by feeding on other organisms or their dead remains

26
Q

Photosynthesis overview

A
  • Series of chemical reactions that occur in autotrophs such as plants and algae
  • Converts light energy into chemical energy which is then stored in biomass of autotrophs (producers)
  • Light energy used to split strong bonds in water
  • Oxygen released into the atmosphere as a waste products
  • Hydrogen combined with carbon dioxide to produce glucose
  • Chemical energy stored in bonds in glucose molecules - therefore function as a fuel for respiration
  • Hydrogen stored in glucose molecules
27
Q

Light dependent reaction

A

1) electrons are excited to higher energy level by energy trapped by chlorophyll molecules in the thylakoid membranes.
2) Electrons passed down electron transport chain from one electron carrier to the next
3) process generate ATP from ADP and inorganic phosphate in a process called photophosphorylation
4)This can be cyclic or non-cyclic
5) Reduced NADP also generated in light-dependent stage as electrons transferred to NADP along with a proton
6) Both ATP and reduced NADP used in light-independent stage of photosynthesis

28
Q

Cyclic phosphorylation

A

1) A photon of light hits a chlorophyll molecule
2) Electrons are excited
3) Electrons taken up by an electron acceptor
4) Electrons passed along an electron transport chain. Energy is released, ATP is synthesised
5) Electron returns to photosystem l chlorophyll

29
Q

Non-cyclic phosphorylation

A

1) Photon hits chlorophyll in photosystem ll
2) Electrons are excited
3) Electrons taken up by an electron acceptor , passed along an electron transport chain to photosystem l chlorophyll. Energy released, ATP is synthesised
4) Photon hits chlorophyll in photosystem l
5) Photolysis - water dissociates into hydrogen and hydroxide ions. Replaces lost electrons in photosystem ll chlorophyll
6) Electrons are excited
7) Electrons are taken up by an alectron acceptor, passed along an electron transport chain to NADP
8) NADP takes up an H+ ion from dissociated water and forms reduced NADP
9) Hydroxide ions react together to from water and oxygen

30
Q

Light independent reaction

A

AKA Calvin-Benson cycle

Final stage of photosynthesis which uses ATP (source of energy) and reduced NADP (reducing power) to produce glucose.

1) RuBP combined with carbon dioxide (carbon fixation), catalysed by RUBISCO
2) RuBP converted into 2 glycerate 3-phosphate (GP) molecules
3) Reduced NADP and ATP used to convert GP to GALP
4) Some GALP molecules used to make glucose, then converted to organic compounds like lipds, amino acids & nucleic acids
5) Remaining GALP molecules used to reform RuBP with help of ATP

Biology (10 decks)

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