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Biology - Molecules to cells > Section 2: Chemistry of life Part 2 > Flashcards

Section 2: Chemistry of life Part 2 Flashcards

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1
Q

What is fermentation?

A

it is a partial degradation of sugars that occur without O2

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2
Q

What does aerobic respiration do?

A

it consumes organic molecules and O2 (and then yields ATP

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3
Q

What is anaerobic respiration?

A

similar to aerobic respiration but does not use oxygen

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4
Q

What does cellular respiration include

A

it includes both anaerobic and aerobic respiration (sometimes there is not oxygen that can be used so other molecules are relied on)

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5
Q

What is a redox reaction?

A

they transfer electrons between reactants

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6
Q

What happens in oxidation?

A

substances loose electrons - oxidized (electron acceptor is called the oxidizing agent)

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7
Q

What happens in reduction?

A

substance gains electrons - reduced (electron donor is called the reducing agent)

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8
Q

What happens in cellular respiration?

A

glucose and other organic molecules are broken down in a series of steps, electrons from organic compounds are usually transferred to NAD+ first (a coenzyme)

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9
Q

What is NAD+?

A

it acts as an oxidizing agent

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10
Q

What are the three stages of cellular respiration?

A
  1. Glycolysis (breaks down glucose into two molecules of pyruvate)
    2 Pyruvate Oxidation and the Citric Acid cycle(completes the breakdown of glucose)
    3 Oxidative Phosphorylation: electron transport and chemiosmosis (accounts for most of the ATP synthesis)
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11
Q

What generates most of the ATP in cellular respiration?

A

oxidative phosphorylation generates most of the ATP, about 90%

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12
Q

What are the two major phases of glycolysis?

A
  • Energy investment phase
  • Energy payoff phase
    (glycolysis occurs whether or not oxygen is present)
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13
Q

What must happen before the citric acid cycle can start?

A

Pyruvate must be converted to acetyl-CoA which links glycolysis to the citric acid cycle

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14
Q

When pyruvate is converted into acetyl-CoA what three reactions are catalyzed?

A
  1. the oxidation of pyruvate and release of CO2
  2. Reduction of NAD+ to NADH
  3. Combination of the remaining two-carbon fragment and coenzyme A to form acetyl-CoA
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15
Q

What is the citric acid cycle (Krebs cycle)?

A

the citric acid cycle completes the breakdown of pyruvate to CO2, then it generates 1 ATP, 3 NADH, and 1 FADH2 per turn.
- there are eight steps in the citric acid cycle each catalyzed by a different enzyme

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16
Q

What do fermentation and anaerobic respiration do?

A

They allow cells to produce ATP without oxygen

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17
Q

What does fermentation use instead of oxygen?

A

fermentation uses substrate-level phosphorylation instead of an electron transport chain to generate ATP

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18
Q

What are two common types of fermentation?

A

alcohol and acid fermentation which generate NAD+

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19
Q

What is a major difference about ATP production between cellular respiration and fermentation?

A

Cellular respiration produces 32 ATP per glucose molecule and fermentation produces 2 ATP per glucose molecule (much less efficient)

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20
Q

What are obligate anaerobes?

A

they carry out fermentation or anaerobic respiration and cannot survive in the presence of O2

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21
Q

What are facultative anaerobes?

A

they can survive using cellular respiration or fermentation (good example is yeast and many bacteria)

22
Q

What does sugar made in chloroplasts do?

A

They supply chemical energy and carbon skeletons to synthesize the organic molecules of cells

23
Q

what is serial endosymbiosis?

A

it assumes that mitochondria evolved before plastids through a sequence of endosymbiotic events

24
Q

What is key evidence that helps prove the endosymbiotic origin of mitochondria and plastids?

A
  1. Inner membranes of both organelles are similar to plasma membranes of living bacteria
  2. DNA structure and cell division are similar to bacteria
  3. both organelles transcribe and translate their own DNA
  4. ribosomes are more similar to bacterial than to eukaryotic ribosomes
25
Q

What is photosynthesis?

A

the process that converts solar energy into chemical energy within chloroplasts

26
Q

Where are chloroplasts mainly found?

A

They are mainly found in the cells of the mesophyll, the interior tissue of the leaf

27
Q

Where does CO2 enter and O2 exit

A

CO2 and O2 exits from pores called the stomata

28
Q

Where is the stroma found?

A

the stroma is found in an envelope of two membranes

29
Q

What are thylakoids?

A

they are connected sacs in the chloroplasts that compose a third membrane system (they may be stacked in columns called grana)

30
Q

What is chlorophyll?

A

The pigment that gives leaves their green colors, and is in the thylakoid membrane

31
Q

Wat equation can be used for photosynthesis?

A

6 CO2 + 12H2O + light energy –> C6 H12 O6 + 6O2 + 6H2O

32
Q

What do chloroplasts do?

A

They spilt H2O into hydrogen and oxygen, incorporating the electrons of hydrogen int sugar molecules and releasing oxygen as a by-product

33
Q

What kind of process is photosynthesis?

A

it is a redox process which means that H2O is oxidized and CO2 is reduced, it is also an endergonic process (energy enters the system)

34
Q

What are the two stages of photosynthesis?

A
  • the light reactions (the photo part)
  • the Calvin cycle (the synthesis part)
35
Q

What do light reactions do? (in thylakoids)

A
  1. split H2O
  2. release O2
  3. reduce the electron acceptor NADP+ to NADPH
  4. generate ATP from ADP by photophosphorylation
36
Q

What does visible light consist of?

A

wavelengths (380 to 750 nm) that produce colors that we can see, it is also what drives photosynthesis

37
Q

What does chlorophyll a absorb?

A

it absorbs blue, violet and red

38
Q

what does chlorophyll b absorb?

A

blue and orange light

39
Q

What happens to wavelengths that are not absorbed?

A

they are reflected or transmitted

40
Q

Why do leaves appear green?

A

because they reflect and transmit green light

41
Q

What colors work best for photosynthesis?

A

violet-blue and red

42
Q

what do carotenoids do?

A

they broaden the spectrum of colors that drive photosynthesis (some work as photoprotection)

43
Q

What is a reaction center complex in photosynthesis?

A

an association of proteins holding a special pair of chlorophyll a molecules and a primary electron acceptor

44
Q

What is the light harvesting complex?

A

it consists of pigment molecules bound to proteins, they transfer the energy of photons to the chlorophyll a molecules

45
Q

What are the two types o photosystems?

A

The two types are photosystem 2 PS ll (first) and photosystem 1
PS l (second).
- PS ll it is best at absorbing a wavelength of 680 nm
PS l best at absorbing a wavelength of 700 nm

46
Q

What are the two possible routes for electron flow?

A

Cyclic and linear
- Linear electron flow, the primary pathway involves both photosystems and produces ATP and NADPH using light energy (8 steps)

47
Q

What are the 8 steps of linear electron flow?

A
  1. Photon hits pigment in a light harvesting complex of PS ll, energy is passed among pigment molecules until it excites P680
  2. excited electron from P680 is transferred to the primary electron acceptor (p680+)
  3. H2O is split by the enzymes and the electrons are transferred from the hydrogen atoms to P680+, thus reducing it to P680. P680+ is the strongest known biological oxidizing agent, the H= are released into the thylakoid space, and O2is released as a byproduct to this reaction
  4. Each electron “falls” down an electron transport chain from the primary electron acceptor of PS ll to PS l. energy released by the fall drives the creation of a proton gradient across thylakoid membrane
  5. Potential energy stored in the proton gradient drives production of ATP by chemiosmosis
  6. In PS l (like PS ll) transferred energy excites p700, which looses an electron to the primary electron acceptor (p700 that is missing an electron) accepts an electron passed down from PS ll via the electron transport chain
  7. each electron falls down an electron transport chain from the primary electron acceptor of PS l to the protein ferredoxin (Fd)
  8. NADP+ reductase catalyzes the transfer if electrons to NADP+ reducing it to NADH
    (WOAH this is long)
48
Q

What happens in cyclic electron flow?

A

the electrons cycle back from Fd to the PS l reaction center via plastocyanin molecule (Pc)
- cyclic electron flow uses only photosystem l and produces ATP, but NOT NADPH
- no oxygen is released

49
Q

What is the difference between chloroplasts and mitochondria?

A

chloroplasts and mitochondria generate ATP by chemiosmosis but they use different sources of energy.
- mitochondria transfer chemical energy from food to ATP, chloroplasts transform light energy

50
Q

What are the three phases of the Calvin cycle?

A
  1. Carbon fixation (catalyzed by rubisco)
  2. Reduction
  3. Regeneration of the CO2 acceptor (RuBp)

Biology - Molecules to cells (4 decks)

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