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Biology Exam > Metabolism (and gene control lol) > Flashcards

Metabolism (and gene control lol) Flashcards

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1
Q

Define Metabolism

A

the sum of all catabolic (breakdown) and anabolic (build up) reactions in a cell or organism

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2
Q

What are the differences between exergonic and endergonic reactions?

A

exergonic: energy is released
e.g. Combustion, bioluminescence, cell respiration

endergonic: energy is absorbed
e.g. photosynthesis

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3
Q

What are the differences between anabolic and catabolic reactions?

A

Anabolic: uses energy to build large molecules from smaller molecules

Catabolic: release energy in the process of breaking down components into smaller molecules

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4
Q

Where is the site for photosynthesis?

A

chloroplasts or folds in the cell membrane

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5
Q

What is the first stage of photosynthesis?

A

-capturing light energy; occurs in the thylakoid membrane

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6
Q

What is stage 2 of photosynthesis?

A

-light energy makes ATP + NADPH + H+; occurs in thylakoid membrane
-NADPH is a high energy intermediate
-the reduction of NADP+ is an endergonic and anabolic reaction
-2 H + NADP+ –> NADPH + H+

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7
Q

What is stage 3 of photosynthesis?

A

-using ATP+NADPH+H+ to synthesize organic compounds (glucose) from CO2; process called Calvin cycle; occurs in stroma

6CO2 + 6H2O + light energy —> C6H12O6 + 6O2

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8
Q

Describe Light energy

A

-light energy travels in wave packets called photons
-visible light has a wavelength of 380 nm to 750 nm

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9
Q

Describe the photosynthetic pigments in plants

A

-clusters of photosynthetic pigments embedded in the thylakoid membrane absorb photons of a particular wavelength
-pigments are clustered in groups called photosystem

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10
Q

What are photosystems?

A

pigments clustered in groups that are embedded in the thylakoid membrane
–> absorb photons of specific wavelength

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11
Q

Describe chlorophyll

A

-has phytol tail/chain (hydrophobic) and porphyrin ring (hydrophilic head)

-absorb all wavelengths accept for green (is reflected)
–> in fall, chlorophyll is no longer produced and is broken down

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12
Q

What does light do to chlorophyll?

A

photoexcitation

  • electron are normally stable in their “ground state”, the lowest possible energy level
    -when a photon strikes a chlorophyll molecule, the electrons have energy added to them and are in a state of ‘excitation’
    -an excited electron has more energy than one in a ground state, but it will return to the ground state in 1 billionth of a second —-> when the electron returns to the ground state, it releases energy (heat and light) –> however instead of being released, they are captured by primary electron acceptor (chlorophyll is oxidized)
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13
Q

describe photosystems in algae and plants

A

-both contain photosystems I and II
-II contains chlorophyll P680, enough energy to break water (photolysis)
-photosystem I contains P700
-are used to produce ATP and NADPH + H+

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14
Q

Describe photolysis

A

-the Z protein (in thylakoid space) uses energy from light to split H2O
-2 electron are given to photosystem II
-2 H+ are released in thylakoid space and create electrochemical gradient
-O2 leaves chloroplast as waste

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15
Q

Describe Chemiosmosis

A

-once the electrochemical gradient of H+ is formed, the H+ move down the concentration gradient
-H+ cannot diffuse across the membrane, so it instead uses ATP synthase to move from the thylakoid space to the stroma
-this movement down the concentration gradient causes the phosphorylation of ADP to ATP

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16
Q

What are the differences between cyclic and non-cyclic phosphorylation

A

-cyclic phosphorylation makes some ATP for glucose synthesis and some ATP for other purposes
-only photosystem I is involved
-electrons from P700 are excited but eventually return to P700 (H2O and NADP reductase are not involved)
-b6-f complex still pumps hydrogen across the thylakoid membrane to create the electrochemical gradient needed to make ATP

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17
Q

What is the purpose of the Calvin Cycle?

A

-Turns carbon dioxide from the air into glucose for various usages

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18
Q

Where does the Calvin Cycle occur?

A

occurs in the stroma

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19
Q

What’s the first phase of the Calvin Cycle?

A

Carbon fixation
-a CO2 is added to a 5-c RuBP to form 6-C intermediate–> splits into two 3-c molecules of PGA
-rubisco is involved (enzyme)
6(5-C RuBP) + 6CO2 –> 12(3-C PGA)`

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20
Q

What is the second phase of the Carbon Cycle

A

Reduction reactions
-PGA is phosphorylated to (BPG) using ATP
-BPG is reduced to G3P by NADPH+H
-it takes 2 molecules of G3P to create glucose –> 1 molecule of G3P for every 5 G3P leaves the cycle

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21
Q

What’s the third phase of the Calvin Cycle

A

RuBP regeneration
-5 molecules of 3-C G3P are converted into 3 molecules of 5-C RuBP
-2 Pi are removed and 3 ATP are consumed, 2 H2O must be added for the H and OH groups to add to the molecules

22
Q

What is the overall equation of the Calvin Cycle

A

3CO2 + 9ATP + 6(NADPH+H+) + 5H2O + 3RUBP –> 9ADP + 8Pi + 6NADP+ + G3P + 3RuBP

23
Q

What is photorespiration?

A

-When it is hot and dry, stromata closes to reduce water loss due to transpiration
- [CO2] leaves and [O2] increases
-oxygen binds to rubisco thus decreasing the production of carbs –> photorespiration is bad

24
Q

What is the overall equation of cellular respiration?

A

C6H12O6 + 6O2 –> 6CO2 + 6H2O + energy (ATP and heat)

25
Q

What is the purpose of Cellular respiration?

A

To convert energy trapped within glucose to energy available to do work in a cell in the form of ATP

26
Q

What is the order of the steps of cellular respiration

A
  1. Glycolysis
  2. Pyruvate oxidation
  3. Kreb’s cycle
  4. electron transport chain and chemiosmosis
27
Q

Where does glycolysis occur?

A

Cytoplasm

28
Q

Where does pyruvate oxidation occur?

A

mitochondrial matrix

29
Q

Where does the Krebs Cycle occur?

A

mitochondrial matrix

30
Q

Where does the electron transport chain/chemiosmosis occur?

A

inner mitochondrial membrane

31
Q

State a summary of glycolysis

A

-glucose is broken down into 2 molecules of pyruvate
-in order to break down glucose, it is first destabilized by the addition of 2 Pi from the addition of 2 ATP
-Once the destabilized molecule breaks in half, it released enough energy to replace the 2 ATP and make an additional 2 ATP
-NADH + H+ is also produced

32
Q

What is the overall reaction of Glycolysis? It’s net energy?

A

glucose + 2 ATP + 2 ADP + 2Pi + NAD+ –> 2 pyruvate + 4 ATP + 2(NADH+H+) + H2O

net energy = 2 ATP (used immediately) and 2 NADH (processed to obtain more ATP) –> overall 2 ATP is created

33
Q

What are the enzymes used in order (look at diagram to help)

A

phosphorylase, isomerase, phosphorylase, isomerase, dehydrogenase and phosphorylase (at the same time, phosphorylase, isomerase, dehydrase, phosphorylase

34
Q

Give summary of Pyruvate Oxidation

A

-only occurs in the presence of oxygen even though oxygen is not a substrate
-If ATP levels are low, acetyl-CoA goes into krebs cycle to produce more ATP
-if high, it goes to produce lipids

35
Q

What is the equation for pyruvate oxidation

A

pyruvate + NAD+ + CoA-SH –> acetyl-CoA + NADH + H+ + CO2

36
Q

Summarize the Krebs cycle

A

-only occurs if oxygen is present
-oxaloacetate is a reactant and a product (cyclical)
-the equation of krebs cycle is doubled as 2 acetyl-CoA molecules are produced per molecule of glucose.

37
Q

What is the purpose of pyruvate oxidation?

A

main purpose of pyruvate oxidation is to oxidize pyruvate to create the acetyl-CoA needed to be the intermediate of the Kreb’s cycle.

38
Q

What’s the equation of the Kreb’s cycle?

A

oxaloacetate + acetyl-CoA + 3NAD+ + FAD + H2O +
ADP + Pi
—> 2CO2 + 3NADH + 3H+ + FADH2 + CoASH + ATP + oxaloacetate (doubled)

39
Q

What’s the purpose of the krebs cycle?

A

-produces energy
-transfers high energy electrons to the ETC to then create the energy substrates needed for the krebs cycle

40
Q

Name the order of the enzymes used in the krebs cycle

A

hydrase, isomerase, dehydrogenase and decarboxylase (both at the same time), dehydrogenase and decarboxylase once more, phosphorylase, dehydrogenase, hydrase, dehydrogenase

41
Q

Provide an overview of the Electron Transport Chain

A
  • a series of oxidation-reduction reactions convert the stored energy in NADH + H+ and FADH2 indirectly into ATP
    -the process involves moving electrons between proteins within the membrane which results in the movement of protons across the membrane
42
Q

What are the sources of FADH2 and NADH + H+

A

Krebs cycle in mitochondrial matrix = 6(NADH + H+), 2FADH2

pyruvate oxidation in mitochondrial matrix = 2(NADH+ H )

glycolysis in cytoplasm = 2(NADH + H+)

43
Q

what happens on the membrane, when NADH + H cannot pass through the membrane into the matrix?

A

energy stored in NAHD can be passed across the
membrane with the electrons to a molecule of FADH2

44
Q

Go through the process of ETC (use diagram to help!)

A

NADH dehydrogenase: accepts 2 efrom NADH + H+ and passes them onto protein Q, 2H+ (p+) follow the e- and pass through the inner membrane into the
intermembrane space

protein Q (ubiquinone): accepts 2 e from NADH dehydrogenase or FADH2, then passes them onto cytochrome b-c1 complex

cytochrome b-c1 complex: accepts 2 e from protein Q and passes them onto cytochrome c, 2H+ (p+) follow the e- and pass through the inner membrane
into the intermembrane space

45
Q

Go through an overview of how chemiosmosis can apply to the ETC

A

during the ETC, protons (H+) accumulate in the intermembrane space; this creates an electrochemical gradient which is a potential difference (voltage) across
the inner membrane (just like a battery)

 the H+ cannot diffuse through the phospholipid bilayer
 the enzyme ATP synthase embedded in the membrane
allows H+
to pass through it
 as the H+ pass through ATP synthase, ADP + Pi–> ATP
 this process is called oxidative phosphorylation

46
Q

How much ATP is produced in ETC per product of each step of cellular respiration?

A

glycolysis: produces 4, however requires 2, from energy product, 4 ATP is produced

pyruvate ox: no ATP is required or produced, from energy product, 6 ATP is produced in ETC

Krebs cycle: 2 ATP is produced, from energy product 18 is produced from NADH + H+ and 4 is produced from FADH2

47
Q

What is fermentation?

A

-the metabolism of glucose in the absence of oxygen
-NADH is oxidized by producing lactic acid or ethanol
-lactic acid occurs in animal cells in temporary absence of oxygen, ethanol occurs in yeast in absence of oxygen

48
Q

Describe what a promoter, operator, repressor protein, and inducer

A
  • promoter – a sequence of DNA that RNA polymerase binds
    to; located ‘upstream’ from the TAC ‘start’ signal on the
    DNA
  • operator – a sequence of DNA beside the promoter that a
    repressor protein binds to; if the repressor protein binds to
    the operator, the RNA polymerase cannot bind to the
    promoter and no transcription occurs
  • repressor protein – binds to the operator and prevents
    transcription
  • inducer – a molecule that binds to the repressor, changes it
    shape, and prevents the repressor from binding to the
    operator; RNA polymerase can bind to the promoter and
    transcription can occur
49
Q

Describe the lac operon

A
  • the repressor protein is LacI protein
  • the inducer is lactose
  • lactose is a rare sugar in the environment, so the lac genes
    are usually OFF (b-galactosidase is not produced)
  • if lactose is present, it binds to LacI and allows transcription to occur
50
Q

Describe the trp Operon

A
  • tryptophan is an amino acid that is rare in the environment
  • gene to produce trp is normally ON
  • if trp is present, it binds to the repressor protein and
    changes its shape so that it can bind to the operator
  • result: operator blocks transcription (gene turns OFF)
51
Q

Describe the trp Operon

A
  • tryptophan is an amino acid that is rare in the environment
  • gene to produce trp is normally ON
  • if trp is present, it binds to the repressor protein and
    changes its shape so that it can bind to the operator
  • result: operator blocks transcription (gene turns OFF)

Biology Exam (3 decks)

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