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Bio 1020 > Lecture 11-15 > Flashcards

Lecture 11-15 Flashcards

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1
Q

What is the role of electrogenic pumps?

A

transport protein that generates voltage (charge difference) across a membrane

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2
Q

How does the proton pump function inside the cell?

A
  • pumps protons into the extracellular fluid using ATP
  • movement of positive charge (hydrogen) against a gradient
  • then create a gradient for H+ back into the cell
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3
Q

What kind of transport is the sucrose-hydrogen pump?

A

active cotransport

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4
Q

Bulk transport is a form of active transport, what is its function?

A
  • large molecules like polysaccharides and proteins cross the membrane in bulk via vesicles
  • requires ATP
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5
Q

Name the types of bulk transport.

A

1) exocytosis
2) endocytosis
- receptor mediated
- pinocytosis

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6
Q

Compare exocytosis, endocytosis, pinocytosis and receptor mediated endocytosis.

A

exocytosis: transport vesicles migrate to the membrane, fuse with it, and release their contents
endocytosis: cell brings materials into the cell by outfolding the cell membrane and surrounding it
pinocytosis: creates an infolding of the plasma membrane to bring in the material
receptor mediated endocytosis: ligand binding to receptor triggers endocytosis

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7
Q

What is an enzyme and what is its function?

A
  • protein catalyst
  • facilitates chemical reactions
  • not consumed by the reaction
  • substrates enter the active site of the enzyme, forming an enzyme-substrate complex
  • products leave the active site and the enzyme is now ready for another reaction
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8
Q

Where are the sites of enzyme activity in the cell?

A
  • cytosol
  • plasma membrane
  • endomembrane
  • mitochondrial membrane
  • thylakoid membrane
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9
Q

Enzymes are inherited from a common ancestor, meaning…?

A

enzymes are subject to natural selection

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10
Q

How did enzyme structure and function evolve?

A

DNA to RNA to enzyme

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11
Q

Artificial selection can change enzyme structure and function how?

A

by causing mutations in DNA and amino acid changes in the enzyme

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12
Q

How can enzyme activity be affected?

A
  • pH
  • temperature
  • concentrations of substrates and products
  • inhibitors
  • activators
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13
Q

What happens when the reaction rate increases due to enzymes?

A

increase in substrate concentrations, then stabilizes due to all the enzymes having a substrate in their active sites

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14
Q

Compare cofactors, activators, allosteric activators, and inhibitors.

A

-all factors that can affect enzyme activity
cofactors: nonprotein enzyme helpers by increasing enzyme activity
activators: increase enzyme activity by stabilizing it
allosteric activators: binds to allosetric regulatory site
inhibitors: decrease enzyme activity

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15
Q

What are the two kinds of inhibitors?

A

1) competitive inhibition: binds to active site and prevents substrate binding
2) allosteric site: binds to other site
3) non competitive inhibition/allosteric inhibition: change in enzyme shape that prevents substrate binding

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16
Q

How does feedback inhibition regulate the metabolic pathways?

A
  • cell shuts off a pathway that is not needed to prevent waste of chemical resources
  • excess intermediate or product shuts off the pathway that produced it
  • allosteric inhibition/ non-competitive also helps shut off the pathway
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17
Q

Name the laws of thermodynamics.

A

1) matter and energy are conserved
2) energy cannot be created nor destroyed nor produced, but is converted
3) there is always an increase in entropy (disorder)
4) cells create ordered structures from less ordered materials; this creates disorder elsewhere

18
Q

Changes in free energy (G).

A

1) high free energy (high potential energy)
- less stable
- greater work capacity
2) spontaneous change in free energy
- more stable
- released free energy can be harnessed to do work
3) less free energy (when closest to the ground)
- more stable
- less work capacity

19
Q

Calculating free energy changes and recognizing which reaction according to the sign.

A

delta G = G products - G reactants

exergonic reaction: negative delta G and release of energy
endergonic reaction: positive delta G and energy input is needed

20
Q

What is the enzyme’s role in chemical reactions?

A
  • speeds up reactions by lowering the energy of activation
  • delta G is not affected
  • does not affect the energy
  • allow molecules to absorb energy and reach the transition state
21
Q

What are the different ways glucose can be broken down in exergonic reactions?

A
  • cellular respiration
  • glycolysis
  • Krebs cycle
  • oxidative phosphorylation
  • fermentation
  • anaerobic respiration
22
Q

What is the role of NADH in glucose catabolism?

A

-shuttles electrons from glucose to the electron transport chain for use in oxidative phosphorylation

23
Q

How would you describe the free energy of electrons in NADH compared to water?

A

NADH: electrons are at high free energy, less stable, have ability to do work
water: electrons have low free energy, more stable, because of electronegativity of oxygen

24
Q

What is the difference between cellular respiration and normal breathing?

A

cellular respiration is at the cellular level

breathing is at the organism level

25
Q

Where does the glycolysis process occur?

A

in the cytosol of the mitochondrion

26
Q

What are the products of glycolysis?

A
  • pyruvate
  • 2 ATP
  • 2 NADH
27
Q

How is ATP synthesized in glycolysis?

A
  • substrate-level phosphorylation
  • enzyme transfers a phosphate group from one molecule to ADP in order to form ATP
  • enzyme is required
  • bond must be broken between organic molecule and phosphate before ATP forms
28
Q

Explain the energy investment phase of glycolysis.

A
  • 2 ATP used to start glucose oxidation

- 6 carbon molecule (glucose) is split into two 3 carbon molecules (glyceraldehyde-3-phosphate)

29
Q

Explain the energy payoff phase of glycolysis.

A
  • 2 NAD+ picks up electrons and becomes 2NADH
  • 2 phosphate groups are broken from bond and form 2 ATP (substrate level phosphorylation)
  • 2 ATP formed pyruvate
30
Q

How many net ATPs are produced from glycolysis and how many total?

A

2 ATPs net

4 ATPs total

31
Q

What 2 carbon atoms are oxidized in the citric acid cycle?

A
  • Acetyl CoA

- 2 CO2

32
Q

What is the role of FADH2 and NADH in the citric acid cycle?

A

electron carriers

33
Q

Identify which of the following is an oxidation or reduction reaction in the citric acid cycle.

a) pyruvate to CO2
b) NAD+ to NADH
c) FAD to FADH2

A

a) oxidized
b) reduced
c) reduced

34
Q

Why are the last two carbons in acetate converted to CO2 in a complex cyclic pathway rather than a simple linear reaction?

A

easier to remove electrons and produce CO2 from compounds with 3 or more carbon atoms than a 2-carbon compound like acetyl CoA

35
Q

What are the products of the citric acid cycle?

A
  • CoA
  • 3 NADH
  • 2 CO2
  • 2 ATP
  • FADH2
36
Q

How does the presence of oxygen affect the cellular respiration process?

A

present: pyruvate oxidized, acetyl CoA formed, and cycle continues into the citric acid cycle
absent: pyruvate oxidized via fermentation in some organisms

37
Q

Where does the citric acid cycle occur?

A

in the mitochondrial matrix of the mitochondrion

38
Q

Where is the majority of the ATP produced during cellular respiration?

A

in the mitochondrion, during oxidative phosphorylation

39
Q

What happens when electrons are passed to oxygen in the electron transport chain?

A

electrons from NADH have a high energy, so when they are transferred to the oxygen, energy is released and there is a drop in free energy

40
Q

Where does the oxidative phosphorylation take place?

A

on the matrix side of the inner membrane of the mitochondrion

41
Q

What is oxygen’s role in the electron transport chain?

A
  • the final electron acceptor due to its high affinity for electrons
  • indirectly drives electron transport
  • forms proton gradient
  • synthesizes ATP
42
Q

How would anaerobic conditions affect the rate of electrons transport and ATP production during oxidative phosphorylation?

A
  • both electron transport and ATP synthesis would stop
  • mitochondria unable to oxidize NADH and FADH2
  • mitochondria unable to oxidize NADH and FADH2 back to NAD+ and FAD (needed as inputs to first 3 stages of cellular respiration)

Bio 1020 (7 decks)

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