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BIOL 1020-MIDTERM 2 > Midterm 2 > Flashcards

Midterm 2 Flashcards

1
Q

What are Catabolic Pathways?

A

release energy by breaking down complex molecules into simpler compounds

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2
Q

What is Aerobic Respiration?

A

oxygen is consumed as a reactant along with organizing fuel

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3
Q

What is Anaerobic Respiration

A

organic fuel is broken down without oxygen

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4
Q

What is Fermentation?

A

partial breakdown of organic fuel (sugars) without oxygen
ex. beer

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5
Q

Briefly describe Cellular Respiration

A

-Aerobic respiration, the electrons stored in the fuel source bonds are transferred to oxygen
-some energy is produced is used to make ATP, rest is lost as heat
-cell regulates the use of energy over multiple steps in the catabolic pathway
-EXERGONIC!!

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6
Q

What do catabolic reactions depend on?

A

depend on the transferring of electrons during chemical reactions
-involve ‘redox’ reactions

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7
Q

What is ‘REDOX’?

A

the transfer of electrons from one molecule to another. ALWAYS COUPLED!!

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8
Q

What is a reducing agent?

A

molecule that gives up electrons and becomes oxidized (loses electrons)

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9
Q

What is the oxidizing agent?

A

molecule that receives electrons and becomes reduced (gains electrons)

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10
Q

How does electron transfer occur?

A

via an electron shuttle

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11
Q

What does NAD+ stand for and what is it?

A

nicotinamide adenine dinucleotide
-an electron transporter (shuttle)
-facilitates the electron over multiple steps in the breakdown of glucose
-its a coenzyme and oxidizing agent
-can cycle between oxidized (NAD+) and reduced (NADH) form

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12
Q

What type of way do electron move?

A

they move in a step-wise process (not all at once)

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13
Q

What would happen if the transfer of electrons was uncontrolled?

A

one big release of energy, with lot’s of heat loss

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14
Q

What would happen if the transfer of electrons was controlled?

A

-small releases of energy at each step, which can be used to make more ATP
-electrons get removed from glucose and are transferred to the electron transport chain via NADH
-The bonds that hold the electrons in the ETC are increasingly unequal for each step

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15
Q

Electrons in a H-H bond are shared how?

A

equally shared= high potential energy

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16
Q

Electrons in O-H bond are shared how?

A

very unequally shared= very low potential energy

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17
Q

In catabolism, ATP is made in two ways, what are they?

A
  1. Substrate-level Phosphorylation
  2. Oxidative Phosphorylation
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18
Q

Describe the first way ATP is made in Catabolism

A
  1. Substrate-level Phosphorylation
    -an enzyme catalyzes the transfer of a phosphate group from a substrate to ADP, forming ATP
    -The substrate is generated as an intermediate in the breakdown of glucose
    -Direct transfer of energy to ATP
    -Accounts for about 10% of ATP generation during cellular respiration
    -Occurs in the cytosol AND mitochondria
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19
Q

Describe the second way ATP is made in Catabolism

A
  1. Oxidative Phosphorylation
    -Energy dissipated from electrons in the ETC makes a H+ gradient
    -Gradient is used to drive a protein complex called ATP synthase
    -Indirect transfer of energy of ATP
    -Maxes approx. 90% of ATP during cellular respiration
    -Mitochondria ONLY!!
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20
Q

How many pyruvate does glycolysis form?

A

The 3-carbon sugars are oxidized and rearranged to form TWO PYRUVATES

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21
Q

What are the two phases glycolysis is split into?

A
  1. Energy Investment- the cell “spends” ATP
  2. Energy Payoff- ATP is produced via substrate-level phosphorylation
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22
Q

What is the OVERALL net gain of Glycolysis?

A

2 ATP and 2NADH

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23
Q

Is there any loss of carbon during Glycolysis?

A

NO, there is no loss of carbon as CO2
-all carbons are accounted for

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24
Q

Can Glycolysis occur withOUT oxygen?

A

YES, it can occur with OR without oxygen
-if oxygen is present, will proceed into the rest of aerobic respiration

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25
Q

How many steps are there in Glycolysis?

A

11

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26
Q

What is Glycolysis?

A

oxidizes glucose to pyruvate, which is later used in the citric cycle

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27
Q

Describe Step 1 of Glycolysis

A

Glucose is phosphorylated (intro of phosphate group) by ATP by hexokinase
- (makes it more chemically reactive)
- first investment of ATP

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28
Q

Describe Step 2 of Glycolysis

A

Glucose 6-phosphate is converted to fructose 6-phosphate by Phosphoglucoisomerase

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29
Q

Describe Step 3 of Glycolysis

A

Phosphofructokinase transfers another phosphate to the other end of fructose 6-phosphate, making Fructose 1,6 diphosphate
-second investment of ATP

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30
Q

Describe Step 4 of Glycolysis

A

Aldolase cuts the Fructose 1,6 diphosphate into TWO different 3-carbon sugars
1. dihydroxyacetone phosphate (DHAP)—> used in adipose cells to generate glycerol backbone
2. Glyceraldehyde 3-phosphate (G3P)—-> moves into the citric acid cycle

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31
Q

Describe Step 5 of Glycolysis

A

G3P and DHAP are converted back and forth (by isomerase) as they are produced (reaction NEVER reaches equilibrium since G3P is used up almost as fast as it is produced)

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32
Q

Describe Step 6 of Glycolysis

A

G3P is oxidized by transferring electrons to NAD+, forming NADH, and the energy from this EXERGONIC reaction is used to phosphorylate the oxidized substrate
-1,3 biphosphoglycerate is formed

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33
Q

Describe Step 7 of Glycolysis

A

The phosphate group is transferred to ADP in and EXERGONIC reaction (substrate level phosphorylation), leaving the carbonyl group of G3P oxidized to a carboxyl group (of 3-phosphoglycerate)

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34
Q

Describe Step 8 of Glycolysis

A

Phosphoglyceromutase (enzyme) relocates the remaining phosphate group
- 2-phosphoglycerate is formed

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35
Q

Describe Step 9 of Glycolysis

A

Enolase (enzyme) causes a double bond to form in the substrate by extracting a water molecule, which makes phosphoenolpyruvate (PEP)
-high energy potential

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36
Q

Describe Step 10 of Glycolysis

A

The phosphate group is transferred from PEP to ADP (substrate-level phosphorylation), forming pyruvate
-by pyruvate kinase

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37
Q

Describe Step 11 of Glycolysis

A

Pyruvate is transferred to the Citric Acid Cycle

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38
Q

After Glycolysis, where does pyruvate get transported to?

A

pyruvate is actively transported into the MITOCHINDRION

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39
Q

How many steps does it take to convert Pyruvate into acetyl CoA?

A

THREE steps

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40
Q

What is the first Step to convert Pyruvate to acetyl CoA?

A
  1. the oxidized carboxyl group on pyruvate is removed
    -releases CO2, now a 2-carbon molecule
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41
Q

What is the second step to convert Pyruvate to acetyl CoA?

A
  1. The 2-carbon molecule is oxidized forming acetate (CH3COO-)
    -extracted electrons are transferred to NAD+ forming NADH (stores energy)
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42
Q

What is the third step to convert pyruvate to acetyl CoA?

A
  1. Coenzyme A (CoA) attaches by its surfer group
    -derived from vitamin B
    -high potential energy
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43
Q

How many pyruvates does Glycolysis make?

A

TWO pyruvates

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44
Q

What is another name for the Citric Acid Cycle?

A

-Krebs Cycle
-Tricarboxylic cycle (TCA)

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45
Q

How many ATP molecules are formed over citric acid cycle? How is this done?

A

1 ATP molecule per cycle, therefore 2 are made
-via substrate-level phosphorylation

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46
Q

What is FAD?

A

Flavin Adenine Dinucleotide, from riboflavin

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47
Q

What is FADH2?

A

reduced form of NADH

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48
Q

What is FAD

A

oxidized form of NAD+

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49
Q

How many main steps are there in the Citric Acid Cycle?

A

8 main steps once acetyl CoA enters the cycle

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50
Q

Describe Step 1 of the Citric Acid Cycle

A
  1. Acetyl CoA (from oxidation of pyruvate) adds it’s 2-carbon acetyl group to oxaloacetate (4-carbons), producing citrate (6-carbons)
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51
Q

Describe Step 2 of the Citric Acid Cycle

A

Citrate is converted to its isomer, isocitrate (6-carbon), by dehydration (removal of water) but also the addition of water
-remove water, add water, to rearrange bonds

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52
Q

Describe Step 3 of the Citric Acid Cycle

A
  1. Isocitrate is oxidized (electron shuttle) reducing NAD+ to NADH. A CO2 molecule is lost (2nd time its removed in cycle). Results in alpha-ketoglutarate (5-carbons)
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53
Q

Describe Step 4 of the Citric Acid Cycle

A
  1. Another CO2 is lost (3rd time) resulting compound is oxidized, transferring electrons to NAD+ to form NADH

-remaining molecule bonds with coenzyme A, resulting in formation of Succinyl CoA (4-carbons) which have very unstable bonds

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54
Q

Describe Step 5 of the Citric Acid Cycle

A
  1. CoA group is displaced by a phosphate group which is transferred to GDP, forming GTP

-GTP can be used indirectly to produce ATP
-results in production of succinate (4-carbon)

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55
Q

Describe Step 6 of the Citric Acid Cycle

A
  1. 2 hydrogens are transferred to FAD, forming FADH2 and oxidizing succinate to result in fumarate
    -FAD accepts 2 electrons and 2 protons to form FADH2
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56
Q

Describe Step 7 of the Citric Acid Cycle

A
  1. Addition of water rearranges the bonds, turning fumarate into malate
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57
Q

Describe Step 8 of the Citric Acid Cycle

A
  1. Malate is oxidized, reducing NAD+ to NADH, which forms oxaloacetate
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58
Q

What is the TOTAL yield per glucose?

A

6 NADH’s, 2FADH2’s, 2 ATP’s

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59
Q

What is the TOTAL amount of ATP formed from glycolysis AND citric acid cycle?

A

2 ATP from glycolysis
2 ATP from Citric Acid Cycle

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60
Q

What is the electron transport chain (ETC)?

A

a collection of protein complexes within the inner membrane of the mitochondrion
-sequential redox reactions
-each component becomes reduced when it accepts electron from its “uphill neighbour”, since its electronegativity is less than uphill
-transporters than return to the oxidized state and returns to the cycles to pick up more electrons

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61
Q

Describe the Pathway of Electron Transport; STEP 1
(via NAD+ transferred from NADH to ETC complex 1)

A
  1. electrons acquired from glycolysis and citric acid cycle via NAD+ are transferred from NADH to the ETC complex1
    -first molecule in C1 is flavoprotein (FMN), which gets reduced as NADH gives up its electrons
62
Q

Describe the Pathway of Electron Transport; STEP 2
(via NAD+ transferred from NADH to ETC complex 1)

A
  1. FMN returns to its oxidized form as it passes the electrons to iron-surfer protein (Fe-S) in complex 1
63
Q

Describe the Pathway of Electron Transport; STEP 3
(via NAD+ transferred from NADH to ETC complex 1)

A
  1. Electrons then moves to ubiquinone (Q)—> not a protein
    -called coenzyme Q
64
Q

Describe the Pathway of Electron Transport; STEP 4
(via NAD+ transferred from NADH to ETC complex 1)

A
  1. Electrons, are transferred to the cytochromes
    -have a heme (iron group) that accepts/ donates electrons
    -complexes III and IV both have cytochromes
65
Q

Describe the Pathway of Electron Transport; STEP 5
(via NAD+ transferred from NADH to ETC complex 1)

A
  1. The cytochromes then pass the electrons to oxygen
    -picks up 2 electrons and 2 protons
    -forms water
66
Q

What is the key difference between electrons acquired from citric acid cycle via FADH2 and NAD+?

A

It joins the ETC via complex II

-lower energy level than complex I and NADH
-both donate the same number of electrons at the end for oxygen reduction but FADH2 converts about 1/3 less energy than NADH

67
Q

What are the TOTALs for Electron Transport Chain?

A

-112 protons
-10 NADH *10 protons
-2 FADH2 *6 protons

68
Q

What are the TOTAL for Oxidative Phosphorylation?

A

-112 protons (via ATP synthase) / 4 protons to make 1 ATP = 28 ATP

69
Q

What are the TOTAL tally’s for each Glucose through Cellular Respiration?

A

Glycolysis:
-2 ATP via SLP -2 NADH -2 pyruvate

Pyruvate Oxidation:
-2 NADH

Citric Acid Cycle:
-2 ATP via SLP -6 NADH -2 FADH2

ETC:
-112 protons - 10 NADH (10 p+) -2 FADH2 (6 p+)

Oxidative Phosphorylation:
-112 protons (via ATP synthase) / 4 protons to make 1 ATP = 28 ATP

TOTAL: Cellular Respiration
-32 ATP

70
Q

What is the range in ATP production due to?

A
  1. we don’t know exactly how many H+ are transported out of the matrix into the intermembrane space
  2. ATP yield varies based not he shuttle being used
    (FAD only makes 1.5 ATP compared to 2.5 ATP per NAD+)
  3. Proton-motor force is used to do other work
71
Q

What is fermentation?

A

does not have an ETC or oxygen as the final e- acceptor
-is not considered cellular respiration
-recycles NAD+ from NADH during glycolysis

72
Q

What would happen if oxygen was not present during oxidative phosphorylation?

A

Recall; glycolysis produces ATP via substrate level phosphorylation, which requires a suffiecient supply of NAD+ to transport the e- during the oxidation step.

If oxygen was not present, NAD+ wouldn’t be recycled from NADH during the oxidative phosphorylation of the ETC, causing the cell to deplete NAD+ and be unable to generate ATP

73
Q

What are the two types of alcohol fermentation?

A
  1. Alcohol fermentation
  2. Lactic Acid FermentationDdes
74
Q

Describe Alcohol Fermentation and an example

A

pyruvate is converted to ethanol (ethyl alcohol)
1. CO2 is released from pyruvate, converting it to 2 molecules of acetaldehyde
2. Acetaldehyde is reduced by NADH to ethanol

this regenerates the NAD+ needed in glycolysis

Example: bacteria, yeasts, sourdough, beer

75
Q

Describe Lactic Acid Fermentation and an example

A

pyruvate is reduced directly by NADH to form lactic acid
-no release of CO2

Example: fungi, bacteria, cheese, yogurt

76
Q

What three methods to generate ATP use glycolysis to oxidize glucose to make pyruvate

A

All THREE methods

77
Q

What methods use NAD+ as the oxidizing agent

A

All THREE methods

78
Q

What is the difference between Fermentation and Cellular Respiration?

A

Fermentation: used organic molecule as the final electron acceptor to oxidize NADH
-pyruvate in lactic acid fermentation
-acetaldehyde in alcohol fermentation
-yields 2 ATP via SLP

Cellular Respiration: uses ETC to regenerate NAD+
-yields up to 32 ATP via SLP + OP

79
Q

What are Obligate Anaerobes?

A

are organisms that only carry out fermentation or anaerobic respiration

80
Q

What are Facultative Anaerobes?

A

are organisms that can utilize both fermentation and cellular respiration to make enough ATP

81
Q

How else do Glycolysis and Citric Acid Cycle connect to other metabolic pathways?

A

Molecules form our food get incorporated into catabolic reactions
-proteins proves the coenzymes, enzymes, and amino functional groups
-carbohydrates are the sugar sources
-fats get broken down into glycerol monomers to make G3P and the fatty acids for Acetyl- CoA ( broken down via beta oxidation)

82
Q

What does Photosynthesis do?

A

Converts light energy to chemical energy
-builds reduced organic molecules from CO2 and H2O
-ENDERGONIC reaction (requires energy from sunlight)
-ANABOLIC (builds complex molecules)
-done by PHOTOAUTOTROPHS (light, self feeder)

83
Q

What are PHOTOAUTOTROPHS?

A

producers of the biosphere
-eaten by heterotrophs

84
Q

Energy + 6CO2 + 6H2O —-> C6H12O6 + 6O2
Which molecule is REDUCED?

A

CO2
-more energy is required to extract e- (thus break) these unequally shared e-

85
Q

Energy + 6CO2 + 6H2O —-> C6H12O6 + 6O2
Which molecule is OXIDIZED?

A

H2O
-Less energy is released when C-H and O=O bonds w/ equally shared electrons are formed

86
Q

How many stages does Photosynthesis occur?

A

2 major stages
-Light Reactions
-Calvin cycle

87
Q

Describe light reactions stage

A

-the “photo part”
-captures light energy to energize electrons
-components include photosystem I and II, ETC, ATP synthase
-makes NADPH and ATP
-electrons are removed from the process to form O2

88
Q

What is another name for the Calvin cycle?

A

“Dark” cycle
-can happen in light or dark conditions just needs the proper components in it

89
Q

Describe the Calvin cycle

A

-uses energy from ATP and NADPH to reduce CO2 to make 3 carbon sugars (which in turn can be used to make glucose)
-ADP and NADP+ are oxidized and recycled
-Occurs in the light but also proceeds in the dark until NADPH and ATP run out

90
Q

Where does photosynthesis take place?

A

In the chloroplast
-surrounded by a double membrane

91
Q

What is the fluid inside the chloroplast called?

A

Stroma

92
Q

What is the fluid inside the chloroplast called?

A

Stroma

93
Q

What occurs in the stroma?

A

The Calvin cycle

94
Q

What occurs during photosynthesis?

A
  1. CO2 enters the plant via stomata (pores) and water is absorbed via the roots
  2. A third membrane system inside the chloroplasts is the thylakoids, which can be stacked to form grana
    -contains chlorophyll, the pigment which absorbs and transforms the photon energy
95
Q

How many chloroplasts does a typical Mesophyll cell have?

A

30-40 chloroplasts

96
Q

What are thylakoids?

A

in the third membrane system, they are stackable and form grant

97
Q

What is the thylakoid intermembrance space called?

A

the lumen

98
Q

Where do light reactions occur?

A

In the lumen which is in the thylakoid intermembrane space

99
Q

What is chlorophyll?

A

the pigment which absorbs and transforms the photon energy

100
Q

When a photon hits matter, what can happen to it?

A
  1. reflected
  2. transmit straight through
  3. absorbed
101
Q

When a photon hits matter it can be either reflected, transmit straight through, or absorbed, what does this depend on?

A

depends on the energy of the photon and the molecule it interacts with

102
Q

What is visible light apart of?

A

Electromagnetic spectrum

103
Q

What type of energy do short wavelengths have?

A

short wavelengths=more energy

ex. UV rays, gamma rays

104
Q

What type of energy do long wavelengths have?

A

long wavelengths= lower energy

105
Q

What is a photon?

A

a little packet of light with no mass

106
Q

What measure the absorbance of light?

A

spectrophotometers

107
Q

What do pigments do to absorb light?

A

Pigments absorb wavelengths of light
if it is not absorbed—> it is reflected giving off “color”
ex. plant leaves are green, they do not absorb green light

Different pigments will absorb different wavelengths

108
Q

What does high transmittance mean?

A

high transmittance= low absorption

109
Q

What does low transmittance mean?

A

low transmittance= high absorption

110
Q

What is the absorption spectrum?

A

the pigment’s light absorption vs. wavelength

111
Q

What is the action spectrum?

A

shows the photosynthetic activity at different wavelengths

112
Q

What colours of light will drive photosynthesis by green plants most efficiently?

A

red and blue

113
Q

What are carotenoids?

A

an accessory pigment aid in photoprotection

114
Q

What is the difference between chlorophyll a and chlorophyll b?

A

a and b have different absorption spectra
-maximizing the amount of light that can be absorbed and used in electron energizing

115
Q

What happens when a photon is absorbed my a molecule?

A
  1. an electron is converted to a higher-energy state (excited state)
  2. excited electron quickly falls back to ‘ground state’ and different things may happen to the energy

-energy may be dissipated as heat
-energy may be re-emitted in form of less-energetic and longer wavelength photon (fluorescence). Small amount of heat is lost if this happens
-Energy may be transferred to another molecule. This is what happens when photosynthetic pigments when arranged properly within a chloroplast. NOTE: just energy is transferred between pigments, not electrons

116
Q

What allows more energy to be absorbed from sunlight?

A

Having a number of pigments all absorbing different wavelengths allows the chloroplast to absorb more energy from sunlight

117
Q

Pigments are organized into photosystems, what are photosystems?

A

are composed of reaction-centre complex (protein) surrounded by many light-harvesting complexes

-an incoming photon can excite any of the pigment molecules, which transfers the energy form the excited stated to its neighbour “like a crowd wave”
-the energy is funnelled to a reaction centre, which consists of specifically arranged molecules called P680 and P700
-pass on the electrons o the primary electron acceptor, which gets reduced

118
Q

What does the “P” in P680 and P700 stand for?

A

P=pigment

119
Q

What does the “680” AND “700” stand for in P680 and P700?

A

is the wavelength absorbed best

120
Q

Describe the linear flow of electrons: Step 1

A
  1. light is captured in the light harvesting complex and transferred to the reaction centre to the pair of special chlorphylls (P680)
    -P680 absorbs so much light energy that ejects electrons from it
121
Q

Describe the linear flow of electrons: Step 2

A

The primary electron acceptor then captures the electron and shuttles it to PHOTOSYSTEM 1

122
Q

Describe the linear flow of electrons: Step 3

A

This oxidizes P680 to P680+. It is the strongest oxidant in the biological system—> it REALLY wants an electron
-this oxidizes P680+ rips an electron from water, which reduces P680+ back to P680

-This results in the use of 2 water molecules to make one O2, removing 4 electrons in the process, which gets repeated 3 times
-the H+ ions released stay inside the thylakoid lumen to help make a protein motive force

123
Q

For each O2 produced at step 3 of the linear flow of electrons, what is produced?

A

-2 H2O molecules are consumed
-four electrons are passed to the primary acceptor

124
Q

Describe the linear flow of electrons: Step 4

A

The electron that gets ejected from PSII gets captured by the primary electron acceptor
-some energy is dissipated and used to drive the proton H+ gradient into the thylakoid lumen
-the electrons carriers are plastoquinone (Pq- a cytochrome complex) and plastocyanin (Pc)

125
Q

What does the cytochrome complex do?

A

pumps the H+ into the thylakoid lumen (step 4)

126
Q

Describe the linear flow of electrons: Step 5

A
  1. Protons build up in the lumen by
    a.) splitting water AND
    b.)the cytochromes complex pumping protons into the lumen

this proton motive force is used to make ATP through ATP synthase embessed int eh thylakoid membrane via chemiosmosis

127
Q

Describe the linear flow of electrons: Step 6

A

Electrons are passed to photosystem 1, where they are re-energized
-the energy excites the light molecules harvesting complexes
-now can accept electrons from ETC

NOTE: no water splitting here

128
Q

Describe the linear flow of electrons: Step 7

A

Photoexcited electrons are passed to a second ETC to the protein ferrodoxin (Fd)
-does not create a proton gradient and thus NO ATP
-no water splitting here

129
Q

Describe the linear flow of electrons: Step 8

A

Once ferrodoxin has TWO ELECTRONS, it passes them onto NADP+ reductase to form NADPH.
-these electrons are carried in a equally-sharing covalent bonds
-now can accept electrons from ETC

NOTE: NADPH has a higher energy level than water so will be used in Calvin cycle. This process also removes H+ from the stroma

130
Q

Why are both photosystems needed?

A

Photosystem II and Photosystem I are both needed to FULLY energise an electron so that it can be used to reduce NADP+

131
Q

What is the cyclic flow of electrons?

A

Photoexcited electrons can by-pass photosystem II into Photosystem I

132
Q

At what rate does the cell divide in an organism?

A

At DIFFERENT rates

ex. skin cells divide all the time
ex. liver cells only when needed
ex. neurons don’t divide

133
Q

What does the results of the mammalian cells experiment conclude?

A

results of fusing a G1 cell with a cell in S or M phase of the cell cycle suggest that molecules in the cytoplasm during S or M phase control progression to those phases

134
Q

What is the cell cycle controlled by?

A

controlled by a distinct cell cycle control system
-a cyclically operating set of molecules that triggers and coordinates events in the cell cycle

ex. washing machine
-regulated and triggered by water level, temp. settings
-can manually override the system

135
Q

What is the cell cycle regulated by?

A

checkpoints
-stop and go ahead signals determine the state of the phases
MAIN CHECKPOINTS: G1,G2,M

-allows the cell to be stuck in the cell cycle at various stages
-must pass certain conditions before it continues

136
Q

What is the cell cycle control system regulated by?

A

CYCLINS and CYCLIN-DEPENDENT KINASES

Cyclins: proteins with fluctuating concentrations within the cytoplasm
-if cyclin is high enough, they attach to cyclin-dependent kinases (cdk) to form a complex
-this activates the kinase to phosphorylate other proteins to activate them, causing the cell to proceed in the cycle
-end of cycle, cyclin is degraded, inactivating the kinase

137
Q

What happens to the Cyclin at the end of the cycle?

A

it is degraded, which inactivates the kinase

138
Q

What is STEP 1 of the cell cycle?

A

Cyclin synthesis begins in late S phase and continues through G2. Protected from degradation, so (cyclin) increases

139
Q

What is STEP 2 of the cell cycle?

A

Cyclin combines with Cdk producing MPF. When MPF accumulation is high, cell passes through G2 checkpoint

140
Q

What is STEP 3 of the cell cycle?

A

MDF promotes mitosis by phosphorylating various proteins. MPF activity peaks during mitosos

141
Q

What is STEP 4 of the cell cycle?

A

During anaphase, the cyclin component of MPF degrades, terminating M phase. The cell enters G1 phase

142
Q

What is STEP 5 of the cell cycle?

A

During G1, cyclin continues to degrade, Cdk components are reycled

143
Q

What is the G1 checkpoint in the cell cycle?

A

Occurs before the S phase (restriction phase)
-if cell is large enough, sufficient nutrients, undamaged——-> proceeds to S,G2,M phse

-NO—-> it stalls in the G0 phase

144
Q

What doesn’t pass the G1 checkpoint in the cell cycle?

A

neurons and non-dividing cells don’t pass

145
Q

What is the G2 checkout of the cell cycle?

A

occurs BEFORE mitosis
-asks “was DNA successfully replicated? undamaged?

Interacts with MPF (which MPF must be activated by signalling molecules from this checkpoint to actually function properly)

146
Q

What is the M checkpoint?

A

occurs during metaphase

-ASKS “ are chromosomes aligned at the metaphase plate? Are kinetochores attached the spindle fibers”?

-ensures the daughter cells are NOT missing chromosomes or have extra chromosomes

-IF go-ahead cell proceeds to anaphase

147
Q

What could happen if the M checkpoint didn’t work properly?

A

DISCUSSION TOPIC

148
Q

What is aneuploidy?

A

incorrect # of chromosomes

149
Q

What is the correct seperation of cell cycle?

A

two nuclei with proper number of chromosomes

150
Q

What is the incorrection seperation of cell cycle?

A

The microtubule is NOT attached

151
Q

What are some other checkpoints in the cell cycle?

A

-S phase—> prevents the cycle to continue if DNA is damaged
-between anaphase and telophase ensures chromosomes are fully seperated and at opposite poles before cyctokinesis proceeds

BIOL 1020-MIDTERM 2 (1 decks)

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