unit 3 - cellular energetics

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bioenergetics

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113 Terms

1

bioenergetics

the study of how energy from the sun is transformed into energy in living things

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2

first law of thermodynamics

energy can’t be created or destroyed // sum of energy in the universe is constant

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3

exergonic reaction

products have less energy than reactants; energy is given off

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4

endergonic reactions

require an input of energy; products have more energy than the reactants

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5

transition state

a high energy molecule that reactants must turn into before becoming products; difficult to achieve

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6

activation energy

certain amount of energy required to reach the transition state

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7

how does activation energy work

chemical bonds must be broken before new ones can form

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8

enzymes

biological catalysts that speed up reactions

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9

enzyme specificity

each enzyme catalyzes only one kind of reaction

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10

substrates

targeted molecules

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11

enzyme-substrate complex

enzymes make the transition state happen by helping substrates get into position

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12

active site

special region on the enzyme where substrates go

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13

how do the structures and active sites relate?

structure (shape and charge) must be compatible with active site of an enzymea

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14

what happens to an enzyme after a reaction

it’s released and goes back to its original state

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15

induced fit

enzyme has to slightly change its shape to fit the substrate

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16

cofactors

factors that sometimes help enzymes catalyze reactions

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17

conenzyme

a type of cofactor; organic molecule, inorganic molecule, ion

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18

what can affect an enzymatic reaction

temperature and pH

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19

what determines reaction speed

concentration of an enzyme and substrate

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20

at what temperature are enzymes denatured?

42 degrees celsius

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21

denatured

what happens when an enzyme is denatured by heat and isn’t able to catalyze reactions anymore

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22

what is the optimum temperature for most human enzymes to function

37 degrees celsius

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23

how does pH alter enzymes

hydrogen bonds are disrupted and structure is altered

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24

what is the optimum pH for most enzymes

7

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25

when there is a high concentration of substrates, what happens to a reaction?

initially speeds up, once all of the enzymes are bound to a substrate, reaction can’t speed up any longer

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26

saturation point

the point where all enzyme are bound to substrates

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27

how does a cell regulate enzyme activity

regulating conditions that influence enzyme shape

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28

allosteric sites

somewhere on the enzyme that substrates can bind to that isn’t the active site

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29

competitive inhibition

a substance binds to the active site in place of the substrate

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30

noncompetitive inhibitor

when an allosteric inhibitor binds to allosteric site

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31

what happens to ATP when a cell needs energy?

the third phosphate is broken off: ATP → ADP + P + energy

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32

how can endergonic reactions be powered

by organisms using exergonic processes that increase energy

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33

cellular respiration

breaking down sugar and making ATP

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34

photosynthesis

how autotrophs get sugar for ATP

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35

what was the earliest photosynthesis done by

prokaryotic cyanobacteria

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36

what is the formula for photosynthesis?

6CO2 + 6H2O → C6H12O6 + 6O2

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37

what happens when light initially strikes a leaf

chlorophyll is activated, electrons are excited

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38

what happens after chlorophyll is activated

sends electrons down electron carriers, which makes ATP and NADPH

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39

What happens to ATP, NADPH, and CO2 during dark reactions

used to make carbs, H2O is split and O2 is released

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40

stroma

fluid filled region

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41

grana

structures in the chloroplasts that look like coin stacks

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42

thylakoids

individual discs within granum; have chlorophyll

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43

chlorophyll

light-absorbing pigment that drives photosynthesis

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44

thylakoid lumen

interior thylakoid

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45

what are the types of reaction centers

photosystem I and photosystem II

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46

photophosphorylation

when light is used to make ATP

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47

absorption spectrum

shows how well a certain pigment can absorb electromagnetic radiation

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48

what happens right after a leaf captures sunlight

energy is sent to P680 and forms active electrons

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49

what is P680

reaction center of PS II

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50

what is P700

reaction center of PS I

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51

photolysis

H2O is split into O2, H2, ions, electrons

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52

where do the electrons from photolysis go

replace missing ones in PS II and replenish those from the thylakoid

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53

what establishes a proton gradient in the ETC

H+ ions being pumped into thylakoid lumen as energized e- from PS II

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54

How is ATP produced during PS II

H+ ions move back into the stroma through ATP synthase

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55

where do e- go after leaving PS II

PS I; they’re passed through a second ETC

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56

when do e- stop on the second ETC

when they reach NADP+ to make NADPH

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57

cyclic electron flow

makes only ATP, no NADPH

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58

what mainly happens during the light independent reactions

use products of light reactions (NADPH and ATP) to make sugar

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59

carbon fixation

CO2 from air is converted into carbs

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60

where does carbon fixation occur?

stroma

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61

what is another term for dark reactions/light independent reactions?

Calvins cycle

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62

stomata

pores on the leaf that allow CO2 to enter the leaf, and O2 and H2O to exit

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63

what do plants do on hot and dry days to their stomata

close them to prevent water loss → limits CO2 access / reduces photosynthetic yield

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64

photorespiration

uses ATP and O2, produces more CO2, doesn’t make sugars

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65

what is the formula for cellular respiration

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

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66

aerobic respiration

when ATP is made in the presence of O2

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67

anaerobic respiration

when ATP is made without O2

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68

what are the four stages of aerobic respiration

glycolysis, formation of acetyl-coA, krebs/citric acid cycle (CAC), oxidative phosphorylation

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69

pyruvic acid

3 C molecules that form when glucose (6C) splits, one glucose breaking down results in 2 pyruvic acid and 2 ATP

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70

how is ATp made in glycolysis

combining ADP and an inorganic phosphate (using an enzyme)

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71

how many NADH does glycolysis make?

2; comes from e- transfer to carrier NAD+ (turns to NADH)

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72

where does glycolysis occur

cytoplasm

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73

where does the formation of acetyl co-A occur?

mitochondrion

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74

what types of C molecules are present in the beginning of the formation of acetyl-coA

two 2-C molecules, extras left as CO2

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75

acetyl coA

2C molecule

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76

how many NADH are made for every initial glucose

2

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77

where does the kreb’s cycle occur

matrix of the mitochondria

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78

what happens to both acetyl-coA molecules as soon as they enter the Kreb’s cycle

turned into CO2

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79

electron transport chain

e- take energy from glucose and carry it with themthe

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80

at the start of oxidative phosphorylation, how many NADH, FADH2 have been produced?

10 NADH, 2 FADH2

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81

what do NADH and FADH do

shuttle e- to ETC → forms NAD+, FADH, can be reused

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82

electron transport chain

a series of protein carrier molecules embedded in cristae

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83

what is the final acceptor in the ETC

O2

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84

what happens when the e- get to the final acceptor

O2 + e- + H+ → H2O

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85

what would happen if there weren’t O2 in the ETC

e- wouldn’t move down it, shuts down electron transport

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86

chemiosmosis

H+ ions from original H atom are pumped across inner mitochondrial membrane from the matrix into inner membrane space; pumping/diffusion of ions

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87

when does chemiosmosis happen

at the same time as electron transport, uses energy released from ETC

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88

pH/proton gradient

caused by the pumping of H+ ions; difference of the concentration of H+ across a membrane

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89

what is the only way H+ ions diffuse across a membrane

ATP synthase

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90

oxidative phosphorylation

when e- are given up, it’s ‘oxidation’ and ADP is phosphorylated to make ADP

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91

what must be maintained about an enzyme

the tertiary shape

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92

negative control

not exposed to experimental treatment or any treatment known to have effect

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positive control

exposed to treatment that is known to have an affect / no exposed to experimental treatment

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94

controlled variable

aspects of an experiment that could be changed but aren’t intentionally

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95

what does a decrease in temperature do to reaction rate

slows it down; fewer enzyme-substrate collisions

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96

what is the only way reaction rate will stay constant

saturation levels are maintained

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97

how do cells manage energy resources

energy coupling; energy releasing processes drive energy storing processes

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98

what does it mean for pathways in biological systems to be sequential

product of one reaction can be a reactant in the next; allows for more controlled and efficient energy transfer

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99

where is chemical energy temporarily stored during light dependent reactions

NADPH

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100

what transfers stored chemical energy to power production of organic molecules in light dependent reactions

ATP and NADPH

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