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freshman > biology EXAM #3 pt. 3 > Flashcards

biology EXAM #3 pt. 3 Flashcards

1
Q

Living cells require a

All heterotrophs, including us, obtain

Energy flows into an ecosystem 
as

A

source of energy from the outside to perform their many tasks

energy for our cells by eating plants and 
other consumers

sunlight and leaves as heat

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2
Q

Coupled reactions:
Anabolic pathways are coupled with

Catabolic pathways release

Electron transfer plays a

A

catabolic pathways as source of energy to perform work.

stored energy by breaking down complex molecules

major role in these pathways
These processes are central to cellular respiration

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3
Q

The breakdown of organic molecules is

Fermentation is a

Aerobic respiration consumes

Anaerobic respiration is similar to

A

exergonic

partial degradation of sugars that occurs without O2

organic molecules and O2 and yields ATP

aerobic respiration but consumes compounds other than O2

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4
Q

COMPLETE Cellular respiration includes both

Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the _____

formula of cellular respiration

A

aerobic and anaerobic respiration but is often used to refer to aerobic respiration

sugar glucose

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy (ATP + heat)

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5
Q

Redox reactions transfer

In oxidation, a substance

In reduction, a substance

Na + Cl  Na+ + Cl-
Here, Na is

A

electrons from one reactant to another by oxidation and reduction

loses electrons, or is oxidized. It is called reducing agent because it is the electron donor.

gains electrons, or is reduced. It is called the oxidizing agent because it is the electron acceptor.

Na is oxidized or reducing agent and Cl is reduced or oxidizing agent.

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6
Q

Oxidation and reduction always

The electron donor is called

The electron acceptor is called

A

go hand in hand

the reducing agent, it reduces the electron acceptor

the oxidizing agent, it oxidizes the electron donor

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7
Q

Instead of fully transferring electrons, some redox reactions :

Oxygen (O) atoms are very ________; they :

what constitutes a redox reaction?

For example, electrons are not completely transferred in the redox reaction between methane and O2

A

change electron sharing in covalent bonds

electronegative; they attract electrons and do not share them equally

The partial “gain” of electrons by O atoms and the partial “loss” of electrons by their bonding partners

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8
Q

Some redox reactions do not completely:

They change :

A

exchange electrons

the degree of electron sharing in covalent bonds

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9
Q

Photosynthesis
-formula

Hydrogen atoms are transferred from :

_________ is required and this comes in the form of :

Chloroplasts convert solar energy to ______ which is then used along with ___________ to:

A

energy + 6CO2+6H2O C6H12O6 + 6O2

water to carbon dioxide and glucose is formed

Energy; form of light energy from the sun

solar energy to ATP;
with hydrogen to reduce carbon dioxide to glucose

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10
Q

During cellular respiration, the fuel (such as glucose) is ________-, and O2 is ________

Organic molecules with an abundance of hydrogen are:

Energy is released as

A

the fuel (such as glucose) is oxidized, and O2 is reduced

excellent sources of high-energy electrons

the electrons associated with hydrogen ions are transferred to oxygen, a lower energy state

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11
Q

During cellular respiration, glucose is __________ and oxygen is _______

co2 is ______ and h2o is _______

Complete oxidation of a mole of glucose produces _____ kcal of energy (____ in the form of ATP)

This energy is used to form ____

A

glucose is oxidized and oxygen is reduced

co2 is oxidizes and h20 is reduced

686 kcal of energy; 262

ATP

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12
Q

Catabolic pathways yield energy by:

A

oxidizing (loss of H+ or e-) organic fuels (Glucose is oxidized thus converted to CO2 and O2 is reduced and converted to H2O)

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13
Q

cellular respiration

Is the most:

Consumes:

Yields how much ATP ?

Each ATP =

A

prevalent and efficient catabolic pathway

oxygen and organic molecules such as glucose

(32-34)

7.3 kcal

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14
Q

About 34% of the energy in a glucose molecule is:

(7.3*32)/686 Kcal = 40% 34% efficiency
The rest = unused energy lost as heat

A

transferred to ATP during cellular respiration, making approximately 38 ATP

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15
Q

One catabolic process, fermentation is a:

The biproducts:

Yields how much ATP ?

A

partial degradation of sugars that occurs without oxygen

lactate-us, lactic acid, alcohol yeast-beer/wine or bacteria -tequila, citric acid…

(2)

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16
Q

To keep working cells must________________– remember coupled reactions:

Catabolic pathways yield ________ due to the transfer of _________

A

regenerate ATP
anabolic and catabolic reactions simultaneously

energy; electrons

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17
Q

Cellular respiration oxidizes __________ in a series of steps

Electrons from organic 
compound are usually 
first transferred to ______,
 which is a ________

A

glucose

NAD+, a coenzyme

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18
Q

Each electron travels with a ________—thus, as a ______ ______

A

proton; hydrogen atom

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19
Q

Hydrogen atoms are usually first passed to _______ _______, rather than directly to ____

A

electron carriers, rather than directly to O2

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20
Q

As an electron acceptor, Nicotinamide adenine dinucleotide, NAD+ functions as an :

Each NADH (the reduced form of NAD+) represents:

A

oxidizing agent during cellular respiration

stored energy that is tapped to synthesize ATP

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21
Q

NADH,
First – picks up the

If electron transfer is not stepwise….

A

electrons removed from food, then it passes the electrons to the electron transport chain

a large release of energy occurs (explosion), as in the reaction of hydrogen and oxygen to form water

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22
Q

the electron transport chain passes:

then, uses the energy from the electron transfer to:

NADH up to (how much ATP)

FADH2 up to (how much ATP)

A

electrons in a series of steps instead of in one explosive reaction

form ATP (26-28 ATP by means of oxidative phosphorilation)

2.5 ATP in Oxidative phosphorilation

1.5

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23
Q

NADH passes electrons to the :

O2, the _____ _______ ______, captures the:

The energy yielded is used to:

A

electron transport chain where they are transferred in a series of redox reactions, each releasing a small amount of energy

final electron acceptor; electrons and the hydrogen nuclei (H+), forming H2O

regenerate ATP

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24
Q

Respiration is a cumulative function of

A

three (four) metabolic stages

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25
Q

The process that generates almost 90% of the ATP is called … because…

A smaller amount of ATP is formed in ________ and the _________ by :

A

oxidative phosphorylation because it is powered by redox reactions

formed in glycolysis and the citric acid cycle by substrate-level phosphorylation

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26
Q

overview of cellular respiration

Oxidation of glucose to carbon dioxide, water, and energy

Exergonic reaction used to

4 phases of respiration are required for complete oxidation of glucose:

Oxidation involves the

A

drive ATP synthesis which is endergonic

glycolisis, preparatory reaction, citric acid cycle, electron transfer chain

removal of hydrogen atoms from substrates by redox coenzymes NAD+ and FAD

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27
Q

Glycolysis breaks down

Glycolysis occurs in the _______ and has:
1)
2)

Glycolysis occurs whether or not

A

glucose into two molecules of pyruvate

occurs in the cytoplasm and has two major phases:
Energy investment phase
Energy payoff phase

O2 is present

28
Q

Glycolysis:

Transition rxn:

The citric acid cycle completes the

Oxidative phosphorylation is driven by:

A

breaks down glucose into two molecules of pyruvate (in cytoplasm

2 pyruvate to 2Acetyl CoA (cytoplasm –matrix)

breakdown of glucose

the electron transport chain and generates ATP

29
Q

Both glycolysis and the citric acid cycle can

A

generate ATP by substrate-level phosphorylation

30
Q

Glycolysis harvests energy by

Glycolysis means:

Breaks down glucose into
Occurs in the

A

oxidizing glucose to pyruvate

“splitting of sugar”

pyruvate

cytoplasm of the cell

31
Q

All of the carbon originally present in glucose is

Glycolysis does not release any ____, and occurs whether or not ___ is present

A

accounted for in the two molecules of pyruvate

CO2, and occurs whether or not O2 is present

32
Q

After pyruvate is oxidized, the citric acid cycle…

Most of the energy in glucose remains

In the presence of O2, pyruvate enters a

A

completes the energy-yielding oxidation of organic molecules

stored in the pyruvate molecules produced by glycolysis

mitochondrion (in eukaryotic cells), where the oxidation of glucose is completed

33
Q

Before the citric acid cycle can begin, pyruvate must be:

This step is carried out by :
(3)

A

converted to acetyl coenzyme A (acetyl CoA), which links glycolysis to the citric acid cycle

a multienzyme complex that catalyzes three reactions:

1)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

34
Q

Before the citric acid cycle can begin, pyruvate must first be converted to

Loss of

A

acetyl CoA, which links the cycle to glycolysis

two C molecules in the form of CO2

35
Q

The citric acid cycle, also called ___________, completes the:

The citric acid cycle oxidizes:

Takes place in the:

Substrate level phosphorilation

Loss of

A

the Krebs cycle
energy-yielding oxidation of organic molecules

organic fuel derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH2 per turn

matrix of the mitochondrion

4 C molecules in the form of CO2

36
Q

The citric acid cycle has

The acetyl group of acetyl CoA joins the cycle by

The next seven steps :

The NADH and FADH2 produced by the cycle relay

A

eight steps, each catalyzed by a specific enzyme

combining with oxaloacetate, forming citrate

decompose the citrate back to oxaloacetate, making the process a cycle

electrons extracted from food to the electron transport chain

37
Q

Oxygen is taken in by breathing
Digested food contains glucose
Oxygen and glucose are carried to cells by the bloodstream
Glucose and oxygen enter cells where respiration occurs
Carbon dioxide is taken by the bloodstream to the lungs

A

leer

38
Q

for glucose:
2C acetyl group from prep reaction combines with a 4C molecule to produce 6C citrate
Oxidation of citrate by removal of hydrogens
Produces 3 NADH and 1 FADH2 per cycle
Produces 1 ATP by direct substrate phosphorylation per cycle
Cycle turns twice per glucose
Total yield:

A

6 NADH, 2 FADH2, 2 ATP, 4 CO2

39
Q

Following glycolysis and the citric acid cycle,

These two electron carriers donate electrons to the _______________, which :

A

NADH and FADH2 account for most of the energy extracted from food

electron transport chain, which powers ATP synthesis via oxidative phosphorylation

40
Q

Molecules of the electron transport chain are

The membrane is folded into

In prokaryotes, the electron transport chain is

A

embedded in the inner mitochondrial membrane (cristae) in eukaryotic cells

cristae to increase surface area for electron transport chains

embedded in the plasma membrane

41
Q

Most of the chain’s components are _____, which exist in :

Electrons drop in ___________ as they :

Electron carriers alternate between:

A

proteins; multiprotein complexes

free energy as they go down the chain and are finally passed to O2, forming H2O

reduced and oxidized states as they accept and donate electrons

42
Q

Electrons are transferred from NADH or FADH2 to the

Electrons are passed through a number of

The electron transport chain generates

It breaks the :

A

electron transport chain

proteins to O2

no ATP directly

large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts

43
Q

In the electron transport chain, electrons from NADH and FADH2 :

A series of

A

lose energy in several steps

redox reactions

44
Q

NADH and FADH2 donate electrons to

At the end of the chain, electrons are passed to:

A

different electron acceptors early in the chain

oxygen, forming water

45
Q

At certain steps along the electron transport chain, electron transfer causes

H+ then moves

A

protein complexes to pump H+ from the mitochondrial matrix to the intermembrane space

down its concentration gradient back across the membrane, passing through the protein complex ATP synthase

46
Q

The resulting H+ gradient stores … and drives…

A

stores energy and drives chemiosmosis in ATP synthase

47
Q

Chemiosmosis is referred to as a

Is an

A

proton-motive force

energy-coupling mechanism that uses energy in the form of a H+ gradient across a membrane to drive cellular work

48
Q

ATP synthase is the

A

enzyme that actually makes ATP

49
Q

During cellular respiration, most energy flows in this sequence:

About __% of the energy in a glucose molecule is ….., making about # ATP

The rest of the energy is lost as

A

glucose → NADH → electron transport chain → proton-motive force → ATP

34% ; transferred to ATP during cellular respiration; 30-32

heat

50
Q

cellular respiration old
3: glycolisis, citic acid cycle, oxidative/electron trans…/chemi

new
4:glycolisis, pyruvate oxidation, citic acid cycle, oxidative/electron trans…/chemi

A
51
Q

There are three reasons why the number of ATP is not known exactly:

A

Photophosphorylation and the redox reactions are not directly coupled; the ratio of NADH to ATP molecules is not a whole number

ATP yield varies depending on whether electrons are passed to NAD+ or FAD in the mitochondrial matrix

The proton-motive force is also used to drive other kinds of work

52
Q

Fermentation and anaerobic 
respiration enable cells to

Most cellular respiration depends on

Without oxygen,

In that case, glycolysis

A

produce ATP without the use of oxygen


electronegative oxygen to pull electrons down the transport chain

the electron transport chain will cease to operate

couples with anaerobic respiration or fermentation to produce ATP

53
Q

Anaerobic respiration uses an…
, for example, ______.

some organisms use a sulfate ion (SO42-) as a final electron acceptor

In this case, H2S (hydrogen sulfide) is made as a by-product instead of H2O

Fermentation uses

A

electron transport chain with a final electron acceptor other than oxygen; for example, sulfate

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

54
Q

Glycolysis can produce ATP:
Couples with:

A

with or without oxygen, in aerobic or anaerobic conditions

fermentation to produce ATP

55
Q

Fermentation consists of

Two common types are

A

glycolysis plus reactions that regenerate NAD+, which can be reused by glycolysis

alcohol fermentation and lactic acid fermentation

56
Q

In alcohol fermentation, ___________ is converted to ___________ in two steps:
1)
2)

Alcohol fermentation by yeast is used in brewing, winemaking, and baking

A

pyruvate is converted to ethanol in two steps:

1)The first step releases CO2 from pyruvate
2)The second step produces NAD+ and ethanol

57
Q

In lactic acid fermentation, _______ is reduced by ________, forming:

Lactic acid fermentation by some fungi and bacteria is used to make cheese and yogurt

Human muscle cells use lactic acid fermentation to

A

pyruvate is reduced by NADH, forming NAD+ and lactate as end products, with no release of CO2

generate ATP during strenuous exercise when O2 is scarce

58
Q

Both fermentation and cellular respiration use glycolysis to

Fermentation and cellular respiration differ in their

Another difference is the

Fermentation produces (ATP)

Cellular respiration harvests ATP by oxidative phosphorylation, # ATP.
This sums up to # ATP total in aerobic respiration

A

oxidize glucose and other organic fuels to pyruvate

final electron acceptor

amount of ATP produced per glucose molecule

2 ATP by substrate-level phosphorylation

26-28 ATP
30-32 ATP

59
Q

Obligate anaerobes carry out

Yeast and many bacteria are ______________, meaning:

A

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

facultative anaerobes, meaning that they can survive using either fermentation or cellular respiration

60
Q

Glycolysis is

Early prokaryotes likely used glycolysis to produce ATP before

Used in both cellular respiration and fermentation, it is the

This pathway occurs in the

A

an ancient process

O2 accumulated in the atmosphere

most widespread metabolic pathway on Earth

cytosol so does not require the membrane-bound organelles of eukaryotic cells

61
Q

Glycolysis and the citric acid cycle connect to:

Catabolic pathways :
-Funnel…
-Proteins used for fuel must be …
-Nitrogenous waste is excreted as…

A

many other metabolic pathways

-electrons from many kinds of organic molecules into cellular respiration
-digested to amino acids and their amino groups must be removed in a process called deamination
-ammonia (NH3), urea, or other products

62
Q

Fats are digested to

Fatty acids are broken down by

An oxidized gram of fat produces more than twice as much ATP as an

A

glycerol and fatty acids

beta oxidation and yield acetyl CoA, NADH, and FADH2

oxidized gram of carbohydrate

63
Q

The body uses small molecules to

These small molecules may come directly from

A

build other substances

food or through glycolysis or the citric acid cycle

64
Q

Cellular respiration:
Feedback inhibition is the

Is controlled by

If ATP concentration drops, ______________; if there is plenty of ATP, ______________

Catabolism is controlled by

A

most common mechanism for metabolic control because it prevents wasteful production

allosteric enzymes at key points in glycolysis and the citric acid cycle

respiration speeds up; ………., respiration slows down

regulating the activity of enzymes at strategic points in the pathway

65
Q

Certain electron carriers in the electron transport chain

In this way, the energy stored in a H+ gradient across a membrane couples the

The H+ gradient is referred to as a

A

accept and release H+ along with the electrons

redox reactions of the electron transport chain to ATP synthesis

proton-motive force, emphasizing its capacity to do work

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