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Flashcards in Chapter 9 Deck (51)
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1

Energy enters most ecosystems as...

sunlight

2

Energy leaves most ecosystems as...

heat

3

Cells harvest...

chemical energy stored in organic molecules that the mitochondria and eukaryotes use as fuel for cellular respiration

4

Catabolic pathways

yield energy by OXIDIZING and BREAKING down organic molecules
via
an exergonic process

5

Fermentation

a catabolic process

-a partial degradation of sugars that occurs in the absence of oxygen

6

Cellular Respiration

the most prevalent and efficient catabolic pathway

- consumes Oxygen and organic molecules such as glucose and yields ATP

7

Cells must regenerate ATP...

in order to keep working

8

Catabolic pathways yield energy based on ...

their ability to cause a transfer of elections

9

Redox reactions

transfer elections from one reactant to another by oxidation and reduction

i.e. redox of table salt: Na+ is oxidized, Cl- is reduced

10

Oxidation

a substance loses elections, or is oxideized

11

Reduction

a substance gains elections, or is reduced

12

the "fall" of electrons during respiration is...

stepwise and occurs by an electron transport chain

13

Electron Transport Chain

found in inter membrane counter of mitochondria

14

During cellular respiration...

glucose is oxidized
oxygen is reduced

done through a series of steps, each of which is catalyzed by a specific enzyme

15

at Key Steps during cellular respiration

electrons are stripped from glucose and the electrons are transferred with a proton as a hydrogen atom

glucose + 6oxygen => 6CO2 + 6water + Energy

O: glucose => 6CO2
R: 6oxygen => 6water

16

During cellular respiration, glucose is oxidized in a...

series of steps and
the H atoms are not directly transferred to oxygen but are ...

passed to a coenzyme called NAD+

17

NAD+

nicotinamide adenine dinucleotide

oxidized form

18

Dehydrogenase enzyme

2 H atoms from glucose are removed by this enzyme and then it transfers 2 electrons and 1 H+ (proton) to NAD+ (creating NADH) and the other proton is released into the solution

19

NADH => NAD+

NADH: the reduced form

passes e- to the "top" or high energy end of the electron transport chain

20

If the electron transfer is not stepwise...

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

21

Electron Transport Chain location

in the mitochondria membranes

22

Electron transport chain

"breaks the fall" of electrons by passing them in a controlled series of steps, and uses the energy from the electron transfer to form ATP

a the "bottom" or lower-energy end, oxygen captures the electrons along with hydrogen to form water

23

During cellular respiration, electrons follow a

"downhill" route

24

Stages of cellular respiration

1) Glycolysis
2) Citric Acid Cycle
3) Oxidative phosphorylation

25

Glycolysis

occurs in the cytoplasm
- breaks down glucose into two molecules of pyruvate (produces some ATP)
glucose => 2 pyruvate + 2 H2O + 2ATP + 2 NADH

26

Citric Acid Cycle

occurs in the mitochondrial membrane
- utilizes pyruvate and completes the breakdown of glucose
2 pyruvate => ATP, CO2, NADH, FADH2

27

Oxidative Phosphorylation

occurs in the inner mitochondrial membrane
- drives the synthesis of ATP by the transfer of electrons from NADH in electron transport chain
NADH + FADH2 => ATP

28

Glycolysis and the citric acid cycle can generate ATP by

substrate level phosphorylation

29

Substrate-Level phosphorylation

an enzyme transfers a phosphate group from an organic substrate to ADP, forming ATP

i.e. Pyruvate Kinase: transfers a phosphate (phosphorylates) ADP from phosphoenolpyruvate (PEP) to make ATP and pyruvate

30

Glycolysis
"splitting of sugar"

harvests energy by oxidizing glucose, a 6 carbon molecule to two, 3-carbon pyruvate molecules

2 major phases
1) energy investment (predatory) phase
2) energy payoff phase