powering the cell part 1

Question 1

what are the two ways cells are fuelled

Answer 1

1) carbon source
2) capturing energy from chemical reactions or light to produce usable energy

Question 2

which macromolecule requires the most amount of energy to synthesise

Answer 2

protein

Question 3

what is a heterotroph

Answer 3

cells which use organic compounds as a source of carbon as well as the source of energy

Question 4

what is an autotroph

Answer 4

cells which use carbon dioxide as a source of carbon and light as a source of energy

Question 5

what is a chemoautotroph

Answer 5

cells which use carbon dioxide as a source of carbon and inorganic compounds as a source of energy

Question 6

outline the structure of ATP

Answer 6

3 phosphates
adenine base
ribose/pentose sugar

Question 7

outline how ATP produces enegry

Answer 7

when hydrolysed with the addition of water the bond between phosphate 2 and 3 becomes unstable so ATP–> ADP which is an exogenic reaction, producing energy

Question 8

how much energy is released when ATP goes to ADP

Answer 8

31 KJoules

Question 9

what processes generate ATP

Answer 9

1) aerobic oxidation
2) fermentation/ anaerobic metabolism of glucose
3) photosynthesis
4) electron transport and proton motive force

Question 10

outline how ATP is generated

Answer 10

1) the addition of a phosphate to ADP
2) electrons lost from a donor in reactions involving chemical substrates release energy
3) this is harvested to phosphorylate ADP to ATP
4) electrons move from a higher energy level to a lower one on the acceptor molecule, this movement released energy to phosphorylate

Question 11

outline oxidative phosphorylation in chemotrophs

Answer 11

electrons move from a high energy level in a chemical molecule to a lower energy level in another molecule
the movement releases energy which turns ADP- ATP

Question 12

outline photophosphorylation in phototrophs

Answer 12

light is used to excite photosynthetic pigments to move the electrons to an excited state which is unstable
therefore the electron is transferred to a lower energy level

Question 13

what happens when a substance is reduced or oxidised

Answer 13

a substrate gains an electron so the positive charge is reduced
a substrate loses an electron so the positive charge is increased

Question 14

define reducing power

Answer 14

the potential of a substance to reduce another substance by the loss or gain or an electron or by the addition or removal of hydrogen

Question 15

what is a hydride ion

Answer 15

an ion made up of a proton (H+) and two electrons

Question 16

outline how hydrogen is transferred

Answer 16

electrons in organic redox reactions are often transferred as hydride ions
therefore movement of an electron occurs in conjunction with the transfer of a proton

Question 17

define dehydrogenation

Answer 17

the loss of electrons and protons from a substrate where they are transferred to a hydrogen acceptor such as NAD or NADP

Question 18

outline how reducing power is used in the cell

Answer 18

NADH can be oxidised to NAD by the removal of electrons and transporting them through the electron transport chain via membrane proteins
at the same time a proton gradient is generated across the cell membrane which is used to generate energy

Question 19

how much energy is needed to make reducing pwoer

Answer 19

219 KJ/mol

Question 20

how many ATP molecules can be produced form one NADH

Answer 20

7

Question 21

what is a bomb calorimeter

Answer 21

a lab instrument which measures the amount of energy in a substance by the heat released when combusted in an excess of oxygen

Question 22

what are the steps of the oxidation of glucose and where do they occur

Answer 22

1) glycolysis - cytosol
2) pyruvic oxidation- mitochondiral matrix or cytosol (prokaryotes)
3) electron transport= inner mitochondrial membrane or plasma membrane (prokaryotes)

Question 23

what is glycolysis and what is produced

Answer 23

= the conversion of glucose to pyruvic acid/ 2 pyruvates
1) 4 ATP (net 2 as 2 are used)
2) 2 NADH
3) hydrogen ions/protons
- 10 cytosolic enzymes are used to catalyse the reactions in this pathway

Question 24

outline pyruvate oxidation and the krebs cycle

Answer 24

1) pyruvate is transported to the matrix where it reacts with coenzyme A forming carbon dioxide and acetyl CoA
2) the acetyl group of acetyl coA is oxidised to co2 via 9 reactions within the krebs cycle

Question 25

what is produced in the krebs cycle

Answer 25

• 3 NADH
• 1 ATP
• 1 FADH

Question 26

where is most the free enegry released in oxidation of glucose to co2 retained

Answer 26

• the reduced co enzymes NADH and FADH generated in glycolysis and the krebs cycle

Question 27

where do the transporters for the ETC gain electrons

Answer 27

cytosolic NADH

Question 28

outline electron transport

Answer 28

1) cytosolic NADH and FADH are oxidised to NAD and FAD
2) electrons are transported across a series of electron carriers in the inner membrane
3) this step by step transfer allows the energy in NADH and FADH to be released in small increments and stored as proton motive force

Question 29

what is proton motive force

Answer 29

the force which promotes the movement of protons across the membrane as a result of an increased proton gradient in the intermembrane space

Question 30

what is ATP synthase

Answer 30

an enzyme complex which uses proton motive force to generate ATP from ADP

Question 31

outline the structure of ATP synthase

Answer 31

a membrane protien formed of two subunits, F0 and F1
- F0= hydrophobic and embedded in the membrane
- F1= is the head of the structure and exposed to cytosol

Question 32

what does the F0 subunit of ATP synthase do

Answer 32

has a cavity which takes in protons where the lower portion Roates in response to ions moving down conc gradient across membrane

rotations of the F0 activated the F1 that binds phosphates to ADP to form ATP

Question 33

outline the oxidation of fatty acids

Answer 33

• fatty acids stored as triacylglycerols are hydrolysed in the cytosol to free fatty acids and glycerol
• fatty acids and acetylcoA form fatty acetyl CoA which are oxidised in two ways which convert it to acteyl CoA and a shorter factty Actyel coA
  1) FAD reduced to FADH and NAD reduced to NADH
  2) cycle repeated until shortened fatty acteyl CoA complety converted to Acetylco A where it enters krebs

Question 34

where are fatty acids oxidised in eukaryotes

Answer 34

mitochondria or perixomes