C1.2 - cell respiration Flashcards

1
Q

adenosine

A

molecule made out of an adenine base bonded to a ribose sugar

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2
Q

covalent bond

A

a bond where electrons are shared between two bonded atoms

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3
Q

decarboxylation

A

loss of a carbon atom, usually in the form of carbon dioxide

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4
Q

oxidation

A

a type of reaction that involves a loss of electrons or hydrogen atoms and an increase in C-O bonds

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5
Q

reduction

A

a type of reaction that involves a gain of electrons or hydrogen atoms and an increase in C-H bonds

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6
Q

ATP

A

adenosine triphosphate - a nucleotide consisting of the adenine base, ribose sugar and three phosphate groups

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7
Q

why is ATP known as the energy currency within cells?

A
  • ATP stores energy that is released when organic molecules are oxidised during respiration
  • last 2 phosphate groups of ATP are attached to the main molecule bu high energy bonds
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8
Q

why are covalent bonds between phosphate groups unstable?

A

the negative charged phosphate groups repel each other

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9
Q

what is the activation energy like and the type of reaction?

A

unstable bonds have low activation energy and are easily hydrolysed in an exergonic reaction

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10
Q

how is energy released from exergonic reactions used?

A

performs cellular work in metabolism
- molecule that distributes energy within cells

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11
Q

what processes does ATP supply energy for?

A
  • active transport across the membranes
  • protein synthesis
  • mitosis
  • movement of small organisms
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12
Q

what is an example of an exergonic reaction?

A

hydrolysis

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13
Q

what is an example of an endergonic reaction?

A

condensation

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14
Q

how do you convert ATP to ADP?

A
  • hydrolysis reaction (exergonic)
    ATP + H2O –> ADP + Pi
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15
Q

where was energy released from hydrolysis of ATP stored?

A

phosphate bond between the second and third phosphate groups

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16
Q

how do you convert ADP to ATP?

A
  • condensation reaction (endergonic)
    ADP + Pi –> ATP + H2O
17
Q

where is energy provided from to turn ADP to ATP?

A

energy is provided from the chemical reactions of cell respiration in which organic molecules are oxidised

18
Q

what are the respiratory substrates of respiration?

A

glucose and fatty acids
- a wide range of carbon compounds can be used

19
Q

what type of reaction occurs during complete breakdown of glucose in cell respiration?

A

catabolic redox reaction

20
Q

what does a catabolic redox reaction in respiration consist of?

A
  • oxidation of respiratory substrate, converting high-energy glucose molecules into low-energy carbon dioxide molecule
  • reduction in which oxygen gains hydrogen atoms, forming water
21
Q

cell respiration

A

chemical reaction that occurs within cells and releases energy

22
Q

gas exchange

A

diffusion of oxygen and carbon dioxide in opposite directions across a cell membrane

23
Q

what is an example of gas exchange?

A

oxygen diffuses out of the alveolar air and into the bloodstream by crossing membranes of the alveolar and capillary cells, with carbon dioxide diffusing in the opposite direction

24
Q

what are the characteristics of aerobic respiration?

A

glucose + oxygen –> carbon dioxide and water
- with oxygen
- high ATP yield
- produces carbon dioxide and water
- occurs in the cytoplasm and mitochondria

25
Q

what are the characteristics of anaerobic respiration?

A

glucose –> lactate
- without oxygen
- low ATP yield
- occurs in the cytoplasm
- produces lactic acid

26
Q

what factors affect cell respiration?

A
  • oxygen concentration
  • temperature
  • respiratory substrate availability
  • cell types
27
Q

how can oxygen concentration affect cell respiration?

A

lower concentrations of oxygen decreases the rate of aerobic cell respiration
- anaerobic respiration occurs when ATP cannot be produced quickly

28
Q

how can temperature affect cell respiration?

A

temperatures above and below the optimum level reduce the activity of enzymes, resulting in a decreased respiration rate

29
Q

how can respiratory substrate availability affect cell respiration?

A

lower concentrations of glucose decrease respiration rate
- if only disaccharides are available, time is needed to hydrolyse these to form monosaccharides to enter respiration pathways

30
Q

how can cell type affect cell respiration?

A

some cells require more energy than others due to their metabolic reactions

31
Q

respirometer

A

apparatus used to determine the rate of cell respiration

32
Q

what is a limitation of a respirometer?

A

temperature and external pressure can affect the position of the water droplet

33
Q

how can accuracy be improved for a respirometer?

A

second control tube is connected to the experimental tube by a manomter tube

34
Q

what are more modern techniques of measuring respiration rate?

A
  • using a pressure monitor with an alkali to absorb carbon dioxide so pressure reduction can be used to measure oxygen consumption
  • using oxygen monitors or oxygen probes to measure the change of oxygen concentration over time
35
Q

how does a simple respirometer work?

A
  1. an alkali is used to absorb carbon dioxide so only oxygen is measured
  2. starting position of a drop is measured
  3. the distance the drop moves over a period of time is dependent on the drop of pressure caused by oxygen consumption
36
Q

how do you calculate oxygen consumption?

A

volume of oxygen consumed = cross-sectional surface area of capillary tube x distance moved by drop

37
Q

how does a more complex respirometer work?

A

coloured fluid in the manometer moves towards the tube with the lower pressure and the rate at which it moves measures oxygen consumption rate

38
Q

what happens in a complex respirometer if there are variations in temperature?

A

affects pressure in both tubes equally, so the fluid doesn’t move as the glass beads and water means there is an equal volume of air in each tube

39
Q

what happens to the number of air molecules, pressure and drop of liquid in the boiling tube over time in a simple respirometer?

A
  • number of air molecules decreases
  • pressure decreases
  • drop of liquid moves towards the respirometer as it has lower pressure than the atmosphere