5 - ENERGY TRANSFERS IN AND BETWEEN ORGANISMS Flashcards
Where does glycolysis take place?
In the cytoplasm within mitochondria
Where does the link reaction take place?
In the mitochondrial matrix
(Pyruvate moves from the cytoplasm into the mitochondrial matrix by active transport)
What happens in glycolysis?
- Glucose is phosphorylated by 2ATP forming hexose biphosphate
- hexose biphosphate splits into two molecules of triose phosphate
- oxidation of triose phosphate (two molecules of hydrogen are removed from triose phosphate and transferred to NAD hydrogen carriers)
- 2 phosphates transferred from intermediates
- 4ADP + Pi formed as well as 2 pyruvages
- net gain of 2 ATP
What happens after glycolysis in anaerobic respiration?
Plants and yeast:
Pyruvate -> ethanal -> ethanol
Pyruvate looses a carbon through CO2 becoming ethanal, ethanal gains a hydrogen from an NAD molecule forming ethanol
Animal cells and some bacteria:
Pyruvate -> lactate (lactic acid)
Pyruvate gains a hydrogen from a hydrogen carrier forming lactate
What happens in the link reaction?
Pyruvate -> acetate -> acetyl coenzyme A
- Pyruvate looses 1 carbon though CO2
- Pyruvate looses a hydrogen to NAD
- acetate formed
- coenzyme A combined with acetate to form acetyl coenzyme A
What is phototropism?
The growth of a plant in response to light
- Shoots are positively phototropic = growth towards light
- Roots are negatively phototropic = grow away from light
What is gravitropism?
The growth of a plant in response to gravity
Shoots are negatively gravitropic = grow upwards
Roots are positively gravitropic = grow downwards
What are auxins and give an example of one
Growth factors that speed up or slow down plant growth
Indoleacetic acid (IAA) is an auxin that is produced in the tips of shoots and roots
- moved around the plant to control tropisms
- moves by diffusion and active transport over short distances and via phloem in long distances
Examples:
Phototropism - IAA increases on the shaded side of a shoot, causes cells to elongate and shoot bends towards light. IAA increases on the shaded side of a root, growth is inhibited so root grows downwards
Gravitropism - IAA increases on the lower side of shoot, cells elongate and shoots grow upwards. IAA increases on lower side, growth inhibited so root grows downwards
What is the tactic response (taxis)?
Directional movement in response to a stimulus, e.g woodlouse moving away from light
What is the kinetic response (kinesis)?
Non directional (random) movement in response to a stimulus e.g when air gets drier, woodlouse move faster and turn more often to get back in a humid environment
