A certain structure in a cell that serves a certain purpose or function.
Explanation: Elephants have been extensively hunted for ivory for more than 300 years, natural selection is often proposed as the underlying mechanism for an increase in the proportion of tuskless or small-tusked elephants in a population.
Answer:
2 molecules of ATP and 2 molecules of NADH
Explanation:
Glycolysis is the first step of cellular respiration (break down of glucose to extract energy) which occurs in the cytoplasm. Glycolysis is a pathway common to all living organisms- prokaryotes and eukaryotes, as it does not require oxygen to occur.
Glycolysis occurs in two major phases (ten steps) requiring 10 enzymes catalyzing each step; the energy-requiring phase and the energy-requiring phase.
In the energy-requiring phase, the starting molecule (glucose) gets rearranged in a series of chemical reactions, and two phosphate groups gets attached to it producing fructose-1,6-bisphosphate which is unstable, This modified sugar then splits in half due to its instability to form two different but inter-convertible phosphate-bearing three-carbon sugars (Dihydroxyacetonephosphate, DHAP and Glyceraldehyde-3-phosphate, G3P). Because the phosphates used in these steps come from 2 ATP molecules, 2 ATP molecules get used up in this phase
All the DHAP molecules get converted to G-3-P in order to enter the next phase.
In the energy-recovering phase, the 3-carbon sugar (G3P) is converted into another three-carbon molecule called pyruvate, through a series of reactions. In these reactions, two ATP and 1 NADH molecules are made. This recovery phase occurs twice (one for each of the two isomeric three-carbon sugars, DHAP and G3P). Hence, a total of 4 ATP and 2 NADH molecules are produced in this phase.
Overall, Glycolysis converts one glucose (six-carbon) molecule to two pyruvate (three-carbon) molecules and a net release of 2 ATP molecules (4 overall - 2 used) and 2 NADH molecules.
Answer:
It lacks a wall thus use the contractile vacuole to collect and expel excess water from the cell.
Explanation:
- The contractile vacuole regulates the quantity of water inside a cell through a process known as osmoregulation.Osmosis constantly drives water in the cell since it is enclosed by a semipermeable membrane that can not keep the water out thus it is needed to prevent rupturing of the cell due to excess water in the cell.
Answer:
Explanation:
brain-
Glucose is the major fuel for the brain metabolism to supply energy for synaptic transmissions. Average of -120g/day.However during hypoglacemia, keto bodies can be used by the brain for energy supply.
the fuel stores of the brain is very low because of high biochemical activities of the brain which need to be supplied with contant fuel.Although it stores little Glycogen, most fuel supply to the brain is from the circulating glucose in the blood.
Heart.
the high energy consuming activities of the heart ensured that molecules with abundant energy supply e.g fatty acids from lipids digestion is preferred. Keto bodies, acetoacetate and lactate can also be fuel . Glucose is last on the scale of preference for the heart as fuel.
It does not reserve or export any fuel.
Liver.
the complex metabolic and multi functional activities of the liver required constant supply of energy in all available forms. Thus glucose, Amino acids and fatty acids are sources of fuel for the liver.
The liver fuel reserve is in the form of glycogen which is stimulated by glucagon to convert to glucose during condition of hypoglycemia. Triacylglycerols is another fuel reserve.
Generally as products of metabolic activities in the liver, fatty acid from lipid metabolisms, Glucose from gluconeogenesis, and glycogensis, and ketone bodies are the export sources.
