Anatomy cells and chemistry

Animation: Cells & Chemistry

Glycolysis

After viewing the animation, answer these questions.

1. Cells derive energy from the oxydation of nutrients, such as glucose .

2. The oxidation of glucose to pyruvate occurs through a series of steps called glycolsis .

3. How many carbons are in a molecule of glucose? 6

4. The energy related during these oxydation reactions is used to form adenosine triphosphate ( ATP ), the Energy currency of the cell.

5. Name the two initials steps in glycolysis. The initial steps are the additions of two phospates to the glucose molecule at the expense of two molecules of ATP.

6. What are the three molecules that results? The three molecules that result are a 6 carbon sugar diphosphate molecule and 2 low energy adenosine diphosphate molecules.

7. What then occurs to the 6-carbon molecule? It is split into two three carbon molecules.

8. The 3-carbon molecules are converted to pyruvate .

9. What happens to the electrons in this reaction? What two molecules are formed?
Electrons are transferred to the coenzyme NAD+ and the two molecules formed are NADH and ATP.

10. What happens to the pyruvate under aerobic conditions?
Under aerobic conditions, the pyruvate is further oxidized to yield more ATP.

11. What happens to the pyruvate under anaerobic conditions?
Under anaerobic conditions, the pyruvate is converted into lactic acid.

Diffusion

After viewing the animation, answer these questions.

1. Molecules dissolved in a solution are in constant random motion due to their kinectic energy.

2. One result of this motion is dissolved molecules become evenly distributed throughout the solution .

3. This tendency of molecules to spread out is an example of diffusion .

4. Even as a solid lump, the individual sugar molecules are in motion .

5. What happens to the lump of sugar when it is dropped into the water? The lump begins to dissolve.

6. How do the individual sugar molecules move?
The individual sugar molecules move randomly and constantly from the area where they are common to the area where they are scarce.

7. How does this movement define diffusion?
The molecules move from an area of higher concentration to an area of lower concentration.

8. How long does diffusion continue?
The diffusion continues until all sugar molecules are evenly dispersed throughout the beaker.

9. What factors affect the rate of diffusion?
The rate of diffusion is affected by temperature, the size of the molecule and the steepness of the concentration gradient.

Osmosis

After viewing the animation, answer these questions.

1. What is diffusion?
Diffusion is the net movement of molecules down a concentration gradient.

2. What does this process allow?
This process allows molecules like carbon dioxide and oxygen to cross the plasma membrane.

3. Do most polar molecules freely cross the lipid cells membrane? Name two groups of polar molecules.
No they do not. Two groups of polar molecules are sugar and protein.

4. What is the name for the special case of diffusion that involves the movement of water molecules across a membrane?
This is called osmosis. 5. Why is a molecule of urea unable to diffuse across the membrane?
A molecule of urea is unable to diffuse across the membrane because it is large and polar.

6. How does a urea molecule interact with water molecules? Why?
The urea molecule interacts with water molecules by reducing the number of free water molecules on the right hand side. It interacts with water molecules because of its polar nature.

7. Why is there now a net movement of water molecules? Which direction do they move?
There is now a net movement of water molecules because there are fewer free water molecules on the right hand side. They move down their concentration gradient to the side with the urea molecules.

8. What happens to the water level on the side of the beaker why the water molecules are moving into?
The water level rises.

9. Define isotonic, hypertonic, and hypotonic.
Isotonic- when osmotic concentrations of two solutions are equal.
Hypertonic-When solutions have unequal osmotic concentrations, it's the solution with a higher concentration of solutes.
Hypotonic-The solution with lower concentration of solutes.

Facilitated Diffusion

After viewing the animation, answer these questions.

1. What occurs in the process of facilitated diffusion?
Facilitated diffusion process is when a carrier protein with a central channel acts as a selective corridor which helps molecules move across the membrane.

2. What is unique about the carrier molecules and the molecules to which they bind?
They bind only to a specific molecule like a particular sugar or amino acid.

3. Once the molecule binds to the carrier protein, the protein will facilitate the diffusion process by changing the shape and moving the molecule down its concentration gradient through the membrane into the cell where it is released. .

4. Facilitated diffusion and simple diffusion are similar in that both involve movement of molecules down their concentration gradient and this movement is carried out without any movement of energy .

5. How is facilitated diffusion different from simple diffusion?
It will only take place if it is helped by a special protein carrier in the membrane.

6. What determines which direction facilitated diffusion occurs?
Facilitated diffusion can occur in either direction depending on the concentration gradient. If there is a higher concentration of the particle inside the cell, then the same carrier protein will carry the molecules outside of the cell.

Cotransport

After viewing the animation, answer these questions.

1. Which direction can small molecules, such as sugars and amino acids, be transported?
Small molecules can be transported up a concentration gradient.

2. How does the sugar move? How does the concentration of sugar compare inside and outside of the cell?
The sugar moves from a membrane transport protein from outside the cell where the sugar concentration is low to the inside of the cell where the sugar concentration is high, 3. How is this transport of sugar driven through a coupled transport protein? Are these counterions moving from a higher to lower concentration or from a lower to higher concentration?
The movement is sugar is driven by the movement of counterions such as sodium ions or protons. The counterions are moving from a lower to higher concentration. 4. What is symport? Why occurs there?
A symport is a transmembrane protein outside of the cell. Sodium ions and the specific sugar or amino acids bind to the transmembrane protein.

5. How is a low concentration of sodium maintained inside the cell? How is it powered?
Low concentration of sodium is maintained inside the cell by the sodium potassium pump and that is powered by the ATP. 6. What is counter-transport?
The inward movement of sodium ions coupled with the outer movement of another substance like calcium ions. 7. What is an antiport? What occurs there? How is this different that what occurs at a symport?
Antiport is when the sodium ions and other substance bind to the same transport protein. In symport, the binding occurs on opposite sides of the membrane and move in opposite directions,

8. How does the sodium-potassium pump come into play in this process?

It maintains the low sodium ion concentration.

Reference

Broyles, R. B. (2012). Workbook to accompany anatomy & physiology revealed version 3.0. New York, NY: McGraw-Hill.