Biology--Quiz 5

Name each of the parts of the plasma membrane and describe their function.

- Phospholipid Bilayer: Makes up the two layer. - Integral Protein/Transport Proteins: Transport certain materials across the cell membrane. - Fatty Acid Tails: Hydrophobic tails of a phospholipid that repel water. - Phosphate Heads: Hydrophilic heads of phospholipid that are attracted to water. Made of phosphate and glycerol. - Peripheral protein: Are found on the one side of the membrane and attach temporarily, usually to aid with a reaction in the cell. - Cholesterol: Maintain flexibility of membrane. - Glycoprotein: Involved in cell-to-cell recognition. - Glycolipids: Also involved in cell to cell recognition.

What trends do you observe when comparing the volume, surface area, and surface area-to-volume ratios of a small, medium, and large cube as the cubes get larger?

As cube size increases, the volume will also increase.

What is the connection between surface area and volume?

As the cell becomes larger, the less surface area it has compared with its volume.

How does surface area-to-volume ratio limit cell size? Explain by comparing an organism that is a single large cell with a multicellular organism made up of many small cells.

Cells can only survive if surface area to volume ratio is large enough. In anemones, they have a large surface area. However when they close up, they have a smaller surface area. A single large cell has a smaller surface area than a multicellular organism that has many small cells.

Explain what is meant by the phrase "as you get bigger, your outside is unable to keep up with the needs of the inside"

In the smaller square the nucleus is closer to the edges so material is much more easily transported, where as in the large square it will take longer to transport material because the nucleus is so far from the edges.

What happened to the surface area to volume as the size increased?

It got smaller.

What happened to the surface area as the size increased?

It increased.

What happened to the volume as the size increased?

It increased.

How are surface area and volume different

Surface area is the sum of all the areas of an object, measured in square units. Volume is the amount of space an object takes up, measured in cubic units.

Volume

The amount of space the object takes up.

Describe the fluid mosaic model of the plasma membrane.

The cell membrane is made up of a phospholipid bi-layer. The phospholipids have hydrophilic heads and hydrophobic tails. They arrange themselves with their heads towards the cell or towards the outside, and the tails are towards the inside. This allows for the membrane to be semi-permiable, so some substances can pass through.

Explain the importance of the plasma membrane in maintaining homeostasis in an organism.

The membrane maintains homeostasis by keeping the cell's internal and external environments separate.

What happens when the ratio surface area to volume ratio decrease? How does it impact the cell?

The rate of diffusion of substances is proportional to the surface area of the plasma membrane, by the rate of using substances is proportional to cell volume. Therefore, cells can only survive if the surface area to volume ratio is large enough.

Surface Area

The sum of all the sides of a figure add up.

If you have something large and you divide it into small pieces, what increases: surface area or volume.

The surface area will increase because you still have the same amount of the substance, it's just in smaller pieces so it is taking up more room. An example of this is slices of bread versus a whole loaf. This is important to biology because when cells are compact, things can move in and out of the cell membrane faster.

Diffusion

When the cell moves materials, is fast over a short distance but extremely slow over a long distance.