Chapter 8- Cellular Transport and the Cell Cycle Flashcards
What is osmosis?
Osmosis is the diffusion of water across a selectively permeable membrane.
What is diffusion?
Diffusion is the movement of particles from an area of high concentration to low concentration.
What controls osmosis?
The unequal distribution of particles, called a concentration gradient, is one factor that controls osmosis.
What is an isotonic solution? Where is there a high concentration of solutes, and where is there a low concentration of solutes? Where will water go? What will the cell look like?
In an isotonic solution, the concentration of the dissolved substance inside the cell is the same as the concentration of the dissolved substance outside the cell. Since the concentration is the same, the water is also equal inside and outside of the cell- osmosis (the diffusion of water) is still occurring, but at an equal rate.
What is a hypotonic solution? Where is there a high concentration of solutes, and where is there a low concentration of solutes? Where will water go? What will the cell look like?
Cells in a hypotonic solution will have a higher concentration of solutes inside the cell and a lower concentration outside the cell. This means there is more water outside of the cell, so as water diffuses into the cell, it swells.
What is a hypertonic solution? Where is there a high concentration of solutes, and where is there a low concentration of solutes? Where will water go? What will the cell look like?
In a hypertonic solution, there is a higher concentration of solutes outside the cell and a lower concentration inside the cell. This means there is more water inside the cell, so as water diffuses to the outside of the cell, the shrinks.
What is passive transport? Does it require energy? Does it go with or against the concentration gradient?
Passive transport is where cells use no energy to move (transport) particles through the plasma membrane. It goes with the concentration gradient and can occur by three methods:
- Simple diffusion
- Facilitated diffusion by channel proteins (form channels that allow specific molecules through)
- Facilitated diffusion by carrier proteins (change shape to allow a substance to pass through the plasma membrane)
Energy comes in what form?
ATP
What are the three methods for passive transport?
- Simple diffusion
- Facilitated diffusion by channel proteins (form channels that allow specific molecules through)
- Facilitated diffusion by carrier proteins (change shape to allow a substance to pass through the plasma membrane)
What is facilitated diffusion?
Facilitated diffusion is the passive transport of materials across the plasma membrane using transport proteins.
What is the difference between carrier proteins and channel proteins?
Cannel proteins form channels that allow specific molecules through, but carrier proteins change shape to allow substances through.
What is active transport? Does it require energy? Does it go with or against the concentration gradient?
Active transport is the movement of materials through a membrane against the concentration gradient. Unlike passive transport, active transport does require energy. There are only two methods for the transport of large particles, both of which require energy like active transport:
- Endocytosis, or the process by which a cells surrounds and takes in materials from its environment (membrane breaks away and the resulting vacuole moves to the inside of the cell).
- Exocytosis, or the expulsion and secretion of materials from a cell (waste is expelled from the cell).
What does “hypo” mean? How does this relate to hypotonic solutions?
“Hypo” means “under,” and hypotonic solutions have a higher concentration of solutes inside the cell and a “under” or lower concentration of solutes outside the cell. Also, the cell will shrink when the water diffuses and moves into the cell by osmosis.
What does “hyper” mean? How does this relate to hypertonic solutions?
“Hyper” means “over,” and hypertonic solutions have a higher or “over” concentration of solutes outside the cell rather than inside the cell. Also, the cell’s size will increase when the water diffuses, or leaves by osmosis.
How does active transport occur? What type of transport protein does it require?
In active transport, a carrier protein first binds with a particle of the substance to be transported, and chemical energy allows the cell to change the shape of the carrier protein so the the particle to be moved is released on the other side of the membrane.
How are large particles transported? Does this require energy?
There are only two methods for the transport of large particles, both of which require energy:
- Endocytosis, or the process by which a cells surrounds and takes in materials from its environment (membrane breaks away and the resulting vacuole moves to the inside of the cell)
- Exocytosis, or the expulsion and secretion of materials from a cell (waste is expelled from the cell)
What is endocytosis?
Endocytosis is the process by which a cells surrounds and takes in materials from its environment. The membrane breaks away, which creates a vacuole. This vacuole then moves to the inside of the cell.
What is exocytosis?
Exocytosis is the expulsion and secretion of materials from a cell, or when wastes are expelled from the cell.
What are the three criteria that will limit cell size?
The three criteria that will limit cell size are:
- Diffusion
- diffusion is a fast and efficient process over a short distance, but a slow a inefficient process over large distances
- DNA
- proteins are used by all organelles to perform critical functions, which limits for how quickly the DNA can be copied in the nucleus and made into proteins in cytoplasm
- Surface area to volume ratio
- as cell size increases, volume increases more quickly than surface area (there would not be enough space for adequate diffusion of nutrients, oxygen, etc.)
