Module 7 - Cellular Structure and Function

Question 1

What are the principles of the cell theory?

Answer 1

1. All living organisms are composed of one or more cells
2. Cells are the basic unit of structure and organization of all living organisms.
3. Cells arise only from previously existing cells, with cells passing copies of their genetic material on to their daughter cells.

Question 2

What is the plasma membrane?

Answer 2

a boundary that helps control what enters and leaves the cell.

Question 3

What are organelles?

Answer 3

specialized membrane-bound structures that carry out specific cell functions in different parts of the cell at the same time.

Question 4

What are prokaryotic cells?

Answer 4

Cells without a nucleus or other membrane-bound organelles

Question 5

What are eukaryotic cells?

Answer 5

Cells with a nucleus and other organelles and other organelles that are bound by membranes.

Question 6

What is the nucleus?

Answer 6

A central organelle that contains the cell’s genetic material in the form of DNA

Question 7

What is the phospholipid bilayer?

Answer 7

Two layers of phospholipids arranged tail to tail that make up the plasma membrane. Fatty acid tails are nonpolar/repelled by water and are on the interior of the membrane. The polar heads are polar and attracted to water, on the edges of the membrane. This keeps water-soluble substances from moving through.

Question 8

What are transport proteins?

Answer 8

Proteins that span the entire membrane and create tunnels through which certain substances enter and leave the cell. Contribute to the selective permeability aspect of plasma membrane.

Question 9

What is a fluid mosaic model?

Answer 9

The concept that the plasma membrane isn’t solid, it moves around as if it were water. They are in constant motion.

Question 10

What is selective permeability?

Answer 10

A key property of the plasma membrane that allows some substances to pass through while keeping others out.

Question 11

What is diffusion?

Answer 11

The net movement of particles from an area of high concentration to an area of low concentration. Passive transport (does not require energy input.)

Question 12

What is facilitated diffusion?

Answer 12

Diffusion through a transport protein

Question 13

What factors affect the rate of diffusion?

Answer 13

concentration, temperature, and pressure

Question 14

What is dynamic equilibrium?

Answer 14

The state of having continuous movement but no overall change.

Question 15

What is osmosis?

Answer 15

The diffusion of water across a selectively permeable membrane. Water moves from a high concentration to a low concentration. Because the solute cannot pass through the membrane, it cannot diffuse and so the water balances out the concentrations by having more water on the side with more solute and less water on the side with less solute. This way both sides have the same concentration level. Passive transport

Question 16

What are Aquaporins?

Answer 16

Channel proteins in the plasma membrane that allow small uncharged molecules (such as water) to pass through.

Question 17

What is an isotonic solution?

Answer 17

A solution that has the same concentration of water and solutes (ions, sugars, proteins, and other substances) as its cytoplasm. Water enters and leaves the cell at the same rate. The cell is at equilibrium.

Question 18

What is a hypotonic solution?

Answer 18

A solution with a lower concentration of solute than the cell. More water outside the cell as a result of osmosis. Net movement of water through the plasma membrane is into the cell.

Question 19

What is a hypertonic solution?

Answer 19

A solution with a higher concentration of solute than the cell. The cell is shriveled. The net movement of water is out of the cell.

Question 20

What is active transport?

Answer 20

THe movement of substances across the plasma membrane against a concentration gradient. It requires energy. Can only happen with the use of carrier proteins or pumps.

Question 21

What is the sodium-potassium ATPase pump?

Answer 21

An active transport pump found in the plasma membrane of animal cells.
1. Sodium ions enter protein from inside the cell and are bound.
2. ATP attaches to protein from inside
3.ATP breaks down into ADP, changing the protein’s shape and allowing sodium ions to leave to the outside of cell.
4. Potassium ions bind to protein from the outside of cell.
5. Binding of potassium causes the release of extra phosphate (From ATP) back into the inside.
6. Protein comes back to original shape and potassium ions move into cell.

Question 22

What is endocytosis?

Answer 22

The process by which a cell surrounds a substance in the outside environment, enclosing the substance in a portion of the plasma membrane. The membrane pinches off leaves the substance inside the cell. Substance coming into the cell. Active transport

Question 23

What is exocytosis?

Answer 23

The secretion of materials at the plasma membrane. Reverse of endocytosis. Active transport.

Question 24

What is the cytoplasm?

Answer 24

The semifluid material that forms the environment inside the plasma membrane. All prokaryotic cell functions take place here while eukaryotic organelles live here.

Question 25

What is a cytoskeleton?

Answer 25

A supporting network of long, thin protein fibers that forms a framework for the cell and provides an anchor for the organelles inside the cell.

Question 26

What is a microtubule?

Answer 26

Long, hollow protein cylinders that form a rigid skeleton for the cell and assist in moving substances within the cell. Part of cytoskeleton

Question 27

What are microfilaments?

Answer 27

Thin protein threads that help give the cell shape and enable the entire cell or parts of the cell to move. Part of cytoskeleton.

Question 28

What are centrioles?

Answer 28

Groups of microtubules that function during cell division. Located in the cytoplasm of animal cells and most protists. Usually near the nucleus.

Question 29

What are cilia?

Answer 29

Short, numerous projections that look like hairs.

Question 30

What are flagella?

Answer 30

Long and less numerous than cilia and move in a whip-like motion.

Question 31

What is the cell wall?

Answer 31

A thick, rigid mesh of fibers that surrounds the outside of the plasma membrane, protects the cell, and gives it support.

Question 32

What is the nucleolus?

Answer 32

A site within the nucleus where ribosome is produced.

Question 33

What are mitochondria?

Answer 33

Energy generators of the cell that convert fuel (mainly sugars) into usable energy. Has an outer membrane and a highly folded inner membrane that provides a large surface area for breaking the bonds in sugar molecules.

Question 34

What are chloroplasts?

Answer 34

Organelles that capture light energy and convert it to chemical energy through photosynthesis. Found in plants and some other eukaryotic cells

Question 35

What is a ribosome?

Answer 35

The organelle that helps manufacture proteins. Made of two components: RNA and protein. Not bound by a membrane.

Question 36

What is an endoplasmic reticulum?

Answer 36

A membrane system of folded sacs and interconnected channels that serves as the site for protein and lipid synthesis.

Question 37

What is the difference between rough endoplasmic reticulum and smooth endoplasmic reticulum?

Answer 37

The rough endoplasmic reticulum has ribosomes and the smooth does not.

Question 38

What is the Golgi apparatus?

Answer 38

A flattened stack of membranes that modifies, sorts, and packages proteins into sacs called vesicles.

Question 39

What is a vacuole?

Answer 39

A sac used to store food, enzymes, and other materials needed by a cell. Not usually found in animal cells.

Question 40

What are lysosomes?

Answer 40

Vesicles that conain substances the digest excess or worn-out organelles and food particles. Also digest bacteria and viruses.The membrane around lysosome prevents the enzymes from destroying the cell. Can fuse with vacuoles and dispense enzymes inside.