Chapter 6

Question 1

What is the plasma membrane?

Answer 1

the cell membrane!

Question 2

What is the plasma membrane made of?

Answer 2

A phospholipid bilayer

Question 3

What is the fluid mosaic model?

Answer 3

The way that we model the nature of scattered proteins within a flexible matrix of phospholipid molecules

Question 4

The plasma membrane is selectively permeable. What does this mean?

Answer 4

Only small, uncharged polar molecules such as Co2 and oxygen can pass freely

Question 5

What are the different kinds of proteins in the plasma membrane?

Answer 5

channel proteins, ion channels, carrier proteins, transport proteins, recognition proteins, receptor proteins, adhesion proteins

Question 6

What do channel proteins do?

Answer 6

provide open passageways through the membrane for certain hydrophilic substances. Aquaporins are channel proteins specifically for water

Question 7

What do ion channel protein do?

Answer 7

allow the passage of ions across the membrane. Sometimes, such as in muscle or nerve cells, these are gated channels that only work for specific ions

Question 8

What do carrier proteins do?

Answer 8

bind to specific molecules, and then change shape to force the molecule into the cell (glucose is an example)

Question 9

What do transport proteins do?

Answer 9

move stuff across the membrane. They are special because they use ATP to do this

Question 10

What do recognition proteins do?

Answer 10

Exactly what their name implies. They are actually glycoproteins; proteins with a short polysaccharide chain that extends away from the surface of the plasma membrane

Question 11

What do receptor proteins do?

Answer 11

Receive hormones/other trigger molecules and then make a response within the cell

Question 12

What is the role of cholesterol in the plasma membrane?

Answer 12

Cholesterol acts as a sort of buffer for the plasma membrane. At higher temperature, it helps maintain membrane firmness and at lower temperatures it helps maintain flexibility.

Question 13

What is the endosymbiotic theory?

Answer 13

The theory that one single celled organism tried to eat another one but instead decided to work with it.

Question 14

What is the nucleus bound by?

Answer 14

The nuclear envelope, which consists of two pholspholipid bilayers

Question 15

Describe DNA’s different chronological states within the nucleus

Answer 15

Usually, it’s spread throughout the nucleus in a thread-like matrix called chromatin. When the cell begins to divide, the chromatin condenses into rod shaped bodies called chromosomes. Chromosomes are organized with histones (which are proteins). The histones coil the DNA into nucleosomes

Question 16

What do the nucleoli do and where?

Answer 16

The nucleoli are little bundles of DNA that manufacture ribosomes within the nucleus, and eject the ribosomes out of the nuclear pores in the nuclear envelope

Question 17

What are ribosomes and what do they do?

Answer 17

Ribosomes are little protein/RNA things that are assembles in the cytoplasm out of subunits shipped from the nucleus. They are involved in the assembling of amino acids into proteins

Question 18

Where do the proteins that attached ribosomes make go?

Answer 18

Out of the cell (maybe) or to the plasma membrane

Question 19

Where do the proteins that free ribosomes make go?

Answer 19

They stay in the cell!

Question 20

What is the endoplasmic reticulum and what does it do?

Answer 20

It’s a bunch of maze-like sacs near the nucleus. Rough ER has ribosomes on it, smooth ER doesn’t. Rough ER is involved in the production of glycoproteins (their path goes RER, Golgi, Vesicle, Membrane), and the smooth ER is involved in detoxification and the synthesis of lipids.

Question 21

What is the golgi apparatus and what does it do?

Answer 21

A group of flattened sacs (cisternae) that collect and modify proteins and lipids made in other areas of the cell and then package them into vesicles.

Question 22

What are lysosomes and what do they do?

Answer 22

They are vesicles from the golgi that contain hydrolytic enxymes (enzymes that break down molecules by hydroysis) They break down food, debris, foreign invaders, etc. Fun fact: they use enzymes that work in low pH, which is maintained inside the lysosomes. This ensure that even if a lysosome breaks, the enzymes will be inactive in the neutral pH of the cytosol