Cell Biology Discoveries and Applications

Question 1

What do Cell-cell recognition proteins do?

Answer 1

Recognize other cells via a sugar molecule

Question 2

What do intercellular joining proteins do?

Answer 2

Joins cells to other cells. For example, skin cells

Question 3

What are the 2 main components of membranes?

Answer 3

Fluid mosaic and phospholipid bilayer

Question 4

Hydrophilic substances pass through the membrane because the membrane is selectively permeable

Answer 4

Diffusion, facilitated diffusion through proteins, 
ATP pump (allows to move molecules against concentration)

Question 5

What separates the cell from its external surroundings?

Answer 5

Plasma membrane

Question 6

In the early days, why was the existence of the cell plasma membrane debated?

Answer 6

The membrane could net yet be visualized with microscopes.
Some claimed that the protoplasm could just stick together on its own, while others thought that membranes were secondary structures that the protoplasm formed upon contact with its external environment

Question 7

When did the existence of the plasma membrane become fully accepted?

Answer 7

The beginning of the 20th century

Question 8

What did Moritz Traube contribute to the acceptance of a cell plasma membrane?

Answer 8

In the 19th century, he perused the idea that there was an outer barrier of the cell.
He created the first artificial semipermeable membrane using droplets of glue in tannic acid.

Question 9

What is osmosis?

Answer 9

The movement of water through a selectively permeable membrane into a region of higher solute concentration to equalize this concentration on both sides

Question 10

What is hypertonic, isotonic, and hypotonic in relation to osmosis and blood cells.

Answer 10

Hypertonic: Solution has very high concentration of solute, causing cells to shrink
Isotonic: Solution is balanced with cells
Hypotonic: Solution has very low concentration of solute, causing cells to burst

Question 11

What suggested that the outer membrane was made of lipids?

Answer 11

Isolated animal cells formed spheres in water

Question 12

In the 1890s, 2 scientists demonstrated what?

Answer 12

Meyer and Overton shows that lipid-soluble chemicals were able to pass through cell membranes. They concluded that the membrane may be composed of phospholipids and cholesterol

Question 13

Cell membranes are not like balloons. What do they facilitate?

Answer 13

Environment interaction and communication

Question 14

What year did the electron microscope show that the cell membrane is a lipid bilayer?

Answer 14

1950s

Question 15

What attributes of the phospholipid bilayer allow it to maintain a barrier between the internal and external?

Answer 15

Hydrophobic tails and hydrophilic heads

Question 16

What do cholesterol molecules do in the phospholipid bilayer?

Answer 16

They enable membrane fluidity

Question 17

In addition to allowing lipids to pass through the cell plasma membrane, ____ are also allowed to pass through

Answer 17

ions

Question 18

What is membrane potential? When and who was it demonstrated by?

Answer 18

The difference in electric potential between the inside and the outside of a biological cell.
In 1910, Rudolf Hober measured the electrical charge on the inside and outside of cells

Question 19

How do ions and other molecules move across the cell plasma membrane?

Answer 19

The membrane contains special protein transporters

Question 20

The plasma membrane contains many embedded _______ and ________ that perform many functions like being receptors and transporters

Answer 20

proteins, molecules

Question 21

What is the current model that describes a cell membrane?

Answer 21

Fluid mosaic

Question 22

What makes the membrane fluid mosaid?

Answer 22

Fluid because molecules move freely past one another

Mosaic because of the diversity of molecules in the membrane

Question 23

When, who, and what demonstrated membrane fluidity?

Answer 23

In 1970, Frye and Edidin labeled 2 cells with dye and watched as the two dye populations mixed

Question 24

Cell membrane are composed mainly of what?

Answer 24

Lipids and proteins

Question 25

What do proteins do in the phospholipid bilayer?

Answer 25

Regulate traffic across the membrane and perform other functions

Question 26

What are two ways substances can move across the membrane?

Answer 26

Passive transport - Requires no energy

Active Transport - Requires energy in the form of ATP

Question 27

What are 2 ways substances move across the membrane with passive transport? Briefly describe them

Answer 27

Diffusion: Hydrophobic and small uncharged polar molecules diffuse through the lipid bilayer
Facilitated Diffusion: Hydrophobic substances diffuse through the membrane with the assistance of transport proteins

Question 28

With facilitated diffusion, what are the 2 types of proteins that can help with it? Briefly describe them

Answer 28

Channel Proteins: Leaves an open channel for substances to move through
Carrier Proteins: Can open and close and let through only a little bit of the substance at a time

Question 29

Describe how active transport works

Answer 29

Transport proteins actively pump substances against the concentration or electrochemical gradients. This requires the input of energy

Question 30

What is osmosis?

Answer 30

The movement of water across the membrane via diffusion or facilitated diffusion

Question 31

Nerve cells send what down their axons?

Answer 31

Electrical impulses/signals

Question 32

At the end of a neuron, electrical signal is converted into what?

Answer 32

Chemical Signal or Neurotransmitter

Question 33

What is the electrical signal passed down in a neuron caused by? How does the signal move down?

Answer 33

The movement of ions through specific transporter proteins in the membrane. The signal moves down by the controlled opening and closing of ion transport channels. (Na goes in, K is pumped out)

Question 34

What is chemiosmosis?

Answer 34

The movement of ions across a semipermeable membrane down their electrical and chemical gradient

Question 35

Who and when proposed the chemiosmotic hypothesis?

Answer 35

Peter Mitchell in 1961

Question 36

What is the chemiosmotic hypothesis?

Answer 36

The movement of protons (H+) down their electrochemical gradient across a membrane can drive the formation of ATP through ATP synthase protein. Protons can also be used to power the rotation of flagella in bacteria

Question 37

What is reverse osmosis?

Answer 37

A water purification process that uses a partially permeable membrane to separate ions, unwanted molecules, and larger particles from drinking water

Question 38

What is reverse osmosis used for?

Answer 38

Water desalination, maple syrup production, low-alcohol beer production, fruit juice concentrate

Question 39

What happens in Cystic Fibrosis?

Answer 39

Airways accumulate thick mucus, making it difficult to breathe. Recurring lung infections can result in lung scarring

Question 40

What is Cystic Fibrosis caused by?

Answer 40

Mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. This gene makes the CFTR membrane channel protein that transports chloride ions in and out of the cell

Question 41

Where the the CFTR protein produced?

Answer 41

Cells that produce mucus, sweat, saliva, tears, and digestive enzymes

Question 42

Why is the transport of chloride ions important in the CFTR protein?

Answer 42

It helps control osmotic movement of water in tissues

Question 43

When happens when CFTR is not functional?

Answer 43

Mucus-producing cells produce abnormally thick and sticky mucus, which can obstruct airways and glands. This happens because water moves only into cells due to the osmotic pressure