The Animal Cell

Question 1

What are 1. monomers, 2. polymers and 3. macromolecules ?

Answer 1

1. Building blocks of organic molecules
2. Chains of monomers are linked together
3. Macromolecules

Question 2

What is the cytoskeleton and what does it contain ?

Answer 2

Fills cytoplasmic space and gives order and structure to cell content.
A comple arrangement of protein fibres comprising
1. Microtubules
2. Intermediate filaments
3. Microfilaments

Question 3

What is the cytoskeleton function 6 ?

Answer 3

1. Organising organelles
2. Maintaining cell shape
3. Allowing anchorage
4. Facilitating cell movement
5. Facilitating cell division
6. Allowing contact and transmitting signals

Question 4

What are anchorage dependent cells able to do when they attach themselves to surfaces ?

Answer 4

1. Maintain their phenotype
2. Have direction and polarity
3. Move
4. Create functional tissues

Question 5

What is a neuronal growth cone ?

Answer 5

The sensory machine that guides an extending axon to its signalling target.

Question 6

What does cell sticking together enable them to do ?

Answer 6

1. Form complex tissues and organs
2. Control the passage of material
3. Communicate with one another and act in a synchronised manner

Question 7

What are the 4 junctions that cells use to attach to one another ?

Answer 7

1. Adherens junctions
2. Desmosomes
3. Tight junctions
4. Gap junctions

Question 8

What properties do these junctions provide ?

Answer 8

1. Give tissue structure and strength
2. Selectively allow or prevent the passage of materials
3. Allow cells to communicate with each other
4. Help to maintain cell phenotype

Question 9

What is an adherent junction, properties and typical location ?

Answer 9

ACTS LIKE BANDS OF WELD BETWEEN CELLS

PROPERTIES

• 1. Form strong sheets of cells
     
     2. Anchored to the actin filaments of the cytoskeleton - spreads the distribution of mechanical stress, including during contraction
     3. Allow substances to pass between cells, through intercellular spaces

TYPICAL LOCATION
1. Many types of epithelial cells

Question 10

What are the properties of Desmosomes and the location its found ?

Answer 10

ACTS LIKE RIVETS OR SPOT WELDS

PROPERTIES
1. Form immensely strong sheets of cells
2. Abrasion resistant
3. Anchored to the intermediate filaments of the cytoskeleton - gives even distribution of mechanical stress
4. Allow substances to pass freely between cells, through intercellular spaces
5. Crucial in tissue development

TYPICAL LOCATION
1. Most types of strong epithelia and other tissue.

Question 11

What are the properties of tight junctions and where are they located ?

Answer 11

TIGHTLY PACKED ROWS OF PROTEIN RIDGES

PROPERTIES
- Form impermeable junctions between cells
- Ensure that adjacent cell membranes are held together
- Good for sealing off body cavities or regions.

EXAMPLE LOCATION

• intestinal epithelial cells
• Endothelial cells lining brain capillaries

Question 12

What are the properties of gap junctions and where are they located ?

Answer 12

PROPERTIES
- Form permeable junctions linking the cytoplasms of adjacent cells
- Allow small molecules to pass between cells
- Allo coordinated cell responses within tissues.

LOCATION
- Nerve cells, heart muscle cells
- Pancreatic islet cells

Question 13

How do materials get in and out of cells ?

Answer 13

It depends on the material and the cell
can occur through
- Osmosis
- Simple diffusion
- Active transport
- Facilitated diffusion
- Endocytosis

Question 14

What is osmosis ?

Answer 14

Passage of water across a semi-permeable membrane -
From a region of low solute conc to a region of high solute conc
Isotonic solutions on both sides of the membrane - water moves by diffusion at the same rate in both directions

Question 15

What are 3 osmotically active solutes ?

Answer 15

• Ions
• Proteins
• Glucose

Question 16

What is simple diffusion ?

Answer 16

Passage if solutes by random molecular motion from a region of high solute concentration to a region of low solute concentration.
No energy is required

Question 17

Whats a reflectance coefficient ?

Answer 17

Solutes vary in their ability to diffuse across cell membranes
Membranes vary in their permeability to solutes
For each solute, this is expressed by a reflectance coefficient

Question 18

Whats facilitated diffusion ?

Answer 18

Passage of solutes across the membrane, down a concentration gradient, helped by a transporter proteins
No energy is required.

Question 19

What is active transport ?

Answer 19

Passage of solutes across the membrane, up a concentration gradient, helped by a transporter protein.
Transporter acts like a pump.

Question 20

Whats 1. uniport, 2. symport and 3. antiport ?

Answer 20

1. Transports one substance
2. Transports more than one substance
3. Exchanges one substance for another

Question 21

What is endocytosis and exocytosis ?

Answer 21

1. ENDOCYTOSIS -
   Describes the transport of molecules into a cell via membrane-wrapped containers
2. EXOCYTOSIS -
   Describes transport of vesicles to the cell surface. Molecules are expelled by the fusion of the vesicle with the cytoplasmic membranes.

Question 22

Recall the 4 ways that cells attach to each other ?

Answer 22

1. GAP JUNCTIONS
2. ADHERENS JUNCTIONS
3. TIGHT JUNCTIONS
   4.DESMOSOMES