Chapter 1- Cytology (1)

Question 1

<p>Who discovered the cell?</p>

Answer 1

<p>Robert Hook in 1663</p>

Question 2

<p>What is the study of cell form known as?</p>

Answer 2

<p>Morphology</p>

Question 3

<p>Give the scales of measurement?</p>

Answer 3

<p>1cm = 0.01 = 10 to the -2m
<br></br>1mm= 0.1 cm= 10 to the -3m
<br></br>
<br></br>Micrometere= 10 to the -6m
<br></br>
<br></br>Nanometre= 10 to the -9m
<br></br>
<br></br>Angstrom= 10 to the -10m</p>

Question 4

<p>What does a general cell consist of?</p>

Answer 4

<p>An outer border which is called the plasma membrane which surrounds the cytoplasm containing organelles.</p>

Question 5

<p>What are the functions of a cell membrane?</p>

Answer 5

<p>1- Maintains the integrity of the cell- controls what comes in and out
<br></br>
<br></br>2- It is selectively permeable- allows certain molecules or ions to pass through it.
<br></br>
<br></br>3- Acts as a communication site- has proteins that act as receptors, e.g hormones.</p>

Question 6

<p>What is the cell membrane the same as?</p>

Answer 6

<p>Plasma membrane</p>

Question 7

<p>What is the structure of the plasma membrane?</p>

Answer 7

<p>1- Has a phospholipid bilayer<br></br>2- Has protein molecules <br></br><br></br>3- Cholesterol molecules <br></br><br></br>4- Sugar groups attached to the surface- e.g, glycocalyx</p>

Question 8

<p>In a phospholipid bilayer, what molecules are non polar and polar?</p>

Answer 8

<p>Lipids are non-polar
<br></br>Water molecules are polar</p>

Question 9

<p>What does non polar mean?</p>

Answer 9

<p>Doesn't carry a charge</p>

Question 10

<p>What is the structure of a phospholipid bilayer?</p>

Answer 10

<p>Contains a polar, hydrophilic head- attracted to water
<br></br>
<br></br>Contains a non polar, hydrophobic tail- repels water</p>

Question 11

<p>What is an amphipathic molecule?</p>

Answer 11

<p>A molecule that has both hydrophobic and hydrophilic parts.</p>

Question 12

<p>What is the benefit of being amphipathic?</p>

Answer 12

<p>If the membrane becomes disrupted, it will automatically reform into a bilayer because of the chemical nature of these lipids, meaning the cell is able to heal itself and less likely to die.</p>

Question 13

<p>What does cholesterol do?</p>

Answer 13

<p>1- Stabilises the phospholipid bilayer.
<br></br>
<br></br>2- Helps maintain the right fluidity of the plasma /cell membrane.</p>

Question 14

<p>How does cholesterol stabilise the phospholipid bilayer?</p>

Answer 14

<p>1- It makes it more rigid by decreasing its permeability to water molecules.
<br></br>
<br></br>2- Also prevents hydrocarbon tails from joining and crystallizing- the process by which a solid forms.</p>

Question 15

<p>What are the types of membrane proteins?</p>

Answer 15

<p>1- Integral proteins - surround the membrane
<br></br>
<br></br>2- Peripheral proteins- Found on the surface of the membrane.</p>

Question 16

<p>What are the functions of the membrane proteins?</p>

Answer 16

<p>1- Transports substances in and out through protein channels- some channels are passive (don’t require energy) and some require energy in the form of ATP.
<br></br>
<br></br>2- Enzymatic activity- proteins can be in the form of enzymes which speed up the rate of chemical reactions inside the membrane.
<br></br>
<br></br>3- Joins cells together- the proteins provide binding sites that allows cells to join.
<br></br>
<br></br>4- Are receptors- a protein may have a binding site with a specific shape that fits the shape of a chemical messenger such as a hormone. This will allow a chain of chemical reactions to take place.</p>

Question 17

<p>What is the glycocalyx?</p>

Answer 17

<p>The sugar coating of the cell</p>

Question 18

<p>Carbohydrates are mainly attached to what type of protein?</p>

Answer 18

<p>Integral proteins</p>

Question 19

<p>What is the function of the glycocalyx?</p>

Answer 19

<p>Allows cell-cell recognition to take place, e.g, enables sperm cell to recognise egg cell.</p>

Question 20

<p>Name the type of junctions between cells</p>

Answer 20

<p>1- Sticky glycoproteins on cell surface- a bit like glue<br>
<br>
2- Mechanical junctions<br>
<br>
3- Specialised cell-cell junctions</p>

Question 21

<p>Give some types of mechanical junctions</p>

Answer 21

<p>1- Ball and socket- e.g, hip shoulder.
<br></br>
<br></br>2- Tongue and groove- this is found between the cells within the lens</p>

Question 22

<p>Give some types of specialised cell-cell junctions</p>

Answer 22

<p>1- Occluding (tight) junctions- acts as an impermeable barrier to molecules
<br></br>
<br></br>2 Anchoring cells- locks two cells strongly together which stops two cells being easily torn apart.</p>

Question 23

<p>Where would you find anchoring junctions?</p>

Answer 23

<p>In tissues which are subject to a lot of mechanical pressure, e.g, skin</p>

Question 24

<p>Name a type of anchoring junction?</p>

Answer 24

<p>Desmosomes</p>

Question 25

<p>Name the type of desmosomes</p>

Answer 25

<p>1- Belt desmosome- goes a long way round the cell
<br></br>
<br></br>2- Spot desmosome- a small area
<br></br>
<br></br>3- Hemidesmosome- only links the membrane to the cytoplasm</p>

Question 26

<p>What is a gap junction?</p>

Answer 26

A channel between cells which allows certain molecules to pass directly from one cell to the next