Topic 2: CFTR protein and CF effects

Question 1

______ protects the lungs.

Goblet cells in airways produce _______ which traps ____, ___________, _____.

Cilia (tiny hair-like structures) beat to ____ ______ to the back of the throat where it can be swallowed.

Answer 1

Mucus

mucus

dirt

microorganisms

dust

move mucus

Question 2

Explain the function of mucus in the human digestive system

2 points

Answer 2

1. mucusis used as a lubricant all the way along the digestive tract, for materials that must pass over membranes (eg. food passing down the oesophagus)
2. and also covers the inner walls of the stomach to protect the cell linings of that organ from the highly acidic environment within it

Question 3

Explain the function of mucus in the respiratory system

2 points

Answer 3

1. Mucus traps dust and bacteria
2. and tiny hairs called cilia beat to move the mucus to the back of the throat where it can be swallowed or coughed out.

Question 4

Explain the function of mucus in the female reproductive system
(2 points)

Answer 4

1. glands in the cervix produce mucus to help prevent infection
2. and to support or inhibit sperm movement.

Question 5

Explain the function of mucus in the male reproductive system
(2 points)

Answer 5

1. Mucus lubricates tubes to aid sperm movement

2. and also neutralises acidic urine in urethra

Question 6

KEY SUMMARY

The CFTR protein

What type of protein is it? (1 point)

Where is it found? (1 point)

What does it do? (1 point)

Answer 6

1. A CHANNEL protein
2. Found in the CELL MEMBRANE OF MUCUS PRODUCING CELLS lining the respiratory, digestive and reproductive systems
3. Transports CHLORIDE IOSN (Cl-) through the cell membrane to regulate mucus thickness

Question 7

Key Summary: Explain how the CFTR protein works to regulate the {thickness/viscosity} of mucus in the body
(5 steps)

Answer 7

1 (this point is important). Chloride ions move THROUGH the CFTR channel protein from cells into mucus

2. Sodium ions follow the chloride ions – move from cells into mucus
3. The {solute/sodium ion/chloride ion} concentration in the mucus INCREASES (so free water decreases)
4. Water moves out of the cells and into mucus by OSMOSIS
5. Mucus becomes {less sticky/thinner/less viscous}

Question 8

Key Summary: Explain how a gene mutation affects a protein

8 steps

Answer 8

1. gene mutation is a change in the base sequence of DNA in a gene
2. changes mRNA codon(s)
3. {different/wrong/no} amino acid included OR stop codon created
4. different {sequence of amino acids/primary structure}
5. different R groups
6. changed bonding between R groups in {protein/named bond}
7. protein forms different {secondary/tertiary/quaternary} structure (as appropriate for given protein – read q)
8. {different/incorrect} 3D SHAPE so cannot function – then state function that cannot be carried out – read question

Question 9

Key Summary: Explain how the {faulty/absent} CFTR protein causes stickier mucus
(5 steps)

Answer 9

1. CFTR channel protein DOES NOT WORK OR IS NOT PRESENT
2. The CFTR protein transports chloride ions, so chloride ions CANNOT MOVE out of (epithelial) cells THROUGH the CFTR protein channel and enter mucus
3. Sodium ions do not move out of cells and into mucus
4. Water does not move out of cells into mucus, or enters cells from mucus by OSMOSIS, due to increased solute concentration in cell
5. Mucus becomes THICKER and STICKIER (NOTE: remember the ER - thickER)

Question 10

What 3 types of body systems can a faulty or absent CFTR protein affect? (3 body systems)

Answer 10

1. Respiratory system
2. Digestive system
3. Reproductive system

Question 11

(Respiratory system)
What do blocked airways due to a faulty CFTR protein cause?
(3 things)

Answer 11

1. repeated lung infections
2. reduced gas exchange, leading to tiredness
3. lung damage

Question 12

(Digestive system)
What does a blocked pancreatic duct due to a faulty CFTR protein cause?
(2 things)

Answer 12

1. Pancreas cysts, leading to diabetes

2. reduced digestion and absorption, leading to tiredness

Question 13

(Reproductive systems)
What does a blocked {male sperm ducts/female cervix} due to a faulty CFTR protein cause?
(1 thing)

Answer 13

1. Reduced chance of pregnancy

Question 14

Key Summary: Explain how the effects of CF on the digestive system cause {lack of energy/tiredness}
(6 steps)

Answer 14

1 (this point is important). {Stickier/thicker} than normal mucus blocks the pancreatic duct

2. PANCREATIC DIGESTIVE ENZYMES cannot ENTER the small intestine
3. lower concentration of enzymes CAUSES LESS EFFICIENT DIGESTION (reduces rate of digestion) of food
4. so LESS PRODUCTS OF DIGESTION ABSORBED, which includes GLUCOSE, into the body (malabsorption syndrome)
5. lack of glucose delivered to body cells for respiration
6. less energy release - sufferer lacks energy

Question 15

Key Summary: Explain how the effects of CF on the digestive system cause damage to the pancreas
(4 steps)

Answer 15

1 (this point is important). {stickier/thicker} than normal mucus blocks the pancreatic duct

2. pancreatic enzymes become trapped behind the mucus
3. the enzymes can DAMAGE the pancreatic cells, including the ones that produce insulin, resulting in a form of DIABETES
4. CYSTS of hard FIBROUS tissue form in the pancreas

Question 16

Key Summary: Explain how the effects of CF on the MALE reproductive system cause a decreased change of {pregnancy/male infertility}
(4 steps)

Answer 16

1 (this point is important). CF males may LACK vas deferens (sperm ducts)
OR
2 (this point is important). Stickier than normal mucus BLOCKS vas deferens

3. so sperm cannot leave testes and cannot pass to {urethra/penis}
4. decreases chance of female pregnancy

Question 17

Key Summary: Explain how the effects of CF on the FEMALE reproductive system cause a decreased change of pregnancy
(4 steps)

Answer 17

1 (this point is important). {Stickier/thicker} mucus forms a mucus plug which blocks the cervix

2. Stops sperm from vagina passing through cervix
3. Sperm cannot reach the egg cell in the oviduct
4. reduced chance of fertilisation and pregnancy

Question 18

Key Summary: Explain how the effects of CF on the lungs cause {lack of energy/tiredness/difficult to exercise}
(7 steps)

Answer 18

1 (this point is important). {Stickier/thicker} mucus blocks airways

2. CILIA CANNOT MOVE MUCUS as the mucus is too thick
3. Mucus {blocks/reduces lumen diameter} of {bronchioles/airways}
4. Reduced ventilation of alveoli below blockage
5. Reduced surface area, so less gas exchange
6. Less oxygen DIFFUSES into blood
7. Less oxygen for respiration in muscles - less energy released

Question 19

Key Summary: Explain how the effects of CF on the lungs cause {repeated infections/lung damage}
(7 steps)

Answer 19

1. {STICKIER/THICKER} MUCUS CANNOT BE MOVED BY CILIA to the back of throat to be swallowed and bacteria destroyed by stomach acid
2. mucus traps bacteria
3. mucus provides IDEAL GROWTH CONDITIONS for pathogenic anaerobic bacteria e.g. lack of oxygen, so bacteria REPRODUCE CAUSING CHEST INFECTIONS
4. {phagocytes/white blood cells} try to kill bacteria but cannot, so die and break down – this releases DNA which makes the mucus even stickier
5. repeated bacterial infections and coughing damages the lung tissue, making lungs more prone to infections

Question 20

Key Summary: Explain how the effects of CF on the lungs cause lung damage
(2 steps)

Answer 20

1. Air which passes blockage when breathing in often cannot pass blockage during breathing out
2. Over-inflation of lung tissue over time makes lungs less elastic