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EDEXCEL BIOLOGY > TOPIC 2: Genes & Health > Flashcards

TOPIC 2: Genes & Health Flashcards

1
Q

How does the trachea separate in the lungs?

A

bronchi - bronchioles - alveoli

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2
Q

What are goblet cells?

A
  • secrete mucus

- located between cilia in respiratory tract

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3
Q

What’s the basement membrane?

A
  • holds cilia to cell

- made of protein-carbohydrate matrix

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4
Q

What is the role of mucus?

A
  • traps bacteria & dust

- moisturises inhaled air

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5
Q

What is the role of cilia?

A

remove mucus with wave-like beating motions

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6
Q

How does cystic fibrosis cause lung infections?

A
  1. mucus traps bacteria but it’s too sticky to be moved
  2. low O2 levels in mucus so anaerobic bacteria thrive
  3. WBC dies and releases DNA, making the mucus stickier
  4. inflammation and infection
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7
Q

How does CF reduce gas exchange?

A

mucus blocks bronchioles so less air reaches alveoli

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8
Q

What factors increases rate of diffusion?

A
  • large conc. gradient
  • short diffusion distance
  • higher temperature
  • larger SA
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9
Q

What does Fick’s law state?

A

rate of diffusion is inversely proportional to thickness of gas exchange surface

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10
Q

What’s surfactant?

A

phospholipid preventing clumping of alveoli

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11
Q

What makes gas exchange efficient in mammals?

A
  • small diffusion distance (one cell thick)
  • large conc. gradient
  • large SA (many small alveoli)
  • lots of capillaries around the alveoli
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12
Q

What are the digestive symptoms of CF?

A
  • reduced digestions and uptake of nutrients because mucus blocks pancreatic duct and small intestine and enzymes can’t reach duodenum
  • trapped enzymes damage pancreatic tissues and Islet of Langerhans so insulin production is affected, leading to T1 diabetes
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13
Q

What are the reproductive symptoms of CF?

A
  • infertility due to blocking of cervix with mucus

- sperm duct blocked with mucus, producing abnormal sperm

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14
Q

What happens to sweat in people with CF?

A

no functional CFTR protein so Na+ and Cl- not reabsorbed into cells

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15
Q

What happens when there’s too much water in the mucus? (non-CF)

A
  1. Na+ pumped across basal membrane (removed from cell)
  2. Na+ in mucus diffuses through Na channel along the concentration gradient
  3. Cl- diffuses out of mucus into basal membrane via intercellular space, down an electrical gradient
  4. H2O moves out of cell and then out of mucus due to osmosis
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16
Q

What happens when there’s too little water in the mucus (non-CF)?

A
  1. Cl- pumped into cells from tissue fluid across basal membrane
  2. CFTR channel opens and Na channel is closed so Cl- diffuses through CFTR
  3. Na+ diffuses down electrical gradient via intercellular space into mucus
  4. H2O moves out of cell and into mucus due to osmosis
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17
Q

Why is mucus sticky in CF patients?

A
  1. CFTR absent, Na+ channel permanently open and Na+ diffuses into cells from mucus
  2. Cl- diffuses out of mucus towards basal membrane via intercellular space
  3. Water removed from mucus by osmosis
  4. bacteria and WBC are trapped; DNA released from dead WBC makes it even more sticky
18
Q

What groups are on an amino acid?

A
  • amino group
  • alpha carbon
  • R group
  • carboxyl group
19
Q

How are peptides made?

A

amino acids joined together in condensation reactions, forming a peptide bond

20
Q

How are peptides broken?

A

hydrolysis

21
Q

What is a protein’s primary structure?

A

linear sequence of amino acids

22
Q

What is a protein’s secondary structure?

A

the regular folding of parts of a protein due to hydrogen bonds between peptide bonds

23
Q

Why is an alpha helix very stable?

A

held together by many hydrogen bonds between peptides

24
Q

What is a beta pleated sheet?

A

polypeptide chain zigzags back and forward forming sheet of antiparallel strands

25
What is a tertiary structure?
overall 3D structure of peptide chain formed by bonds between R groups
26
What are the bonds involved in tertiary structures in order of increasing strength?
- hydrophobic interactions between R groups - hydrogen bonds between H and O of R groups - ionic bonds between charged R groups - disulphate bonds between 2 cysteine R groups
27
What is a quaternary structure?
3D structure of several polypeptide chains interacting with each other via bonds between R groups
28
What are conjugated proteins?
proteins joined to non-protein molecules
29
Compare globular and fibrous proteins
1 - globular has a complex tertiary structure whereas fibrous has little tertiary structure 2 - globular is spherical whereas fibrous is long 3 - fibrous is larger than globular 4 - globular is soluble and fibrous is insoluble
30
What does the fluid-mosaic model show?
- movement of lipids and proteins | - composed of different types of macromolecules
31
Describe the structure of a phospholipid
- hydrophilic phosphate head - hydrophobic fatty acid tail - glycerol
32
Describe the phospholipid bilayer
- hydrophilic heads face towards solution | - hydrophobic tails face away from the solution
33
How can membrane fluidity be increased?
adding more unsaturated fatty acids because phospholipids are less tightly packed
34
How can membrane fluidity be decreased?
more cholesterol reduces movement of phospholipids
35
Describe the structure of a cell membrane
- partially permeable | - phospholipid bilayer with glycoproteins, transport proteins and receptors
36
What is passive transport and give examples?
Non energy dependent: - diffusion - osmosis - facilitated diffusion
37
What is active transport and where is it used?
Energy dependent | Used in endocytosis/exocytosis
38
What is facilitated diffusion?
High concentration to low concentration via carrier protein across a membrane
39
What is osmosis?
Movement of water molecules from a high water potential to a low water potential across a selectively permeable membrane
40
What does it mean if a solution is hypertonic?
Solution with higher solute concentration than cell, water moves out of cell
41
What does it mean if a solution is hypotonic?
Solution with lower solute concentration than cell, water moves into cell
42
What happens when there is too much water in mucus? (healthy)
1. Na+ pumped across basal membrane 2. Diffuses through Na channel in top membrane along conc. gradient 3. Cl- diffuses out of mucus via intercellular space down electrical gradient 4. Water moves out of cells due to high salt conc in tissue fluid 5. Water moves out of mucus: LESS RUNNY

EDEXCEL BIOLOGY (14 decks)

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