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topic 2 cystic fibrosis Flashcards

1
Q

lungs allow

A

rapid gas exchange between the atmosphere and the blood.

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2
Q

what produces mucus and what is mucus used for

A

mucus is produced by goblet cells moved out of the lungs by cilia
traps dust, derbies and microorganisms

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3
Q

what happens with the mucus in CF lungs

A

cf lung mucus is too sticky meaning it cant be removed by the cilia leading to a production build up.
this means pathogens do get removed.
low levels of oxygen in the mucus allows the perfect anaerobic conditions where pathogens can grow.

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4
Q

surface area to volume ratio

A

if there is a small surface area to volume then the organism must rely on special organs like the lungs to increase the surface area.

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5
Q

equation for rate of diffusion

A

surface area x difference in concentration /

thickness of gas exchange surface

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6
Q

how do aveoli increase the rate of diffusion

A

provide a large surface area and a steep concentration gradient between air and blood maintained by ventilation and constant blood flow, thin walls of aveoli and capillary then combine giving rapid rate of diffusion

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7
Q

what happens to the diffusion rate in CF

A

mucus blocks and narrows airways preventing movement of air into the alveoli and reducing the surface area.

blockages allow air to pass in but not out resulting in over inflation of lung tissue damaging elasticity of lungs.

lower amount of gas exchange cannot deliver enough oxygen to muscle cells.

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8
Q

as body mass increases the rate of oxygen consumption decreases because

A

bigger animals have smaller surface area to volume ratio so less respiration is needed to replace loss of heat.

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9
Q

oxygen consumption equation

A

(body mass x respiration) x time

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10
Q

what is rate of diffusion proportional to

A

surface area, concentration difference, distance and diffusion constant (how permeable the cell membrane is to substances)

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11
Q

what is the primary structure of a protein

A

a chain of amino acids joined in condensation raction forming peptide bonds

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12
Q

what is the secondary structure of proteins

A

polypeptide chain twist to form alpha helix within it H bonds form between s- C=O and s+ -NH above and below.

B pleated sheets: amino acids chains fold back on themselves and link together with H bonds

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13
Q

what is the tertiary structure of proteins

A

folds further to produce a precise 3d shape.
polar R groups for H bonds with other polar molecules
non polar R groups face inwards excluding water from the centre of the molecule but keeping the molecule water soluble.

ionic bonds form between R groups with charges
cystiene contains SH group which bonds with other -SH forming a disulphide bond

sensitive to pH differences

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14
Q

what is the Quaternary structure of proteins

A

globular proteins: multiple peptide chains fold in compact spherical shape hydrophilic chains face outwards making them water soluble

fibrous proteins: remain as long chains cross linked for additional strength. insoluble and important structural molecules

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15
Q

what are conjugated proteins

A

have other chemical groups associated with polypeptide chain

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16
Q

the model used for cell surface membrane is called

A

fluid mosaic model

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17
Q

the cell surface membrane is made up of

A

two layers of phospholipids.
phospholipids have a phosphate group which makes up the head this is polar and so hydrophilic. the tails are made up of 2 fatty acid chains which are non polar and hydrophobic
the tails face inwards and the heads face outwards

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18
Q

explain the fluid mosaic model

A

contains proteins (as enzymes, carrier, channel proteins), cholesterol (between the phospholipid to maintain fluidity), glycoproteins / glycolipids (with polysaccharides recognition receptors)

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19
Q

what is the evidence for the fluid mosaic model

A
  • experiments showed types of proteins could dissociated from the membrane and others that could not. this supports fluidity and the fact there are some peripheral proteins and some integrated proteins
  • freeze-fracture electron microscopy fractured between the lipid layer to show that the inner surface was a smooth mosaic interspersed with large proteins.
  • plant proteins lectins bind to polysaccharides labled and when mixed with membrane lectins only bond to the outer surface membrane showing polysacharides where on outside.
  • fusing mouse and human cells after 40 mins protein completely intermixed showing components are fluid
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20
Q

what is the protein lipid sandwich

A

the protein lipid sandwich has the same inner outer surface of protein s not fluid and proteins were integrated on both sides of lipids.

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21
Q

what is wrong with the protein lipid sandwich

A
  • does not allow hydrophilic heads to be in water.
  • unsaturated phospholipids more fluid as kinks mean cant pack closely together
  • there are peripheral and integrated proteins
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22
Q

what are the properties of the fluid mosaic model (3)

A
  • flexible
  • fluid
  • selectively permeable
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23
Q

molecules and ions can move across the membrane by (5)

A
  • diffusion
  • osmosis
  • active transport
  • exocytosis
  • endocytosis
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24
Q

what happens in diffusion

A

down the concentration gradient. high to low of substance until eqm is reached.
hydrophobic or small uncharged molecules pass through phospholipid bilayer this way.
passive no energy needed
O2 and CO2

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25
Q

what happens in faculutated diffusion

A

down concentration gradient high to low of substance until eqm is reached.
hydrophilic polar molecules or ions.
through channel proteins.
passive no energy required

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26
Q

what happens in osmosis

A

is the movement of free water molecules from region of low solute concentration to high solute concentration. until solute concentration are equally concentrated / isotonic.
through partially permeable membrane.
passive no energy required

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27
Q

what happens in active transport

A

against concentration gradient. low to high
through carrier proteins which change shape
which requires energy (ATP)
active

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28
Q

what happens in exocytosis

A

bulk / mass transport of substances out of the cell

vesicles carry substances fuse with cell surface membrane releasing contents

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29
Q

what happens in endocytosis

A

bulk transport of substances into cell. vesicles created from surface membrane brings contents into cell
part of the cell membrane engulfs the solid or liquid material to be transported or the substances attaches to receptors in the membrane and then absorbed

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30
Q

regulating mucus water content: excess water (5 steps)

A
  1. Na+ actively pumped across the basal membrane out of the cell into tissue fluid making a concentration difference between mucus and cell.
  2. Na+ diffuses through sodium channel (ENaC) in apical membrane into cell down concentration gradient.
  3. electrical gradient between tissue fluid and mucus. Cl- diffuses down electrical gradient from mucus between cells to tissue fluid
  4. water is drawn out of cell in tissue fluid by osmosis due to high salt conc. in tissue fluid
  5. water is drawn out of mucus by osmosis into cell down concentration gradient.
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31
Q

regulating mucus water content: too little water (5 steps)

A
  1. Cl- from tissue fluid is pumped into cell across basal membrane
  2. Cl- diffuses through the open CFTR channel into mucus down concentration gradient.
  3. Na+ diffuses down electrical gradient from tissue fluid into mucus via gap between cells
  4. elevated salt concentration in mucus draws water out of the cell by osmosis
  5. water is drawn into cell by osmosis
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32
Q

regulating mucus water content: CF lungs

A
  1. CFTR channel is absent or not functioning
  2. Na+ channel is permanently open allowing Na+ to diffuse into cell
  3. Na+ is pumped out of the cell into tissue fluid
  4. Cl- down electrical gradient into tissue fluid
  5. water is continually removed from mucus by osmosis
33
Q

what are ENaCs

A

epithelial sodium ions channels on apical membrane

34
Q

what are CFTR protein channels

A

channels that take chlorine ions out of the cell into mucus over apical membrane

35
Q

what is the result of water being continually removed from the mucus in CF lungs

A

mucus is too sticky and cant be moved by cilia

  1. mucus to build up effecting ventilation of aveoli
  2. mucus becomes infected with bacteria
  3. phagocytic cells that kill pathogens are produced
  4. phagocytes break down releasing DNA which makes the mucus even more sticky
  5. causing airway inflammation and lung damage
36
Q

lock and key theory

A

substrate has complementary shape to active site
substrate forms temporary bonds with amino acids in active site to produce a
enzyme - substrate complex.
enzyme holds substrate in such a way that it reacts more easily.

37
Q

induced fit theory

A

activation site is flexible
substrate enters active site enzyme shape changes slightly to fit more closely.
specifically shaped substrate will induce correct change.

38
Q

activation energy

A

energy needed to break bonds and start the reaction.

39
Q

how do enzymes reduce activation energy

A

specific shape of active site and substrate is such that electrical charged groups on the surface interact.
attraction of oppositely charged groups distort shapes of substances assisting breaking of bonds.
active site with specific amino acids produce favourable conditions for reactions.

40
Q

reactions that happen inside cells

A

inter-cellular reactions

41
Q

reactions that happen outside cells

A

extra cellular reactions

42
Q

reactions that break something down is called

A

catabolic reactions

43
Q

reactions that build up something is called

A

anabolic reactions

44
Q

decarboxylase

A

removes a carboxyl group to form CO2

45
Q

maltase

A

breakdowns maltose to glucose

46
Q

DNA polymerase

A

joins nucleotide together

47
Q

catalase

A

breaks down of by product hydrogen peroxide (H2O2)

48
Q

pancreatic lipase

A

breaks down triglycerides into glycerol and fatty acids

49
Q

what are enzymes and what do they do

A
  • globular proteins (active sites allow binding with specific substrate)
  • catalyses reaction
  • reduce activation energy
  • do not alter end product or nature of reaction
  • do not get used up and remain unchanged by end of reaction
50
Q

what are the factors that affect enzymes (4)

A
  • enzyme concentration
  • temperature (37oc body temp)
  • pH (use buffer solutions)
  • substrate concentration
51
Q

how does CF effect the digestive system

A

have high basal metabolic rate 120 - 140% energy intake

52
Q

what is an exocrine gland

A

cells in gland secrete into duct. duct carries secretion to where they are required

53
Q

what are endocrine glands

A

glands that secrete directly into the blood

54
Q

what do pancreatic cells do

A

produce enzymes that helps the break down of proteins, carbohydrates, lipids.

55
Q

how are the enzymes produced by the pancreatic cells delivered to the gut

A

delivered to gut in pancreatic juice through pancreatic duct.

56
Q

what happens to the pancreas in CF

A

pancreatic duct becomes blocked by mucus impairing the release of enzymes.
low concentration of enzymes reduces rate of digestion resulting in malabsorption syndrome.
pancreatic enzymes become trapped and damage pancreas producing cysts of fibrous tissue.
enzymes damage cells that produce insulin causing diabetes.

57
Q

how does CF effect the reproductive system

A

sticky mucus plugs the cervix stopping sperm reducing chance of pregnancy
males lack vas deferens (sperm ducts) or if present become blocked by mucus fewer sperm present.

58
Q

how does CF effect sweat

A

sweat glands are exocrine glands initially secrete a solution of salt and water into there lumens.
CFTR and ENaC proteins allow re absorption of NaCl as sweat moves up the duct. sweat on the skin is hypotonic.
in CF sodium chloride doesn’t get reabsorbed they have salty sweat.

59
Q

DNA

A

deoxyribonucleic acid

60
Q

what is DNA

A

is a polymer of units called mononucleotides which contain deoxyribose (5 carbon pentose sugar), phosphate group, organic base contain nitrogen. linked together in condensation reaction

61
Q

what are the 4 bases of DNA

A

adenine (A)
cytosine (C)
guanine (G)
thymine (T)

62
Q

how do the bases bond together

A

held together by hydrogen bonds.
A - T
C- G

63
Q

how are the mononucleotides linked

A

linked together by condensation reactions because the sugar of one nucleotide and the phosphate of the next one.
the bond that forms between the two nucleotides is known as a
phosphodiester bond

64
Q

what is RNA

A

is a single strand of polunucleotides contains phosphate group, ribose sugar, bases
instead of T RNA have base uracil
A & U
C & G

65
Q

what happens protein synthesis transcription

A
  1. RNA polymerase attaches to DNA and gene being transcribed unzips as hydrogen bonds break between bases
  2. sequence of one strand (template strand) is transcribed to make mRNA molecule with the same sequence as DNA coding strand
  3. free RNA nucleotides in nucleus pair up with its complementary DNA base and attaches. phosphodiester bonds form between RNA nucleotides
  4. produces a single strand molecule mRNA
  5. mRNA detaches from DNA and leaves nucleus through pore in nuclear envelope.
  6. DNA molecule re-zips
66
Q

what happens in protein synthesis translation

A
  1. the mRNA leaves nucleus and attaches to small ribosomal subunit.
  2. the robosome exposes 6 bases at a time so 2 tRNA molecules can be transcribed at a time
  3. the first codon exposed is AUG this is the start codon (met)
  4. tRNA binds to ribosome larger sub unit
  5. tRNA with the complementary anticodon UAC will pair up bringing attached amino acid with it.
  6. following this the next codon of mRNA will pair up with complementary tRNA anticodon.
  7. tRNA carry with them amino acids when bought together two amino acids form peptide bond between them.
  8. mRNA move along the ribosome exposing the next three bases which attracts complementary tRNA bringing another amino acid and the process continues
  9. polypeptide chain will continue to grow until stop codon is exposed.
67
Q

what is 3 features of the genetic code

A
  1. degenerate: several triplets codes can code for same amino acid.
  2. non overlapping: each triplet code are adjacent and don’t overlap
  3. triplet code
68
Q

how does mutation in DNA sequence effect proteins

A

change in amino acid sequence and primary structure effecting protein three dimensional structure and properties

69
Q

4 types of mutations

A

subsidisation
insertions
deletions
inversions

70
Q

3 bases code for

A

1 amino acid

71
Q

what happens in DNA replication

A

the entire DNA double helix unwinds as H bonds break between bases. free DNA nucleotides line up alongside each single DNA strand hydrogen bonds form between complementary bases
enzyme DNA polymerase links adjacent nucleotides with phosphodiester bonds to form new cimpolementart strand.
each orignal strand acts as template to produce 2 DNA strands identical to original.
the two new strands contain one old strand and one new strand.

72
Q

DNA replication is a type of what replication

A

semi conservative replication

73
Q

the experiment to prove DNA replication is semi conservative

A
  • DNA either replicates fragmentary, semi conservatively or conservatively.
  • melso and stah grow escherichia coli DNA bacterium in medium contain heavy isotope N15 alll nucleotides contain heavy nitrogen making DNA more dense.
    bacteria then moved to medium containing normal N14 all new nucleotides light.
    bacteria allowed to divide once. DNA then extracted and centrifuged producing a bond of medium density DNA so DNA did not replicate conservatively
    if allowed to undergo a second division producing a strand of medium DNA and one light band of DNA proving DNA did not replicate fragmentary
74
Q

if DNA mutation happens or exists in sperm or egg cells then

A

mutations could be passed to future generations

75
Q

what mutations cause CF

A

CF gene on chromosome 7 codes for CFTR protein. there are hundreds of different mutations.
some cases causes ATP to be unable to bind and open ion channel.
common mutation DF508 deletion of 3 nucleotides causing a loss of phenylalanine the 508th amino aicd resulting in misfolding of protein

76
Q

ways to test for CF

A
  • test babies for high conc. of salt in sweat or elevated levels of protein trypsinogen in their blood in newborn blood spot screening program
  • genetic testing. abnormal alleles of CF gene in DNA identify carrier s and diagnose in embryos or fetuses.
    however large amount of mutations so false negatives common.
77
Q

how to test for CF in fetuses and embryos

A

amniocentesis: inserting needle into amniotic fluid to collect fetal cells. 15 -17 weeks. 1% risk of miss carriage

chorionic villus sampling: sample of precental tissue removed through wall of abdomen or vagina. 8-12 weeks 1- 2% risk of miss carriage

non invases prenatal diagnosis NIPD: analysing DNA fragments in mother’s blood plasma 10-20% embryo cell free fetal DNA. 7-9 weeks. no risk of misscarrige

testing before implantation PGD: first undergo IVF them embryo at around 8 cells and 1 cell removed DNA tested . the healthy embryos are then implanted. low live birth rate. expensive but no need for abortion

78
Q

4 different ethical principles

A
  1. rights and duties
  2. maximising good in the world
  3. making decisions yourself
  4. leading a virtuous life

Biology (13 decks)

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