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Bio mock AS > TOPIC 2: Genes and Health > Flashcards

TOPIC 2: Genes and Health Flashcards

1
Q

Name the components of a mononucleotide. (3)

A
  • nitrogenous base
  • a sugar
  • a phosphate group
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2
Q

Describe the role of tRNA in the production of the protein part of a glycoprotein. (2)

A
  • each tRNA brings a specific amino acid
  • tRNA w/ complementary anticodon binds to the mRNA codon
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3
Q

Compare and contrast the process of transcription and DNA replication. (4)

A

similarities:
- involve formation of phosphodiester bonds
- involve DNA helicase

differences:
trans: RNA nucleotides/ rep: DNA nucleotides

trans: RNA polymerase/ rep: DNA polymerase

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4
Q

Explain how the change of one amino acid could lead to a change in the structure and properties of the haemoglobin protein. (4)

A
  • diff. primary structure
  • diff. R group
  • therefore, change in tertiary structure
  • haemoglobin may not bond to oxygen
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5
Q

Describe the role of tRNA in the production of leptin. (3)

A
  • tRNA molecules transport amino acids to ribosome
  • tRNA molecule has n anticodon that binds to a codon on mRNA
  • each tRNA carries a particular amino acid
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6
Q

Describe how the primary structure of leptin enables it to be soluble in water. (3)

A
  • primary structure determines folding of the polypeptide
  • forming a globular structure
  • water forms H-bonds w/ protein
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7
Q

Describe how a frameshift mutation could result in the production of leptin with a variety of shorter primary structures. (2)

A
  • changes in the triplet code
  • coding for a shorter sequence of amino acids
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8
Q

Describe how mRNA is synthesised at a template strand of DNA. (2)

A
  • RNA nucleotides align w/ complementary bases on DNA
  • RNA nucleotides join together by RNA polymerase
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9
Q

Describe the differences b/w DNA and RNA structure. (3)

A
  • DNA = double stranded, RNA = single
  • DNA contains deoxyribose,
    RNA = ribose
  • DNA = thymine, RNA = uracil
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10
Q

Explain how deletion and substitution have different effects on protein structure. (4)

A
  • deletion could affect every codon
    ^ more likely to affect position of stop codon
  • substitution may code for the same A.A.
    ^ due to the degenerate nature of the genetic code
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11
Q

Describe how nucleotides join together to form DNA. (2)

A
  • join via phosphodiester bonds during a condensation reaction
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12
Q

Explain why these antibiotics could affect the production of proteins in bacteria. (3)

A
  • ribosome shape altered
  • therefore translation cannot occur
  • polypeptide not synthesised
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13
Q

Deduce why these new antibiotics might be used to treat bacteria that are resistant to other antibiotics. (2)

A
  • bacteria have developed resistance by natural selection
  • therefore, there’s no mutation present to give resistance
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14
Q

Describe the role of the CFTR protein in ensuring that the mucus produced in the lungs has the right consistency. (3)

A
  • chloride ions leave cell
  • sodium ions leave cell
  • water moves out of cell via osmosis
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15
Q

Describe the roles of transcription and translation in the synthesis of a globular protein by a muscle cell. (5)

A
  • gene for globular protein is transcribed
  • complementary base pairing b/w RNA nucleotides & DNA
  • mRNA leaves nucleus & attaches to ribosome
  • pairing b/w codons on mRNA & anticodons on tRNA
  • tRNA provides specific amino acids
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16
Q

Compare and contrast the structure of ATP & a DNA nucleotide. (3)

A

similarities:
- both contain a phosphate group, pentose sugar & a base

differences:
- DNA nucleotides: deoxyribose
ATP: ribose

  • DNA nuc: one phosphate
    ATP: is a triphosphate (3)
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17
Q

State where transcription occurs in an animal cell

A

nucleus

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18
Q

Explain why betalain molecules cannot move through intact cell membranes. (3)

A
  • betalain molecules = too large
  • no carrier proteins for betalain molecules to move through
  • bet. molecules are polar & repelled by hydrophobic fatty acid tails
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19
Q

Explain how the blood-gas barrier of a chicken is adapted to give more efficient gas exchange than that of a dog. (3)

A
  • thinner blood-gas barrier
  • bcs of thinner capillary walls
  • therefore, faster rate of diffusion
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20
Q

Compare and contrast active transport and diffusion. (3)

A

similarities:
- both move through phospholipid bilayer
- both can move through proteins

differences:
- active transport requires ATP
diffusion doesn’t require ATP

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21
Q

Compare and contrast exocytosis and endocytosis. (3)

A

similarities:
- both involve vesicles
- both involve energy from ATP

differences:
- exo involves substances leaving cell
endo involves substances entering cell

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22
Q

Describe how glucose molecules move into the cell. (2)

A
  • facilitated diffusion
  • through carrier proteins
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23
Q

Explain how the structure of glycogen allows it to be an energy store. (3)

A
  • polymer of glucose
  • to provide glucose for respiration
  • compact: large amount of energy stored in small space
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24
Q

Give one function of the glycoproteins found in the cell surface membrane. (1)

A

cell recognition

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25
Q

Explain how the structure of a phospholipid molecule contributes to the partial permeability of a cell surface membrane. (3)

A
  • contains a hydrophilic phosphate head & hydrophobic fatty acid chains
  • allows non-polar molecules to pass through membrane
  • polar molecules cannot pass through phospholipid bilayer
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26
Q

Give reasons for the variation in lung volumes of healthy individuals. (2)

A
  • different weight
  • different age
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27
Q

Give two differences b/w exocytosis and endocytosis. (2)

A
  • exocytosis involves substances leaving cell, endo = entering cell
  • exocytosis involves vesicles fusing with cell surface membrane
    endocytosis involves formation of vesicles
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28
Q

Explain how phospholipids form a cell surface membrane. (3)

A
  • hydrophilic parts associate with water
  • hydrophobic parts repel water
  • a bilayer forms w/ hydrophobic parts pointing towards each other
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29
Q

Explain why the phospholipids are arranged in two layers in a cell surface membrane. (3)

A
  • hydrophilic parts orientated towards water
  • & hydrophobic regions away from water
  • water-based solution on either side of cell membrane
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30
Q

Describe the function of carrier proteins in a cell surface membrane. (4)

A
  • involved in facilitated diffusion
  • involved in active transport
  • movement of large molecules
  • needs ATP to move molecules against the conc. gradient
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31
Q

Describe why single-celled organism do not need a specialised gas exchange surface. (2)

A
  • larger s.a : vol ratio
  • shorter diffusion distance
32
Q

Describe the structure of the cell surface membrane. (3)

A
  • cell membrane made of mainly phospholipids and proteins
  • phospholipids form a bilayer
  • proteins float in phospholipids
33
Q

Give the name of the bond that joins a fatty acid and glycerol molecule in a phospholipid

A

Ester bond

34
Q

Explain how the structure of a human lung enables rapid gas exchange. (4)

A
  • many alveoli provide a large s.a
  • one cell thick walls allow for a short diffusion pathway
  • high conc. gradient maintained by circulation
  • extensive capillary network around alveoli provides large s.a for gas exchange.
35
Q

Explain why cystic fibrosis affects the rate of oxygen uptake in the lungs. (3)

A
  • thick mucus

^ which cannot be removed by cilia

  • restricting air flow through bronchi
36
Q

Explain why thicker mucus is produced if the functioning of the CFTR channel protein is impaired. (2)

A
  • chloride ions cannot leave cell
  • therefore, water moves into cell by osmosis
37
Q

Explain why different mutations in the CFTR gene can lead to differences in the severity of symptoms of CF. (2)

A
  • diff. mutations will have diff. effects on the protein produced
  • varying the thickness of the mucuc
38
Q

Explain why these children would be given dietary supplements and digestive enzymes. (5)

A
  • CF causes production of thicker mucus
  • which blocks pancreatic duct
  • prevents enzymes digesting proteins in intestines
  • reduced amino acids causes a slower growth rate
  • digestive enzymes would increase their growth rate
39
Q

Explain why a couple may not want a prenatal test. (3)

A
  • risk of miscarriage
  • against their beliefs
  • test results may be inaccurate
40
Q

Define: inherited recessive disorder

A
  • caused by faulty allele
  • only expressed in homozygous condition
41
Q

Define: allele

A
  • alternative form of a gene
  • found at the same locus on a chromosome
42
Q

Describe what happens to the lactate in these cells. (2)

A
  • pyruvate is converted into glucose
  • pyruvate is used in respiration
43
Q

Describe the interaction b/w P & Q that allows muscle contraction. (2)

A
  • P changes shape
  • causing Q to move away from the myosin-binding sites
44
Q

Explain the importance of the primary structure for the functioning of the enzyme. (3)

A
  • determines tertiary structure
  • therefore, affecting shape of active site
    ^ which is complementary to ATP
45
Q

Explain how a change in the primary structure of factor VIII could cause difficulties with blood clotting. (4)

A
  • diff. sequence of A.As
  • change in R group changes tertiary structure
  • changing shape of active site, preventing substrate from binding
  • stopping the production of fibrin
46
Q

State why enzymes are described as biological catalysts. (1)

A
  • reduce activation energy of biological reaction
47
Q

Explain how a single base mutation can lead to an altered primary structure of enzyme G. (3)

A
  • change in base causes a change in the triplet code

^ which changes the codons in mRNA

  • resulting in a different A.A sequence
48
Q

Describe what happens to these proteins following the process of translation until they’re released from the cell. (3)

A
  • proteins folded in rough endoplasmic reticulum (rER)
  • packaged into vesicles
  • modified in Golgi apparatus
49
Q

Explain why enzymes that are incorrectly folded cannot carry out their function. (3)

A
  • different tertiary structure
  • active sit of enzyme would not bind w/ substrate
  • therefore, not able to catalyse reaction
50
Q

Describe how an enzyme could break down the polysaccharide component on mucopolysaccharides. (2)

A
  • hydrolysis
  • of glycosidic bonds
51
Q

Describe how the tertiary structure of myosin is related to its function. (3)

A
  • folded into a specific shape w/ a globular head
  • that can bind to actin
  • myosin has site that can bind w/ ATP
52
Q

Compare and contrast the molecular structures of globular and fibrous proteins. (4)

A

similarities:
- both = chains of A.As joined by peptide bonds

differences:
-glob: hydrophilic groups on outside
fibr: hydrophobic outside

-glob: tertiary/quaternary structure
fibr: little/no tertiary structure

-glob: folded into compact shapes
fibr: have long chains

53
Q

Describe how a peptide bond is formed. (2)

A
  • condensation reaction
  • b/w the amine group & carboxyl group
54
Q

Describe how the structure of phospholipase allows it to hydrolyse phospholipids. (4)

A
  • provides active site
    ^ which is complementary to phospholipid
  • to break ester bonds b/w fatty acids & glycerol
  • enzyme structure determine by sequence of A.As
55
Q

Name the products formed when several amino acids are joined together. (2)

A
  • polypeptide AND water
56
Q

Explain why plasma membranes are described as having a fluid-mosaic structure. (2)

A
  • molecules can move within the membrane via diffusion
  • membrane contains both proteins & phospholipids arranged in a scattered pattern (that looks like a mosaic if viewed from above)
57
Q

State three functions of a phospholipid bilayer

A
  • creates enclosed space, separating internal cell environment from external
  • enables membrane to fuse w/ other membranes
  • provides fluidity to membrane
58
Q

Explain two features of DNA that help stabilise its structure. (2)

A
  • H-bonds b/w base pairs
  • many H-bonds provide strength
59
Q

Describe the structure of DNA. (5)

A
  • a polymer of nucleotides
  • each made up of: deoxyribose, phosphate group & a nitrogenous base
  • phosphodiester bonds b/w nucleotides
  • double helix held by H-bonds
  • H-bonds b/w: adenine & thymine
    cytosine & guanine
60
Q

Give 2 benefits of DNA having a double helix. (2)

A
  • gives stability
  • protects bases from digestive enzymes
61
Q

Explain the importance of antiparallel nature of DNA strands. (3)

A
  • DNA strands run in opp. directions
    ^ have a 3’ and 5’ end
  • DNA polymerase can only build in 1 direction
62
Q

Explain how structure of DNA relates to its function. (6)

A
  • strong covalent bonds of backbone: preserve base sequence
  • comp. base pairing:
    keeps equal distance b/w 2 strands to increase stability of DNA molecule
  • many H-bonds:
    increases stability of DNA
  • weakness of H-bonds
    easily broken during replication & transcription
  • base pairing:
    complem. strand can be replicated
  • base sequence:
    act as store of our genetic info to build protein
63
Q

compare the structure of mRNA and tRNA. (3)

A
  • mRNA is longer
  • mRNA = straight molecule, tRNA = folded
  • mRNA = no H-bonds, tRNA = H-bonds
64
Q

Explain the importance of transcription in protein synthesis. (2)

A
  • produces single-stranded molecule of mRNA
  • carries a complementary copy of the code from a gene
65
Q

Explain how mRNA controls the process of translation. (3)

A
  • contains a start codon that acts as a signal to start translation
  • has stop codon to signal end of translation
  • to produce a complete polypeptide
66
Q

Explain importance of tRNA in protein synthesis. (3)

A
  • bind w/ their specific A.A & bring them to mRNA
  • anticodon on tRNA pairs w/ complete codon on mRNA
  • for a peptide bond to form
67
Q

Explain how the structure of a globular protein enables it to perform its function. (3)

A
  • orientation of R groups enable protein to be soluble

^ enables them to perform metabolic reactions

68
Q

Explain why one of the symptoms of anaemia would be fatigue. (3)

A
  • haem contains iron
  • insufficient iron means less haemoglobin

^ therefore, decrease in oxygen supplied to cells

69
Q

How may bromelain act as a treatment. (2)

A
  • removes dead skin cell from wound
  • promoting healing
70
Q

Name the enzymes used in DNA replication and their function. (2)

A

DNA helicase: unzips hydrogen bonds

DNA polymerase: joins nucleotides together

71
Q

Explain the role of free DNA nucleotides. (1)

A
  • to form complementary base pairs
  • to form a complementary DNA strand
72
Q

State how 2 features of DNA are important for semi-conservation replication. (2)

A
  • 2 strands
    ^ both can act as templates
  • complementary base pairing
    ^ accurate replication
73
Q

Define: genotype

A

all the alleles present in an organism

74
Q

Define: phenotype

A

the expression due to genotype & due to environment

75
Q

Explain why scientists use nitrogen isotopes in replication. (2)

A
  • essential chemical component of DNA
  • therefore everytime DNA reps, it incorporates new nitrogen atoms into DNA

Bio mock AS (4 decks)

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