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genes and health Flashcards

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Biology 101 flashcards
1
Q

why can large polar molecules not move through cell membranes

A
  • too large
  • no channel/ carrier proteins
  • repelled by hydrophobic fatty acid tails
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2
Q

compare and contrast diffusion and active transport

A
  • both move molecules through cell surface membrane
    *in both molecules can move through proteins
    *diffusion is down a concentration gradient but active transport is against
  • diffusion does not require ATP but active transport does
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3
Q

compare and contrast endocytosis and exocytosis

A
  • both involve vesicles
  • both involve energy from ATP
  • exo involves substances leaving cell but endo involves substances entering cell
  • exo involves vesicles fusing w cell surface membrane but endo involves forming vesicles from cell surface membrane
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4
Q

what are the functions of glycoproteins found in the cell surface membrane?

A
  • cell recognition
  • antigens
  • receptors on cell surface membrane
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5
Q

how does the structure of a phospholipid molecule contribute to the partial permeability of a cell surface membrane?

A
  • contains a polar head and non polar fatty acid chains
  • allows non polar molecules to pass through
    *polar molecules cannot move through
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6
Q

what is meant by the term gene?

A
  • sequence of bases in DNA
    *that codes for a sequence of amino acids
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7
Q

what is the role of tRNA in the production of proteins?

A
  • tRNA molecules transport amino acids to the ribosome
  • tRNA molecule has an anticodon that binds to a complementary codon on the mRNA
    *each tRNA carries a particular amino acid
  • tRNA bonds to ribosome
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8
Q

how does the primary structure of a protein allow it to be soluble in water

A

*sequence of amino acids determines the folding of the polypeptide
* forming a globular structure
*hydrophobic R groups located in the centre of the protein
* hydrophilic R groups located on the outside of the protein
* water forms h bonds with hydrophilic groups

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9
Q

what effect does removing one base from a DNA sequence have on the protein structure? (deletion)

A
  • could effect every codon
  • like to affect the position of the stop/ start codon
  • results in diff sequence of amino acids
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10
Q

what effect does changing one base for another in a DNA sequence have on the protein structure? (substitution)

A
  • only effects one codon
  • may not affect the sequence of amino acids
  • may code for the same amino acid due to the degenerate nature of the genetic code
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11
Q

what is the importance of primary structure for functioning of enzymes?

A
  • determines interaction between amino acids
  • primary structure determines folding and tertiary structure
  • affecting the shape of the active site
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12
Q

what is the effect on an increase of temperature on enzyme activity?

A
  • more kinetic energy available
  • so more frequent collisions between between enzyme and substrate
  • more enzyme- substrate complexes formed
  • but when too high, enzyme denatures
  • so substrate no longer fits active site
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13
Q

why are enzymes described as biological catalysts?

A

they are proteins which reduce activation energy of biological reactions

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14
Q

how can a single base mutation lead to an altered primary structure?

A
  • changing a base results in a change in the triplet code
  • this changes the codon in the mRNA
  • resulting in a different amino acid sequence
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15
Q

what happens to proteins that become extracellular enzymes after translation until they are released from the cell?

A
  • folded in the RER
  • transported in vesicles
  • modified in the Golgi apparatus
  • exocytosis
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16
Q

compare and contrast transcription with DNA replication

A
  • both involve formation of phosphodiester bonds
  • both involve DNA helicase unzipping the DNA
  • transcription uses RNA nucleotides but replication uses DNA nucleotides
  • transcription uses RNA polymerase but replication uses DNA polymerase
  • transcription produces a single strand of mRNA but replication produces double stranded DNA
  • replication produces identical copies but transcription produces a complementary copy
17
Q

how does a change of one amino acid lead to a change in the structure and properties of haemoglobin?

A
  • different primary structure
  • different R group
  • tertiary structure will change
  • due to change in disulphide bridges
  • haemoglobin may not bind to oxygen
18
Q

how could a frameshift mutation result in the production of a protein with a shorter primary structure?

A
  • changes the triplet code
  • introducing a new stop codon
  • coding for a shorter sequence of amino acids
19
Q

how is mRNA synthesised at a template strand of DNA?

A
  • RNA nucleotides align with complementary bases on DNA
  • RNA nucleotides joined together by phosphodiester bonds
20
Q

what is the difference between the structure of DNA and RNA?

A
  • DNA is double stranded but RNA is single stranded
  • DNA contains deoxyribose but RNA contains ribose
  • DNA contains T but RNA contains U
21
Q

how do nucleotides join together to form DNA?

A
  • condensation reaction
  • phosphodiester bonds
  • DNA polymerase
22
Q

why are men with cystic fibrosis less likely to be able to release sperm?

A
  • sperm duct blocked with mucus so sperm cannot leave testes
23
Q

why do people with cystic fibrosis require a higher energy diet?

A
  • enzymes cannot enter intestine because pancreatic duct blocked with mucus
  • digestion is less efficient
24
Q

why are people with cystic fibrosis more likely to develop problems in the pancreas?

A
  • pancreatic enzymes trapped behind mucus damage pancreatic cells such as those that produce insulin
  • cysts form in pancreas
25
Q

why does cystic fibrosis affect the rate of oxygen uptake in the lungs?

A
  • thick sticky mucus
  • cannot be moved by cilia
  • restricting air flow through bronchi
  • increasing diffusion distance/ reducing surface area for gas exchange in the alveoli
26
Q

why is thicker mucus produces if the functioning of the CFTR channel protein is impaired?

A
  • Cl- cannot enter mucus/ leave cell
  • Na+ do not move into the mucus/ out of the cells
  • so water moves out of mucus by osmosis
27
Q

what is the role of mRNA in protein synthesis?

A
  • carries genetic code for a protein
  • binds to ribosome
  • complementary tRNA anticodon binds to mRNA codon
  • sequence of bases on mRNA determines sequence of amino acids
28
Q

how do Cl- move through the basal membrane? (into cell)

A
  • active transport
  • against conc grad
  • energy from ATP
29
Q

how do Cl- move through the apical membrane? (out of cell)

A
  • facilitated diffusion
  • down conc grad
30
Q

explain direction of movement of water molecules caused by Cl- moving into mucus

A
  • higher concentration of Cl- in the mucus than the tissue fluid
  • water would move into the mucus by osmosis
  • from a higher concentration of free water molecules to a lower concentration in the mucus
31
Q

chorionic villus sampling

A

*cells taken from placenta
*10-14 weeks
* earlier diagnosis

32
Q

amniocentesis

A
  • amniotic fluid containing cells
  • 14-20 weeks
  • lower risk of miscarriage
33
Q

Why did meselson and stahl accept one model for DNA replication and reject the other?

A

Semi conservative model was accepted
Gen 1 has a single band halfway between 15N and 14N
Because DNA has one strand with 15N and one with 14N
In semi conservative, further generations would have no band at 15N

34
Q

Describe how DNA is organised in a bacterial cell

A

Large circular DNA
Not associated with histone proteins
Small plasmids
Located in the cytoplasm

35
Q

Explain the role of the enzyme ligase in DNA replication

A

Joins sections of DNA together
By forming phosphodiester bonds
Between phosphate and sugar

36
Q

describe the roles of transcription and translation in the synthesis of a globular protein by a muscle cell

A

gene for the protein is transcribed
complementary base pairing between RNA nucleotides and DNA
mRNA leaves nucleus and attaches to a ribosome
pairing between codons on mRNA and anticodons on tRNA
tRNA provides specific amino acids
sequence of bases determines the primary structure of the protein

37
Q

compare and contrast the structure of a DNA double helix with the structure of tRNA

A

both contain nucleotides/ phosphate group, pentose sugar and base
both contain phosphodiester bonds/ h bonds between bases
DNA is double stranded but tRNA is single stranded
DNA contains deoxyribose sugar/ thymine but tRNA contains ribose/ uracil
tRNA has a specific amino acid binding site

38
Q

describe the role of the CFTR protein in ensuring that the mucus produced in the lungs has the right consistency

A

Cl- leave cells thru CFTR protein
Na+ leave cells
increasing solute conc in mucus
water moves out of the cells and into the mucus by osmosis

39
Q
A

bio questions (6 decks)

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