TOPIC 2 QUESTIONS

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  • Created by: Kyrarenee
  • Created on: 13-03-18 12:12
Describe how the mammalian lung is adapted for gaseous exchange [5]
A large number of alveoli provide a large surface area , This increases the rate of diffusion, The alveoli and the capillary have thin walls and are made out of a single layer of flattened cells meaning they are one cell thick , This creates a shosho
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Why do phospholipids molecules form a (continuous) bilayer? [3]
 The phosphate heads are hydrophilic  So they are attracted to water  The 2 fatty acid tails are hydrophobic  So they orientate away from water
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How does cholesterol affect membrane fluidity? [3]
 The cholesterol combines with fatty acid tails  Which restrict movement of the phospholipids  Making the cell membrane more rigid
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How does fusing a cell explain the structure of a cell membrane? [3]
 Both types of protein would be found in the fused cell  Proteins will have intermixed  There would be the same original number of proteins  Hence the fluidity in cell membranes
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CORE PRACTICAL 3: Investigate membrane structure, including the effect of alcohol concentration or temperature on membrane permeability. Using my knowledge on the structure of cell membranes, explain the effect of temperature [4]
 Increasing the temperature increases the kinetic energy of phospholipids  The phospholipids move more  High temperatures disrupt the membrane structure causing more red pigment to escape  The proteins will denature
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Explain the effect of ethanol concentration on the permeability of cell membranes [4]
 It causes the membrane to be disrupted  Because the phospholipids dissolve in ethanol  The proteins will then denature  Pigment will escape easily from a disrupted membrane hence the increase in permeability
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2.4 i) Understand what is meant by passive transport (diffusion, facilitated diffusion), active transport (including the role of ATP as an immediate source of energy), endocytosis and exocytosis. Explain how newly made proteins end up as glycoprotein
 Proteins are released from the ribosomes  They are packaged into rough ER vesicles  The vesicles move towards the golgi apparatus and the fuse with it  Proteins are modified here  They are packaged into vesicles  The vesicles move and fuse wil
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ii) Understand the involvement of carrier and channel proteins in membrane transport. What are the differences between active transport and diffusion? [3]  Active transport requires energy in the form of ATP, diffusion is passive transport  Active
 Active transport requires energy in the form of ATP, diffusion is passive transport  Active transport occurs against a concentration gradient  Active transport uses carrier proteins found in cell membranes
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Describe the role of proteins in active transport [4]
 A molecule binds to a carrier protein  The carrier protein changes shape  The carrier protein moves the molecule against a concentration gradient  It uses ATP
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Describe the role of proteins in facilitated diffusion
 To transport large/ charged/ polar molecules  Using carrier and channel proteins  Carrier proteins change shape, channel proteins open and close  Molecules will move down a concentration gradient
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How are channel proteins involved in passive transport? [3]
 They open and close  They move molecules by diffusion down a concentration gradient  They allow the transport of large/ charged/ polar molecules
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2.6 i) Understand the process of protein synthesis (transcription) including the role of RNA polymerase, translation, messenger RNA, transfer RNA, ribosomes and the role of start and stop codons. ii) Understand the roles of the DNA template (antisens
 RNA polymerase unwinds the DNA double helix  RNA polymerase breaks the hydrogen bonds  One strand is used as an anti- sense strand which contains the start codons to the stop codon  RNA nucleotides line up along the strand and complementary base
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Describe how proteins are made in translation [5]
 tRNA carries amino acids and the anti codon to the mRNA in the ribosomes  the anti codon is complementary to the start codon on the mRNA  Complementary base pairing occurs  A second tRNA molecule attaches itself to the next codon the same way 
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Describe the structure of tRNA [4]
 Clover shaped  Contains anti codons  Has an amino acid binding site  Has hydrogen bonds
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Describe the structure of mRNA [3]
 It is straight  The length depends on the size of the gene  It contains codons
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What is meant by a template for the synthesis of mRNA ?
 RNA nucleotides attach to it
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2.7 Understand the nature of the genetic code (triplet code, non-overlapping and degenerate). Explain the nature of the genetic code [4]
 Triplet codons  That code for an amino acid  Non overlapping, meaning triplet codons do not share their bases  Degenerate, meaning amino acids are coded by more than one triplet
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2.9 iii) Understand the significance of a protein’s primary structure in determining its three-dimensional structure and properties (globular and fibrous proteins and the types of bonds involved in its three-dimensional structure). How does a mutatio
 A mutation causes a change in the sequence of amino acids  The R groups will be different  The bonding will be different  This will change the folding into it’s tertiary structure so the 3D shape will be different
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iv) Know the molecular structure of a globular protein and a fibrous protein and understand how their structures relate to their functions (including haemoglobin and collagen). Compare and contrast the molecular structures of globular and fibrous pro
 They are both chains of amino acids that are joined by peptide bonds  They both contain hydrogen and ionic bonds and disulphide bridges  In globular proteins they hydrophilic group is outside but in fibrous proteins they have hydrophobic groups o
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2.10 i) Understand the mechanism of action and the specificity of enzymes in terms of their three-dimensional structure. What are enzymes?
 Temperature dependant  Biological catalyst  Proteins
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What is meant by the term ‘biological catalyst’? [4]
 Enzymes reduce activation energy  Speed up the rate of reaction  They do not get used up  Produced by cells
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What is meant by the term ‘activation energy’? [2]
 The energy needed for a reaction to occur  By increasing the number of collisions between enzymes and substrate
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Why is it necessary to measure the initial rate of reaction? [3]
 To ensure that substrate is not the limiting factor  It is the highest at this point  The substrate gets used up in the reaction
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Explain how the primary structure of an enzyme determines it’s three dimensional structure and properties [6]
 The primary structure is the sequence of amino acids which determine the type of bonds  E.g disulphide, ionic, hydrogen bonds and hydrophilic and hydrophobic properties  Hydrophilic properties are on the outside and hydrophobic properties on the
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CORE PRACTICAL 4: Investigate the effect of enzyme and substrate concentrations on the initial rates of reactions. Describe the effect of enzyme concentration on the initial rate of reaction [4]
 Enzymes reduce the activation energy  This causes increased collisions of enzymes with substrates  Many active sites are occupied  It levels off as substrate becomes the limiting factor
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Explain the changes in the total volume of oxygen produced over the course of the reaction [4]
 There is a faster initial rate of reaction due to the substrate not being a limiting factor  There are enzyme substrate complexes  Then the volume of oxygen produced slows down because there are fewer active sites occupied  It levels off because
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2.11 i) Understand the process of DNA replication, including the role of DNA polymerase. Describe the process of DNA replication [6]
 DNA helicase unwinds the DNA double helix  Breaking the hydrogen bonds  Both strands act as template strands  DNA polymerase brings free floating nucleotides, they line up along both exposed strands  Complementary base pairing occurs where aden
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What is semi conservative replication?
 A new DNA is synthesized, it contains a new and original strand
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2.12 i) Understand how errors in DNA replication can give rise to mutations. How does deletion affect the primary structure of a protein? [3]
 Removing a base is called a frame shift mutation  This means it will alter all the subsequent codons  Therefore the order of amino acids will be different
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2.13 i) Know the meaning of the terms: gene, allele, genotype, phenotype, recessive, dominant, incomplete dominance, homozygote and heterozygote. What is meant by the term ‘genotype’?
 A set of genes in our DNA that are responsible for a particular trait
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What is meant by ‘incomplete dominance’?
 a form of intermediate inheritance in which one allele for a specific trait is not completely expressed over its paired allele. This results in a third phenotype in which the expressed physical trait is a combination of the phenotypes of both allel
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What is meant by a recessive genetic disorder?
 A faulty allele that is only expressed if both alleles are present
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2.14 Understand how the expression of a gene mutation in people with cystic fibrosis impairs the functioning of the gaseous exchange, digestive and reproductive systems. Describe the location of a CFTR protein [2]
 In the cell membranes  Of mucus producing cells
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Explain the effects of having smaller quantities of CFTR protein in cell membranes [5]
 Fewer chloride ions are transported across cell membranes  So less water moves into the mucus by osmosis  This makes mucus more sticky  This blocks the airways, pancreatic duct, cervix and sperm duct  Causing breathing, digestive and fertility
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Explain how a gene mutation causes a build up of mucus in the respiratory system of a person with cystic fibrosis [7]
 A mutation causes a change in the sequence of amino acids coding for the CFTR protein  This causes the shape of the CFTR protein to be different in its 3D structure  As the CFTR protein transports chloride ions across cell membranes, a different
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Why are people with cystic fibrosis more likely to suffer from lung infections ? [3]
 Mucus can trap bacteria  Sticky mucus cannot be removed by the cilia towards our noses and mouth  So this sticky mucus provides conditions for the bacteria to live and reproduce
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Explain the treatments used to reduce the lung symptoms of people with cystic fibrosis [3]
 Antibiotics are used to kill bacteria  Because people with cystic fibrosis are more prone to bacterial infection  Physiotherapy are used to dislodge mucus  This allows more efficient gas exchange  Gene therapy can be used to produce the functio
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What are some of the similarities between amniocentesis and chorionic villus sampling? [2]
 They both require a needle to obtain foetal cells  They both have a risk of miscarriage
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What are some of the differences between amniocentesis and chorionic villus sampling? [5]
 Foetal cells are obtained from the amniotic fluid in amniocentesis and the placenta in CVSIn amniocentesis the needle is inserted into the abdomen and in CVS, a tube is inserted into the vagina, Amniocentesis is carried out 15-20 weeks and CVS
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Other cards in this set

Card 2

Front

Why do phospholipids molecules form a (continuous) bilayer? [3]

Back

 The phosphate heads are hydrophilic  So they are attracted to water  The 2 fatty acid tails are hydrophobic  So they orientate away from water

Card 3

Front

How does cholesterol affect membrane fluidity? [3]

Back

Preview of the front of card 3

Card 4

Front

How does fusing a cell explain the structure of a cell membrane? [3]

Back

Preview of the front of card 4

Card 5

Front

CORE PRACTICAL 3: Investigate membrane structure, including the effect of alcohol concentration or temperature on membrane permeability. Using my knowledge on the structure of cell membranes, explain the effect of temperature [4]

Back

Preview of the front of card 5
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