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Biology- OCR > Paper 2- Jan Mock > Flashcards

Paper 2- Jan Mock Flashcards

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1
Q

What is an immobilised enzyme?

A

Immobilised enzyme is an enzyme that is attached to an insoluble material to prevent mixing with the product.

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2
Q

How can an enzyme be immobilised?

A
  • Attached to an INERT substance
  • Enclosed in a capsule
  • Contained within a partially permeable membrane
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3
Q

Why/ when are enzymes immobilised?

A
  • Enzymes are often immobilised for use in INDUSTRIAL PROCESSES
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4
Q

Why are enzymes used in INDUSTRIAL PROCESSES?

A
  • as it means the enzyme can be RESUED in future processes rather than being discarded after it has been used once.
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5
Q

What does reusing the enzyme stop/prevent?

A
  • it avoids the need to separate the enzyme from the product in DOWNSTREAM PROCESSING.
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6
Q

Explain DOWNSTREAM PROCESSING

A
  • immobilised enzymes are contained into a column through which the substrate is filtered in solution.
  • as the substrate runs through the column, enzyme-substrate complexes are formed and products are produced
  • These products then flow out of the column, leaving the enzymes behind to catalyse the reaction again.
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7
Q

Advantages of immobilised enzymes

A
  • No enzyme in the product (product uncontaminated) and therefore there is no need to further process or filter the end product.
  • Immobilised enzyme can be REUSED multiple times which is EFFICIENT and COST- EFFECTIVE.
  • Immobilised enzymes have a GREATER TOLERANCE OF TEMPERATURE AND PH CHANGES (Immobilised enzymes often more stable)
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8
Q

DISADVANTAGES of immobilised enzymes

A
  • specialised expensive equipment is required
  • Immobilised enzymes are more costly to buy, so are unlikely to be financially worthwhile for smaller industries
  • RATE OF REACTION is sometimes LOWER when using immobilised enzymes as the enzymes cannot freely mix with substances
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9
Q

Examples of where immobilised enzymes are used in INDUSTRIAL PROCESSES

A
  • MEDICINE: Immobolised enzymes are used to diagnose diseases and in pregnancy tests.
  • BIOFUELS: enzymes can break down carbs to produce ethanol- based fuels.
  • FOOD PRODUCTION: the manufacture of dairy products involves immobilised enzymes.
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10
Q

Advantages of plant cloning

A
  • all the plants have the same GENOTYPES and PHENOTYPES
  • plants produced are FREE OF DISEASES
  • plants can be grown in any country, in any season
  • process can yield larger numbers of new plants.
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11
Q

Disadvantages of plant cloning

A
  • expensive and labour intensive
  • there’s no genetic variation, so all offspring are susceptible to same disease or other environmental factors.
  • process is susceptible to microbial contamination
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12
Q

Arguments FOR animal cloning

A
  • embryo cloning is well accepted and non controversial in the field of livestock’s farming.
  • Many animals with desirable characteristics can be cloned, ideal for maximising agricultural output e.g milk yield in cattle.
  • can remove desirable characteristics from gene pool over time
  • help preserve endangered species
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13
Q

Arguments AGAINST animal cloning:

A
  • Process of somatic cell nuclear transfer is very hit and miss.
  • unknown long-term effects of cloning process
  • some cloned animals that survive birth and infancy tend to grow abnormally large, can have breathing problems.
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14
Q

What are Intracellular enzymes?

A

Enzymes that work WITHIN cells

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15
Q

What are some example of INTRACELLULAR ENZYMES?

A
  • Hydrogen peroxide is a toxic product of many metabolic pathways
  • Enzyme CATALASE ensures hydrogen peroxide is BROKEN down into oxygen and water quickly.
  • this prevents accumulation of
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16
Q

What are extracellular enzymes?

A

An enzyme that is SECRETED by a cell and functions OUTSIDE that cell.

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17
Q

Why are enzymes released from cells?

A
  • to break down larger molecules

E.G large nutrients like proteins are broken down into smaller molecules.

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18
Q

Explain how temperature affects the activity of an enzyme

A
  • increasing temperature= increases kinetic energy of the particles
  • so particles move faster and collide more frequently
  • leads to increase in rate of reaction
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19
Q

Explain denaturing from temperature

A
  • enzymes are proteins and so are affected by temperature
  • higher temps= binds holding protein together vibrate more
  • as temp increases more, vibration occurs more and so bonds strain and BREAK.
  • breaking bonds change tertiary structure
  • enzyme has changed shape and so has been denatured
  • active site has changed shape so is no longer complementary to the substrate
  • enzyme can no longer function
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20
Q

Temperature extremes in enzymes

A

THERMOPHILES: organisms adapted to living in very HOT environments

  • more stable than other enzymes due to increased number of bonds (particularly hydrogen and sulfur bridges)
  • the enzymes are more RESISTANT to changes in temp.
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21
Q

What are COFACTORS?

A

Cofactors= NON proteins that can activate enzymes

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22
Q

What are INHIBITORS?

A

INHIBITORS- stop enzymes from working

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23
Q

What are competitive inhibitors?

A
  • they are molecules or part of a molecule that has a similar shape to the substrate of enzymes and can fit into the enzymes active site.
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24
Q

How do competitive inhibitors work?

A
  • Blocks the substrate from entering the active site, preventing the enzyme catalysing a reaction.
  • so enzyme cannot carry out it’s function.
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25
Q

Are competitive inhibitors effective reversible or irreversible?

  • give an example of an exception
A
  • Effect is usually REVERSIBLE due to them only binding to active site TEMPORARILY.
  • EXCEPTION= aspirin
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26
Q

What are the effects of competitive inhibitors on the rate of reactions?

A
  • REDUCES rate of reaction for a given concentration of substrate
  • If substrate concentration INCREASES, original v max of enzyme can be reached.
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27
Q

What are NON competitive inhibitors?

A
  • Inhibitor binds to the ALLOSTERIC SITE of the enzyme rather than the ACTIVE SITE.
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28
Q

How do NON competitive inhibitors work?

A
  • Binding of inhibitor causes tertiary structure of the enzyme, meaning the active site changes shape.
  • Results in the active site no longer complementing the shape of the substrate so it’s unable to bind to the enzyme
  • enzyme cannot carry out function so is inhibited.
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29
Q

What are the effects of Non competitive inhibition on the rate of reactions?

A
  • Increasing the concentration of enzyme or substrate will NOT overcome the effect of non- competitive inhibitors.
  • reaction decreases as inhibitor changes shape of active site.
30
Q

Is the effect of Non competitive inhibitors reversible or irreversible on enzymes?

A
  • can be IRREVERSIBLE
31
Q

Explain the LOCK and KEY HYPOTHESIS?

A
  • When the substrate is bound to the active site of an enzyme, ENZYME- SUBSTRATE COMPLEX is formed.
  • When substrate or substrates then react and the product or products are formed, an ENZYME- PRODUCT COMPLEX is formed.
32
Q

Explain how substrates are held when attached to enzymes

A
  • the substrate is held in such a way by the enzyme that the RIGHT ATOM- GROUPS are CLOSE enough to react.
  • The R-groups within the active site of the enzyme will also INTERACT with the SUBSTRATE, forming temporary bonds
  • These put strain on the bonds within the substrate, which also helps the reaction along.
33
Q

Describe the structure of an ANTIBODY

A
  • ANTIBODY is a Y shaped protein which has a CONSTANT region and a VARIABLE region.
  • VARIABLE region of an antibody is COMPLEMENTARY SHAPE to a specific PATHOGENIC ANTIGEN.
  • This allows the antibody to BIND to the ANTIGEN ad neutralise the pathogen
  • CONSTANT REGION of antibody is the same for ALL proteins.
  • antibodies also have a HINGE REGION
34
Q

Describe the VARIABLE and CONSTANT region of anti body structure in more detail

A

VARIABLE REGION:
- shape of the variable region varies between different antibodies therefore different antibodies can bind to different antigens

CONSTANT REGION:
- same for ALL antibodies
- Allows PHAGOCYTES to bind to the antibody
- This allows the antibodies to act as OPSONINS which means they help the pathogen to be PHAGOCYSED by phagocytes

35
Q

What is the HINGE REGION on an antibody and what does is do?

A

HINGE REGION increases their FLEXIBILITY and allows them to bind multiple pathogens at once.

  • this is called AGGLUTINATION
36
Q

What type of proteins are antibodies?

A

Antibodies= GLYCOPROTEINS

37
Q

Describe the antibody structure in terms of protein structure and chains

A
  • Each antibody has 4 POLYPEPTIDE CHAINS making it up
  • 2 heavy chains
  • 2 light chains
38
Q

Name the 4 types of antibody functions

A
  • NEUTRALISATION
  • AGGLUTINATION
  • MAKING
  • LYSIS
39
Q

Describe the 2 types of neutralisation (antibody function):

A

NEUTRALISING TOXINS:
- Many pathogens can produce ENDOTOXINS, which harm the host organism.

  • Antibodies can bind to ENDOTOXINS and neutralise them

NEUTRALISING ANTIGENS:
- Antibodies can directly neutralise viruses
- most viruses have attachment proteins that are necessary for binding to infecting host cells,
- If an antibody binds to these viral attachment proteins, the virus cannot infect cells

40
Q

Describe AGGLUTINATION (antibody functions)

A
  • antibodies will CLUMP pathogens together
  • antibodies can bind to multiple antigens and therefore clump the pathogens into 1 big group.
  • the big group cannot infect cells, and also makes it easier for phagocytes to ENGLUF multiple pathogens in one go.
41
Q

Describe MARKING (antibody functions)

A
  • antibodies MARK pathogens
  • antibodies bound to a pathogen are BEACONS for IMMUNOLOGICAL CELLS and attract phagocytes and lymphocytes to the area.
42
Q

Describe LYSIS (antibody functions)

A
  • Enzymes can work WITH antibodies
  • Enzymes can bind to antibodies bound to PATHOGENIC ANTIGENS
  • These enzymes can then catalyse enzymatic reactions which break down the bacteria which are bound to the antibodies.
43
Q

Describe bacteria’s immunity to antibodies

A
  • through mutation and selection, bacteria can develop defence mechanisms against antibiotics
  • mutations can occur in DNA of the cell during replication.
44
Q

What is an AUTOSOME?

A
  • Any chromosome that isn’t a sex chromosome
45
Q

What is autosomal linkage?

A
  • When 2 or more genes appear on the same autosome (biologists call this autosomal linkage).
46
Q

Describe autosomes and diploid cells

A
  • In diploid cells, AUTOSOMES come in HOMOLOGOUS PAIRS
47
Q

Describe the possible allele combinations of 2 heterozygous individuals with autosomal linked genes, a- b, a- B, A-b and A-B.

A
48
Q

How can linked genes get separated?

A

Separated in MEIOSIS due to crossing over

49
Q

What is the PHENOTYPIC ratios of autosomal linkage WITHOUT crossing over?

A

3:1

50
Q

What is the PHENOTYPIC RATIO of autosomal linkage WITH crossing over?

A

9:3:3:1

51
Q

Explain:

Benedict’s test: Reducing sugars

A
  1. Add BENEDICTS SOLUTIONS (add blue Benedict’s solution to your sample)
  2. Heat the mixture (place ample in a water bath ad bring it to boil)
  3. Observe colour change (if sample contain reducing sugars, the chemcial reaction between the reducing sugar and the Benedict’s solution will result in the formation of a coloured precipitate (solid particles after a reaction between 2 liquids)
52
Q

What does no colour change indicate about the Benedict’s test for reducing sugars?

A

NO COLOUR CHANGE= indicates a lack of reducing sugars in the sample.
- It could be that there are non-reducing sugars present, or non sugar at all.

53
Q

How can you take the Benedict’s test for further to see if NON-REDUCING SUGARS are present?

A
  1. ADD DILUTE HYDROCHLORIC ACID, then NEUTRALISE.
    - the acid will break down the NON-REDUCING sugars into monosaccharides.
    - after adding acid, neutralise the solution with sodium hydrogen carbonate.
  2. HEAT AND OBSERVE COLOUR CHANGE
    - we can then do the Benedict’s test, as we did above for reducing sugars.
    - if there are NON- REDUCING sugars in the sample, we will observe a colour change similar to the one we see in reducing sugars

(Blue to green to yellow to organic to brick red)

54
Q

What type of sugar is glucose?

A

HEXOSE SUGAR

  • consists of 6 carbon atoms
55
Q

What are the 2 isomers of glucose?

A

Alpha glucose

Beta glucose

56
Q

What is DNA sequencing?

A

Identify the base sequence of DNA fragment

57
Q

How have sequencing methods changed over time?

A
  • used to be a manual process however now it has become automated
  • entire genomes can now be read
58
Q

Benefits of genome-wide comparisons

A
  • comparing between species allows us to determine evolutionary relationships
  • comparing between individuals of the same species allows us to tailor medical treatment to the individual
59
Q

How can DNA sequencing be used in synthetic biology?

A
  • knowing the sequence of a gene allows us to predict the sequence of the amino acid that will make up the polypeptide it produces
  • this in turn allows for development of synthetic biology.
60
Q

What is DNA profiling?

A
  • identifying the unique areas of persons DNA, in order to create a profile that is individual to them.
61
Q

State uses of DNA profiling

A

FORENSICS= DNA obtained during crime investigations can be compared to that of victims or suspects.

MEDICINE= to screen for particular base sequence in order to identify heritable diseases.

62
Q

How can we amplify DNA fragment in order to sequence them?

A

Using the polymerase chain reaction (PCR).

Makes millions of copies of a fragment, which are then cut at different lengths in order to be sequenced

63
Q

Describe the reaction mixture in the first stage of PCR

A
  • contains the DNA fragments to be amplified primers that are complementary to the start of the fragment, free nucleotides to match up the exposed bases, and DNA polymerase to create the new DNA.
64
Q

Summarise the process of amplifying DNA fragments using PCR

A
  1. Heated to break apart the DNA strands
  2. Cooled to all primers to bind
  3. Heated again to activate DNA polymerase and allow free nucleotides to join.
  4. New DNA acts as template for next cycle
65
Q

What is it meant by genetic engineering?

A

Where a DNA fragment from one organism is inserted into the DNA of another organism, sometimes across different species.

This is done through use of a vector and a host cell.

66
Q

Summarise the process of isolating a DNA fragment

A
  • Restriction enzymes (RE) cut DNA at specific sequences
  • Different REs cut at different points, but one RE will always cut at the same sequence.
  • Therefore using particular REs allows you to cut out a certain gene of interest.
67
Q

Summarise the process of inserting a DNA fragment into a vector

A
  • A plasmid (circular DNA from bacteria) is used as the vector, and is cut using the same restriction enzymes as the DNA, so that the ends are complementary.
  • DNA ligaments joins the fragment and plasmid together.
68
Q

Summarise the process of inserting a vector into a host cell

A

The host cells (bacteria) are mixed with the vectors in an ice-cold solution, then shocked to increase the permeability of the cell membrane (electroporation) which encourages the cells to take up the vectors .

69
Q

Ethical issues of genetic engineering

A
  • insect resistance can be introduced to crops
  • GE animals used to produce pharmaceuticals
  • GE pathogens can be produced for research
  • GE seeds would be hard to acquire for poorer farmers.
70
Q

What is gene therapy?

A

Replacing a faulty allele (e.g one that codes for a genetic disease) with a normal allele.

The 2 types are somatic and germ line.

71
Q

Differentiate between somatic gene therapy and germ line gene therapy

A
  • SOMATIC = allele introduced to target cells only. Short term, needs repeating
  • GERM LINE= allele introduced to embryonic cells so it is present in all resultant cells. Permanent, will be passed to offspring.

Biology- OCR (5 decks)

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