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Biology (NCERT) - Class XII > XII Chap 11 Biotechnology > Flashcards

XII Chap 11 Biotechnology Flashcards

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1
Q

Define biotechnology.

Examples?

A

using live organisms or enzymes to produce useful products / processes

e.g. GMO or IVF

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2
Q

Synthesizing a gene, correcting a gene or developing DNA vaccine are all examples of biotechnology. T or F?

A

True

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3
Q

Making curd, bread and wine can also be thought of as biotechnology. T or F?

A

True, but not using genetically modified organisms / large scale

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4
Q

What is the definition of biotechnology as per the European Federation of Biotech?

A

integration of natural science and organisms, cells, parts thereof, and molecular analogues for products & services

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5
Q

Two core techniques that led to modern biotechnology?

A
  1. Genetic engineering

2. Bioprocess engineering

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6
Q

Define genetic engineering

A

Techniques to alter the chemistry of genetic material (DNA/RNA)
=> introduce into host
=> change the phenotype of host

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7
Q

What is bioprocess engineering?

A

Maintaining sterile ambience in chemical eng. processes to enable growth of only the desired microbes/eukaryotic cells in large quantities

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8
Q

________ reproduction preserves genetic information, while ________ reproduction permits variation

A

Asexual;

Sexual

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9
Q

Traditional hybridisation procedures allow us to choose isolate and transfer only desired set of genes without introducing undesirable genes. T or F?

A

False; only genetic engineering allows us to do that e.g. recombinant DNA, gene cloning and gene transfer

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10
Q

What is origin of replication?

A

specific DNA sequence in chromosome responsible for initiating replication

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11
Q

What is cloning?

A

Alien DNA is linked with chromosome(s) that contain the origin of replication => alien piece can replicate and multiply inside the host organism

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12
Q

First instance of construction of artificial recombinant DNA molecule was ?

A

gene encoding antibiotic resistance
native plasmid
salmonella typhimurium
Stanley Cohen, Herbert Boyer - 1972

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13
Q

What is a plasmid?

A

Autonomously replicating circular extra-chromosomal DNA;

acts as vector to transfer alien DNA to into host organism

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14
Q

Restriction enzymes are also called ___________

A

molecular scissors

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15
Q

What do restriction enzymes allow us to do?

A

cut DNA at specific locations

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16
Q

What are vectors in recombinant DNA?

A

plasmid DNA;

molecules that are able to covalently bond to and carry foreign DNA into cells

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17
Q

What is DNA ligase?

A

enzyme that joins cut ends of DNA molecules

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18
Q

What is recombinant DNA ?

A

a new combination of circular autonomously replicating DNA created in vitro

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19
Q

When DNA is transferred into E. coil instead of Salmonela it ______

A

replicates using the new host DNA’s polymerase enzyme and make multiple copies i.e. cloning

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20
Q

What are the 3 basic steps in genetically modifying an organism?

A
  1. identification of DNA with desirable genes
  2. introducing identified DNA into host
  3. maintenance of introduced DNA in the host & transfer of DNA to progeny
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21
Q

What are the key tools in recombinant DNA technology?

A
  1. restriction enzymes
  2. ligases
  3. vectors
  4. host organism
  5. polymerase enzymes
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22
Q

What is a restriction endonuclease?

A

same as restriction enzyme

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23
Q

What is recognition sequence?

A

Specific base sequence where an enzyme cuts DNA

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24
Q

How many base pairs in the recognition sequence for Hind II?

A

6

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25
Q

Since discovering Hind II, how many restriction enzymes have been isolated?

A

900+ from 230+ strains of bacteria

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26
Q

What is the convention for naming enzymes?

A

First letter from genus
Second 2 letters from species
One letter(?) for name of strain
Roman Numbers showing order in which isolated

e.g. EcoRI

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27
Q

What are exonucleases?

A

Enzymes that remove nucleotides from the ends of DNA

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28
Q

Endonuclease vs exonuclease

A

Endo - make cut in DNA

Exo - remove nucleotides from ends of DNA

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29
Q

What are the steps in endonuclease’s functioning?

A

Inspect the length of DNA
Finds recognition sequence/palindromic nucleotide sequence
Binds to DNA
Cut both DNA strands at the same site (little away from center but between same two bases on both ends => sticky ends
(Does this for vector and foreign DNA)
DNA ligase joins foreign DNA and vector DNA

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30
Q

Vector and source DNA can be cut with different restriction enzymes. T or F?

A

False, has to be same (recognition sequence)

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31
Q

EcoRI is an ________ enzyme isolated from ____________ organism and has the recognition sequence __________

A

endonuclease;
Escherichia coli R Y 13;
GAATTC

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32
Q

What is gel electrophoresis?

A

Technique to separate DNA fragements

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33
Q

DNA fragments are positively or negatively charged?

A

Negatively charged

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34
Q

How does gel electrophoresis work?

A

Negatively charged DNA fragments are forced to move towards the anode under an electric field through a medium/matrix => DNA resolve/separate according to their size through sieving effect

smaller => moves farther

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35
Q

What is the most commonly used matrix in gel electrophoresis? Where does it come from?

A

Agarose gel - natural polymer extracted from sea weeds

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36
Q

How do we make DNA fragments visible in gel electrophoresis?

A

Staining often with ethidium bromide + exposure to UV radiation => bright orange colored bands

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37
Q

What is elution?

A

Separated bands of DNA are cut out from the agarose gel and extracted => purified to use in recombinant DNA

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38
Q

_____ and _____ have the ability to replicate within bacterial cells independent of control of chromosomal DNA

A

Plasmids

Bacteriophages

39
Q

What are the copy numbers of bacteriophages and plasmids?

A

Bacteriophages - HIGH copy numbers of genome

Plasmids - one or two copies per cell OR 15-100 copies per cell

40
Q

Two factors that determine using something as a cloning vector?

A
  1. easy linking of foreign DNA

2. easy selection of recombinants from non-recombinants

41
Q

Features required for cloning into vectors:

A
  1. Origin of replication (ori) - controls copy number of linked DNA
  2. Selectable marker - identify and eliminate non-transformant, permit growth of transformants
  3. Cloning sites - very few or single recognition site for restriction enzyme
  4. Vectors for cloning genes into plants and animals
42
Q

In E. Coli, the ligation of alien DNA is carried out at a restriction site present in one of the two ____________ genes

A

antibiotic resistance genes

43
Q

Alternative selectable markers (so not antibiotics) have been developed. What are these and how do they work?

A

marker - colour in presence of chromogenic substrate

DNA inserted within coding sequence of β-galactosidase; insertional inactivation (i.e. no color) of gene; present of insert would have given blue color colonies

44
Q

What is insertional inactivation?

A

when inserting a recombinant DNA results into inactivation of the gene for synthesis of a particular enzyme

45
Q

______________ a pathogen is able to deliver piece of DNA known as _____ to transform normal plant cells into tumor cells

A

Agrobacterium tumifaciens

T-DNA

46
Q

Retroviruses have what effect in animals?

A

Normal cells => cancerous cells

47
Q

What are the two pathogens that have been converted into vectors for cloning?

A 
Agrobacterium tumifaciens (Ti plasmid) 
Retroviruses
48
Q

What is transformation?

A

Procedure through which piece of DNA is introduced in host bacterium

49
Q

What is done to make bacterial cells ‘competent’ to host DNA?

A

Treatment with specific concentration of a divalent cation e.g. calcium => increased efficiency for DNA entry through cell wall pores;

incubation on ice with recombinant DNA => heat shock (42°C) => again on ice

50
Q

What is micro-injection?

A

Method to make host cell competent for DNA entry

recombinant DNA injected directly into nucleus of animal cell

51
Q

What is gene gun? Another name for it?

A

for plant cells; bombarded with high velocity micro-particles of gold or tungsten coated with DNA

Another name: biolistics

52
Q

What are the methods to make host competent?

A
  1. Divalent cation + ice-heat-ice
  2. Micro-injection (animal cells)
  3. Biolistics / gene gun (plant cells)
  4. using ‘disarmed pathogen’ vectors that ‘infect’ cells and transfer the recombinant DNA
53
Q

Steps in Recombinant DNA technology?

A
  1. Isolation of DNA
  2. Fragmentation of DNA
  3. Isolation of desired DNA fragment
  4. ligation of DNA fragment + vector
  5. transfer of recombinant DNA into host
  6. culturing the host cells at large scale
  7. extraction of desired product
54
Q

Nucleic acid is the genetic material of all organisms without exception. T or F?

A

True

55
Q

Most animals have RNA. T or F?

A

False, DNA

56
Q

DNA needs to be in ___ form free from _____ in order to be cut

A

pure form;

free from other macro-molecules

57
Q

Why do we have to break the cell open in recombinant DNA technology?

A

Since DNA is enclosed in membranes, to release other macromolecules (RNA, proteins, etc)

58
Q

What are the macro-molecules present in a cell along with DNA?

A

RNA, proteins, polysaccharides, lipids

59
Q

How is DNA isolated from other macromolecules in cell?

A

By treating the cell / tissue with enzymes e.g. RNA removed with ribonuclease, proteins removed by protease

60
Q

What do each of these enzymes act on?
lyosozyme?
cellulase?
chitinase?

What is their effect?

A

lyosozyme - bacteria
cellulase - plant cells
chitinase - fungus

Break cell open to release macromolecules

61
Q

The last step in isolating DNA involves precipitating it out after the addition of ________

A

chilled ethanol

62
Q

What is PCR?

A

Polymerase Chain Reaction

  • multiple copies of the gene of interest
  • in vitro
  • using 2 sets of primers + DNA polymerase
63
Q

What is a primer?

A

small chemically synthesised oligonucleotides

complementary to the regions of DNA

64
Q

What are the 3 steps in a cycle of PCR?

A
  1. Denaturation
  2. Primer annealing
  3. Extension of primers
65
Q

How is repeated amplification in PCR achieved?

A

use of a thermostable DNA polymerase (from bacterium Thermus aquaticus)

66
Q

What is a recombinant protein?

A

Protein encoding gene expressed in a heterologous host

67
Q

What type of culturing method produces larger biomass and higher yields of desired proteins?

A

Continuous culture system => used medium is drained out from one side while fresh added from other => cells maintained in their physiologically most active/exponential phase

68
Q

What is technology is required to produce cultures in large quantities?

A

Bioreactors (100-1000 litres) with optimum growth conditions (oxygen, temp, pH, substrate, salts, vitamins); cylindrical
+ agitator system
+ foam control system
+ sampling ports

69
Q

Most commonly used bioreactors are of type _______

A

stirring type

70
Q

What are the two types of stirred tanks?

A

Simple and sparged (sterile air bubbles)

71
Q

What is downstream processing?

A

Separation and purification of product in recombinant DNA technology;
formulation with suitable preservatives;
clinical trials (if drugs)
QC testing

72
Q

Why does a host cell need to be made competent to take up a foreign DNA?

A

Because DNA is a hydrophilic molecule

73
Q

Why is taq polymerase used in PCR?

A

Because it is thermostable

74
Q

_________ was the first type II restriction endonuclease that could cut dsDNA specific site

A

Hind II

75
Q

Restriction enzymes are synthesized by which kind of cells?

bacteria, yeast, eukaryotic cells

A

bacteria only

76
Q

PCR steps occur at what temperatures?

A

95-98° C
55° C
72° C

77
Q

What is the tag polymerase enzyme obtained from?

A

A thermophilic bacterium - Thermus aquaticus

78
Q

__________ is the first artificial cloning vector constructed

By whom?
In which year?

A

pBR322
Boliver and Rodriguez
1977

79
Q

1960s, 2 enzymes were discovered in bacteria that provided immunity against bacteriophages. What are they?

A

Restriction endonuclease

Methylase

80
Q

What are the names associated with the construction of the first Recombinant DNA?

A

Annie Chang, Boyer, Berg and Cohen

81
Q

Variations as a result of sexual reproduction are not always good for the individual but are always good for the population. T or F?

A

False, not always good for either

82
Q

Which of the following is NOT associated with the first recombinant DNA molecule?
plasmid of salmonella typhimurium - antibiotic resistance gene - 1975 - Stanley Cohen

A

1975

83
Q

EcoRI cuts between

A

G and A in GAATTC

84
Q

EcoRI cuts both strands at the same time a little away from center. T or F?

A

True

85
Q

Primers are not:

small - biologically synthesized - oligonucleotides - complimentary to the regions of DNA

A

biologically synthesized

86
Q

After 30 cycles of PCR, how many times will DNA be amplified?

A

1 billion

87
Q

Use of primers in PCR occurs in which step?

A

Annealing

88
Q

Which of the following processes is not associated with the protein produced by recombinant DNA?
Restriction Digestion - Optimization - Purification - Expression

A

Restriction Digestion

89
Q

Increased surface area for oxygen transfer is a feature found specifically in _________________

A

sparged stirred-tank bioreactor

90
Q

Quality control testing a part of downstream processing. T or F?

A

False, happens after

91
Q

A molecular technique in which DNA sequences between 2 oligonucleotide primers can be amplified is known as _________

A

PCR

92
Q

Which of the following is not a feature of the plasmids?

circular structure - transferable - single-stranded - independent replication

A

single-stranded

93
Q

In recombinant DNA, antibiotics are used to:

  1. keep medium bacteria-free
  2. to detect alien DNA
  3. to impart disease-resistance to the host plant
  4. as selectable markers
A
  1. to detect alien DNA

Biology (NCERT) - Class XII (18 decks)

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