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Year 12 Biology > Chapter 12 > Flashcards

Chapter 12 Flashcards

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1
Q

Genetic engineering

A

technology that allows the genetic material of an organism to be manipulated through using modern molecular biology techniques - e.g. introducing, eliminating or changing DNA.

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2
Q

Genetic engineering is used because of…

A

economical reasons

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3
Q

Major steps of genetic engineering

A

isolation of genes of interest, insertion into transfer vector, transfer vector to the organism to be modified, transformation of the cells of the organism, selection of GMO

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4
Q

Genetically modified organism

A

an organism whose genetic make-up has been altered by artificial means

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5
Q

Restriction enzymes

A

One class of enzymes that can cut DNA into a reproducible number of fragments and which can occur naturally in micro-organisms, such as bacteria

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6
Q

Why are they called restriction enzymes

A

restricted to where they can cut

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7
Q

How are restriction enzymes labelled

A

letters = organism it came from, roman numerals = order extracted

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8
Q

Where do restriction enzymes originate from

A

e.g. immune system of bacteria

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9
Q

How do restriction enzymes work

A
  • cuts made at specific points on a DNA strand

- either makes a blunt end or sticky end cut

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10
Q

Sticky ends are…

A

complementary

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11
Q

How do restriction enzymes cut

A

break phosphodiester linkages

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12
Q

Phosphodiester linkages

A

join between sugar and phosphate backbone

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13
Q

Each restriction enzyme has a specific…

A

recognition sequence

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14
Q

Recognition sequence

A

sequence of three to six nucleotides within a DNA molecule that forms the specific site for a restriction enzyme that can cut the DNA at that point; also termed a cutting site

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15
Q

Gel electrophoresis

A

technique for sorting through an electric field a mixture of DNA fragments (and other molecules with a net charge) on the basis of different fragment lengths

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16
Q

Gel electrophoresis purpose

A

to sort out DNA according to size

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17
Q

How does gel electrophoresis work

A
  • DNA is placed at one end of a gel-like substance
    • Blue tracking dye is added
    • Gel is exposed to an electric field (i.e. an electric current is passed through it): negative end is where you place the DNA and positive end is the opposite pole
    • DNA moves towards positive end (net negative charge)
    • Fragments move through reptation
  • Shorter fragments move more quickly and further than longer fragments
  • Fragments are dyed with ethidium bromide (UV) so can see
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18
Q

Why do shorter DNA fragments travel further

A

fit through smaller pores, less resistance

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19
Q

Name of gel

A

agarose gel

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20
Q

What is gel placed in (blue solution)

A

methylene blue solution

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21
Q

How can one particular DNA fragment can be picked out from millions

A

probe

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22
Q

Probe

A

single-stranded segment of DNA (or RNA) with a base sequence complementary to that in a target strand of DNA and that carries a radioactive or fluorescent label to detect it.

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23
Q

How does a probe work

A
  • it has a radioactive or fluorescent marker
  • located particular sequence
  • has a sequence complementary to that of the target DNA
24
Q

Why does it have to be denatured

A

to become single stranded so it can be located

25
Q

Ligase

A

enzyme that catalyses the joining of two double-stranded DNA fragments. Makes sugar-phosphate back bone bond permanent.

26
Q

Ligase can form… (shape of DNA)

A

linear or circular DNA

27
Q

Plasmids act… from central chromosome

A

act separately

28
Q

Plasmids can…

A

cross membranes

29
Q

Vectors

A

in genetics, refers to an agent such as a plasmid or a virus that carries passenger DNA into a cell.

30
Q

Steps of vectors/recombinant DNA

A
  1. DNA of plasmid is cut using restriction enzyme (sticky ends)
  2. passenger DNA cut with same restriction enzyme
  3. passenger DNA is mixed with plasmid DNA
  4. ligase makes join permanent
  5. plasmids with passenger DNA are selected + placed in plasmid
31
Q

Gene cloning

A

process of making multiple identical copies of a specific gene or segment of DNA

32
Q

Gene cloning process

A

Gene to be cloned is inserted into a bacterial plasmid, the plasmid is then reinserted into the bacterial cell, plasmid may multiply up to 20 times within the cell= 20 copies of the gene, bacterial cell multiplies every 20 mins, within these new cells plasmids multiply again, cell divides etc.

33
Q

What does PCR stand for

A

Polymerase Chain Reaction

34
Q

PCR

A

technique for amplifying tiny amounts of DNA exponentially through many cycles of multiplication; sometimes termed ‘DNA xeroxing’

35
Q

PCR purpose

A

to amplify DNA

36
Q

PCR steps

A
  1. Denature
  2. Bind primers
  3. Extend primers
37
Q

Denature (PCR)

A

DNA is heated to 94ºC for 2 minutes to separate into single stranded DNA

38
Q

Bind primers

A

DNA heated to 55º for 2 minutes to add short segments of single stranded DNA that bind to either end

39
Q

Extend primers

A

polymerase uses primers as a starting point to extend to form 2 complete strands. Must supply nucleotides. 72C for 1 min

40
Q

Time length of each cycle (PCR)

A

5 minutes

41
Q

Taq polymerase

A

used to synthesise DNA (PCR)

42
Q

How is DNA extracted

A

amniocentesis, chorionic villus, blood cells/cheek cells

43
Q

Chorionic Villus Sampling CVS

A

placenta section removed (pregnancy)

44
Q

Conjugation

A

bacteria can transfer plasmids to other bacteria

45
Q

Other ways of obtaining specific segments of DNA

A

synthesise DNA from nucleotide building blocks (DNA synthesiser), and make a copy of the DNA using an mRNA template (reverse transcriptase)

46
Q

Reverse transcriptase

A

enzyme that directs the formation of copy DNA from a messenger RNA template

47
Q

Transgenic organisms

A

organisms that carry in their genomes one or more genes artificially introduced from another species

48
Q

DNA profiling

A

technique for identifying DNA from different individuals based on variable regions
Variable regions - STR, (aka micro-satellites)

49
Q

Detection of variation uses…

A

a combination of single-locus probes, each specific to a different STR (locus LSTR)

50
Q

STRs and HVRs

A

very variable between unrelated people

51
Q

STR

A

chromosomal sites where many copies of a short DNA sequence are joined end to end

52
Q

STR sequences are normally… bases long

A

2-4 bases long and the number of repeats are variable between unrelated people.

53
Q

HVR stands for

A

hyper-variable regions

54
Q

HVR

A

regions of chromosomal DNA in which great variation exists in unrelated individuals, often as a result of variation in the number of repeats of short base sequence

55
Q

Differences between DNA fingerprinting and DNA profiling (9)

A

DNA profiling is more sensitive, requires smaller quantities of DNA, based on alleles, shorter time, can use several single-locus robes rather than one multi locus probe, coloured fluorescent labels rather than radioactive labels, each STR can be identified in both colour and size, produces less complex patterns and is easily interpreted.

56
Q

Restriction fragment length polymorphism (RFLP)

A

variation that may be detected in members of a family depending on the presence or absence of a restriction enzyme cutting site within the DNA of a given gene

Year 12 Biology (9 decks)

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