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A levels > BY5.6 - Applications of Reproduction and Genetics > Flashcards

BY5.6 - Applications of Reproduction and Genetics Flashcards

1
Q

What are clones?

A

Organisms that have been produced asexually and are genetically identical to the “parent” organism

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2
Q

What are stem cells?

A

Totipotent or Undifferentiated cells

From a blastocyst (3-5 day old embryo)

Capable of dividing into different types of specialised cells

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3
Q

Name the 2 main methods of cloning:

A

1) Embryo Splitting
2) Nuclear Transfer

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4
Q

Describe the method of embryo splitting:

A

1) A blastocyst produced sexually is split into separate cells
2) cells divide, forming embryos
3) Embryos are transplanted into surrogate’s uterus

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5
Q

Give the Advantages of embryo splitting

A

1) Used to conserve rare breeds
2) Farmers can increase their stock more than they would through sexual reproduction

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6
Q

Give the disadvantages of Embryo Splitting

A

No Guarantee the traits of parents will be present in the identical offspring, as they were produced sexually

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7
Q

Describe briefly the Method for Nuclear Transfer Cloning

A

1) Take the nucleus from a somatic cell of individual to be cloned
2) Insert into enucleated ovum

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8
Q

Describe in full the Method for Nuclear Transfer Cloning

A

1) A somatic cell is taken in a biopsy from the donor
2) An unfertilised ovum is taken from the recipient and enucleated
3) Donor and Recipient cells fuse
4) Cell divides by mitosis
5) Totipotent Blastocyst forms –> embryo
6) Embryo implanted into uterus of recipient
7) Offspring genetically identical to donor born

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9
Q

What are the Advantages of Nuclear Transfer?

A

1) Useful for production of genetically identically cells in quantity
- cancer cells for medical research
- monoclonal antibodies
2) Maintains genetic stocks - produces single identical line of cells

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10
Q

What are the disadvantages of nuclear transfer?

A

1) Expensive and Unreliable in Mammals
2) Can cause inadvertent selection of disadvantageous alleles
3) Progeny can cause long term unseen effects - premature ageing

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11
Q

What are bulbs?

A

Have short stems with closely packed leaves

Leaves swollen with stored food

Terminal bud produces next year’s flowering shoot

Lateral bud produces new plants

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12
Q

What are Corms?

A

1) Have short, swollen stem - stores food
2) Papery thin leaves
3) Terminal bud produces next years flowering shoot

Lateral bud produces new plants

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13
Q

What are suckers?

A

New plant grows from meristem of root or lower stem

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14
Q

What are the three different methods plants use for vegetive propagation?

A

Bulbs

Corms

Suckers

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15
Q

What is the technique of micropropagation based off?

A

Plant cells are totipotent:

  • The ability of undifferentiated plant cells to give rise to all the differentiated cells of an adult plant
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16
Q

What parts of the plant are used in micropropagation and why are they used?

A

The meristems (tips of roots and shoots)

as their cells are dividing rapidly

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17
Q

Describe the Method of micropropagation

A

1) A plant with the desired characteristics is selected
2) meristem is removed from shoot with scalpel
3) meristem is cut into explants
4) explants are placed onto sterile, aerated nutrient rich agar
5) cells divide - mitosis
6) mass of undifferentiated cells - Callus - produced
7) Callus is subdivided & pieces differentiate into Plantlets
8) Plantlets transferred to sterile soil once a suitable size is reached

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18
Q

Define Donor DNA

A

A gene that is isolated for insertion

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19
Q

Define Plasmids

A

Circular loops of DNA in bacteria which acts as a vector

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20
Q

Define Restriction Endonucleases

A

Enzymes which cut DNA molecules between specific base sequences called restrictions sites

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21
Q

Define DNA ligases

A

Enzymes which join sections of DNA together (splices)

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22
Q

Define sticky ends

A

The two ends of the ‘cut’ DNA segment, which comprise of unpaired bases

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23
Q

Define recombinant DNA

A

DNA which is formed when a piece of ‘foreign’ DNA is incorporated into the plasmid from a bacterium

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24
Q

Define reverse transcriptase

A

Enzymes which use mRNA as a template for making a DNA molecule

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25
Q

What is Genetic Engineering?

A

A technique used to extract genes from one organism (the donor) to another organism (the recipient)

to produce a genetically modified organism with a new genotype

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26
Q

Why would donor genes be inserted into the recipient organism?

A

so that the gene codes for the synthesis of useful gene products e.g. bacteria producing insulin

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27
Q

How is a gene isolated from donor DNA in recombinant genetic technology? Use the example of human insulin as the donor gene

A

1) human insulin producing genes are located using a gene probe
2) the gene is isolated using restriction endonuclease enzymes
3) each specific restriction endonuclease cuts the DNA at a specific base sequence - the restriction site e.g AATT
4) the unpaired DNA bases are called sticky ends

28
Q

what is used to insert the donor gene into the recipient? give an example for the case of human insulin synthesis

A
  • a vector - a plasmid from e.Coli
29
Q

what does the marker gene in the synthesis of human insulin code for?

A

antibiotic resistance to ampicillin

30
Q

Describe the process of inserting the gene into a vector for recombinant DNA technology

A

*Plasmid DNA is cut using the same restriction endonucleases/ as the donor DNA

sticky ends are produced in plasmid DNA *

sticky ends on donor insulin gene and plasmids are complementary - base pairing occurs

DNA ligase enzymes join sections of DNA from donor and plasmid together

Recombinant DNA is formed

31
Q

Why are marker genes used in recombinant DNA technology?

A

When bacteria and plasmids are mixed together only a small number of bacteria take up the recombinant plasmids.

The bacteria which contain the recombinant plasmids are identified by their marker gene

32
Q

give an example of a marker gene

A

antibiotic resistance to ampicillin

33
Q

How does the ampicillin-resistance marker gene show which bacteria contain recombinant plasmids?

A

1) all the bacteria are cultured on an agar plate containing ampicillin
2) the surviving bacteria must contain the ampicillin resistance gene
3) therefore the surviving bacteria must contain the recombinant plasmid, and therefore the human insulin production gene

34
Q

Once the bacteria are shown to contain recombinant plasmids, what is done with them?

A

They are cultured in an industrial fermenter to divide and produce insulin-synthesising clones the human insulin is then extracted and purified

35
Q

Why is it difficult to locate the correct gene for synthesis?

A

There are only 2 copies of the gene in a cell

36
Q

Why is using mRNA an alternative to locating the gene itself?

A

there are many copies of mRNA in a cell that has been transcribed from the gene, which are complementary to the gene itself.

37
Q

Give the method of synthesising recombinant DNA using mRNA

A

1) mRNA is extracted
2) mRNA is mixed with reverse transcriptase enzymes
3) This synthesises many copies of a single stranded DNA polynucleotide called cDNA
4) DNA polymerase enzymes are added to convert cDNA into a double stranded DNA molecule to be inserted into a plasmid

38
Q

What are the advantages of recombinant DNA technology?

A

1) produces complex proteins or peptides in quantity which cannot be produced by other methods
2) produces higher yielding crops with superior keeping qualities
3) can be used for treating genetic diseases

39
Q

What are disadvantages of Recombinant DNA technology?

A

1) techinically complicated - very expensive on an industrial scale
2) difficulties in identifying the genes of value in a huge genome -
3) synthesis of a required protein may require /several genes
4) treatment of human DNA with restriction enzymes produces millions of fragments of no use
5) not all eukaryote genes will express themselves in prokaryote cells
6) bacteria readily exchange genetic material - use of antibiotic resistant genes in E.coli means that genes could be accidentally transferred to human pathogens
7) Possibility of transfer of DNA with linked pathogen genes e.g. oncogenes - increase cancer risk

40
Q

What allele, when mutated, expresses the non-functioning protein (of the same name) that causes cystic fibrosis?

A

Cystic Fibrosis Transmembrane Regulator

41
Q

How does the non - functional Cystic Fibrosis transmembrane regulator protein cause cystic fibrosis?

A

The non functional protein cannot actively transports Cl- ions out of epithelial cells

2) Cl- and Na+ build up in the cells
3) lowers water potential in the cell
4) water moves into the cell by osmosis down the water potential gradient
5) causes the mucus to be thick and sticky

42
Q

what are the problems caused by the thick mucus cystic fibrosis suffers have?

A

1) blocked pancreatic duct
- prevents pancreatic enzymes from being secreted into the duodenum
- > food digestion incomplete
- > limited absorption of food
2) clogged bronchioles and alveoli
- > congestion and difficulty breathing

hard to move mucus = trapped bacteria/virus

= reoccurring infections e.g. bronchitis/pneumonia

frequent daily chest physiotherapy needed to keep bronchioles open

43
Q

What is the aim of gene therapy?

A

to treat genetic diseases by replacing the defective alleles in the patients cells with copies of the normal allele

44
Q

What are the 2 types of gene therapy?

A

1) Somatic cell therapy
2) Germ line therapy

45
Q

When in someones life would germ line therapy take place?

A

when they are a gamete e.g. sperm/ovum

46
Q

Why would the genetic changes from somatic cell therapy not be inherited by the patients offspring?

A

only somatic cells are treated - gametes are not altered

47
Q

Give the method for cystic fibrosis somatic cell therapy

A

1) identify and clone the CFTR gene by PCR
2) Insert the normal CFTR allele into liposomes
3) aerosol inhaler adds the normal allele to the lung epithelial cells
4) Liposomes fuse with phospholipid bilayer of the cell membrane
5) DNA enters the cells
6) epithelial cells with normal CFTR allele express the normal CFTR protein/
7) Symptoms are alleviated

48
Q

What is germ line therapy?

A

When normal genes are inserted into germ line cells - e.g. sperm/ovum - enabling genetic corrections to be inherited

49
Q

What biological techniques need PCR to work, and why?

A

1) Gene therapy:

  • millions of alleles needed to have an overall effect on the body

2) Genetic fingerprinting:

  • needed if little DNA is found at crime scene
50
Q

What does PCR stand for?

A

Polymerase Chain Reaction

51
Q

What is PCR?

A

a process which can /copy a single gene etc. many times by mimicing semi-conservative replication

52
Q

What do you need for PCR?

A

1) PCR machine
2) Gene/DNA fragment to be copied
3) buffer solution
4) Free DNA nucleotides
5) DNA Polymerase
6) Primer

53
Q

Describe the method of PCR

A

1) heat to 95 degrees
2) hydrogen bonds in the gene break (denature)
3) 2 template strands are formed
4) cool to 55 degrees
5) the primers attach to complementary bases on target DNA
6) heat to 70 degrees
7) DNA polymerase pairs the free nucleotide bases to the DNA
8) a identical copy of the DNA is formed
9) repeat 25 times, producing 1 million copies

54
Q

What is a persons genetic fingerprint?

A

their DNA profile, which is unique to then

55
Q

what are exons?

A

regions of DNA that code for proteins

56
Q

What are introns?

A

regions of non-coding DNA

contain blocks of repeated nucleotides called /short tandem repeats (STR’s)

the number of repeats produces variation in induviduals

57
Q

How is Genetic Fingerprinting used to settle paternity disputes?

A

1) white blood cells are taken from the mother, child, and potential dad
2) DNA taken from the cells undergo electrophoresis
3) the bands of the mother are subtracted from the child’s genetic fingerprint
4) if the man is the father, he must possess all the remaining bands in the childs fingerprint

58
Q

what is a genome?

A

All the DNA including genes, in an organism

59
Q

What are the main aims of the Human Genome Project?

A

1) determine the sequence of bases in all human DNA
2) Identify all the genes formed by the bases
3) Find the locus of all genes on all 23 chromosomes
4) Store this information on a database
5) consider the social, ethical and legal issues from obtaining and storing the information

60
Q

what is the main benefit of the human genome project?

A

the information identifies which genes on particular chromosomes are responsible for different inherited diseases

61
Q

What are the 2 types of genetic tests?

A

1) Mutated base sequences
a) DNA probes, complementary to the mutated sequence, are added to the patients blood.
b) If the mutated sequence is present, the probe will bind to it, labelling it.
2) DNA sequence comparison :

the patients DNA sequence of a gene is compared to the DNA sequence of the normal gene

62
Q

Give 3 uses of genetic testing?

A

1) Carrier screening
- identifies unaffected parents which carry a recessive allele

for an inherited disease

which requires a homozygous recessive genotype to be expressed (cystic fibrosis)

2) pre-symptomatic testing for predicting adult onset disorders (huntington’s) disease)
3) pre-symptomatic testing for estimating the risk of developing adult onset diseases (alzheimer’s, breast cancer)

63
Q

What factors is the advice in genetic counselling based on?

A

1) whether there is a family history of the disorder
2) whether the parents are closely related
3) The frequency of the allele in the general population

64
Q

What are the tests to determine whether an embryo is affected with a disorder before it is born?

A

1) Blood test - cystic fibrosis
2) Amniocentesis,

which involves withdrawing some amniotic fluid, which contains embryonic cells which can be analysed using a microscope

3) Chorionic villus sampling - removing foetal tissue (8-10 weeks) where the cells are cultured and examined under the microscope

65
Q

What are the Social, Ethical, and Legal concerns with gene testing/therapy?

A

1) Anxiety
2) Concerns that the risks of discrimination and social stigmatization could outweigh the benefits of testing
3) some believe that if prenatal tests are carried out, finding defective alleles will lead to an increase in the number of abortions
4) who should have access to personal genetic information and how it should be used e.g employers/health insurance

A levels (12 decks)

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