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Medical sciences > DNA > Flashcards

DNA Flashcards

1
Q

Was Hooke’s observation on cell walls or living cells?

A

cell walls

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2
Q

what did Anthonie Van Leeuwenhoek call the living cells?

A

animalcules

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3
Q

who was the first person to identify the nucleus and what type of cells did he observe it in?

A

Anton Van Leeuwenhoak, salmon RBCs

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4
Q

Who made the link between the nucleus and cell division?

A

Shleiden

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5
Q

what did Shleiden call the nucleus?

A

cytoblast “cell builder”

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6
Q

What did Oscar Hertwig identify?

A

sperms transfers their nuclei to the oocyte

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7
Q

what was believed before Hertwig identification in regard to sperm?

A

sperms contained tiny human “homunculus”

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8
Q

who discovered the DNA?

A

Friedrich Miescher

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9
Q

Who was the first person to extract cell nuclei?

A

Friedrich Miescher

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10
Q

Why did the components of the nuclei tested positive in protein tests in Friedrich experiments?

A

DNA interacts closely with proteins

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11
Q

what was the name of deoxyribonucleic acid before it was renamed?

A

nuclein

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12
Q

What is the name of the dye that stains DNA and why was it important?

A

fuchsin, the discovery that all cells contain DNA

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13
Q

what was the identification of Griffith?

A

that there was a transforming factor that could make non-virulent bacteria virulent

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14
Q

what was the identification of Oswald Avery in regard to the transforming factor and what process did he use to make the identification?

A

The transforming factor was DNA
used a process of elimination (eliminating RNA and the protein)

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15
Q

What was the Phoebus Levene discovery?

A

he discovered that DNA is made of nucleic acids that consist of:
* nitrogen containing bases
* sugar molecule
* phosphate molecule

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16
Q

What is Chargraff’s rule?

A

There is always the same amount of:
* Adenine (A) as Thymine (T)
* Guanine (G) as Cytosine (C)

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17
Q

What was the idea of Levene that was debunked by Chargraff?

A

idea of an ordered repetitive sequence

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18
Q

What was the contribution of Rosalind Franklin and Raymond Gosling into the discovery of DNA’s structure?

A

that it was helical

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19
Q

What was the contribution of Maurice Wilkins into the discovery of DNA’s structure?

A

nucleotides of DNA had to be arranged with hydrogen bonds facing inward

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20
Q

Who discovered the overall structure of DNA using the information of from different scientists?

A

Watson and Crick

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21
Q

What are the benefits of knowing the structure of DNA?

A
  • help explain how cells can replicate DNA
  • help explain how DNA make transcripts of genes
  • help explain how proteins bind to DNA for regulation
  • helps explain the packaging of DNA in the nucleus
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22
Q

how long the human genome is?

A

2 m

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23
Q

So how does a 2 m long piece of DNA fit into a 5 µm nucleus?

A

wrap around itself in a highly ordered process so that genes used as necessary (chromatin)

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24
Q

How much shorter is the mitotic chromosome in comparison to it’s extended length?

A

10,000 times

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25
Q

what did Matthew Meselson and Franklin Stahl discovered?

A

DNA replicate using template strands that replicate a new duplicate strand (semiconservative model)

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26
Q

How was the semiconservative model proved?

A

DNA built with N( isotope 15) bases left to replicate in a medium with N( isotope 14) bases:
the proportion of N(15)-containing strands decreased with each replication (1, 0.5, 0.25, …) (DNA with N(15) fells down as it’s heavier)

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27
Q

who was the first to use the term gene?

A

Wilhelm Johannsen

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28
Q

What did Thomas Hunt Morgan claim?

A

genes lay in chromosomes (experiments on flies)

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29
Q

What is a gene?

A

is the genetic code that codes for an mRNA

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30
Q

What is the central dogma?

A

theory that states that genetic information flows only in one direction (DNA > RNA > Protein, or RNA > Protein) but not the other way around

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31
Q

What do genes express?

A

proteins (structural, signaling, enzyme, transcription factors)

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32
Q

What did Archibald Garrod formulate?

A

one gene, one enzyme hypothesis

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33
Q

how did Beadle and Tantum try to prove the one gene, one enzyme hypothesis?

A

experimenting on the metabolic pathway of a mould (neurospora) which require the amino acid arginine to grow

34
Q

How does a cell switch a gene on and off?

A

on: promoters and enhancers
off: repressors

35
Q

regulation points in transcription and translation:

A
  1. remodeling of chromatin
  2. transcriptional control
  3. processing control
  4. transport control
  5. mRNA stability control
  6. translational control of protein synthesis
  7. posttranslational control of protein stability
  8. protein degradation
36
Q

Where does transcription factors act ?

A

Promoters (recognition sequence, TATA box)

37
Q

What are transcription factors and what is their importance?

A

regulatory proteins - they must assemble on the chromosome before RNA polymerase can bind to the promoter

38
Q

What transcription factors bind to the TATA box?

A

transcription factor II D (TFIID) and then others to form a transcription complex

39
Q

how does regulation of transcription aid cell differentiation?

A

some sequences (promoters) are specific to a few genes and are recognised by TF found only in certain cells

40
Q

What sequences regulate rate of transcription?

A

enhancers (positive)
repressors (negative)

41
Q

What are the three criteria in which a DNA recognises a protein motif?

A
  • fits into major and minor groove
  • has amino acids that projects the interior of double helix
  • has amino acids that can bond with interior bases
42
Q

what are genetic mutations?

A

changes in the nucleotide sequences of DNA that are passed to the next generation

43
Q

what are the main types of mutation?

A

somatic mutation (body cells)
germ line mutation (germ cells -gametes-)

44
Q

what are the categories of molecular mutation?

A

point mutation (single nucleotide)
chromosomal mutation ( DNA segment)

45
Q

what might be the consequence of a genetic mutation?

A

abnormal protein

46
Q

what causes the disease phenylketonuria?

A

build up of phenylpyruvic acid in the urine due to a mutation in a gene that encode one protein of the proteins that make up the phenylalanine hydroxylase

47
Q

what are the effects of phenylketonuria in the body?

A

mental retardation, light skin and hair colour

48
Q

how are genetic diseases treated?

A
  • alleviate the symptoms of the disease
  • modifying the disease phenotype
  • replacing the defective gene
  • restrict substrate
  • add metabolic inhibitor
  • restore missing enzyme
49
Q

how do anti-depressants work?

A

inhibitors of neurotransmitters in the brain

50
Q

examples of treatments replacing dysfunctional protein:

A

insulin
blood factor VIII

51
Q

challenges of gene therapy:

A
  • finding appropriate vector
  • precise insertion into host DNA
  • appropriate expression
  • selecting cells to target
52
Q

what is ex vivo technique?

A

removing cells from the body
inserting genes (using virus with viral DNA and normal allele)
returning the cell in the body

53
Q

example of genetic disease that has been treated with gene therapy:

A

immunodeficiency disease

54
Q

how does SCID occur?

A

mutation in a single gene that encode IL2RG receptor which is required for white blood cells maturation

55
Q

how does gene therapy work in in vivo approach?

A

gene inserted directly into body cells

56
Q

how long were the fragments of DNA used in sequencing the entire human body:

A

500 bp

57
Q

how long is the human genome?

A

3.3 billion bp

58
Q

how many fragment the human genome was cut into?

A

6.6 million bp

59
Q

what are the larger overlapping fragments called?

A

contigs

60
Q

what is the field that was developed to analyse DNA sequences?

A

bioinformatics

61
Q

What are the approaches in which the sequencing of the human genome was accomplished?

A
  • hierarchical sequencing “larger fragments”
  • shotgun sequencing (faster and cheaper) “smaller fragments”
62
Q

how many genes M. genitalium require to survive?

A

382 genes

63
Q

how does eukaryotic cells differ from prokaryotic cells?

A
  • larger and have more protein coding genes
  • have more regulatory sequences
  • much of it is noncoding (introns, control sequences, repeated sequences)
64
Q

what is the percentage of protein-coding genes?

A

2% (24,000)

65
Q

what can be concluded from the fact that there is more protein than there is protein-coding genes?

A
  • each gene must code for several proteins
  • the norm is not one gene, one protein
66
Q

what is the genome percentage that humans share with chimpanzee and rhesus macaque?

A

95% and 91% respectively

67
Q

what is the genome percentage that eukaryotic and prokaryotic cells share?

A

21% (functions necessary for life/ cell components)

68
Q

what is the genome percentage that different eukaryotic cells share?

A

32% (multicellularity/ development)

69
Q

what is the genome percentage that vertebrates and animals share?

A

24% (immune system)

70
Q

what is the genome percentage that different vertebrates share?

A

22% (nervous system)

71
Q

what is the benefits of pharmacogenomics?

A
  • makes it possible to predict whether a drug will be effective
  • personalised drugs
72
Q

what is a totipotent cell and where can it be found?

A

cells that can differentiate to all type of cells
plant cells

73
Q

what property does the embryonic cells have that allow it to differentiate cells?

A

totipotency

74
Q

what gives the animal eggs their totipotent property?

A

cytoplasmic environment

75
Q

how was the dolly sheep cloning done?

A
  • starved somatic cell trapped in cell cycle
  • fused with enucleated egg
  • cytoplasmic signal stimulate the cell to enter S phase
  • resulting embryo transplanted into the womb
76
Q

what is pharming?

A

production of pharmaceutical in farm animals and plants

77
Q

what is a transgenic animal?

A

animal with inserted gene that encode desired protein (e.g. human growth hormone gene inserted in cows to produce large quantities of the hormone in the cow’s milk)

78
Q

how does pharming used to improve nutritional characteristic of rice?

A

genes that encode an enzyme that synthesise B-carotene from daffodils inserted in rice cells

79
Q

what is a multipotent cell?

A

cell that can differentiate into few cell types (stem cells)

80
Q

where can pluripotent cells be found?

A

blastocysts embryonic stage

81
Q

what property does a pluripotent cell have?

A

form all type of cells

82
Q

how can ESCs be induced to differentiate into specific cell type?

A

by treating it with specific nutrients or growth factors

Medical sciences (5 decks)

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