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bot grade 12 > Molecular basis > Flashcards

Molecular basis Flashcards

1
Q

Even tho the disc of —— by —- and —– by —- were almost at the same time, but that the —-acts as the genetic material took long to be —– and –

A

Nuclein- Meischer
Principle of inheritance- Mendel

DNA, discovered and proven

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2
Q

By —, the quest for determining the —— had reached the molecular level

A

1926
mechanism of genetic inheritance

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3
Q

previous dic by —,— and —- and numerous other scientists had narrowed the search to chromosomes located in —–
but, the q of what —– the genetic material had not been answered

A

Mendel, Sutton, Morgan
nucleus of MOST cells

molecule was actually

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4
Q

In —-, Frederick — in a series of exps with —– (bac responsible for —) witnessed miraculous — in the bac.
During the course of his exp, a living organism (bac) had —-

A

1928, Griffith
Streptococcus pneumoniae
pneumonia
transformation

changed in physical form

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5
Q

when streptococcus pneumoniae (—-) bacteria are grown on —-, some produce —- colonies (S) while others produce — colonies (R)

A

pneumococcus
culture plate
smooth, shiny
rough

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6
Q

S strain bac have a —– coat while R strain do not

A

mucous (polysaccharide)

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7
Q

Mice infected with S strain (—) — from pneumonia but mice infected with R strain —- pneumonia

A

virulent- die from
do not develop

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8
Q

Griffith was able to kill bac by

A

heating them

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9
Q

heat killed —- did not kill the mice, but a mixture of heat killed —- and —- killed the mice
moreover, griffith recovered —- from the dead mice

A

S strain
S strain and live R
living S bac

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10
Q

Griffith concluded that

A

R strain bac had somehow been transformed by the heat killed S strain bac

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11
Q

Some —– transferred from heat killed s strain had enabled r strain to —-

This must be due to the tranfer of —-. however the — nature of —- was not defined from his exp

A

transforming principle
synthesise a smooth polysaccharide coat and become virulent

genetic material
biochemical nature, genetic material

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12
Q

Prior to the work of —-, —-, —- (—–) the genetic material was thought to be —-
The worked to determine —— in griffiths exp

A

Oswald avery, Maclyn Mccarty, Colin Macleod
(1933-44)
protein

biochemical nature of transforming principle

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13
Q

They purified —- (—) from the heat killed S cells to see which ones could transform live R cells into S cells

A

biochemicals (proteins, dna, rna)

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14
Q

avery, mc cleoid, mc carty disc that — alone from s bac caused r bac to be transformed

A

dna

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15
Q

They also discovered that protein-digesting enzymes (—-) and
RNA-digesting enzymes (—-) did not affect —–, so the transforming substance was not a protein or RNA.

A

proteases, RNases
transformation

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16
Q

Digestion with DNase
did —- suggesting that the DNA caused the transformation.

A

inhibit transformation,

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17
Q

—- concluded that DNA is the hereditary material, but
not all biologists were convinced.

A

Mc cleois, mc carty, avery

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18
Q

At the time of Mendel, the nature of those ‘—–’ regulating the pattern of inheritance was not clear. Over the next —-, the nature of the —–
was investigated culminating in the realisation that DNA – deoxyribonucleic acid – is the genetic material, —-

A

factors, hundred years
putative genetic material
at least for the majority of organisms.

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19
Q

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are the two types of —- found in —-.

A

nucleic acids, living
systems

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20
Q

DNA acts as the —- in MOST of the organisms.

A

genetic material

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21
Q

RNA though it also acts as a genetic material in —-, mostly functions as a —-.

A

some viruses- messenger

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22
Q

RNA has additional roles as well. It functions as —, —- and in some cases as a — molecule.

A

adapter, structural, catalytic

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23
Q

The determination of complete nucleotide sequence of —- genome during—- has set in a new era of —-.

A

human
last decade, genomics

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24
Q

_____ is the most abundant genetic material

A

DNA

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25
Q

DNA is a — polymer of —.

A

long
deoxyribonucleotides

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26
Q

The length of DNA is usually defined as —- (or a —–) present in it.

A

number of nucleotides
pair of nucleotide referred
to as base pairs

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27
Q

—– is the characteristic of an organism.

A

No of Nts or bp

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28
Q

bacteriophage known as φ ×174 has —-
Bacteriophage lambda has —-, Escherichia coli has ———-
HAPLOID content of human DNA is

A

5386 nucleotides,
48502 base pairs (bp)
4.6 × 106 bp,
3.3 × 109 bp.

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29
Q

A nucleotide has three components – —-, —, —-.

A

a nitrogenous base, a pentose sugar and a phosphate group

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30
Q

Pentose sugar is

A

(ribose in case of RNA, and deoxyribose for DNA),

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31
Q

There are two types of nitrogenous bases – —-, —–

A

Purines (Adenine and Guanine), and Pyrimidines (Cytosine, Uracil and Thymine).

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32
Q

—- is common for both DNA and RNA and —- is present in
DNA.

A

Cytosine, Thymine

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33
Q

—- is present in RNA at the place of Thymine.

A

Uracil

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34
Q

A nitrogenous base is linked to the —- of —- pentose sugar through a —
linkage to form a —-, such as adenosine or deoxyadenosine,
guanosine or deoxyguanosine, cytidine or deoxycytidine and —- or —–

A

OH , 1’ C
N-glycosidic, nucleoside
uridine or deoxythymidine.

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35
Q

When a phosphate group is linked to OH of—of a nucleoside through — linkage, a corresponding nucleotide (or deoxynucleotide depending upon the type of sugar present) is formed.

A

5’ C , phosphoester

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36
Q

Two nucleotides are linked through —- linkage to form a dinucleotide.
More nucleotides can be joined in such a manner to form a polynucleotide chain.

A

3’-5’ phosphodiester

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37
Q

A polymer thus formed has at one end a free —- at 5’ -end of sugar, which is referred to as 5’-end of
polynucleotide chain.

A

phosphate moiety

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38
Q

Similarly, at the other end of the polymer the sugar has a free —- of 3’C group which is referred to as 3’ -end of the polynucleotide chain.

A

OH

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39
Q

The backbone of a polynucleotide chain is formed due to —-.

A

sugar and phosphates

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40
Q

The nitrogenous bases linked to sugar moiety project from —

A

the backbone

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41
Q

In RNA, every nucleotide residue has an additional —- present
at — -position in the ribose.

A

–OH group, 2

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42
Q

Also, in —- the uracil is found at the place of thymine

A

RNA

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43
Q

5-methyl —, another chemical name for —

A

uracil, thymine

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44
Q

DNA as an — substance present in nucleus was first identified by
—- in —-. He named it as ‘—-’

A

acidic
Friedrich Meischer in 1869
Nuclein

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45
Q

However, due to —- in — such a long polymer intact, the elucidation
of structure of DNA remained — for a very long period of time.

A

technical limitation, isolating
elusive

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46
Q

It was only in — that —- Watson and — Crick based on the — data produced by —, proposed a — but —- Double Helix model for the — of DNA.

A

1953, James Watson and Francis Crick, X-ray diffraction
Maurice Wilkins and Rosalind Franklin
very simple but famous, structure

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47
Q

One of the hallmarks of Double helix proposition was — between
the —-.
However, this proposition was
also based on the observation of — that for a —, the ratios between Adenine and Thymine and Guanine and Cytosine are — and —

A

base pairing, two strands of polynucleotide chains
Erwin Chargaff, double stranded
DNA
constant and equals one.

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48
Q

The —- confers a very unique property to the polynucleotide
chains.

A

base pairing

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49
Q

They are said to be — to each other, and therefore if the sequence of bases in one strand is known then the sequence in other
strand can be predicted.

A

complementary

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50
Q

Also, if each strand from a DNA (let us call it as a —) acts as a — for synthesis of a new strand, the two
double stranded DNA (let us call them as —-) thus, produced
would be identical to the parental DNA molecule.
Because of this, the —- of the structure of DNA became very clear.

A

parental DNA, template
daughter DNA

genetic implications

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51
Q

The salient features of the Double-helix structure of DNA are as follows:
(i) It is made of —–, where the — is constituted by sugar-phosphate, and the bases —-

A

two polynucleotide chains
backbone, project inside.

52
Q

(ii) The two chains have —- polarity. It means, if one chain has the polarity 5’à3’, the other has 3’à5’.

A

anti-parallel

53
Q

(iii) The bases in two strands are paired through —- forming base pairs (bp).

A

hydrogen bond (H-bonds)

54
Q

Adenine forms —- hydrogen
bonds with Thymine from opposite strand and vice-versa.

A

two

55
Q

Similarly, Guanine is bonded with Cytosine with —- H-bonds.

A

three

56
Q

As a result, always a — come opposite to —-. This generates approximately —- between the two
strands of the helix

A

purine comes opposite to a pyrimidine
uniform distance

57
Q

(iv) The two chains are coiled in a —-fashion.

A

right-handed

58
Q

The pitch of the helix is — (a nanometre is one billionth of a
metre, that is 10-9 m) and there are roughly —- in each turn.

A

3.4 nm, 10 bp

59
Q

Consequently, the distance
between a bp in a helix is
approximately —-

A

0.34 nm.

60
Q

(v) The —– in double helix. This, in addition to — confers
—-of the helical structure

A

The plane of one base pair stacks over the other
H-bonds, stability

61
Q

The proposition of a —- for DNA and its — became revolutionary.

A

double helix structure
simplicity in explaining the genetic implication

62
Q

Very soon, —- proposed the —- which states that the GENETIC
INFORMATION flows from DNA–>RNA—–>Protein.

A

Francis Crick, Central dogma in molecular biology,

63
Q

In some — the flow of information is in reverse direction, that is, from —
Process ==

A

viruses, RNA to DNA
reverse transcription

64
Q

Taken the distance between two consecutive base pairs as —, if the length of DNA double helix in a typical —- cell is calculated (simply
by multiplying the —- by —–, that is, ), it comes out to be approximately
—-.

A

0.34 nm , mammalian
total number of bp with distance
between two consecutive bp:
6.6 × 109 bp × 0.34 × 10-9m/bp
2.2 metres

65
Q

A length of DNA that is far greater than the dimension of a typical nucleus (approximately —).
How is such a long polymer packaged in a cell?

A

10–6 m

66
Q

In prokaryotes, such as,—- though they do not have a —-, the DNA is — throughout the cell.

A

E. coli, defined nucleus
not scattered

67
Q

DNA (being —- charged)
is held with some —- (that have — charges) in a region termed as ‘—’, in pro

A

negatively, proteins
positive
nucleoid

68
Q

The DNA in nucleoid is organised in — held by —-

A

large loops, proteins

69
Q

In eukaryotes, this — of DNA much more complex.

A

organisation

70
Q

In eu- There is a set of positively charged, —proteins called —–

A

basic
histones

71
Q

A protein acquires charge
depending upon the abundance of —–

A

amino acids residues with charged side chains.

72
Q

Histones are rich in the basic amino acid residues—, —–
Both the amino acid residues carry positive charges in their—-

A

lysine and arginine.
side chains.

73
Q

Histones are organised to form
a unit of —- called —–

A

eight molecules
histone octamer.

74
Q

The negatively charged DNA is wrapped around the positively charged histone octamer to form a structure called —-

A

nucleosome

75
Q

A typical nucleosome contains— of DNA helix.

A

200 bp

76
Q

Nucleosomes constitute the repeating unit of a structure in nucleus called —

A

chromatin

77
Q

Chromation are —– bodies seen in nucleus.

A

threadlike stained (coloured)

78
Q

The nucleosomes in chromatin are seen as —- structure when viewed under—-

A

‘beads-on-string’
electron microscope (EM)

79
Q

The beads-on-string structure in chromatin is packaged to form
—- that are further coiled and condensed at —- of cell division to form —-.

A

chromatin fibers, metaphase stage
chromosomes

80
Q

The packaging of chromatin at higher level requires additional set of — that collectively are referred to as —–

A

proteins, Non-histone Chromosomal (NHC) proteins

81
Q

In a typical nucleus, some
region of chromatin are loosely packed (and stains —-) and are referred to as — .

A

light, euchromatin

82
Q

The chromatin that is more densely packed and stains
— are called as —-.

A

dark, Heterochromatin

83
Q

Euchromatin is said to be —- chromatin, whereas heterochromatin is —-.

A

transcriptionally active
inactive

84
Q

The unequivocal proof that DNA is the genetic material came from the
experiments of —- (—).

A

Alfred Hershey and Martha Chase (1952)

85
Q

Alfred Hershey and Martha Chase worked with viruses that infect bacteria called —–.

A

bacteriophages

86
Q

The bacteriophage attaches to the bacteria and its — then enters the bacterial cell.

A

genetic material

87
Q

The bacterial cell treats the —- as if it was its own and subsequently manufactures —-

A

viral genetic material
more virus particles.

88
Q

Hershey and Chase worked to discover whether it was —- from the viruses that entered the bacteria.

A

protein or DNA

89
Q

They grew some viruses on a medium that contained radioactive
phosphorus (—) and some others on medium that contained radioactive sulfur (—).

A

P 32
S 35

90
Q

Viruses grown in the presence of radioactive phosphorus contained
radioactive —- but not radioactive — because DNA contains phosphorus but protein does not.

A

DNA,protein

91
Q

Similarly, viruses grown on radioactive — contained radioactive protein but not radioactive DNA because
DNA does not contain sulfur

A

sulfur

92
Q

Radioactive phages were allowed to attach to —-

A

E. coli bacteria.

93
Q

Then, as the infection proceeded, the —- were removed from the bacteria by — them in a blender.

A

viral coats, agitating

94
Q

The virus particles were separated from the bacteria by —-

A

spinning them in a centrifuge.

95
Q

Bacteria which was infected with viruses that had —- were radioactive, indicating that DNA was the material that passed from
the virus to the bacteria.

A

radioactive DNA

96
Q

Bacteria that were infected with viruses that had radioactive proteins were not radioactive. This indicates that—-.

A

proteins did not enter the bacteria from the viruses

97
Q

DNA is therefore the genetic material that is passed from — to —-

A

virus to bacteria

98
Q

Radioactive S 35 is detected in

A

Supernatant

99
Q

From the foregoing discussion, it is clear that the debate between proteins versus DNA as the genetic material was — resolved from Hershey-Chase experiment.

A

unequivocally

100
Q

It became an established fact that it is — that acts as genetic material. However, it subsequently became clear that in some —, is the genetic material

A

DNA
viruses, RNA

101
Q

RNA is the genetic material for

A

Tobacco Mosaic viruses, QB bacteriophage

102
Q

Answer to some of the questions such as, why DNA is the — genetic material, whereas RNA performs
— functions of —- has to be found from the differences between chemical structures of the two nucleic acid molecules.-

A

predominant , dynamic
messenger and adapter
chemical structures

103
Q

A molecule that can act as a genetic material must fulfill the following
criteria:
(i) It should be able to generate —-
(ii) It should be stable —-
(iii) It should provide the scope for — that are required for evolution.
(iv) It should be able to express itself in the form of—-

A

its replica (Replication).
chemically and structurally.
slow changes (mutation)
‘Mendelian
Characters’.

104
Q

If one examines each requirement one by one, because of rule of —-, both the nucleic acids (DNA and RNA) have the ability to direct their duplications.

A

base
pairing and complementarity

105
Q

The other molecules in the living
system, such as — fail to fulfill first criteria itself (–).

A

proteins- duplication

106
Q

The genetic material should be stable enough not to change with
—, — or —-.

A

different stages of life cycle, age or change in physiological of the org

107
Q

Stability as one of the properties of genetic material was very
evident in —-

A

Griffith’s ‘transforming principle’

108
Q

In Griffiths exp- heat, which killed
the — , at least did not destroy —
This now can easily be explained in light of the DNA that the two strands being —if separated by heating come together, when —- are provided.

A

bacteria, some of the properties of genetic material.
complementary , appropriate conditions

109
Q

Further, —– present at every nucleotide in RNA is a — group and makes RNA — and —

A

2’-OH group, reactive
labile and easily degradable

110
Q

RNA is also now known to be —, hence reactive.

A

catalytic

111
Q

Therefore, DNA — is less reactive and —- more stable when compared to RNA.

A

chemically, structurally

112
Q

Therefore, among the two nucleic acids, the DNA is a —-

A

better genetic material.

113
Q

In fact, the presence of thymine at the place of uracil also confers
— to DNA.
(Detailed discussion about this requires understanding of the process of —– in DNA)

A

additional stability
repair

114
Q

Both DNA and RNA are able to mutate. In fact, RNA being —-,
mutate at a — rate.

A

unstable, faster

115
Q

Consequently, viruses having —genome and having —- mutate and evolve faster.

A

RNA, shorter life span

116
Q

RNA can directly code for the —-, hence can easily express the characters.

A

synthesis of proteins

117
Q

DNA, however, is dependent on RNA for —-.

A

synthesis of proteins

118
Q

The —- has evolved around RNA.

A

protein synthesising machinery

119
Q

The above discussion indicate that both RNA and DNA can function as genetic material, but DNA being more stable is preferred for—-. For the —-, RNA is better

A

storage of genetic information
transmission of genetic information

120
Q

From foregoing discussion, an immediate question becomes evident – which is the first genetic material?

A

RNA was the first genetic material.

121
Q

There is now enough evidence to
suggest that essential life processes (such as —, —, —–, etc.), evolved around RNA.

A

metabolism, translation,
splicing

122
Q

RNA used to act as a — and —-

A

genetic material as well as a catalyst

123
Q

There are some important — in living systems that are catalysed by RNA catalysts and not by protein
enzymes.

A

biochemical reactions

124
Q

But, RNA being a catalyst was reactive and hence —-.
Therefore, DNA has evolved from RNA with —- that make it more stable.

A

unstable, chemical modifications

125
Q

DNA being double stranded and having —- further resists changes by evolving a process of —-.

A

complementary strand
repair

126
Q
A

bot grade 12 (5 decks)

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