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Biology NEET 2023 > XII: Chapter 6- Molecular basis of inheritance > Flashcards

XII: Chapter 6- Molecular basis of inheritance Flashcards

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1
Q

What is the haploid content of human DNA?

A

3.3 x 10^9 bp

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2
Q

What type of chemical compound is deoxyguanosine?

A

Nucleoside

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3
Q

What type of chemical compound in deoxycytidine?

A

Nucleoside

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4
Q

What type of chemical compound is uridine?

A

Nucleoside

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5
Q

DNA was first identified by

A

Friedrich Meischer

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6
Q

When was DNA first identified?

A

1869

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7
Q

What did Friedrich Meischer name DNA?

A

Nuclein

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8
Q

How is uniform distance maintained between the two strands of DNA?

A

A purine always pairs with a pyrimidine, which maintains a uniform distance between them.

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9
Q

In which direction are the two chains of DNA coiled?

A

RIght handed

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10
Q

Histones are rich in which amino acids?

A

Lysine and arginine

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11
Q

What is the length of DNA wrapped around a histone octamer?

A

200 bp

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12
Q

While working with which bacteria did Griffith give his transforming principle?

A

Streptococcus pneumoniae

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13
Q

Why do the S strain Streptococcus pneumoniae produce smooth and shiny colonies?

A

Because they have a mucous (polysaccharide) coating

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14
Q

Which scientists described the biochemical nature of Griffith’s transforming principle?

A

Avery, MacLeod and McCarty

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15
Q

The unequivocal proof that DNA is the genetic material came from

A

Hershey-Chase experiments

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16
Q

Which scientists proved that DNA replicates semi-conservatively?

A

Meselson and Stahl

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17
Q

How could the heavy DNA in Meselson Stahl experiment be distinguished from normal DNA?

A

By centrifugation in a cesium chloride density gradient

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18
Q

Which experiment was performed by Taylor et al to prove the semiconservative nature of DNA?

A

Radioactive thymidine was used to detect distribution of newly synthesised DNA in the chromosomes of Vicia faba

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19
Q

Which phosphates of deoxynucleoside triphosphates are high energy phosphates?

A

Two terminal phosphates

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20
Q

In which direction can DNA dependent DNA polymerase catalyse polymerisation?

A

5’ -> 3’

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21
Q

Which strand of DNA is known as the template strand?

A

strand with 3’ -> 5’ polarity

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22
Q

Which strand of DNA is known as the coding strand?

A

strand with 5’ -> 3’ polarity

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23
Q

Towards which ends of DNA are promoter and terminator flanked?

A 
Promoter= 5' end of coding strand
Terminator= 3' end of coding strand
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24
Q

What is a segment of DNA which codes for a polypeptide called?

A

Cistron

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25
Q

Monocistronic genes are found in

A

Eukaryotes

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26
Q

Polycistronic genes are found in

A

Prokaryotes

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27
Q

How many DNA dependent RNA polymerase catalyse the transcription of RNA in bacteria?

A

one

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28
Q

How many DNA dependent RNA polymerase catalyse the transcription of RNA in eukaryotes?

A

At least 3

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29
Q

RNA polymerase I polymerises the transcription of

A

rRNAs (28s, 18s, 5.8s)

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30
Q

RNA polymerase III polymerises the transcription of

A

tRNA, 5s rRNA and snRNAs

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31
Q

RNA polymerase II polymerises the transcription of

A

hnRNA (precursor of mRNA)

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32
Q

In capping, which molecule is added to the hnRNA? Towards which end of RNA is it added?

A

Methyl guanosine triphosphosphate, 5’ end

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33
Q

In tailing what is added to the hnRNA?. Towards which end of RNA is it added?

A

Adenylate residues (200-300), 3’ end

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34
Q

Which physicist suggested that in order to code for 20 amino acids, the code should be made of 3 nucleotides?

A

George Gamow

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35
Q

Which scientist developed the cell free system using which the genetic code was deciphered?

A

Marshall Nirenberg

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36
Q

What is Severo Ochoa enzyme?

A

Polynucleotide phosphorylase

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37
Q

The genetic code is nearly universal, exception to this are

A

mitochondrial codons, some protozoans

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38
Q

Three stop codons exist in the genetic code. How many tRNA exist for these stop codons?

A

Zero

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39
Q

Which letter does the tRNA resemble?

A

Inverted L

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40
Q

What happens in the first phase of translation?

A

Amino acids are activated in the presence of ATP and linked to the cognate tRNA

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41
Q

Charging of tRNA is also known as

A

Aminoacylation of tRNA

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42
Q

Which unit of ribosome encounters mRNA?

A

Smaller subunit

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43
Q

How many sites are present in the larger subunit of ribosome for the amino acids to bind to?

A

2

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44
Q

A transational unit in mRNA codes for

A

Polypeptide

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45
Q

The untranslated regions in mRNA have no function. True/false?

A

False. The UTRs are required for efficient translation process.

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46
Q

WHat binds to stop codon for terminalisation of translation?

A

Release factor

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47
Q

Which is the predominant site for regulation of gene expression in prokaryotes?

A

Control of the rate of transcriptional initiation

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48
Q

What regulate the ability of RNA polymerase to recognise start sites for transcription?

A

Accessory proteins

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49
Q

Which scientists elucidated the lac operon?

A

Monod and Jacob

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50
Q

Does the lac operon have a polycistronic or a monoscistronic structural gene?

A

Polycistronic structural gene

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51
Q

In the i gene of lac operon, ‘i’ refers to

A

Inhibitor

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52
Q

Which protein does the z gene of lac operon code for? What is its function?

A

z gene codes for β-galactosidase which hydrolyses lactose to form galactose and glucose.

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53
Q

Which protein does the y gene of lac operon code for? What is its function?

A

y gene codes for permease which increases permeability of the cell to β-galactosidase.

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54
Q

Which protein does the a-gene of lac operon code for?

A

a-gene codes for transacetylase.

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55
Q

The human genome project was closely associated with the rapid development of a new area in biology called

A

Bioinformatics

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56
Q

How many genes are present in Human DNA?

A

30,000

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57
Q

Expand ELSI.

A

Ethical, legal and social issues (implications)

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58
Q

How long did the Human Genome Project take?

A

13 years

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59
Q

Name a free living non pathogenic nematode whose complete DNA has been sequenced?

A

Caenorhabditis elegans

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60
Q

Which plants were completely sequenced in the Human Genome Project?

A

Arabidopsis and rice

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61
Q

What are expressed sequence tags?

A

Expressed sequence tags (ESTs) are fragments of mRNA sequences

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62
Q

What was the sequence annotation method used in human genome project?

A

Sequencing the whole set of genome and then assigning different regions in the sequence with functions.

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63
Q

Which were the commonly used hosts and vectors in human genome project?

A

The commonly used hosts were bacteria and yeast and the vectors were called as bacterial artificial chromosomes (BAC) and yeast artificial chromosomes (YAC).

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64
Q

DNA sequencers used in human genome project worked on the principle of a method developed by

A

Frederick Sanger

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65
Q

WHo developed the method for determination of amino acid sequences in proteins?

A

Frederick Sanger.

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66
Q

Which was the last chromosome to be completely sequenced? When was it completely sequenced?

A

Chromosome 1, 2006

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67
Q

How were genetic and physical maps on the genome developed?

A

Using the information of polymorphism of restriction endonuclease recognition sites and some repetitive DNA sequences known as microsatellites.

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68
Q

How many bases are present in the average gene?

A

3000 bases

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69
Q

Which is the largest gene? How many base pairs does it have?

A

Dystrophin, 2.4 million bases

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70
Q

What percent of the genome codes for proteins?

A

< 2%

71
Q

Which chromosomes have the maximum and the minimum number of genes? How many genes are present on them?

A

Max- chromosome 1, 2968

Min- chromosome y- 231

72
Q

How many locations have been identified by scientists where single base DNA differences occur?

A

1.4 million

73
Q

The bulk genomic DNA form a __1___ peak while the satellite DNA form the __2___ peak.
1 and 2 refer to

A

1- major

2-minor

74
Q

DNA can be classified into many categories such as mini satellite, micro satellite,etc based on

A

Base composition (A:T rich or G:C rich)
Length segment
Number of repetitive segments

75
Q

Allelic sequence variations have been described as DNA polymorphism if more than one variant at a locus occurs in human population with a frequency

A

> 0.01%

76
Q

Who developed the technique of DNA fingerprinting?

A

Alec Jeffreys

77
Q

Alec Jeffreys initially developed the technique of DNA fingerprinting using a satellite DNA that shows a very high degree of polymorphism, as a probe which was called

A

Variable Number of Tandem Repeats

78
Q

Which blotting technique is used in DNA fingerprinting?

A

Southern blot

79
Q

VNTR belongs to a class of satellite DNA referred to as

A

Mini satellite

80
Q

The size of VNTR varies from

A

0.1 to 20 kb

81
Q

What is base ratio?

A

G+C

82
Q

Base ratio in organisms of the same species can vary. True/False.

A

False. Base ratio is constant for any species

83
Q

What is the base ratio for humans?

A

1.55

84
Q

WHat are the non histone proteins found in prkaryotes which bind DNA called?

A

Polyamines

85
Q

Which has more DNA content as compared to RNA content- heterochromatin or euchromatin?

A

euchromatin

86
Q

What is the base ratio of eukaryotes?

A

> 1

87
Q

What is the base ratio of prokaryotes?

A

<1

88
Q

80% of all RNAs are

A

rRNAs

89
Q

5% of all RNAs are

A

mRNAs

90
Q

15% of all RNAs are

A

tRNAs

91
Q

Which are the smallest RNAs?

A

tRNAs

92
Q

Which are the longest RNAs?

A

mRNAs

93
Q

rRNAs are synthesised in

A

Nucleolus

94
Q

mRNAs are synthesised in

A

Nucleoplasm

95
Q

tRNAs are synthesised in

A

Nucleoplasm

96
Q

Which type of RNA is the most stable?

A

rRNA

97
Q

Which type of RNA is the least stable?

A

mRNA

98
Q

Insoluble RNA is also known as

A

rRNA

99
Q

Soluble RNA is also known as

A

tRNA

100
Q

What do the P site, A site and E site in ribosome stand for?

A

Peptidyl site
Aminoacyl site
Exit site

101
Q

How many loops does the clover leaf model of tRNA have?

A

3

102
Q

How many arms does the clover leaf model of tRNA have?

A

5

103
Q

Which is the largest loop of clover leaf model of tRNA?

A

DHU loop

104
Q

What is the function of DHU loop of clover leaf model of tRNA?

A

Binding aminoacyl tRNA synthetase

105
Q

How many N-bases are present in DHU loop of clover leaf model of tRNA?

A

8to 10

106
Q

How many N-bases are present in TΨC loop of clover leaf model of tRNA?

A

7 N bases

107
Q

WHat is the function of TΨC loop of clover leaf model of tRNA?

A

Helps in binding two ribosomal subunits during photosynthesis

108
Q

Is the short variable arm present in all tRNA?

A

No

109
Q

Where is the CCA sequence present in tRNA?

A

On amino acid attachment site’s 3’ end.

110
Q

WHere does the amino acid bind in tRNA?

A

The amino acid loaded onto the tRNA by aminoacyl tRNA synthetases, to form aminoacyl-tRNA, is covalently bonded to the 3’-hydroxyl group on the CCA tail.

111
Q

If recombination occurs in a cistron it is called

A

Recon

112
Q

If mutation occus in a cistron it is called

A

Muton

113
Q

Double stranded RNA is found in which viruses?

A

Reovirus, wound tumour virus

114
Q

What is the function of small nuclear RNA?

A

Splicing

115
Q

How many ori do prokaryotes have?

A

One

116
Q

Eukaryotes have many ori in their DNA. True/false?

A

True

117
Q

Which enzyme opens the DNA to form a replication fork?

A

Helicase

118
Q

What prevent the replication fork of DNA from closing?

A

Single stranded binding proteins

119
Q

Which enzyme is called DNA gyrase in prokaryotes?

A

Topoisomerase

120
Q

Which enzyme removes the coiling tension created by Helicase enzyme in DNA?

A

Topoisomerase

121
Q

What is the function of RNA primase in DNA replication?

A

It synthesises a small stretch of RNA at the free 3’ end of the DNA strand

122
Q

What happens to the RNA primer synthesised by RNA primase during DNA replication?

A

It is converted into DNA by DNA polymerase II

123
Q

Which DNA polymerase synthesises the new DNA strand in 5’ to 3’ direction?

A

DNA polymerase III

124
Q

Which are the major and minor repair enzymes in DNA replication?

A

DNA Polymerase III

DNA polymerase II

125
Q

What are the fragments of DNA formed during DNA replication from lagging strand called?

A

Okazaki fragments

126
Q

What is the core subunit of RNA polymerase made of?

A

two alpha (2α), one beta (β), one beta prime (β’) and one omega (ω)

127
Q

What is TATA box?

A

Sequence that is recognised by sigma factor (σ) during transcirption of DNA.

128
Q

What is the TATA box called in eukaryotes? WHat is its sequence?

A

Hogness box

TATAAAA…

129
Q

What is the homologue of TATA box in prokaryotes? What is its sequence?

A

Pribnow box

TATAAT…

130
Q

What is the size of TATA box?

A

10bp to 30 bp

131
Q

What is the size of CAT box?

A

40 bp to 70 bp

132
Q

What is CAT box?

A

Sequence that is recognised by sigma factor (σ) during transcirption of DNA.

133
Q

When RNA polymerase binds on the promoter region, DNA helix unwinds. The opened stretch of DNA is called

A

Transcription bubble

134
Q

Which is the sense strand of DNA?

A

The strand running in 5’ -> 3’ direction

135
Q

Where is mRNA modified post-transcriptionally?

A

Nucleoplasm

136
Q

Which was the first discovered codon?

A

UUU- phenylalanine

137
Q

The codon UUC codes for

A

Phenylalanine

138
Q

The codon CCC codes for

A

Proline

139
Q

The codon AAA codes for

A

Lysine

140
Q

The codon GGG codes for

A

Glycine

141
Q

The codon CUC codes for

A

Leucine

142
Q

The codon UGG codes for

A

Tryptophan

143
Q

Which amino acids are not degenerate in reference to the genetic code?

A

Tryptophan and methionin

144
Q

In yeast, UGA codes for

A

Tryptophan

145
Q

In the human mitochondria, which is the stop codon?

A

AGA and AGG

146
Q

What is transversion (point mutation)?

A

A purine base is replaced by a pyrimidine base and vie versa

147
Q

What is transition (point mutation)?

A

A purine base is replaced by another purine.
OR
A pyrimidine base is replaced by another pyrimidine base.

148
Q

How do UV rays cause mutations in genetic code?

A

Affects DNA by forming thymine dimers

149
Q

How do X rays cause mutations?

A

Deaminating, dehydroxylase nitrogenous bases forming peroxides and oxidise deoxyribose

150
Q

What is the wobble hypothesis? Who proposed it?

A

According to the wobble hypothesis, an amino acid is identified by the first two nitrogenous bases, and the third nitrogenous base of a codon is a wobble. It was proposed by Francis Crick.

151
Q

How many initiation factors are required in prokaryotes and eukaryotes for the initiation of translation?

A

Prokaryotes-3

Eukaryotes- 9

152
Q

What is called translation initiation complex?

A

rRNA-tRNA-mRNA complex

153
Q

Which enzymes link amino acids to their corresponding tRNA molecules?

A

Aminoacyl-tRNA synthetases

154
Q

What are the functions of P site and A site of ribosome?

A

the P site holds the peptide chain and the A site accepts the tRNA.

155
Q

During elongation of peptide chain in translation, which molecule is hydrolysed for energy?

A

GTP

156
Q

During the charging of tRNA which molecule is hydrolysed as a source of energy?

A

ATP

157
Q

How many release factors (for translation) are present in prokaryotes and eukaryotes?

A

Prokaryotes- 2

Eukaryotes- 1

158
Q

What is an inducible operon?

A

Substrate has to be added to carry out protein synthesis

159
Q

What is a repressible operon?

A

In such operon, the substrate is added to stop the protein synthesis.

160
Q

The regulatory gene in inducible and repressible operons are represented by

A

Inducible- i

Repressible- r

161
Q

What is the example of repressible operon?

A

Tryp-operon

162
Q

What is the function of transacetylase enzyme?

A

Transfer acetyl group to β-galactosidase

163
Q

What is an aporepressor in reference to an operon?

A

It is a protein molecule that is synthesised by the regulatory gene which may bind to the operator and prevent the transcription.

164
Q

What is a corepressor in reference to an operon?

A

Non-protein part that attaches to the repressor protein, activates it and stimulates it to bind to the operator region to prevent transcription.

165
Q

Southern blotting is used for blotting which molecule?

A

DNA

166
Q

Northern blotting is used for blotting which molecule?

A

RNA

167
Q

Western blotting is used for blotting which molecule?

A

Proteins

168
Q

Eastern blotting is used for blotting which molecule?

A

There is nothing like eastern blotting (Different types of blotting include- Northern, Southern and Western blotting)

169
Q

What is the principle of DNA fingerprinting?

A

RFLP- restriction fragment length polymorphisim

170
Q

What is the length of minisatellite (in DNA)?

A

11-60 bp repeating upto 100 times

171
Q

What is the length of microsatellite (in DNA)?

A

5-6 bp repeating upto 10 - 100 times

172
Q

What is the science of matching the prints of fingers, thumbs, toes and skin called?

A

Dermatoglyphics

173
Q

Which is the smallest gene in human genome?

A

Testis determining factor on Y-chromosome

Biology NEET 2023 (39 decks)

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