Biology NEET - XII: Chapter 6- Molecular Basis of Inheritance Part 1
The haploid content of human DNA is approximately 3.3 × 10⁹ base pairs (bp). This represents the amount of genetic material present in a single set of human chromosomes, which is inherited from one parent and contains the complete blueprint for building and maintaining the human body.
What is the haploid content of human DNA?
3.3 x 10^9 bp
Key Terms
What is the haploid content of human DNA?
3.3 x 10^9 bp
What type of chemical compound is deoxyguanosine?
Nucleoside
What type of chemical compound in deoxycytidine?
Nucleoside
What type of chemical compound is uridine?
Nucleoside
DNA was first identified by
Friedrich Meischer
When was DNA first identified?
1869
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| Term | Definition |
|---|---|
What is the haploid content of human DNA? | 3.3 x 10^9 bp |
What type of chemical compound is deoxyguanosine? | Nucleoside |
What type of chemical compound in deoxycytidine? | Nucleoside |
What type of chemical compound is uridine? | Nucleoside |
DNA was first identified by | Friedrich Meischer |
When was DNA first identified? | 1869 |
What did Friedrich Meischer name DNA? | Nuclein |
How is uniform distance maintained between the two strands of DNA? | A purine always pairs with a pyrimidine, which maintains a uniform distance between them. |
In which direction are the two chains of DNA coiled? | RIght handed |
Histones are rich in which amino acids? | Lysine and arginine |
What is the length of DNA wrapped around a histone octamer? | 200 bp |
While working with which bacteria did Griffith give his transforming principle? | Streptococcus pneumoniae |
Why do the S strain Streptococcus pneumoniae produce smooth and shiny colonies? | Because they have a mucous (polysaccharide) coating |
Which scientists described the biochemical nature of Griffith’s transforming principle? | Avery, MacLeod and McCarty |
The unequivocal proof that DNA is the genetic material came from | Hershey-Chase experiments |
Which scientists proved that DNA replicates semi-conservatively? | Meselson and Stahl |
How could the heavy DNA in Meselson Stahl experiment be distinguished from normal DNA? | By centrifugation in a cesium chloride density gradient |
Which experiment was performed by Taylor et al to prove the semiconservative nature of DNA? | Radioactive thymidine was used to detect distribution of newly synthesised DNA in the chromosomes of Vicia faba |
Which phosphates of deoxynucleoside triphosphates are high energy phosphates? | Two terminal phosphates |
In which direction can DNA dependent DNA polymerase catalyse polymerisation? | 5’ -> 3’ |
Which strand of DNA is known as the template strand? | strand with 3’ -> 5’ polarity |
Which strand of DNA is known as the coding strand? | strand with 5’ -> 3’ polarity |
Towards which ends of DNA are promoter and terminator flanked? | Promoter= 5' end of coding strand Terminator= 3' end of coding strand |
What is a segment of DNA which codes for a polypeptide called? | Cistron |
Monocistronic genes are found in | Eukaryotes |
Polycistronic genes are found in | Prokaryotes |
How many DNA dependent RNA polymerase catalyse the transcription of RNA in bacteria? | one |
How many DNA dependent RNA polymerase catalyse the transcription of RNA in eukaryotes? | At least 3 |
RNA polymerase I polymerises the transcription of | rRNAs (28s, 18s, 5.8s) |
RNA polymerase III polymerises the transcription of | tRNA, 5s rRNA and snRNAs |
RNA polymerase II polymerises the transcription of | hnRNA (precursor of mRNA) |
In capping, which molecule is added to the hnRNA? Towards which end of RNA is it added? | Methyl guanosine triphosphosphate, 5' end |
In tailing what is added to the hnRNA?. Towards which end of RNA is it added? | Adenylate residues (200-300), 3' end |
Which physicist suggested that in order to code for 20 amino acids, the code should be made of 3 nucleotides? | George Gamow |
Which scientist developed the cell free system using which the genetic code was deciphered? | Marshall Nirenberg |
What is Severo Ochoa enzyme? | Polynucleotide phosphorylase |
The genetic code is nearly universal, exception to this are | mitochondrial codons, some protozoans |
Three stop codons exist in the genetic code. How many tRNA exist for these stop codons? | Zero |
Which letter does the tRNA resemble? | Inverted L |
What happens in the first phase of translation? | Amino acids are activated in the presence of ATP and linked to the cognate tRNA |
Charging of tRNA is also known as | Aminoacylation of tRNA |
Which unit of ribosome encounters mRNA? | Smaller subunit |
How many sites are present in the larger subunit of ribosome for the amino acids to bind to? | 2 |
A transational unit in mRNA codes for | Polypeptide |
The untranslated regions in mRNA have no function. True/false? | False. The UTRs are required for efficient translation process. |
WHat binds to stop codon for terminalisation of translation? | Release factor |
Which is the predominant site for regulation of gene expression in prokaryotes? | Control of the rate of transcriptional initiation |
What regulate the ability of RNA polymerase to recognise start sites for transcription? | Accessory proteins |
Which scientists elucidated the lac operon? | Monod and Jacob |
Does the lac operon have a polycistronic or a monoscistronic structural gene? | Polycistronic structural gene |
In the i gene of lac operon, 'i' refers to | Inhibitor |
Which protein does the z gene of lac operon code for? What is its function? | z gene codes for β-galactosidase which hydrolyses lactose to form galactose and glucose. |
Which protein does the y gene of lac operon code for? What is its function? | y gene codes for permease which increases permeability of the cell to β-galactosidase. |
Which protein does the a-gene of lac operon code for? | a-gene codes for transacetylase. |
The human genome project was closely associated with the rapid development of a new area in biology called | Bioinformatics |
How many genes are present in Human DNA? | 30,000 |
Expand ELSI. | Ethical, legal and social issues (implications) |
How long did the Human Genome Project take? | 13 years |
Name a free living non pathogenic nematode whose complete DNA has been sequenced? | Caenorhabditis elegans |
Which plants were completely sequenced in the Human Genome Project? | Arabidopsis and rice |
What are expressed sequence tags? | Expressed sequence tags (ESTs) are fragments of mRNA sequences |
What was the sequence annotation method used in human genome project? | Sequencing the whole set of genome and then assigning different regions in the sequence with functions. |
Which were the commonly used hosts and vectors in human genome project? | The commonly used hosts were bacteria and yeast and the vectors were called as bacterial artificial chromosomes (BAC) and yeast artificial chromosomes (YAC). |
DNA sequencers used in human genome project worked on the principle of a method developed by | Frederick Sanger |
WHo developed the method for determination of amino acid sequences in proteins? | Frederick Sanger. |
Which was the last chromosome to be completely sequenced? When was it completely sequenced? | Chromosome 1, 2006 |
How were genetic and physical maps on the genome developed? | Using the information of polymorphism of restriction endonuclease recognition sites and some repetitive DNA sequences known as microsatellites. |
How many bases are present in the average gene? | 3000 bases |
Which is the largest gene? How many base pairs does it have? | Dystrophin, 2.4 million bases |
What percent of the genome codes for proteins? | < 2% |
Which chromosomes have the maximum and the minimum number of genes? How many genes are present on them? | Max- chromosome 1, 2968 | Min- chromosome y- 231 |
How many locations have been identified by scientists where single base DNA differences occur? | 1.4 million |
The bulk genomic DNA form a 1_ peak while the satellite DNA form the 2_ peak. | 1- major | 2-minor |
DNA can be classified into many categories such as mini satellite, micro satellite,etc based on | Base composition (A:T rich or G:C rich) Length segment Number of repetitive segments |
Allelic sequence variations have been described as DNA polymorphism if more than one variant at a locus occurs in human population with a frequency | 0.01% |
Who developed the technique of DNA fingerprinting? | Alec Jeffreys |
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 | Variable Number of Tandem Repeats |
Which blotting technique is used in DNA fingerprinting? | Southern blot |
VNTR belongs to a class of satellite DNA referred to as | Mini satellite |
The size of VNTR varies from | 0.1 to 20 kb |
What is base ratio? | A+T G+C |
Base ratio in organisms of the same species can vary. True/False. | False. Base ratio is constant for any species |
What is the base ratio for humans? | 1.55 |
WHat are the non histone proteins found in prkaryotes which bind DNA called? | Polyamines |
Which has more DNA content as compared to RNA content- heterochromatin or euchromatin? | euchromatin |
What is the base ratio of eukaryotes? | 1 |
What is the base ratio of prokaryotes? | <1 |
80% of all RNAs are | rRNAs |
5% of all RNAs are | mRNAs |
15% of all RNAs are | tRNAs |
Which are the smallest RNAs? | tRNAs |
Which are the longest RNAs? | mRNAs |
rRNAs are synthesised in | Nucleolus |
mRNAs are synthesised in | Nucleoplasm |
tRNAs are synthesised in | Nucleoplasm |
Which type of RNA is the most stable? | rRNA |
Which type of RNA is the least stable? | mRNA |
Insoluble RNA is also known as | rRNA |
Soluble RNA is also known as | tRNA |
What do the P site, A site and E site in ribosome stand for? | Peptidyl site Aminoacyl site Exit site |