Describe the molecular model of DNA in brief as given by Watson and Crick.

Describe the molecular model of DNA in brief as given by Watson and Crick.  
by

1 Answer

Answer :

Ans: 1. DNA is double helical structure resembles a twisted ladder.

2. Each strand shows 5'→ 3' polarity and one strand is antiparallel to the other. Every strand has deoxyribonucleotides.

3. Each nucleotide has a Deoxyribose sugar, Phosphate and a nitrogen base. Backbone of the strand is made of alternately arranged Sugar and phosphate with diester bonds between them.

4. The nitrogen bases are Thymine (T) and Cytosine (C) as Pyrimidines and Adenine (A) and Guanine (G) as purines.

5. Thymine of one strand pairs with Adenine of another strand by forming 2 hydrogen bonds between them. Similarly G pairs with C and forms 3 hydrogen bonds.

6. Length is variable but the diameter is 20Ao. Length of each spiral is 34Ao and consists of 10 base pairs. The angle between the successive nucleotides of the same strand is 36o. 

by

Related questions

Double helical structure model of the DNA was proposed by (A) Pauling and Corey (B) Peter Mitchell (C) Watson and Crick (D) King and Wooten

Description : Double helical structure model of the DNA was proposed by (A) Pauling and Corey (B) Peter Mitchell (C) Watson and Crick (D) King and Wooten

Last Answer : Answer : C

Explain the Watson - Crick Model of DNA.

Description : Explain the Watson - Crick Model of DNA.

Last Answer : The structure of DNA molecule resembles a spirally twisted ladder called double helix. It has a pair of polynucleotide chain running anti-parallel (run parallel to each other but with opposite ... alternatively. The nitrogenous bases connect the two opposite strands like the rungs of a ladder.

What is Watson and crick Model of DNA?

Description : What is Watson and crick Model of DNA?

Last Answer : Each DNA molecule is made of thousands of small units called nucleotides. There are four types of nucleotides in DNA. I. Adenine (A) nucleotides II. Thymine (T) nucleotides III. Cytosine (C) ... two stands formed of nucleotides. These two are linked with each other by cross bands like a ladder.

Fluid mosaic model of cell membrane was put forward by (a) Danielli and Davson (b) Singer and Nicolson (c) Garner and Allard (d) Watson and Crick.

Description : Fluid mosaic model of cell membrane was put forward by (a) Danielli and Davson (b) Singer and Nicolson (c) Garner and Allard (d) Watson and Crick.

Last Answer : (b) Singer and Nicolson

DNA synthesis in laboratory was first achieved by (A) Watson and crick (B) Khorana (C) A.Kornberg (D) Ochoa

Description : DNA synthesis in laboratory was first achieved by (A) Watson and crick (B) Khorana (C) A.Kornberg (D) Ochoa

Last Answer : Answer : C

Which of the following events occurred first? (1) DNA structure of genes was discovered by James D Watson and Francis Crick (2) Yuri Gagarin became the first man in space (3) World's first human heart transplant was performed by Dr. Christian Barnard (4) World's first test tube baby Louise Brown was born in U.K.

Description : Which of the following events occurred first? (1) DNA structure of genes was discovered by James D Watson and Francis Crick (2) Yuri Gagarin became the first man in space (3) World's first human heart ... by Dr. Christian Barnard (4) World's first test tube baby Louise Brown was born in U.K.

Last Answer : (1) DNA structure of genes was discovered by James D Watson and Francis Crick Explanation: Discovery of DNA structure of genes: 25 April, 1953; Yuri Gagarin's feat of becoming the first man in space: ... human heart transplant: 3 December, 1967; and World's first test tube baby: 25 July, 1978.

DNA test was developed by – (1) Dr. Alec Jeffreys (2) Dr. V.K. Kashyap (3) Watson and Crick (4) Gregor Mendel

Description : DNA test was developed by – (1) Dr. Alec Jeffreys (2) Dr. V.K. Kashyap (3) Watson and Crick (4) Gregor Mendel

Last Answer : (3) Watson and Crick Explanation: A genealogical. DNA test looks at a person's genetic code at specific locations. Results give information about genealogy or personal ancestry. James D. Watson and Francis Crick are the two scientists who discovered the structure of DNA in 1953.

DNA mRNA C Proposed by Protein A B The figure gives an important concept in the genetic implication of DNA. Fill the blanks A, B and C. (a) A-Maurice Wilkins, B-Transcription, C-Translation (b) A-James Watson, B-Replication, C-Extension (c) A-Erwin Chargaff, B-Translation, C-Replication (d) A-Francis Crick, B-Translation, C-Transcription

Description : DNA mRNA C Proposed by Protein A B The figure gives an important concept in the genetic implication of DNA. Fill the blanks A, B and C. (a) A-Maurice Wilkins, B-Transcription, C-Translation ... c) A-Erwin Chargaff, B-Translation, C-Replication (d) A-Francis Crick, B-Translation, C-Transcription

Last Answer : (d) A-Francis Crick, B-Translation, C-Transcription

The diagram shows an important concept in the genetic implication of DNA. Fill in the blanks A to C. DNA mRNA Proposed by Protein C A B (a) A - Transcription, B -Translation, C - Francis Crick (b) A - Translation, B - Extension, C - Rosalind Franklin (c) A - Transcription, B - Replication, C - James Watson (d) A - Translation, B - Transcription, C - Ervin Chargaff

Description : The diagram shows an important concept in the genetic implication of DNA. Fill in the blanks A to C. DNA mRNA Proposed by Protein C A B (a) A - Transcription, B -Translation, C - Francis Crick (b) ... , B - Replication, C - James Watson (d) A - Translation, B - Transcription, C - Ervin Chargaff

Last Answer : (a) A - Transcription, B -Translation, C - Francis Crick

Which of the following events occurred first ? (1) DNA structure of genes was discovered by James D Watson and Francis Crick (2) Yuri Gagarin became the first man in space (3) World’s first human heart transplant was performed by Dr. Christian Barnard (4) World’s first test tube baby Louise Brown was born in U.K

Description : Which of the following events occurred first ? (1) DNA structure of genes was discovered by James D Watson and Francis Crick (2) Yuri Gagarin became the first man in space (3) World's first human heart ... by Dr. Christian Barnard (4) World's first test tube baby Louise Brown was born in U.K

Last Answer :  DNA structure of genes was discovered by James D Watson and Francis Crick

DNA test was developed by (1) Dr. Alec Jeffreys (2) Dr. V.K. Kashyap (3) Watson and Crick (4) Gregor Mendel

Description : DNA test was developed by (1) Dr. Alec Jeffreys (2) Dr. V.K. Kashyap (3) Watson and Crick (4) Gregor Mendel

Last Answer : Watson and Crick

Do you believe that Watson and crick went about their research in an ethical way why or why not?

Description : Do you believe that Watson and crick went about their research in an ethical way why or why not?

Last Answer : Need answer

Both α-helix and β-pleated sheet conformation of proteins were proposed by (A) Watson and Crick (B) Pauling and Corey (C) Waugh and King (D) Y.S.Rao

Description : Both α-helix and β-pleated sheet conformation of proteins were proposed by (A) Watson and Crick (B) Pauling and Corey (C) Waugh and King (D) Y.S.Rao

Last Answer : Answer : B

That some human diseases are genetically controlled was first established by (a) Gregor Mendel (b) A E Garrod (c) Watson and Crick (d) William Bateson

Description : That some human diseases are genetically controlled was first established by (a) Gregor Mendel (b) A E Garrod (c) Watson and Crick (d) William Bateson

Last Answer : Ans:(b)

Transposable genetic elements (transposons) a. Were First Discovered By Watson And Crick. b. Are Smaller Than Insertion Sequences. c. Are Examples Of Plasmids. d. May Have Information For Antibiotic Resistance.

Description : Transposable genetic elements (transposons) a. Were First Discovered By Watson And Crick. b. Are Smaller Than Insertion Sequences. c. Are Examples Of Plasmids. d. May Have Information For Antibiotic Resistance.

Last Answer : d. May Have Information For Antibiotic Resistance.

Vitamin theory was proposed by (a) Hepkins and Funk (b) Holly and Khorana (c) Watson and Crick (d) Jensen and Meischer

Description : Vitamin theory was proposed by (a) Hepkins and Funk (b) Holly and Khorana (c) Watson and Crick (d) Jensen and Meischer

Last Answer : (a) Hepkins and Funk

Describe Plasma membrane with reference to Fluid Mosaic model.

Description : Describe Plasma membrane with reference to Fluid Mosaic model.  

Last Answer : Ans: Fluid Mosaic model was proposed by Singer and Nicholson. This model states that plasma membrane is semi-solid. It has bimolecular fluid like lipid zone in which the solid like proteins are ... ). This model best explains the functions of plasma membrane. Hence it is most acceptable model.  

Under anaerobic conditions, bacterium Pseudomonas changes (a) Nitrate to molecular nitrogen (b) Nitrate to ammonia (c) Nitrate to nitrite (d) Nitrite to nitrate

Description : Under anaerobic conditions, bacterium Pseudomonas changes (a) Nitrate to molecular nitrogen (b) Nitrate to ammonia (c) Nitrate to nitrite (d) Nitrite to nitrate

Last Answer : Ans. ((a))

Operon model of gene regulation and organisation of prokaryotes was proposed by: (a) Messelson and Stahl (b) Wilkins and Franklin (c) Beadle and Tatum (d) Jacob and Monod

Description : Operon model of gene regulation and organisation of prokaryotes was proposed by: (a) Messelson and Stahl (b) Wilkins and Franklin (c) Beadle and Tatum (d) Jacob and Monod

Last Answer : Ans. ((d))

Consider the following statements: (1) Copper is present in cytochrome oxidane (2) Pantothenic acid is precursor of co-enzyme-A (3) Thiamine prohosphate is the prosthetic group in decarboxylases (4) Zinc is present in RNA and DNA polymerases

Description : Consider the following statements: (1) Copper is present in cytochrome oxidane (2) Pantothenic acid is precursor of co-enzyme-A (3) Thiamine prohosphate is the prosthetic group in decarboxylases (4) Zinc is present in RNA and DNA polymerases

Last Answer : Ans. ((b))

In the bacteria: (1) Mesosome is present (2) Nucleoid represents the genome (3) Ribosomes are found in cytoplasm (4) Histone proteins complexed with DNA

Description : In the bacteria: (1) Mesosome is present (2) Nucleoid represents the genome (3) Ribosomes are found in cytoplasm (4) Histone proteins complexed with DNA

Last Answer : Ans. ((a))

The process through which the amount of DNA, RNA and protein can be known at a time is called (a) Autoradiography (b) Tissue culture (c) Cellular fractioning (d) Phase contrast microscopy

Description : The process through which the amount of DNA, RNA and protein can be known at a time is called (a) Autoradiography (b) Tissue culture (c) Cellular fractioning (d) Phase contrast microscopy

Last Answer : Ans. ((c))

The process by which the amount of DNA, RNA and protein can be known at a time is: (a) Cell fractionation (b) Autoradiography (c) Phase-contrast microscopy (d) Tissue culture

Description : The process by which the amount of DNA, RNA and protein can be known at a time is: (a) Cell fractionation (b) Autoradiography (c) Phase-contrast microscopy (d) Tissue culture

Last Answer : Ans. ((b))

Prokaryotic genetic material is: (a) Liner DNA + his tones (b) Circular DNA + his tones (c) Liner DNA without his tones (d) Circular DNA without his tones

Description : Prokaryotic genetic material is: (a) Liner DNA + his tones (b) Circular DNA + his tones (c) Liner DNA without his tones (d) Circular DNA without his tones

Last Answer : Ans. ((d))

B-DNA is: (a) Antiparallel and right handed (b) Antiparallel and left handed (c) Parallel and right handed (d) Parallel and left handed

Description : B-DNA is: (a) Antiparallel and right handed (b) Antiparallel and left handed (c) Parallel and right handed (d) Parallel and left handed

Last Answer : Ans. ((a))

The diameter of Z-DNA is: (a) 34 A (b) 20A (c) 18A (d) 45A

Description : The diameter of Z-DNA is: (a) 34 A (b) 20A (c) 18A (d) 45A

Last Answer : Ans. ((c))

? X l74 has: (a) Single stranded DNA (b) Single stranded RNA (c) Double stranded RNA (d) Double stranded DNA

Description : ? X l74 has: (a) Single stranded DNA (b) Single stranded RNA (c) Double stranded RNA (d) Double stranded DNA

Last Answer : Ans. ((a))

Coacervates were formed by a) DNA b) Radiations c) Polymerization d) Polymerisation and aggregation

Description : Coacervates were formed by a) DNA b) Radiations c) Polymerization d) Polymerisation and aggregation

Last Answer : d) Polymerisation and aggregation

Who among the following analysed DNA for the first time? (1) Arthur Cornberg (2) Hargobind Khurana (3) M. W. Nirenberg (4) Watson and Krick

Description : Who among the following analysed DNA for the first time? (1) Arthur Cornberg (2) Hargobind Khurana (3) M. W. Nirenberg (4) Watson and Krick

Last Answer : (4) Watson and Krick Explanation: James D Watson and Fracis Crick, the two scientists who discovered the structure of DNA in 1953. Watson and Crick took a crucial conceptual step, suggesting ... pairs interlocked in the middle of the double helix to keep the distance between the chains constant.

Who proved that DNA is basic genetic material? (a) Griffith (b) Watson (c) Boveri and Sutton (d) Hershey and Chase

Description : Who proved that DNA is basic genetic material? (a) Griffith (b) Watson (c) Boveri and Sutton (d) Hershey and Chase

Last Answer : d) Hershey and Chase

Who proved that DNA is basic genetic material? (a) Griffith (b) Watson (c) Boveri and Sutton (d) Hershey and Chase

Description : Who proved that DNA is basic genetic material? (a) Griffith (b) Watson (c) Boveri and Sutton (d) Hershey and Chase

Last Answer : (d) Hershey and Chase

Who among the following analysed DNA for the first time ? (1) Arthur Cornberg (2) Hargobind Khurana (3) M. W. Nirenberg (4) Watson and Krick

Description : Who among the following analysed DNA for the first time ? (1) Arthur Cornberg (2) Hargobind Khurana (3) M. W. Nirenberg (4) Watson and Krick

Last Answer :  Watson and Krick

Describe some asexual processes occurring in animal reproduction. What is the chief disadvantage of this form of reproduction?

Description : Describe some asexual processes occurring in animal reproduction. What is the chief disadvantage of this form of reproduction?

Last Answer : Parthenogenetic development of unfertilized eggs as a regular procedure in the production of male ants and bees and Artificial stimulation of sea urchin eggs induces cleavage. Although the egg is ... In almost all animal organisms, asexual reproduction is only a supplement to sexual reproduction.  

Describe the metaphase of Mitosis

Description : Describe the metaphase of Mitosis 

Last Answer : Ans: Metaphase is the second stage of karyokinesis of mitosis. In this the karyotype of an organism is determined. In this the spindle is totally organized. Chromosomes are in highly condensed ... artifact). The chromatids of chromosomes and the kinetochores of centromere are clearly visible.  

Describe the cell organelle which is responsible for the synthesis of starch.

Description : Describe the cell organelle which is responsible for the synthesis of starch. 

Last Answer : The cell organelle responsible for the formation of starch is Chloroplast. It was discovered by Sachs and named by Schimper. It is usually disc shaped or Biconvex or Oval or spherical.   ... granum and the unstacked thylakoids that connect the adjacent grana are called as Stroma thylakoids.  

Describe the essential organs of Malvaceae

Description : Describe the essential organs of Malvaceae  

Last Answer : Ans: Androecium: Stamens are many, epipetalous, monadelphous, anthers are reniform, monothcous, extrorse, dorsifixed, transverse dehiscence and pollen grains are large, spherical, spiny and polysiphonous. Gynoecium ... capitate and lobed. Lobes may be either equal or double the number of carpels.  

Describe the various outgrowths of seed.

Description : Describe the various outgrowths of seed.

Last Answer : Ans: The outgrowths of seed are Caruncle and Aril. Caruncle: It is developed from integumentary cells of micropylar region. It is spongy and helps in absorbing water during seed germination. It is seen in ... commonly called as mace and is used as spice. In Pithecalobium, it is edible and spongy. 

Describe double fertilization in angiosperms.

Description : Describe double fertilization in angiosperms.

Last Answer : Ans: Occurrence of two types of fertilizations in the same embryosac is called as double fertilization. It was discovered by Nawaschin in Fritillaria and Lilium. It is a feature of angiosperms. ... . It was discovered by Nawaschin in Fritillaria and Lilium. PEN develops into endosperm. 

Describe the structure of ovule with the help of neat labeled diagram

Description : Describe the structure of ovule with the help of neat labeled diagram

Last Answer : Ans: Ovules are seen in flowering plants. In Gymnosperms they are exposed and in angiosperms they are enclosed.   Typical ovule has a stalk known as Funiculus and ovule body. ... as in Monocots and Polypetalae and ategmic without integuments as in parasites such as Balanophora, Loranthus.  

Describe the structure of anther with the help of a neat diagram

Description : Describe the structure of anther with the help of a neat diagram 

Last Answer : Ans: Structure of anther is clearly understood in the transverse section of anther. In the T.S. of a dithecous anther the two thecae are joined by connective consisting of sterile ... later separate from each other and liberated individually. Individual microspores are called as pollen grains. 

What is placentation? Describe the various types of placentation in plants.

Description : What is placentation? Describe the various types of placentation in plants. 

Last Answer : Ans: It is arrangement of ovules in the ovary. Part of the ovary from which ovules arise is called as placenta. Placentation is of the following types. I. Marginal placentation: Ovules are borne along ... : One or few ovules arise from the base of the unilocular ovary. Ex: Tridax, Helianthus. 

Describe adhesion of stamens

Description : Describe adhesion of stamens 

Last Answer : Ans: Fusion of stamens with other floral parts like sepals, petals, stamens and carpels is called as adhesion. It is of the following types. I. Epipetalous: Stamens are fused with the petals ... lobes. Ex: Asparagus IV. Gynostegium: Stamens fused with the stigma of gynoecium. Ex: Calotropis

Describe various types of aestivations with the help of suitable examples.

Description : Describe various types of aestivations with the help of suitable examples.

Last Answer : Ans: Arrangement of perianth lobes in bud condition is called as aestivation. They are of the following types. I. Valvate: Perianth lobes of cycle are arranged side by side but not overlapped. ... remaining one has one margin inside and one margin outside. Ex: Calyx of Ipomoea and Catharanthus. 

Describe various types of symmetry of flower based on the arrangement of floral parts.

Description : Describe various types of symmetry of flower based on the arrangement of floral parts.

Last Answer : Ans: On the basis of this character, floral symmetry is of the following three types. I. Spiral : The free sepals, petals, stamens and carpels are arranged spirally over the conical or convex ... Cyclic: All the four floral parts are arranged in cycles over the thalamus. Ex: Hibiscus, Datura

What are insectivorous plants and describe the mechanism of insect trapping in Nepenthes.

Description : What are insectivorous plants and describe the mechanism of insect trapping in Nepenthes.  

Last Answer : Ans: Plants that fulfill their nitrogen requirements by digesting the insects are called as insectivorous plants. Nepenthes is commonly called as Pitcher plant. It has petiole whose lower portion is green, ... protein component of insect body which is absorbed by the cells of pitcher.  

Define phylloclade and describe it.

Description : Define phylloclade and describe it.

Last Answer : Ans: Phylloclade is an aerial modified stem or branch with several internodes whose axis becomes green colored to perform photosynthesis. It may be cylindrical as in Casuarina or flat as in ... known as areole. This type of modifications reduce transpiration and an adaptation of xerophytes.  

Reserve transcription was discovered by : (1) Beadle & Tatum (2) Waston & Crick (3) Temin & Baltimore (4) har Govind Khorana

Description : Reserve transcription was discovered by : (1) Beadle & Tatum (2) Waston & Crick (3) Temin & Baltimore (4) har Govind Khorana

Last Answer : Temin & Baltimore

The hypogeal germination is found in: (a) Bean (b) Maize (c) Rhizophora (d) Cucurbita Ans. (b) Directions: In the following questions more than one answer given may be correct select the correct answers according to the code— Code— (a) 1, 2 and 3 are correct (b) 1 and 2 are correct (c) 1, 2 and 4 are correct (d) 1 and 3 are correct 26. Which of following matched correctly? (1) Piper—Climbing root (2) Ficus—Climbing root (3) Buttress root—Bombax (4) Vitis—Nodulated root

Description : The hypogeal germination is found in: (a) Bean (b) Maize (c) Rhizophora (d) Cucurbita Ans. (b) Directions: In the following questions more than one answer given may be correct select the correct ... (1) Piper-Climbing root (2) Ficus-Climbing root (3) Buttress root-Bombax (4) Vitis-Nodulated root

Last Answer : Ans. ((d))

Law of limiting factor was given by: (a) Blackman (b) Hill (c) Taylor (d) Amon

Description : Law of limiting factor was given by: (a) Blackman (b) Hill (c) Taylor (d) Amon

Last Answer : Ans. ((a))