Tag: structure of chromosome, cell cycle and cell division

Questions Related to structure of chromosome, cell cycle and cell division

The DNA strands are anti-parallel because of

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. H bonds

  2. Phospho-diester bonds

  3. Disulphide bonds

  4. Phosphate bonds

Show answer
Correct Option: B
Explanation:

The DNA strands runs anti-parallel, due to phosphodiester bonds. A phosphodiester bond occurs when exactly two of the hydroxyl groups in phosphoric acid react with hydroxyl groups on other molecules to form two ester bonds. Phosphodiester bonds are central to most life on Earth, as they make up the backbone of the strands of DNA. In DNA and RNA, the phosphodiester bond is the linkage between the 3' carbon atom of one sugar molecule and the 5' carbon atom of another, deoxyribose in DNA and ribose in RNA. Strong covalent bonds form between the phosphate group and two 5-carbon ring  two ester bonds. Due to this bond the DNA strands run anti-parallel.

In the DNA molecule,

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. The proportion of adenine in relation to thymine varies with the organism.

  2. There are two strands which run antiparallel one in $5'\rightarrow 3'$ direction and other in $3'\rightarrow 5'$.

  3. The total amount of purine nucleotides and pyrimidine nucleotides is not always equal.

  4. There are two strands which run parallel in the $5'\rightarrow 3'$ direction.

Show answer
Correct Option: B
Explanation:

DNA (Deoxyribonucleic Acid) is composed of two polynucleotide strands (the polymers of nucleotides), which form what looks like a ladder. The nitrogenous bases in DNA store the instructions for making polypeptide chains, essentially coding for every feature of the entire organism. The two polynucleotide strands run 'antiparallel' to each other, with nitrogenous bases projecting inwards. The term 'antiparallel' means that the strands run in opposite directions, parallel to one another. The antiparallel strands twist in a complete DNA structure, forming a double helix.

In the speculation concering the origins of life, one theory states that the combination of purines, pyrimidines, sugars, and phosphates is called as______________.

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. Nucleotides

  2. Nucleosides

  3. Carbohydrates

  4. Fats

  5. Proteins

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Correct Option: A

If one strand of DNA sequence is - 5'-GAATTG-3' - then the sequence of the opposite strand is

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. 5'-CAATTC-3'

  2. 5'-CTTAAC-3'

  3. 5'-GAATTG-3'

  4. 5'-GTTAAG-3'

  5. 5'-TAATTC-3'

Show answer
Correct Option: A
Explanation:

A DNA strand is complementary. This means adenine pairs with thymine and cytosine pairs with guanine in the opposite strand. The given strand has a sequence 5'-GAATTG-3'. Hence the complementary strand will have a sequence 5'-CAATTC-3'. Thus the correct answer is option A.

DNA is directly involved in the synthesis except that of

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. DNA

  2. Protein

  3. tRNA

  4. mRNA

Show answer
Correct Option: B
Explanation:
DNA is genetic material found in the living cell. It helps to carry characters from one generation to the other. The process by which the DNA replicated and forms another DNA molecule is known as replication. Parent strand of the DNA strand act as a template for synthesis of another DNA molecule.
Transcription is the process by which DNA is converted into RNA. The enzyme RNA polymerase plays an important role in transcription. The sequence of the nitrogenous base on the DNA acts as a template and determines the sequence of the nitrogenous base on the RNA. The RNA formed by the DNA are messenger RNA, t- RNA and ribosomal RNA.
Protein is formed by the m-RNA by process of translation.
So, the correct answer is option B.

A $340\overset{o}{A}$ long segment of DNA molecule has $20$ thymine nitrogenous bases, what will be the number of guanine nitrogen bases in the same segment?

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. $10$

  2. $40$

  3. $30$

  4. $160$

Show answer
Correct Option: C
Explanation:
Option (C) 30

$ 34A = 10 $ nucleotides
$ 340A = 100 $ nuclotides
$ A = T = 20 $
$ 100-40 = 60 $ nucleotides
$ G = C = 60 $
Hence $ G = 60/2 = 30 $ nuclotides

The DNA strands are antiparallel because of the presence of

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. H-bonds

  2. Peptide bonds

  3. Disulphide bonds

  4. Phosphate-diester bonds

  5. None of the above

Show answer
Correct Option: A
Explanation:

When DNA strands run in opposite direction one strand from 5 prime to 3 prime and another strand from 3 prime to 5 prime is called as antiparallel. The 5 prime end have phosphate in 5$^{th}$position of sugar and 3 prime end have a hydroxyl group on 3$^{rd}$ position of sugar. DNA strands are antiparallel because of the presence of hydrogen bond. Hydrogen bond binds the complementary bases (purine and pyrimidine)

In DNA, adenine pairs with

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. Guanine

  2. Thymine

  3. Cytosine

  4. Uracil

Show answer
Correct Option: B
Explanation:

The nitrogenous bases present in the DNA are purines and pyrimidines. The purines are adenine and guanine. The pyrimidines are thymine and cytosine. The purines are double ring structure while the pyrimidines are the single ring made up of carbon and nitrogen. Purines pair with the pyrimidines by hydrogen bonds. Adenine pairs with thymine by two hydrogen bond while the cytosine pairs with the guanosine by three hydrogen bonds.

So, the correct answer is option B.

DNA is composed of repeating units of

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. Ribonucleosides

  2. Deoxyribonucleosides

  3. Ribonucleotides

  4. Deoxyribonucleotides

Show answer
Correct Option: A
Explanation:
DNA is a chain of polynucleotide which are joined by the phosphodiester bonds. The nucleotide consists of a deoxyribose sugar, nitrogenous bases, and phosphate.The two nucleotide is linked by the phosphodiester bond. It is formed by the linkage between the 3' carbon atom of one sugar molecule and the 5' carbon atom of another. Two hydroxyls (OH) groups on the phosphate molecule bind to the 3’ and 5’ carbons on two independent pentose sugars to form a bond.
So, the correct answer is option D.

Major and minor grooves can be seen in

zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

  1. Polypeptide

  2. RNA

  3. DNA

  4. Chromatin

Show answer
Correct Option: C
Explanation:
DNA has the double helical structure where the two strands are tightly coiled over each other. B- DNA has right-handed helix with the major and minor groove. The diameter of the DNA is 20 A$^o$. The number of base pairs in one turn is 10 and the distance between base pairs is 3.4 A$^o$. At major grooves, the base pairs are far apart while at minor groove the base pairs are closer. Major grooves have base pairs at a distance the DNA binding protein can easily interact with the bases.
So, the correct answer is option A.