Tag: structure of chromosome, cell cycle and cell division

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

Base pairs present in one turn of DNA are

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

  1. $12$

  2. $11$

  3. $10$

  4. $9$

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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 distance between base pairs is 3.4 A$^o$. The total length of one turn of DNA is 34 A$^o$. The total number of the base pair in each turn is 34/3.4 = 10.
So, the correct answer is option C.

The similarity between bacterial and eukaryotic DNA is that both are

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

  1. Circular

  2. Single stranded

  3. Double stranded

  4. All the above

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Correct Option: C
Explanation:
Nucleic acids are DNA and RNA. DNA is a genetic material which is mainly present in the nucleus of the cell in eukaryotes like mammals. The genetic material is covered by a nuclear membrane. In prokaryotes like bacteria the genetic material lie freely in the cytoplasm. The region where the nucleic acid are present is known as nucleoid. The similarity between bacterial and eukaryotic DNA is that both are double stranded DNA.
So, the correct answer is option C.

Length of one turn of DNA is

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

  1. $34 \mathring{A}$

  2. $3.4 \mathring{A}$

  3. $0.34 \mathring{A}$

  4. $20 \mathring{A}$

Show answer
Correct Option: A
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$^o$. So the total length of one turn of DNA is 10 x 3.4 =  34 A$^o$.
So, the correct answer is option A.

The two strands of DNA are held together by bonds of

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

  1. Nitrogen

  2. Oxygen

  3. Hydrogen

  4. Carbon

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Correct Option: C
Explanation:
The nitrogenous bases present in the DNA are purines and pyrimidines. Purines are double ring while pyrimidines are single ring structure. Adenine and guanine are purines while thymine, uracil, and cytosine are pyrimidines. A purine is attached to pyrimidine by hydrogen bond. Adenine is attached to thymine by two hydrogen bonds while three hydrogen bond is present between guanine and cytosine.
So, the correct answer is option C.

DNA is very long. It is accommodated in small sized nucleus by

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

  1. DNA-ase digestion

  2. Super coiling

  3. Elimination of repetitive DNA

  4. Deletion of non-essential genes

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Correct Option: B
Explanation:

DNA is very long. It is accommodated in the small-sized nucleus by super coiling. The enzyme topoisomerase helps in the supercoiling of the DNA which helps in packaging and some biological process. The super coiled DNA is uncoiled during the process of transcription and translation. During transcription the enzyme helicase cuts the phosphate backbone and separates the two super coiled DNA strands while the topoisomerase balances the strain and prevents the recoiling of the DNA.

So, the correct answer is option B.

A $68nm$ length double stranded DNA has 24 adenine nucleotices. What must be the number of guanine nucleotides?

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

  1. $48$

  2. $72$

  3. $76$

  4. $176$

Show answer
Correct Option: D
Explanation:

Length of $3.4 nm $ includes $10$ base pairs.So, $68 nm $ will include $200$ base pairs that is $400$ bases.

A=T AND G=C,
A+T+G+C=$400$,
$24$+$24$+$2G$=$400$.,
$2G$ = $352$.
So, Guanine nucleotides would be $176$.
Hence, the correct answer is option D.

The genetic information in the body is encoded in the

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

  1. Structural proteins

  2. Enzymes

  3. DNA

  4. DNA and enzymes

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Correct Option: C
Explanation:

Deoxyribose Nucleic Acid or DNA carries the genetic information in the form of small segments known as genes and is also the genetic material in various organisms including humans.

Structural proteins and enzymes are the gene products that are synthesised from DNA through the process of translation.
Hence, the correct answer is 'DNA'.

Information from X-ray crystallographic data collected by was used by Watson and Crick in their development of the model of DNA.

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

  1. Chargaff

  2. Griffith

  3. Franklin

  4. Hershey and Chase

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Correct Option: C
Explanation:

Although the discovery of the structure of DNA was attributed to Watson and Crick, a keynote player in helping them discover this structure was a scientist by the name of Rosalind Franklin. Rosalind Franklin, along with Francis Wilkins, worked on DNA applying X-ray crystallography to find out its structural properties. X-ray crystallography required the process of exposing a crystal specimen (DNA) to X-rays to determine the locations of the atoms in the “molecules that comprises basic unit of crystal called unit cell”. 

So, the correct option is 'Franklin'.

The purines of DNA are represented by guanine and thymine.

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

  1. True

  2. False

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Correct Option: B
Explanation:

Adenine and Guanine are the two purines found in DNA and RNA. The pyrimidines of DNA are represented by thymine and cytosine. 

Hence, the correct answer is false. 

Which of the following general statement about the structure of DNA is true?

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

  1. The hydrogen bonds connecting base pairs exist in a polar environment.

  2. Both major and minor grooves are formed between the phosphate-sugar backbone.

  3. The same C and N atoms are present in each groove.

  4. The amount of energy required to break down the AT and GC pairs is the same.

Show answer
Correct Option: A
Explanation:

The DNA double helical structure has two different environments. The nitrogenous bases have an aromatic ring structure and are hydrophobic and interact with each other through base pair stacking interactions. At the same time, the back bone of DNA formed by phosphodiester bonds is hydrophilic and interacts with water. The nitrogenous bases of one nucleotide chain form hydrogen bonds with the nitrogenous bases present directly opposite them on the other chain. The hydrogen bonds are formed in polar aqueous environment. The adenine base pairs with thymine with two hydrogen bonds and guanine base pairs with cytosine with three hydrogen bonds.
So, the correct answer is option A.