16 Questions
What is the primary function of nucleic acids like DNA and RNA?
Storage of genetic information
The length of DNA is usually determined by the number of nucleotides present in it.
True
What is the name of the sugar molecule found in DNA?
deoxyribose
The two types of nitrogenous bases are __________ and __________.
purines and pyrimidines
What is the linkage between a nitrogenous base and the sugar molecule in a nucleotide?
N-glycosidic linkage
The 5'-end of a polynucleotide chain is formed by a free phosphate moiety at the 3'-end of the sugar.
False
The polynucleotide chain has a __________ formed by a free phosphate moiety at the 5'-end of the sugar and a __________ formed by a free -OH of 3' C group of the sugar.
5'-end; 3'-end
Match the following organisms with their respective DNA lengths:
Bacteriophage f ×174 = 5386 nucleotides Bacteriophage lambda = 48502 base pairs Escherichia coli = 4.6 × 106 bp Human DNA = 3.3 × 109 bp
Purines found both in DNA and RNA are
Adenine and guanine
Adenine pairs with thymine through one H-bond.
False
Who first identified DNA in 1869?
Friedrich Miescher
The pentose sugar and phosphate group are linked together by a ___________ linkage.
phosphodiester
Match the scientists with their contributions:
Rosalind Franklin = Used X-ray diffraction method to investigate the structure of DNA Maurice Wilkins = Used X-ray diffraction method to investigate the structure of DNA Watson and Crick = Proposed a molecular model of the basic structure of DNA Erwin Chargaff = Observed the nitrogenous bases of DNA and generalized the Chargaff's base equivalence rule
According to Chargaff's rule, the ratios between Adenine and Guanine, and Thymine and Cytosine are constant and equal to one.
False
In the polynucleotide chain of DNA, a nitrogenous base is linked to the -OH of
2'C pentose sugar
What is the shape of the DNA molecule revealed by X-ray diffraction method?
double helix
Study Notes
Inheritance Patterns and Genetic Basis
- After identifying the inheritance patterns and genetic basis, scientists focused on the factors regulating these patterns, leading to the discovery of biomolecules responsible for genetic information inheritance.
Structure of DNA
- DNA consists of a helix of two polynucleotide chains attached by hydrogen bonds.
- The length of DNA is determined by the number of nucleotides (or base pairs) present.
- Examples of DNA lengths: Bacteriophage f ×174 (5386 nucleotides), Bacteriophage lambda (48502 base pairs), Escherichia coli (4.6 × 106 bp), and human DNA (3.3 × 109 bp).
Polynucleotide Chain Structure
- A polynucleotide chain is composed of many nucleotides.
- A nucleotide consists of a nitrogenous base, a pentose sugar (ribose in RNA, deoxyribose in DNA), and a phosphate group.
- There are two types of nitrogenous bases: purines (Adenine and Guanine) and pyrimidines (Cytosine, Uracil, and Thymine).
- A nitrogenous base is linked to the hydroxyl group (-OH) of 1' C (carbon) of pentose sugar through a N-glycosidic linkage to form a nucleoside.
- A phosphate group is linked to -OH of 5' C of a nucleoside through phosphoester linkage to form a nucleotide.
- Nucleotides are linked through 3'-5' phosphodiester linkage to form a polynucleotide chain.
Nitrogenous Base Linkage
- In the polynucleotide chain of DNA, a nitrogenous base is linked to the -OH of 1' C pentose sugar.
- Purines found in both DNA and RNA are Adenine and Guanine.
DNA Discovery and Structure
- DNA was first identified by Friedrich Miescher in 1869 in the nucleus of pus cells.
- Rosalind Franklin and Maurice Wilkins used X-ray diffraction to investigate the structure of DNA, revealing its nature (double-stranded), shape (double helix), and orientation of nitrogenous bases.
- Watson and Crick proposed a molecular model of the basic structure of DNA in 1953, using data from Wilkins and Franklin.
- Watson, Crick, and Wilkins received the Nobel Prize in 1962 for discovering the double helical structure of DNA.
Chargaff's Base Equivalence Rule
- Erwin Chargaff observed the nitrogenous bases of DNA and formulated the Chargaff's base equivalence rule in 1950.
- The rule states that for a double-stranded DNA, the ratios between Adenine and Thymine, and Guanine and Cytosine are constant and equal to one.
Explore the inheritance patterns and genetic basis, and learn about the structure of DNA, including its helix shape and composition.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
