Nucleic Acids Overview and DNA History

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Questions and Answers

What is the primary function of DNA in organisms?

To catalyze biochemical reactions

To facilitate energy transfer

To form structural components of cells

To serve as the hereditary material (correct)

What is a nucleoside composed of?

A sugar and a phosphate group

A phosphate group and an amino acid

A phosphate group and a nitrogenous base

A nitrogenous base and a sugar (correct)

Which structure was proposed for DNA by Watson and Crick?

Double-stranded helix (correct)

Circular plasmid

Single-stranded helix

Triple-stranded ladder

What type of sugar is found in the nucleic acids?

Pentose sugar (C) Signup and view all the answers

Which bond links the base and sugar in a nucleoside?

N-glycosidic linkage (A) Signup and view all the answers

What significant contribution did Friedrich Miescher make to the field of molecular biology?

Isolated nuclein from white blood cells (D) Signup and view all the answers

The term 'nucleic acid' was created by which scientist?

Richard Altmann (A) Signup and view all the answers

Where is most DNA located in human cells?

Nucleus (D) Signup and view all the answers

What is the correct description of the structure of DNA?

It is made up of two antiparallel polynucleotide chains forming a right-handed double-helix. (A) Signup and view all the answers

Which characteristic of DNA is described by Chargaff's rule?

Adenine and thymine ratios are equal, while guanine and cytosine ratios are also equal. (C) Signup and view all the answers

What is a notable feature of DNA's molecular structure?

The diameter of a DNA helix is approximately 2.0 nm. (D) Signup and view all the answers

Who were awarded the Nobel Prize in medicine in 1962 for their work on DNA?

Watson, Crick, and Wilkins. (C) Signup and view all the answers

What does the 'gene' refer to in the context of DNA?

The part of DNA that carries genetic information for proteins. (B) Signup and view all the answers

Which form of DNA is most commonly represented in molecular biology?

B-form DNA. (A) Signup and view all the answers

What is the distance between adjacent bases in a DNA strand?

0.34 nm. (A) Signup and view all the answers

What are the dimensions of the minor and major grooves in DNA?

Minor groove: 1.2 nm; Major groove: 2.2 nm. (A) Signup and view all the answers

Study Notes

Nucleic Acids

Nucleic acids are biopolymers, essential for all living organisms.
Two types of nucleic acids exist: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

Structure of Nucleic Acids

Composed of three components: a pentose sugar, a phosphate group, and a nitrogenous base.

DNA Overview

DNA is the hereditary material in humans and almost all other organisms.
Most DNA is located in the cell nucleus (nuclear DNA), but small amounts are found in mitochondria and chloroplasts.
Each cell in a human body contains the same DNA.

History of DNA Research

Friedrich Miescher discovered nuclein in 1869.
Richard Altmann coined the term "nucleic acid" in 1889.
In 1953, James Watson and Francis Crick determined DNA's double-helix structure.
Rosalind Franklin and Maurice Wilkins contributed to the understanding of DNA's structure through X-ray diffraction studies.

DNA Structure

A nucleoside is formed when a nitrogenous base attaches to a sugar through an N-glycosidic linkage.
A phosphate group added to a nucleoside via a phosphoester linkage creates a nucleotide.
Joining two nucleotides with a phosphodiester bond forms a polynucleotide.
DNA is a polynucleotide, consisting of two antiparallel polynucleotide chains spiraling around a common axis, forming a right-handed double helix.

DNA Features

The two strands of DNA run in opposite directions (3' end of one chain faces the 5' end of the other).
Gene: The portion of DNA providing information for protein synthesis.
Gene: Unit of genetics.
DNA sequence: The order of bases in a polynucleotide chain, carrying genetic information.
Chargaff's rules: The amount of guanine equals cytosine, and the amount of adenine equals thymine.

Additional DNA Details

Diameter of DNA: 2.0 nm or 20 Angstroms.
Distance between adjacent bases: 0.34 nm or 3.4 Angstroms.
Complete helix turn length: 3.4 nm or 34 Angstroms.
Number of base pairs per turn: 10.
Minor groove: Shallow groove (-1.2 nm) in DNA molecule.
Major groove: Deep groove (-2.2 nm) in DNA molecule.

DNA Forms

A-form DNA
B-form DNA
Z-form DNA

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Description

Explore the fundamentals of nucleic acids including their structure, types, and significance in living organisms. Learn about the history of DNA research and the key contributions that led to the understanding of its double-helix structure.