Скачать или смотреть Watson and Crick Model of DNA

The Watson and Crick model, often referred to as the Watson-Crick double helix model, is a foundational concept in molecular biology that describes the structure of DNA (deoxyribonucleic acid). This model was proposed by James Watson and Francis Crick in 1953 and is considered one of the most significant scientific discoveries of the 20th century. It revolutionized our understanding of genetics and the transmission of hereditary information.

Here's an explanation of the Watson and Crick model:

Double Helix Structure: Watson and Crick's model describes DNA as a double helix, which is like a twisted ladder or spiral staircase. This structure is made up of two long chains of nucleotides running in opposite directions, which are coiled around each other.

Complementary Base Pairing: Within the DNA double helix, there are four types of nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G). Watson and Crick proposed that these bases form pairs in a very specific manner. Adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G). This is known as complementary base pairing.

Antiparallel Strands: The two DNA strands are oriented in an antiparallel fashion, meaning they run in opposite directions. One strand runs from 5' to 3' (5 prime to 3 prime), while the other runs from 3' to 5'. This antiparallel arrangement ensures that the complementary base pairing can occur.

Sugar-Phosphate Backbone: Along the outside of each DNA strand, there is a sugar-phosphate backbone. The sugar molecules (deoxyribose) and phosphate groups form a repeating pattern, providing structural support to the molecule.

Base Pairing Held Together by Hydrogen Bonds: The complementary base pairs (A-T and C-G) are held together by hydrogen bonds. Specifically, there are two hydrogen bonds between adenine (A) and thymine (T), and three hydrogen bonds between cytosine (C) and guanine (G). These hydrogen bonds are relatively weak individually but collectively provide stability to the DNA double helix.

Information Storage: DNA's primary function is to store genetic information. The sequence of nucleotide bases along the DNA strands encodes the genetic instructions necessary for building and maintaining living organisms.


#biology
#biologyworld
#biologylecture
#biologyeducation