DNA Model

CELLS

Cells are the basic units of all living things – which include plants and animals! Every organism, including humans, is made up of cells. Organisms with cells that have a nucleus are called eukaryotes, and ones that don’t are called prokaryotes (such as bacteria).

Our body is made up of about 36 trillion cells. The ones in the human body are so tiny that you need a microscope to see them!

Eukaryotic cells have multiple components, like the nucleus and cytoplasm!

NUCLEUS

The nucleus is a crucial part of the cell. It is surrounded by a double membrane called the nuclear envelope. Nuclear pores in the envelope allow the exchange of materials between the nucleus and the cytoplasm (a fluid that fills the cell).

Inside the nucleus is the nucleoplasm, where the DNA is located. DNA in the nucleus is organized into chromosomes, carrying the cell’s genetic instructions.

WHAT’S DNA?

DNA is the molecule that carries genetic information in cells. It is composed of nucleotides, which are the building blocks of DNA.

These nucleotides form long chains, with the sequence of bases encoding genetic information. The entire set of DNA in an organism, including all its genes, is called the genome. The human genome has over 3 billion base pairs!

The genome contains instructions for building and maintaining the organism, guiding processes like growth, development, and reproduction.

NUCLEOTIDES

Nucleotides are the building blocks of DNA, consisting of a sugar, a phosphate group, and a nitrogenous base. In DNA, there are four types of nucleotides, each with a different base: adenine (A), thymine (T), cytosine (C), and guanine (G).

These nucleotides pair specifically (A with T, C with G) to form the rungs of DNA’s double helix structure.

The sequence of nucleotides along the two strands of the double helix encodes genetic information, while hydrogen bonds protect the stability between the base pairs.

CENTRAL DOGMA

The central dogma is a theory stating that genetic information flows from DNA, to RNA, to protein.

RNA is a copy, or a transcription, of DNA. While the DNA stays in the nucleus, the RNA goes to the cytoplasm which helps to make proteins using amino acids.

Proteins are complex molecules made up of chains of amino acids. Each protein’s unique sequence of 20 possible amino acids determines its structure and function. These proteins fold into complex shapes that perform vital cellular functions.

DISCOVERY OF DNA

The discovery of DNA’s structure was an important moment in science. James Watson and Francis Crick, in 1953, proposed the double helix model of DNA.

Their breakthrough was significantly aided by Rosalind Franklin, whose X-ray

images of DNA provided crucial evidence of the helical structure. Franklin’s meticulous work revealed key details about the DNA molecule, although she didn’t receive the same recognition at the time.

Watson and Crick used her data, along with other findings, to build their famous model, which explained how DNA carries genetic information and replicates, revolutionizing our understanding of biology. They got a Nobel Prize for it!

WHAT’S GENOMICS?

Genomics is the study of an organism’s complete set of DNA, called the genome. It looks at all the genes and other DNA sequences to understand how they influence traits, health, and disease. By analyzing genomes, scientists can discover how genes work, identify genetic disorders, and improve things like medicine and crops. Genomics uses advanced technologies to explore how DNA shapes living organisms and their functions.