Question

What molecule stores and transmits genetic information in the cell? How large is this molecule? Where in the cell is this molecule found?

Short answer

The molecule responsible for storing and transmitting genetic information in the cell is deoxyribonucleic acid (DNA). It is a large molecule consisting of millions of nucleotides, with the size varying between organisms. In human cells, DNA is approximately 3.2 billion base pairs long and measures around 2 meters when stretched out in linear form. In eukaryotic cells, DNA is primarily located within the nucleus, with a small portion also found in mitochondria as mitochondrial DNA. In contrast, prokaryotic cells do not have a nucleus, and their DNA is located in the cytoplasm, typically as a single circular molecule or additional smaller circular pieces called plasmids.

Step-by-step solution

Identify the Molecule Responsible for Storing and Transmitting Genetic Information

The molecule that stores and transmits genetic information in the cell is deoxyribonucleic acid, or more commonly known as DNA.

Describe the Size of the DNA Molecule

The DNA molecule is a very large molecule consisting of millions of subunits called nucleotides. The size of the DNA varies from one organism to another, depending on the number of genes present in that organism. In human cells, the DNA is roughly 3.2 billion base pairs (A-T and G-C) long, which is equivalent to approximately 2 meters when stretched out in linear form.

Locate the DNA Molecule Within the Cell

In eukaryotic cells, such as those found in humans and other multicellular organisms, the DNA molecule is primarily found within the nucleus, which is a membrane-bound structure located in the center of the cell. This is where the genetic information in the form of DNA is protected and replicated. Additionally, a small amount of DNA can also be found in the mitochondria, which are the energy-producing organelles of the cell. This small portion of DNA is known as mitochondrial DNA. In prokaryotic cells, such as bacteria, the DNA is not enclosed within a nucleus; instead, it is located in the cytoplasm. The DNA in these cells is usually found as a single circular molecule, though some prokaryotes may have additional smaller circular pieces of DNA called plasmids.

Key concepts

Genetic Information

Genetic information refers to the data encoded in DNA that determines the traits and characteristics of any living organism. DNA, or deoxyribonucleic acid, is the molecule responsible for storing and transmitting this information. It is structured as a double helix and composed of four types of nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). These nucleotides pair as A with T, and C with G, forming base pairs that create the genetic code.

This genetic code dictates how organisms grow, develop, and function. Within DNA, specific sequences of base pairs form units called genes, which act as instructions for making proteins. Proteins are essential for the construction and maintenance of cells.

• DNA sequences are unique to each organism.
• Genes are arranged in specific orders, influencing traits.
• Alterations in genetic information can result in mutations, which may affect an organism's phenotype.

Cell Nucleus

The cell nucleus is a vital organelle in eukaryotic cells where DNA is stored and organized. As a membrane-bound structure, the nucleus provides a protective environment for DNA against potential damage from cellular processes. It ensures the accurate replication and expression of genetic information.

Inside the nucleus, DNA is packaged into structures called chromosomes. Each chromosome contains a long strand of DNA wrapped around proteins known as histones, forming a complex called chromatin. This packaging system allows long DNA molecules to fit inside the nucleus efficiently.

• The nucleus regulates gene expression, determining which genes are active.
• Nuclear pores in the nucleus membrane control material movement in and out of the nucleus.
• During cell division, the nucleus orchestrates the distribution of DNA to daughter cells.

Eukaryotic Cells

Eukaryotic cells are complex cells that contain a nucleus and other membrane-bound organelles, distinguishing them from prokaryotic cells. These cells are found in multicellular organisms, such as animals, plants, and fungi. The nucleus houses the eukaryotic cell's DNA, making it the command center for genetic operations.

Aside from the nucleus, eukaryotic cells have various specialized organelles, each performing specific functions. Some key organelles include mitochondria, which produce energy for the cell, and the endoplasmic reticulum, which synthesizes proteins and lipids.

• Eukaryotic cells are larger and more complex than prokaryotic cells.
• They reproduce through processes like mitosis and meiosis, ensuring genetic consistency.
• The presence of a cytoskeleton provides structural support and facilitates intracellular transport.

Prokaryotic Cells

Prokaryotic cells are simpler and typically smaller than eukaryotic cells, lacking a nucleus and membrane-bound organelles. Instead, their DNA is located in the cytoplasm and usually forms a single circular chromosome. Prokaryotic cells are primarily found in organisms like bacteria and archaea.

Despite their simplicity, prokaryotic cells carry out all necessary life functions. They often have additional small DNA molecules known as plasmids, which provide functions such as antibiotic resistance.

• Prokaryotic cells reproduce quickly through binary fission.
• They have a cell wall providing shape and protection.
• The simplicity of prokaryotic cells allows them to adapt swiftly to environmental changes.