Organic Molecules, Cells, and Cellular Structures

Organic Molecules

Organic molecules are those consisting essentially of carbon atoms linked by covalent bonds.

• Fabrics: Clusters of specialized cells that perform the same function and have one origin.
• Organs: The structural and functional units of higher living beings. They consist of several different tissues and perform a specific action.
• Systems: Clusters of similar bodies that perform independent actions. For example, the nervous system, bone, muscle, or endocrine system.
• Apparatus: Sets of organs that can be very different, but whose actions are coordinated to form what is called a function.

Prokaryotic Cell

A cell whose genetic material is not organized in a well-defined nucleus and is distributed during cell reproduction.

• In prokaryotic cells, the genetic material (DNA) is free in the cytoplasm without any structure that delimits it; that is, it is diffuse.

Eukaryotic Cells

Eukaryotic cells are generally larger and have a more complex structure than prokaryotic cells. They are characterized by having a nucleus bounded by a double nuclear membrane that separates it from the rest of the cytoplasm. They have more DNA than prokaryotes.

Plasma Membrane

The plasma membrane surrounds the cell structure and separates it from the external environment. It acts as a barrier that allows the cell to incorporate water and nutrients and remove metabolic waste.

Cytoplasm

The cytoplasm is a colloid inside the plasma membrane that contains water, salts, and organic molecules such as proteins and sugars, all membranous and non-membranous organelles found in the cell.

Ribosomes

Ribosomes are organelles formed by the combination of different proteins and RNA. They are located in the cytoplasm, from which they translate the genetic message contained in the DNA, according to a code for synthesizing the proteins the cell needs.

Cytoskeleton

The cytoskeleton is the internal support structure of animal cells. It is built as a framework with three types of fibrillar proteins.

Golgi Apparatus

The Golgi apparatus is involved in the modification and packaging of proteins that are produced by the ribosomes of the RER and taken to the Golgi apparatus.

Endoplasmic Reticulum (ER)

The endoplasmic reticulum is a double membrane system that runs through the cell and is contiguous to the nuclear envelope. The ER is a network of tubules called lamellae and sacs.

• The RER plays an important role in protein synthesis. The RER-bound ribosomes synthesize proteins to be secreted by the cell or for the cell membrane and cellular organelles. These proteins move within the lumen, where they are folded, and when carbohydrates are added, they become glycoproteins. These are transported to the Golgi apparatus, where they are sorted to their final destinations.

Lysosomes

The primary function of lysosomes is the destruction of foreign material entering the cell and the destruction of cell organelles.

Peroxisomes

Peroxisomes are involved in metabolic reactions that produce hydrogen peroxide.

Chloroplasts

Chloroplasts are organelles of plant cells containing chlorophyll and the enzymes required for photosynthesis. Chloroplasts are elongated organelles, composed of a double membrane, and contain DNA.

Nucleus

The nucleus contains most of the genetic material (DNA) of the cell. Additional DNA is located in mitochondria and chloroplasts. DNA, together with some proteins, forms chromatin, which forms the chromosomes. Genetic control of the cell is to produce RNA in the nucleus.