Developmental biology: no red cell is an island

Most DNA resides in the nucleus of a cell. However, some organelles in the cell cytoplasm⁠—such as chloroplasts and mitochondria⁠—also have their own DNA. These organelles replicate their DNA independently of the nuclear DNA of the cell in which they reside. Non-nuclear inheritance describes the inheritance of genes from structures other than the nucleus.

Red blood cells  (RBCs) transport oxygen to all body tissues. These cells survive only for 120 days and then need to be replenished. Erythropoiesis is the process of RBC production. In healthy individuals, erythropoiesis ensures all tissues are amply supplied with oxygen. In addition, blood loss due to injury leads to a drop in the physiological oxygen level that will cause erythropoiesis. Any defect in erythropoiesis leads to several physiological disorders, including thalassemia, anemia, and...

The concept of a cell started with microscopic observations of dead cork tissue by Robert Hooke in 1665. Hooke coined the term "cell" based on the resemblance of the small subdivisions in the cork to the rooms that monks inhabited, called cells. About ten years later, Antonie van Leeuwenhoek became the first person to observe the living and moving cells under a microscope. In the century that followed, the theory that cells represented the basic unit of life developed.
Multicellular organisms...

The epidermis is made of four or five layers of epithelial cells, depending on its location in the body. From deep to superficial, these layers are the stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.
The cells in all these layers except the stratum basale are called keratinocytes, a type of cell that manufactures and stores the protein keratin. The keratinocytes in the stratum corneum are dead and regularly slough away, being replaced by cells from...

Red blood cells  (RBCs) transport oxygen to all body tissues. These cells survive only for 120 days and then need to be replenished. Erythropoiesis is the process of RBC production. In healthy individuals, erythropoiesis ensures all tissues are amply supplied with oxygen. In addition, blood loss due to injury leads to a drop in the physiological oxygen level that will cause erythropoiesis. Any defect in erythropoiesis leads to several physiological disorders, including thalassemia, anemia, and...

Red algae, also known as rhodophytes, are primarily found in marine environments, though some species inhabit freshwater and terrestrial ecosystems. These organisms exist in both unicellular and multicellular forms, with some multicellular varieties reaching macroscopic sizes.As phototrophic organisms, red algae contain chlorophyll a; however, their chloroplasts lack chlorophyll b. Instead, they possess phycobiliproteins, which serve as major light-harvesting pigments, similar to those found in...