Cell Biology
13 questions tagged Cell Biology — spanning every one of the seven Ws.
What are histones?
Histones are proteins that DNA wraps around to form chromatin. They help pack DNA tightly and regulate gene activity.
What is chromatin?
Chromatin is the DNA-protein material that makes up chromosomes inside the nucleus. It helps package DNA and control gene access.
Where is the melanocyte located in the human body?
Melanocytes are located mainly in the skin, hair follicles, and eyes. They produce melanin, the pigment that helps determine color and protect against UV radiation.
Whose discovery revealed the Golgi apparatus?
Camillo Golgi discovered the Golgi apparatus in 1898. The structure is a major cell organelle involved in processing and packaging proteins.
How do stem cells know what cell to become?
Stem cells respond to chemical signals and gene-regulation programs that tell them when to specialize. Once a cell commits to a certain path, its gene activity changes to match that role.
What is peptidoglycan?
Peptidoglycan is a strong mesh-like molecule that forms much of bacterial cell walls. It helps bacteria keep their shape and resist bursting.
When was the first bacterial flagellum structure solved?
The structure of the bacterial flagellum began to be worked out in the late 20th century, with major structural breakthroughs in the 1990s and 2000s. It was a key advance in understanding bacterial motility.
Where is mitochondrial DNA found in human cells?
Mitochondrial DNA is found inside mitochondria, the cell's energy-producing organelles. Humans have many copies per cell, especially in energy-demanding tissues.
Which human cell is the largest by diameter?
The human egg cell, or ovum, is the largest human cell by diameter. It is about 0.1 millimetres across and is visible without a microscope.
Which human cell is the smallest by length?
The human sperm cell is one of the smallest human cells by length. It is about 50 to 60 micrometres long, including the tail.
Whose cells were used to create the first immortal human cell line, HeLa?
Henrietta Lacks’ cancer cells were taken in 1951 and became the HeLa cell line. They were the first widely used immortal human cells in research.
How many cell divisions are needed to make the human body?
There is no single fixed number, but the body must produce trillions of cells through countless divisions from a single fertilized egg. In adulthood, cells are constantly being replaced in many tissues.
How do mitochondria produce energy in cells?
Mitochondria make ATP through cellular respiration, using oxygen to extract energy from nutrients. They are often called the powerhouses of the cell.