Final answer:
Cells are the fundamental units of life with a basic structure that includes cytoplasm and a plasma membrane; they contain DNA, which carries genetic information. The nucleus is an organelle in eukaryotic cells that contains most of the DNA. Cell theory encompasses the unifying principles of cell biology, including the fact that all living organisms are composed of cells.
Step-by-step explanation:
Introduction to Cells and DNA
Cells are the basic units of life that make up all living organisms, from the simplest bacteria to complex beings like humans. All cells have a fundamental structure comprising a gel-like substance known as cytoplasm, enclosed within a plasma membrane. Within this enclosed environment, cells house DNA (deoxyribonucleic acid), which is the genetic material essential for the inheritance of traits and control of cellular activities. The nucleus, an organelle found in eukaryotic cells, contains most of the cell's DNA and acts as the control center.
DNA is responsible for storing the genetic information used in the growth and functioning of all living organisms. It replicates itself and is passed down from parent to daughter cells, ensuring that genetic information is inherited by future generations. Human body cells are typically diploid, with a full set of 46 chromosomes, while gametes, the reproductive cells, contain a single set of 23 chromosomes.
The cell theory posits that cells are the fundamental units of life, and despite their diversity in size and function, all cells share some common components such as a plasma membrane, cytoplasm, chromosomes, and ribosomes. Cells are capable of different functions because they express only a subset of genes at any given time.