knowverseQuestion 1
What does cell theory say about living organisms?
Cells are the basic units making up organisms.
Source excerpt
This brings us to the second pillar: all living organisms are made of cells.
From the Knowverse course text.
Read more about the topic
Compartments and boundaries
Cells are the basic units of living organisms, and new cells descend from existing cells. Their components work together to maintain life. Prokaryotic cells, such as bacteria, lack a membrane-bound nucleus. Eukaryotic cells usually contain a nucleus and other membrane-bound compartments that separate different activities within the same cell.
The plasma membrane forms a flexible boundary around a cell. Its lipid bilayer and embedded proteins provide selective permeability, allowing different substances to cross in different ways. In eukaryotic cells, the cytoplasm includes the material between the nucleus and membrane. Cytosol is the fluid portion in which many reactions occur.
Source excerpt
This ability to choose what passes through is known as selective permeability.
From the Knowverse course text.
Making, moving and using molecules
The nucleus stores most of a eukaryotic cell's DNA, organized with proteins as chromatin. Ribosomes assemble proteins. Some work in the cytosol, while others attach to the endoplasmic reticulum. Proteins entering this membrane system can travel in vesicles to the Golgi apparatus for further processing and delivery.
Lysosomes contain enzymes that break down materials and help recycle cell components. Mitochondria convert energy from nutrients into ATP through cellular respiration. Photosynthetic plant cells also have chloroplasts, which capture light energy for photosynthesis. These structures carry out different tasks, so identifying a cell part means asking what work it performs.
Source excerpt
The structures responsible for creating most of this ATP are the mitochondria.
From the Knowverse course text.