Video Transcript
Put the following structures in the
order in which they are organized in the human body, from largest to smallest:
cells, molecules, atoms, organelles.
This question is asking us to
compare the size of biological structures in the human body. To answer this question, we’ll
review key facts about the name, structures, and the levels of organization within
the human body.
Many complex organisms, like
humans, have a high degree of organization. So to understand how the body
functions, it can be helpful to consider the levels of organization, that is, how
the smallest parts of the organism are assembled into the larger structures. Let’s review the levels of
organization in the human body in hierarchical order, starting with the smallest
structure, the atom, and ending with the largest structure, the organism.
Atoms are the smallest unit of
matter. At the most basic level, your body
is made up of atoms like oxygen. Oxygen atoms are the most abundant
atom by mass in the human body. Groups of atoms can be organized
into larger structures called molecules. A molecule is two or more atoms
joined by chemical bonds. For example, a water molecule is
made from one oxygen atom bonding with two different hydrogen atoms.
Through the process of
polymerization, single molecules can be joined together to form larger structures
called macromolecules. The most common macromolecules
found in the human body are lipids, proteins, carbohydrates, and nucleic acids.
Macromolecules that play the same
function can be aggregated into a larger structure called an organelle. Organelles are functional subunits
found within a cell. Examples of organelles include the
nucleus, mitochondria, and the endoplasmic reticulum. Organelles carry out specialized
functions like releasing energy for the cell or storing genetic information.
Groups of organelles that work
together to carry out a common function form larger structures called cells. A cell is the smallest structural
and functional unit of an organism. Cells consist of a flexible cell
membrane that encloses cytoplasm, which surround a variety of organelles. Groups of cells that work together
to carry out a common function create larger structures called tissues.
After cells, the hierarchical order
continues and includes tissues, organs, organ systems, and organisms, like a
human. So to summarize, groups of atoms
join together to form molecules. Many molecules with the same
function form organelles. And many organelles working
together form a cell. With this knowledge, we can answer
our question. The correct order of the structures
from largest to smallest is cells, organelles, molecules, atoms.
