The document describes a journey through a cell, referred to as Cell Town, to learn about its major components and their functions. It explains that the nucleus is the cell's control center that contains DNA. The cytoplasm contains organelles like the mitochondria, which produces energy for the cell, and the endoplasmic reticulum and Golgi apparatus, which are involved in manufacturing and transporting proteins. The lesson aims to provide an understanding of the structures and roles of key parts of the human cell.
2. Introduction
The cell is a small, but complex structure. Take a look
inside the outer plasma membrane of a cell and discover
the functions of some common cellular components,
including the nucleus, endoplasmic reticulum, Golgi
apparatus and mitochondria, in this lesson.
3. The Cell
You have trillions of cells in your body, and each one is like
a little town with its own power station, manufacturing
plants and city hall. While no two cells are identical, we see
many common elements found within all human cells. In
this lesson, we'll take a trip through a typical body cell that
we'll refer to as Cell Town.
4. Nucleus
City hall is the nucleus of Cell Town. This means it's the
control center of the cell that contains DNA. DNA is the
abbreviation of deoxyribonucleic acid, which is the genetic
material that contains the instructions for building the
body. As you can imagine, this is a function worth
protecting and why the plasma membrane is so selective in
deciding who or what can come inside a cell.
5. Cytoplasm
You can see the nucleus positioned near the center of Cell
Town, but in order to get there, you realize that you must
wade through the cytoplasm, which is the gel-like
substance inside the plasma membrane. This is where
much of the cell's activity take place, and you notice it
contains the metabolic machines or organs of the cell,
called organelles. The term organelles means 'little organs,'
which makes this term a bit easier to recall.
6. Organelles: Mitochondria
The first organelle that catches your eye is a funny-looking
oblong structure that seems to be hard at work. This is the
mitochondria, which is the cell's power plant because it's a
place the cell produces energy, namely ATP, or adenosine
triphosphate.
7. Organelles: Golgi Apparatus
You see that ribosomes and rough ER work nicely together.
While ribosomes act as the protein factories, the rough ER
is the protein packaging plant where proteins are readied
for transport. These protein packages then head off to the
Golgi apparatus, which is another structure that kind of
looks like pita bread folded up on itself. This is a sorting
and distribution center for proteins. The proteins that come
into the Golgi apparatus get modified and then tagged for
shipment to wherever they are needed.
8. Organelles: Smooth E.R.
There's another structure in this manufacturing part of Cell
Town that is referred to as smooth endoplasmic reticulum,
or smooth ER. It's smooth because it's not studded with
ribosomes. Whereas rough ER is all about proteins, smooth
ER has nothing to do with them. Instead, it makes lipids,
which are fats. The smooth ER also acts as a detoxification
center. Because of these functions, you might want to think
of smooth ER as the slick emergency room where fat little
baby lipids are born and drugs come to dry out or get
detoxed.
9. End of Journey
It has been an interesting journey through Cell Town, but
you're getting somewhat tired of trudging through the
cytoplasm, so you decide to stop getting distracted and
push on to the nucleus of town before it's time to head home,
content with your new knowledge of the structures and
functions of the human cell.
10. End of Journey
It has been an interesting journey through Cell Town, but
you're getting somewhat tired of trudging through the
cytoplasm, so you decide to stop getting distracted and
push on to the nucleus of town before it's time to head home,
content with your new knowledge of the structures and
functions of the human cell.
11. Lesson Summary (Part 1)
Let's review. Our imaginary Cell Town, like all cells in your body,
has a plasma membrane, which is a barrier that surrounds the
entire outside of the cell. This membrane is selectively
permeable, which means it allows some substances in and denies
access to other substances. This helps protect the nucleus, which
is the control center of the cell that contains DNA, which is the
genetic material of the cell. Cytoplasm is the gel-like substance
inside the plasma membrane where we find the organelles. The
first organelle we learned about was the mitochondria, which is
the cell's power plant because it produces ATP.
12. Lesson Summary (Part 2)
We also walked through the manufacturing area of the cell
where we saw the rough endoplasmic reticulum. This is a
tubular maze of membranes covered with tiny, dark bumps.
Those bumps are ribosomes, which are the protein factories.
The proteins made in the ribosomes are packaged and readied
for transport within the rough ER. These protein packages then
head off to the Golgi apparatus, which is a sorting and
distribution center for proteins. We also saw the smooth
endoplasmic reticulum, or smooth ER, which makes lipids and
acts as a detoxification center.
