Welcome back, everyone! Today we're going to be contrasting plant and animal cells.
A lot of videos cover the different organelles, but this video does that AND
compares how the different cell types tackle the same problems. At the end,
we'll also be organizing all that information into a handy chart that
makes a great study reference, so be sure to stick with us! The first task we're
going to discuss is how cells maintain an internal environment that's different
than their external environment. Both plant and animal cells use a selectively
permeable membrane that's composed of two layers of phospholipids and studded
with channels. These channels only allow certain molecules to pass through and
thus play a major role in regulating the internal environment. Plant and animal
cells both use a selectively permeable membrane. To store and pass on genetic
information, both plant and animal cells use a nucleus and a nucleolus. The
nucleus contains genetic information that controls growth, cellular activity,
and protein creation. The nucleolus assembles components of ribosomes which
play an important role in protein creation. When it comes to creating
proteins, ribosomes string together amino acids with peptide bonds. Even though
they're really important, ribosomes are technically not considered to be
organelles because they're not membrane bound. The Golgi apparatus then takes
this long polypeptide chain created by the ribosomes and folds it up into a
protein. Plant and animal cells need to be able to move the proteins around the
cell. The endoplasmic reticulum assists with transport and also plays several
other roles, depending on whether it is rough or smooth. The rough endoplasmic
reticulum is studded with ribosomes so that it can aid in protein synthesis. It
also attaches instructional tags to polypeptides. The smooth ER participates
in lipid synthesis, stores ions, and aids in detoxification. So, the next time you
survive drinking an alcoholic beverage, definitely thank your smooth ER!
So far, plant and animal cells have tackled their problems in very similar ways, but
here's where we're going to start to diverge a little bit. Both cell types use
vacuoles for storage, but they differ in the specifics. Plant cells have a large
central vacuole, and when it's full, it helps to provide support to the cell by
creating turgor pressure. This is why, if you forget to water a plant for a few
days, it gets all droopy and wilts, but if you finally water it,
it tends to perk right back up. Animal cells can have either many small
vacuoles, or none at all, and they only use them for storage rather than support.
Plant and animal cells continue to differ in terms of how they obtain
energy. Both cell types are capable of undergoing cellular respiration, which
they perform using mitochondria. Most of the time plants perform photosynthesis
in order to harvest energy from the Sun. However, they do do cellular respiration
when they're only seedlings and don't have any leaves yet. Animal cells can't
photosynthesize at all, so they use cellular respiration to obtain energy.
Scientists believe that both chloroplasts and mitochondria were
originally bacteria that were ingested by early cells. We call this the
Endosymbiotic Theory. Both plant and animal cells use mitosis for somatic
cells and meiosis for sex cells. Each cell type has specializations that
assist with the division process. Animal cells have centrioles that initiate
spindle fiber formation. Plants don't have centrioles, but they do have
vesicles that deliver cell wall components along the cell plate. This
separates the newly forming cells when it comes to maintaining cell shape. Plant
and animal cells have very different strategies. Plants use their large
central vacuole to create turgor pressure and use that in conjunction
with their supportive cell walls. The cell walls are usually made of cellulose,
which is what makes plants crunchy. Animal cells are more squishy, so they
rely on a protein scaffolding called the cytoskeleton. The cytoskeleton is
produced by organelles called centrosomes, which my students always
say look like "churros". (I totally agree but they're probably a lot less delicious!)
All living things produce waste, but plant and animal cells have different
methods for getting rid of it. In animal cells, enzyme-filled sacs called
lysosomes degrade waste products. They also perform a process called exocytosis,
where a waste filled vesicle docks up against the cell membrane and releases
its contents. Plants don't have lysosomes but they can release gasses via
transpiration through their stomata. They can also use enzymes called
proteases to degrade proteins, although these are not well understood.
Finally, cell to cell communication presents some unique challenges for each cell type.
Plants often communicate through plasmodesmata;
tiny channels in the cell wall. But because animal tissues
are so diverse, they need multiple methods of communication. A few
examples include endocytosis, exocytosis, and gap junctions, although the details
are outside the scope of this video. Okay, that was definitely a lot of content, so
here's a recap. Plant and animal cells are very different from one another, but
also have a lot of processes in common. They maintain their internal environment,
store, and pass on genetic information, create proteins, and move items around
the cell in much the same ways. They also contain organelles that allow them to
store items, and obtain energy in related ways. When it comes time to divide,
maintain cell shape, remove waste, or communicate from cell to cell
plants and animals require different organelles to get the job done. That's it
for this week! if you found this video useful, I hope you'll consider checking
out some of my other work, or looking at some of my other materials on Twitter
and Instagram. Thanks again for watching, and please remember to subscribe!