ch. 1: cell structure & function -...
TRANSCRIPT
Ch. 1: Cell Structure &
Function
Sect. 1: Types of Unicellular
Organisms - Recap
Sect. 2: How Cells Work
Types of Unicellular Organisms
There are many different types of
unicellular organisms, all of which fall
into two general categories: prokaryotic
organisms (also called bacteria) and
eukaryotic organisms. In general,
eukaryotic cells are more complex than
prokaryotic organisms, because
prokaryotes don't have membrane-
bound organelles.
Classifications Prokaryotes and eukaryotes also differ
in the chemical composition of some of
their structures as well as in the
organization of their DNA. Below is a
chart which highlights the important
differences between the two types of
cells. Although you probably aren't yet
familiar with the terms on the chart, you
may find it helpful to return back to this
page as you learn new information later
on.
Classification Operations - Prokaryote
Eukaryote
cell membrane yes yes
nucleus no
membranes surrounded by two membranes
endoplasmic
reticulum no yes
Golgi bodies no yes
mitochondria no yes
vacuoles no yes
lysosomes no yes
ribosomes yes yes
chromosomes
circular
without
histones
linear with histones
Classifications Cont. -
In addition to this classification, organisms
may also be classified be their method of
nutrition. Heterotrophs are organisms
which obtain food from the environment,
whereas autotrophs have a method of
producing their own food. Also, aerobes
are organisms which require oxygen to
survive, whereas anaerobes do not
need oxygen.
We have discussed the main 4 types of
unicellular organism that we are required
to, but we get into more detail with
vocabulary in plant and animal
chapters which describe the
differences mentioned in the charts
above on cellular organelle operation.
This way, you will first have an
understanding of the what the terms above
mean before you learn which cells have
what.
How the Cells Work!
During Plant and Animal cell observation
we explain all of the details about how a
cell works, but here is a general
explanation to get you started. Cells have
tiny structures inside of them called
organelles. Organelles are very similar to
human organs in that they help perform
specific functions. However, cells don't
have organelles called "the liver" or "the
heart."
Some of the names of cell organelles
include the mitochondria, lysosomes,
and the endoplasmic reticulum. Don't
get scared by the strange names; Later
we focus on cell organelles so that you
can understand them completely. The cell
organelles float around in a fluidic
substance called the cytoplasm. The
cytoplasm is similar to very watery jelly.
As the cytoplasm moves around within
the cell, organelles can come into
contact with one another, allowing
certain processes to occur. This
movement of the cytoplasm is called
cyclosis. Just like humans, cells need to
perform certain processes similar to our
processes for eating, breathing, and
reproduction.
These processes have some very
interesting names: phagocytosis,
glycolysis, mitosis.