Download Key Points on Prokaryotic vs. Eukaryotic Cells

Key Points on Characteristics of Life:
1. For something to be considered living, it must have fit the following rules.
a. Must be made up of cells.
i. Cells are the smallest unit of life.
b. Must have different levels of organization.
i. Atoms are organized into molecules that make up the cell.
ii. Different types of cells are organized together to do different
jobs.
c. Must get and use energy.
i. Living things take in energy and use it for maintenance and
growth.
ii. Energy can come from the sun, other organisms, or
chemicals.
d. Must respond to its environment.
i. Living things will change their behavior in response to
changes in their environment.
e. Must be able to grow.
i. Cell division forms new cells. Cells also increase in size before
dividing.
ii. An organism gets larger as the number of its cells increases.
f. Must be able to reproduce.
i. Reproduction is not essential for the survival of individual
organisms, but must occur for a species to survive.
g. Must control its internal environment.
i. Called homeostasis. Humans sweat or shiver to control
temperature.
Key Points on Central Dogma of Life:
1. The Central Dogma of Life describes how information is stored in the cell
and how that information is used to make the cell do its job.
a. This idea was created by Francis Crick in 1958.
2. Crick’s idea states that DNA is how the instructions for how cell should
operate are stored.
a. DNA is made of deoxyribose sugar, a phosphate group, and one of
four nitrogenous bases.
3. When a cell needs to carry out a task, its DNA is transcribed into a
substance called RNA.
a. RNA is very similar to DNA, but it has only one strand.
4. But for the instructions to actually control a cell’s actions, it must be
changed into protein. This is called translation. Proteins are the actors of
the cell.
a. Proteins are made of amino acids. There are 20 different types of
amino acids.
5. MEMORY AID: Transcribing means to copy and translating creates
something completely new. Since DNA and RNA are so similar, think of this
as copying. Protein is a completely new substance.
6. Skepticism
a. Most scientists in the 1950s believed that proteins were the
instructions for how the cell operates.
b. Most scientists thought that since there were twenty different amino
acids and only four different bases, that he information that needed
to be stored would be stored using protein.
c. However, two scientists named Hershey and Chase, were skeptical.
They doubted this idea because no experiments had been done
proving this.
d. They decided to do two experiments. One to see if DNA were the
instructions passed to a new cell and another to see if it was
protein.
e. Analyzing their results, they realized that DNA was passed to new
cells.
Key Points on Prokaryotic vs. Eukaryotic Cells:
1. There are two main categories of cells, prokaryotic and eukaryotic cells.
a. The word “karyose” is Greek means kernel which we use in biology
to refer to a nucleus. “Pro” means before and “eu” means true.
b. Thus prokaryote means before nucleus and eukaryote means true
nucleus.
2. Similarities
a. The instructions for both cell types are stored as DNA. And both are
made out of the same bases.
b. Both types of cells change DNA into RNA through transcription and
RNA to protein through translation.
i. Translation happens in ribosomes which are found in both cell
types.
c. Both cell types can have photosynthesis and/or respiration occur.
3. Differences
a. Eukaryotes have a nucleus while prokaryotes do not have a
nucleus.
b. DNA
i. The DNA inside of a prokaryotic cell is circular while it is linear
in a eukaryote.
ii. DNA is packed tightly into chromosomes in eukaryotes while it
is not packed in prokaryotes.
c. Eukaryotes are much larger than prokaryotes.
d. Eukaryotes contain membrane-bound organelles inside of the cell
which have special functions happen inside of them allowing
eukaryotes to behavior in many different ways.
4. Why
a. Eukaryotes have more similarities than differences. Thus scientists
believe that life began as prokaryotes and then over millions of
years, these cells evolved into prokaryotic cells.