Review 3b, 3d
3.1 and 3.3 Eukaryotic vs. Prokaryotic
Prokaryotic cells
Prokaryotic cells are very simple and do not have a nucleus.
Instead of a nucleus, prokaryotic cells have a nucleoid.
The only organelles that prokaryotic cells have are ribosomes.
In prokaryotes DNA is found in the nucleoid.
Prokaryotic cells are called prokaryotes.
Bacteria are prokaryotic cells.
Bacteria are single-celled organisms.
Eukaryotes
Eukaryotic cells are more complex and have a nucleus.
They have a lot of organelles including ribosomes.
In eukaryotes DNA is found in the nucleus.
Organisms with eukaryotic cells are called eukaryotes.
Animals, plants, and fungi have eukaryotic cells.
They can be single-celled or multi-cellular
3.2 The Nucleus
The nucleus of the cell controls everything that happens in a cell. It is the brain of a cell because
it stores all of the genetic material. We call genetic material DNA.
A nucleus is enclosed by the nuclear envelope which helps protect the DNA. A nucleoid is not
enclosed by a membrane; instead the DNA just bunches together with nothing to contain it.
DNA is very important because it is the directions for making different parts of our bodies.
3.4 DNA
•DNA is a very large molecule that contains the instructions for how things should look and
work in an organism.
•A gene is a small piece of DNA that determines a trait.
•Traits are things about an organism’s appearance.
3.5 Sexual vs. Asexual Reproduction - Make-up Notes
There are two ways an organism can reproduce:
- Sexual reproduction
- Asexual reproduction
Both sexual and asexual reproduction are used to create offspring
In asexual reproduction
- An organism inherits DNA from one parent
- The DNA it inherits is identical to the parent’s DNA
- All prokaryotes reproduce asexually.
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Plants can reproduce asexually from bulbs, runners, and cuttings.
Some animals like starfish and sponges can reproduce asexually.
In sexual reproduction
- An organism inherits DNA from two parents
- The DNA it inherits is a combination of the parent’s DNA
o The organism will be unique
- Most animals reproduce sexually
- Plants can reproduce sexually through pollination
3.6 Genetics Make-up Notes
Mendel discovered that traits are passed or inherited from one generation to the next.
Organisms inherit one gene for a trait from each parent. As a result, an organism can have
two different genes for the same trait.
Some genes are dominant, while others are recessive
o “Stronger” traits are called dominant.
o “Weaker” traits are called recessive.
Dominant genes hide recessive genes when both are inherited by an organism.
If most of the offspring from parents with two different traits have one of the traits, that is
usually the dominant trait. The trait that none or few of the offspring has is the recessive trait.
3.7 Comparing and Contrasting Sexual and Asexual Reproduction Make-up Notes
Sexual and Asexual Reproduction are both used to create offspring. However, they are
different in many ways. Sexual reproduction happens between 2 parents, while asexual
reproduction involves only 1 parent. The offspring produced by sexual reproduction have similar
DNA to/from the parents. However, the offspring produced by asexual reproduction have
identical DNA to the parent.