Types of Cells

Learners can:

• relate the domains of life to the types of cells

• differentiate between prokaryotes and eukaryotes

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Vocabulary: plasma membrane, prokaryote, ribosome

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Types of Cells

Draw

Draw a cell. Try to include as many parts of the cell that you know!

​Prokaryotic vs. Eukaryotic

​What is different when you compare a prokaryotic cell to a eukaryotic cell?

Types of Cells

All organisms are composed of cells. Unicellular organisms consist of a single cell, while multicellular organisms consist of many cells. Biologists often divide living things into two categories based on the structure of their cells. These categories are:

• prokaryotes

• eukaryotes

​A prokaryote is a cell that lacks a nucleus. Examine the table below to learn the meaning of each part of the word.

Characteristics of Prokaryotic Cells

A prokaryote consists of a single prokaryotic cell. Recall that prokaryotic cells lack a nucleus to surround their DNA. Organisms in the domains Archaea and Bacteria also lack a nucleus. All organisms in the domains Archaea and Bacteria are prokaryotes.

Each purple circle is a single bacteria cell. In the petri dish, the big blobs are called colonies. There can be thousands of bacteria cells in one blob. This particular bacteria is Streptococcus pyogenes.

The same bacteria that causes strep throat!

Recall that cells are living systems that consist of smaller structures that each perform a function. The smaller structures within cells are called organelles. Prokaryotic cells contain a small number of organelles, including:

• plasma membrane

• cell wall

• cytoplasm

• ribosomes

​Prokaryotic cells always contain a plasma membrane, which is a flexible barrier that surrounds the cell and holds the cell contents inside. Prokaryotes also contain cytoplasm, a jelly-like substance that surrounds and supports the other organelles. Instead of being surrounded by a nucleus, the DNA floats freely in the cytoplasm in a region called the nucleoid.

What could we compare this to in a city?

​Plasma Membrane

Ribosomes are organelles that produce proteins. Ribosomes are one of the tiniest organelles and are present in all prokaryotes. In diagrams, they are usually drawn as dots. You can view the ribosomes and plasma membrane in this diagram.

What could we compare this to in a city?

Ribosomes

The vast majority of prokaryotes also contain cell walls, which provide rigid support and protection, just outside of the plasma membrane. The other organelles shown in this diagram occur in some, but not all, prokaryotes.

What could we compare this to in a city?

Cell Wall

Cytoplasm is the watery substance inside of the cell!

The primary function of cytoplasm is to provide a medium for cellular processes, suspend organelles, and maintain the cell's shape and structure.


What could we compare this to in a city?

Cytoplasm

Multiple Choice

What is bigger? An atom or a cell?

• Atom

• Cell

​Relative Sizes of Biological Structures

​In addition to membrane-bound organelles, eukaryotic cells also contain many of the same organelles as prokaryotes. Like prokaryotes, all eukaryotic cells contain:

• plasma membrane

• cytoplasm

• ribosomes

​Now, you will view a eukaryote using a microscope.

Obtain slide 20, Dog Stomach Pyloric Region, section.

View the slide on all three magnifications.

​​The Dog Stomach Pyloric Region, section should look like this!

Here is a comparison between prokaryotic and eukaryotic cells under a high-powered microscope. Which is which?

​Prokaryotic vs. Eukaryotic Cells Video

Multiple Select

Which organelles are found in both prokaryotic and eukaryotic cells?

Select 3 of the 4

• ribosome

• plasma membrane

• cytoplasm

• nucleus

​GIMKIT!!! Quiz Monday!