<meta http-equiv="refresh" content="1; url=/nojavascript/"> Prokaryotic and Eukaryotic Cells | CK-12 Foundation
Dismiss
Skip Navigation

2.2: Prokaryotic and Eukaryotic Cells

Difficulty Level: At Grade Created by: CK-12
%
Progress
Practice Prokaryotic and Eukaryotic Cells
Practice
Progress
%
Practice Now

How many different types of cells are there?

There are many different types of cells. For example, in you there are blood cells and skin cells and bone cells and even bacteria. Here we have drawings of bacteria and human cells. Can you tell which depicts various types of bacteria? However, all cells - whether from bacteria, human, or any other organism - will be one of two general types. In fact, all cells other than bacteria will be one type, and bacterial cells will be the other. And it all depends on how the cell stores its DNA.

Two Types of Cells

There is another basic cell structure that is present in many but not all living cells: the nucleus. The nucleus of a cell is a structure in the cytoplasm that is surrounded by a membrane (the nuclear membrane) and contains DNA. Based on whether they have a nucleus, there are two basic types of cells: prokaryotic cells and eukaryotic cells. You can watch animations of both types of cells at the link below. http://www.learnerstv.com/animation/animation.php?ani=162&cat=biology

Prokaryotic Cells

Prokaryotic cells are cells without a nucleus. The DNA in prokaryotic cells is in the cytoplasm rather than enclosed within a nuclear membrane. Prokaryotic cells are found in single-celled organisms, such as bacteria, like the one shown in Figure below . Organisms with prokaryotic cells are called prokaryotes . They were the first type of organisms to evolve and are still the most common organisms today.

A diagram of a typical prokaryotic cell and its structure

Prokaryotic Cell. This diagram shows the structure of a typical prokaryotic cell, a bacterium. Like other prokaryotic cells, this bacterial cell lacks a nucleus but has other cell parts, including a plasma membrane, cytoplasm, ribosomes, and DNA. Identify each of these parts in the diagram.

Bacteria are described in the following video http://www.youtube.com/watch?v=TDoGrbpJJ14 (18:26).

Eukaryotic Cells

Eukaryotic cells are cells that contain a nucleus. A typical eukaryotic cell is shown in Figure below . Eukaryotic cells are usually larger than prokaryotic cells, and they are found mainly in multicellular organisms. Organisms with eukaryotic cells are called eukaryotes , and they range from fungi to people.

Eukaryotic cells also contain other organelles besides the nucleus. An organelle is a structure within the cytoplasm that performs a specific job in the cell. Organelles called mitochondria, for example, provide energy to the cell, and organelles called vacuoles store substances in the cell. Organelles allow eukaryotic cells to carry out more functions than prokaryotic cells can. This allows eukaryotic cells to have greater cell specificity than prokaryotic cells. Ribosomes, the organelle where proteins are made, are the only organelles in prokaryotic cells.

A diagram of the parts of a typical eukaryotic cell

Eukaryotic Cell. Compare and contrast the eukaryotic cell shown here with the prokaryotic cell. What similarities and differences do you see?

In some ways, a cell resembles a plastic bag full of Jell-O. Its basic structure is a plasma membrane filled with cytoplasm. Like Jell-O containing mixed fruit, the cytoplasm of the cell also contains various structures, such as a nucleus and other organelles. You can also explore the structures of an interactive animal cell at this link: http://www.cellsalive.com/cells/cell_model.htm .

Summary

  • Prokaryotic cells are cells without a nucleus.
  • Eukaryotic cells are cells that contain a nucleus.
  • Eukaryotic cells have other organelles besides the nucleus. The only organelles in a prokaryotic cell are ribosomes.

Practice

Use these resources to answer the questions that follow.

Explore More I

  1. What types of organisms are prokaryotic?
  2. What organisms have eukaryotic cells?
  3. Compare prokaryotic to eukaryotic cells.
  4. Describe where the DNA is located in a prokaryotic cell.

Explore More II

  1. Which cells have a nucleus?
  2. Which cells usually form unicellular organisms?
  3. Which cells have ribosomes?
  4. Which cells have mitochondria?
  5. Which cells have DNA?

Explore More III

Review

  1. What is the cell nucleus?
  2. What is the main difference between prokaryotic and eukaryotic cells?
  3. Give an example of a prokaryotic cell.
  4. Define organelle.
  5. What is the advantage of having organelles?

Vocabulary

eukaryotic cell

eukaryotic cell

Cell that contains a nucleus and other membrane-bound organelles.
organelle

organelle

Structure within the cytoplasm of a cell; has a specific role.
prokaryote

prokaryote

Single-celled organism that lacks a nucleus or membrane-bound organelles.
prokaryotic cell

prokaryotic cell

Cell without a nucleus; characteristic of many, but not all, single-celled organisms.

Image Attributions

Description

Difficulty Level:

At Grade

Grades:

Date Created:

Feb 24, 2012

Last Modified:

Dec 17, 2014
You can only attach files to Modality which belong to you
If you would like to associate files with this Modality, please make a copy first.

Reviews

Please wait...
Please wait...
Image Detail
Sizes: Medium | Original
 
SCI.BIO.223.L.1

Original text