cell theory assignments

It's All About Cell Theory

Engage: what do you think.

Print a copy of the "What Do You Think? Anticipation Guide" handout found in Related Items .  Read each statement. If you agree with the statement, circle  A     in the Before Learning column on your handout. If you disagree with the statement, circle D   in the Before Learning column. 

Be sure to keep this anticipation guide. You will complete the last column in Elaborate 2.

In this lesson, you will learn

• how cells were first discovered,
• how the cell theory was developed, and
• the main components of the cell theory.

Explore: Cells—Necessary for Life?

  Listen for the answers to the following questions.

• What are some functions of, or jobs performed  by, organelles found in cells?
• What tools are used to study cells?
• What are the parts of the cell theory?
• Which scientists were involved in the development of the cell theory?

The "Cells—Necessary for Life?" handout is provided to record your answers.   The handout is located in Related Items . 

Explain 1: Development of the Cell Theory

Watch the video about the cell theory.

Watch the video a second time and complete the "Cell Theory" handout located in  Related Items.

Explain 2: Who Would Have Said. . .

Many times in science, the work of one scientist leads to a new development or discovery by another scientist. The development of the   cell theory would not have been possible without the invention of the microscope and the use of the microscope to look at the structure of   living things.

In the following activity, match the scientist with the best description of that scientist’s contribution. Refer to your Explore "Cells—Necessary for Life?" and Explain "Cell Theory" handouts if needed.

Elaborate 1: Understanding the Cell Theory

Life on Earth is very diverse. Organisms are diverse; each has a specific role in its ecosystem. From the frozen tundra to the tropical rainforests to the arid deserts, every species is different and uniquely adapted to survive in a specific environment.

While living things can be very different, they are alike in one fundamental way. All living things are made of cells. Cells are the building blocks of life on Earth.

In the following sorting activity, determine the best placement for each descriptor as it relates to the cell theory.

To retake the quiz, reload the page and then select No when the Resume Quiz dialog box appears.

Elaborate 2: What Did You Learn?

Revisit your "What Do You Think? Anticipation Guide" handout from Engage. 

Reread each statement. In the After Learning column of your handout, circle A  if you agree with the statement or D if you disagree with the statement.

Compare your answers with those in the Before Learning column. Then, check your answers with the answer key located in Related Items .

What did you learn about the cell theory?

Evaluate: Assess Your Learning!

Follow the directions to complete the assessment. To retake the quiz, reload the page and then select No when the Resume Quiz dialog box appears.

Teacher Notes

In this lesson, students recognize the components of the cell theory, TEKS (7)(12)(F). The contributions of scientists, TEKS (7)(3)(D), as they relate to the cell theory are embedded throughout the lesson.

Copy and paste the link code above.

Related Items

• school Campus Bookshelves
• menu_book Bookshelves
• perm_media Learning Objects
• login Login
• how_to_reg Request Instructor Account
• hub Instructor Commons
• Download Page (PDF)
• Download Full Book (PDF)
• Periodic Table
• Physics Constants
• Scientific Calculator
• Reference & Cite
• Tools expand_more
• Readability

selected template will load here

This action is not available.

4.3: Studying Cells - Cell Theory

• Last updated
• Save as PDF
• Page ID 12710

Learning Objectives

• Identify the components of cell theory

Cell Theory

The microscopes we use today are far more complex than those used in the 1600s by Antony van Leeuwenhoek, a Dutch shopkeeper who had great skill in crafting lenses. Despite the limitations of his now-ancient lenses, van Leeuwenhoek observed the movements of protista (a type of single-celled organism) and sperm, which he collectively termed “animalcules. ”

In a 1665 publication called Micrographia , experimental scientist Robert Hooke coined the term “cell” for the box-like structures he observed when viewing cork tissue through a lens. In the 1670s, van Leeuwenhoek discovered bacteria and protozoa. Later advances in lenses, microscope construction, and staining techniques enabled other scientists to see some components inside cells.

By the late 1830s, botanist Matthias Schleiden and zoologist Theodor Schwann were studying tissues and proposed the unified cell theory. The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells. Rudolf Virchow later made important contributions to this theory.

Schleiden and Schwann proposed spontaneous generation as the method for cell origination, but spontaneous generation (also called abiogenesis) was later disproven. Rudolf Virchow famously stated “Omnis cellula e cellula”… “All cells only arise from pre-existing cells. “The parts of the theory that did not have to do with the origin of cells, however, held up to scientific scrutiny and are widely agreed upon by the scientific community today. The generally accepted portions of the modern Cell Theory are as follows:

• The cell is the fundamental unit of structure and function in living things.
• All organisms are made up of one or more cells.
• Cells arise from other cells through cellular division.

The expanded version of the cell theory can also include:

• Cells carry genetic material passed to daughter cells during cellular division
• All cells are essentially the same in chemical composition
• Energy flow (metabolism and biochemistry) occurs within cells
• The cell theory describes the basic properties of all cells.
• The three scientists that contributed to the development of cell theory are Matthias Schleiden, Theodor Schwann, and Rudolf Virchow.
• A component of the cell theory is that all living things are composed of one or more cells.
• A component of the cell theory is that the cell is the basic unit of life.
• A component of the cell theory is that all new cells arise from existing cells.
• cell theory : The scientific theory that all living organisms are made of cells as the smallest functional unit.

Want to create or adapt books like this? Learn more about how Pressbooks supports open publishing practices.

Cell Theory

Cell theory of life.

Most cells are tiny; so tiny, in fact, that it wasn’t until the invention of the microscope in the 1600s that humans were aware of the existence of this minuscule building blocks of life.  Once the existence of cells was recognized, it took scientists many more years to truly understand the significance of these important units.

In the 1800s, several scientists investigating cells were able to devise what is known today as the ‘Cell Theory of Life’, which describes common attributes of cells.  Contributors to this theory included Matthias Jakob Schleiden and Theodor Schwann.

The Cell Theory has become accepted as one of the most fundamental concepts in biology.  The Cell Theory consists of three key principles:

• Every organism is comprised of one or more cells
• The cell is the most basic unit of life
• All cells are derived from preexisting cells

Through further scientific investigation of cells over the ensuing centuries, scientists have also discovered that all cells share other properties, including:

• A plasma membrane which surrounds the cell and separates the internal environment of the cell from the external environment.  The plasma membrane also plays a significant role in regulating the transport of water and nutrients across its boundary
• The presence of cytoplasm , a fluid environment inside of the cell, containing water, salts and various macromolecules.  Most of the chemical reactions that support life occur in the cytoplasm.
• The use of DNA as genetic material.  DNA provides the genetic blueprint necessary to allow cells to reproduce and carry out their specific function(s) while the RNA molecule represents copies of specific genes which are used to build proteins inside the cell.

The video below presents the key principles of the ‘Cell Theory of Life’

BIO109 Biology I Introduction to Biology Copyright © by Diane Rinehart. All Rights Reserved.

Share This Book

Lesson Plan: Robert Hooke’s Contributions to Cells and the Cell Theory

Interactive Notebooks , Lesson Plans

We are fascinated by cells! But, “cells” might be one of the most difficult life science topics for middle school students. Even though most students learn about cells in elementary school, many middle schoolers don’t remember much about them. The idea of a cell, and all of its vital roles, is just so amazingly abstract it is difficult for many students to conceptualize. For that reason, we like to spend some time exploring “What is a Cell?”  We love to paint a picture to help students understand the excitement scientists felt upon seeing the first cells under a microscope or discovering that life doesn’t just “POOF!” and spontaneously generate out of thin air. By the end of this lesson students should be able to explain Robert Hooke’s contribution to cell studies and explain the cell theory.

Here’s what we’d typically do:

Sponge or bell work: Our lesson always starts with a bell-work question or activity that gets kids thinking about the topic at hand. For example:

• Ask the students: What is a cell, and how do you see it? What do cells do? Where did the word cell come from anyway?
• Begin the KWL template from our  Cells Interactive Notebook activities
• One thing we love about teaching Science is making it fun for kids and this video , ‘The Wacky History of the Cell Theory,’ (TedEd) is a great way to engage your students with lighthearted humor and solid scientific background knowledge.

Let’s Explore: Set-up stations to allow students to explore background information about Robert Hooke. You can provide laptops with suggested websites, printed articles, and even class textbooks. Students can use their own devices at BYOD schools.  Or we have a great set of Cell Theory STEAM based lab stations  in which students will learn about the discovery of the cell, cell theory, the scientists that developed it, microscope discovery, and usage. Have students complete the “Robert Hooke’s Contribution to Cell Studies” template from the Cells Interactive Notebook .

Cell Theory: An Overview

Microorganisms were unknown before the invention of improved microscopes, and human beings were believed to be the fundamental building blocks of life. Early scientists could observe cells and make assumptions about what they witnessed. It is rarely possible to know how a cell operates under a microscope.

This theory is based on the observation that all microscopically observed organisms can be easily separated into various distinct cells. Some cells, like a frog egg, are enormous. Some bacterial cells, for example, are so tiny that we can hardly detect them under a standard light microscope.

Table of Contents

History and contributions, parts of cell theory.

• Frequently Asked Questions (FAQs)

A postulated and widely accepted hypothesis of how most life on Earth operates is known as the “cell theory.” The hypothesis states that cells comprise all organisms. Organs, tissues, and organisms are made up of groups of cells. These are the fundamental assumptions of cell theory.

The modern iteration of the cell theory consists of the following concepts:

• Energy moves through cells.
• DNA is transferred from cell to cell, carrying genetic information.
• All cells share the same primary chemical makeup.

In addition to cell theory, the fundamental precepts that serve as the basis for studying life include evolution, homeostasis, gene theory, and the laws of thermodynamics.

Magnification technology progressed to the point that it could be used to find cells due to ongoing advances in microscopes. Robert Hooke is usually credited with making this discovery, which launched cell biology as a field of study. Under the scope, he could discern pores in a piece of cork.

Schleiden and Schwann first proposed the cell theory, which was later modified by Rudolf Virchow. Since the discovery of the first cells , cell theory has evolved and grown, and many amazing experiments have been designed to demonstrate its many components.

There are three main postulates of cell theory are as follows:

• First, cells make up all living things.
• Second, cells are the basic building blocks for developing tissues, organs, and fully developed living creatures.
• The third, and maybe most crucial, aspect of the hypothesis is that cells can only develop from other cells.

Thus, all living things begin as individual cells. These cells multiply, divide through mitosis, and eventually form multicellular organisms. Mitosis is a type of cell division that yields identical cells. When mixed signals are applied to these cells, they can differentiate to form various tissues and organs. This is the process used to produce enormous, complex organisms. However, when a single-celled organism divides, the cells split into two new organisms. This process of reproduction is asexual.

Prokaryotes

Prokaryotes are generally small cells that are enclosed by the plasma membrane. Depending on the species, they have a distinctive cell wall, varying in composition. Prokaryotes do not contain a nucleus and membrane-bound organelles. They possess circular or linear DNA. The chromosomal area and the cytoplasm are found in the protoplasm of prokaryotes. Prokaryotes are divided into two domains: archaea and bacteria .

Eukaryotic cells have a nucleus, organelles, and a plasma membrane surrounding them. Eukaryotic cells evolved particular organelles, parts of the cell that have a specific function. These organelles include the endoplasmic reticulum, which sorts and bundles proteins; the mitochondria, which provide energy; and chloroplasts, found in plants and produce food from sunlight and carbon dioxide.

Related Link: Difference between Prokaryotic and Eukaryotic Cells

Single-celled Organisms

Cell theory can be well understood by looking at single-celled species. Modern microscopes made it simple to observe and study cell theory mechanisms. Placing a drop of pond water under a microscope provides an excellent opportunity to observe the application of the cell theory.

Cells were first observed in plants. Plants may maintain their rigidity because of the sizeable cell walls. The first person to identify cells was Robert Hooke, who used a simple microscope focused on a thin cork slice. He assumed that the structures were exclusive to plant tissues. Cell theory was not widely recognised by science until the 1840s.

Scientist Theodor Schwann produced evidence in 1839 demonstrating that animals were made up of several cell types. Compared to earlier scientists, modern microscopy techniques give scientists a more complete and accurate image of cells.

Every cell in the human body is a different type of cell. According to cell theory, each of these cells originated from the zygote, a single cell produced upon the fertilisation of an egg by a sperm. Then, this cell multiplies, divides, and starts differentiating into the various types of cells that make up the human body. A fully developed organism is eventually formed.

Related Links:

• Eukaryotic Cells
• Cell Biology
• Cell Organelles

Visit BYJU’S Biology for more information.

Frequently Asked Questions – FAQs

Mention the principle theories of cells..

• Every living thing consists of one or more cells.
• Cells are the primary functional and structural component of all life.
• Every cell develops from a preceding cell.

Why is cell theory important?

• Share Share

Register with BYJU'S & Download Free PDFs

Register with byju's & watch live videos.

The Cell Theory

In biology, cell theory is a scientific theory which describes the properties of cells. This lecture briefly present on the Cell Theory. Here also focus on discovery of Cells. 1665- English Scientist, Robert Hooke, discovered cells while looking at a thin slice of cork. He described the cells as tiny boxes or a honeycomb. He thought that cells only existed in plants and fungi. The average human being is composed of around 100 Trillion individual cells! It would take as many as 50 cells to cover the area of a dot on the letter “i”.

Fertilisers and Pesticides

Control of the heart beat, food pyramid, intensive farming for minimising energy loss, star’s strange composition points to new type of explosion 10 times larger than supernova, a visit to a historical place/building (al-kadhimiya mosque, iraq), the station: uber slurps up drizly, ford doubles its ev budget and rad power bikes plots an expansion, lecture on legal issues for the entrepreneur, open market operations, flu symptoms, latest post, inflatable building, palaeogeography – a study of historical geography, physicists build more effective solar cells, potassium depletion in soils threatens global agriculture yields, scientists create an ultra-thin, minimally invasive pacemaker operated by light, geodynamics – a subfield of geophysics.