NTA Level 4 • Semester 1 • PST04103

Structure, Types and Functions of Cells

Human Anatomy and Physiology • Source Session/Topic 2

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Session 2: Structure, Types and Functions of Cells

Total Session Time: 120 minutes + 60 minutes take home assignment

Prerequisites

• None

Learning Tasks

By the end of this session students are expected to be able to:

• Define the Cell

• Mention Types of Cells

• Describe the Structure of the Generalized Animal Cell

• Describe Characteristics of the Animal Cell

• Outline Functions of the Animal Cell

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board, chalk and whiteboard markers

• Charts, OHP, Multimedia Projector, Computer, Pointer

SESSION OVERVIEW

SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing

STEP 2: Definition of the Cell (10 minutes)

|Activity: Brainstorming (5 minutes) |

| |

|Ask students to brainstorm on the following question: |

| |

|What is a cell? |

| |

|ALLOW few students to respond |

| |

|WRITE their responses on the flip chart/ board |

| |

|CLARIFY and SUMMARISE by using the content below |

• A cell:

o Is the smallest living structural and functional unit of life

▪ It is the smallest unit of an organism that is classified as living,

and is often called building block of life

▪ All cells come from pre-existing cells

▪ Most cells are microscopic and can replicate independently

▪ Some organisms are unicellular (consist of a single cell) e.g. some

bacteria

▪ Other organisms are multicellular(consist of many cells) e.g. humans

▪ Vital functions of an organism occur within cells, and all cells

contain the hereditary information necessary for regulating cell

functions and for transmitting information to the next generation of

cells

▪ Cells of the body perform specific functions, and therefore their

structures vary greatly

STEP 3: Types of Cells (15 minutes)

|Activity: Buzzing (5 minutes) |

| |

|ASK students to pair up and buzz on the following question for 5 |

|minutes |

| |

|What are the types of cells? |

| |

|ALLOW few pairs to respond and let other pairs to add on points not |

|mentioned |

| |

|WRITE their response on the flip chart/board |

| |

|CLARIFY and SUMMARIZE by using the content below |

• There are two types of cells:

o Eukaryotic

o Prokaryotic

Eukaryotic Cells

• Cells in higher animals (mammals) are eukaryotic, that is they have

membrane bound nucleus, which is well protected, inside the cell

• Eukaryotic cells are often found in multicellular organisms

• Eukaryote is an organism whose cells contain complex structures inside

the membranes

• Most eukaryotic cells also contain other membrane-bound organelles such a

mitochondria, and the Golgi apparatus

• Eukaryotes do have "true" nuclei containing DNA

• Eukaryotic organisms may be unicellular, as in amoebae, or multicellular,

as in humans

• Cell division in eukaryotes is different from that in organisms without a

nucleus (prokaryotes)

Prokaryotic Cells

• Do not contain membrane bound organelles and genetic material is

scattered in the cytoplasm

• The simple forms of life like bacteria are made up entirely of single

cell are prokaryotic, the nucleus is not membrane bound it is scattered

in the protoplasm and is vulnerable

• Prokaryotic cells are usually independent

• Prokaryotes generally lack membrane-bound cell compartments: such as

mitochondria and chloroplasts.

• Instead processes such as oxidative phosphorylation and photosynthesis

take place across the prokaryotic plasma membrane.

• However, prokaryotes do possess some internal structures, such as

cytoskeletons.

• Prokaryotes also differ from eukaryotes in that they contain only a

single loop of stable chromosomal DNA stored in an area named the

nucleoid, while eukaryote

• DNA is found on tightly bound and organized chromosomes

STEP 4: Structure of a Generalized Animal Cell (50 minutes)

| |

|Activity: Small Group Discussion ( 30 minutes) |

| |

|DIVIDE students into small manageable groups |

| |

|ASK students to discuss on the following task: |

|Draw and label major parts of a generalized animal cell by using |

|various resources |

| |

|ALLOW students to do the task for 20 minutes |

| |

|ALLOW few groups to present and the rest to add points not mentioned |

| |

|CLARIFY and SUMMARIZE by using the contents below |

Structure of a generalized animal cell

• The cell is divided into three main parts namely: plasma membrane,

cytoplasm and nucleus

• The plasma membrane: Forms the cell’s outer surface separating the cell’s

internal environment from the external environment. It regulates the flow

of material into and out of the cell

• The cytoplasm: It is the fluid-filled cell interior. It has two

components: cytosol and organelles.

o The cytosol is the liquid portion containing water and dissolved

solutes.

o The organelles are small structures with highly specialized

functions, many of which are contained within a membrane.

▪ They include nucleus, mitochondria, ribosomes, endoplasmic

reticulum (ER), Golgi apparatus, cell membrane, microfilaments

and microtubules.

• The Nucleus: It is the large organelle that stores genetic information as

DNA. It controls all the activities of the cell.

[pic]

Source: EnchantedLearning.com (2015)

Figure 1.1: The Generalized Animal Cell

STEP 5: Characteristics of the Cell (10 minutes)

• Certain processes distinguish living things from non-living things

• The following are six most important characteristics of the cell:

o Metabolism-are the sum of all chemical processes that occur in the

body including anabolism and catabolism.

o Responsiveness- ability to detect and respond to changes like

temperature, pressure, sound etc.

o Movement- includes motion of the whole cell and tiny structures inside

the cell.

o Growth- is the increase in the size and number of the existing cells.

o Differentiation- the development of a cell from unspecialized to

specialized state

o Reproduction- the formation of new cells for tissue growth, repair and

replacement or to the production of a new individual.

STEP 6: Functions of the Human Cell (15 Minutes)

The functions of animal cell are all carried out by the different cell

organelles

These cell organelles function as a unit and regulate the activities of

the cell on the whole.

Cell nucleus

• The nucleus is referred to as the heart of the cell

• The nucleus houses the genetic material of the organism which is the DNA.

• DNA replication and RNA synthesis occurs in the nucleus.

Mitochondria

• The mitochondria is also referred to as the power house of the cell

• It is a double membrane organelle

• It helps in energy production for the cell.

• The energy is generated in the form of ATP from the glucose.

• This occurs in the process called cellular respiration.

Endoplasmic Reticulum

• The endoplasmic reticulum is a network for transportation of certain

critical substances in and out of the nucleus.

• There are two kinds of ER namely

o Rough ER a

o Smooth ER.

• Rough ER has ribosome molecules attached to its surface

• Smooth ER does not have ribosome molecules attached to its surface

Golgi apparatus

• Is involved with processing and packaging of the molecules synthesized by

the cell mainly the proteins ready for secretion

• The ER transports the proteins in their crude form to the golgi

apparatus

Ribosomes

• Is involved in protein synthesis. It consists of two sub units

• Protein synthesis primarily occurs in the ribosomes

• The ribosomes may be found freely floating in the cytoplasm or may be

found attached to the ER

Lysosomes

• Are referred to as suicide bags of the cell.

• They are involved in clearing the unwanted and waste materials from the

cell

• The lysosomes contain hydrolytic enzymes that are destructive.

• They kill the toxic materials of the cell time to time.

• They engulf materials like damaged organelles, virus, bacteria and food

particles

Vacuole

• The vacuole is a large empty storage organelle.

• They store excess water or food. It is present in many numbers within the

cell floating in the cytoplasm

STEP 7: Key Points (5 minutes)

• Cell is the smallest living structural and functional unit of life

• The cell is divided into three main parts namely plasma membrane,

cytoplasm and nucleus

• There are two types of cells: Eukaryotic and Prokaryotic

• There are six most important characteristics of the cell

• The functions of animal cell are all carried out by the different cell

organelles

STEP 8: Evaluation (5 hours)

• What is a cell?

• What are the three main parts of the animal cell?

• What are the functions of nucleus?

• Mention types of cell?

• What are the functions of animal cell?

Step 9: Assignment (10 minutes)

|Activity: Take Home Assignment (10 minutes) |

| |

|DIVIDE learners in groups or individual. |

| |

|ASK the learners to work on the following assignment |

| |

|Explain function of animal cell organelle |

| |

|ALLOCATE time for learners to do the assignment and submit |

| |

|REFER learners to recommended references |

References

Enchanted Learning (2015). Animal Cell. Retrieved from:

http://www.enchantedlearning.com/subjects/animals/cell/. Retrieved

September 2015

Kumar, A. et al (2004). Robbins Basic Pathology. WB: Saunders.

Spector, T.D. & Axford, J. S. (1999). Introduction to General Pathology.

Edinburgh:

Seeley, R. R., Stephens, T. D.& Tate, P. (2003). Anatomy and Physiology.

New York:

McGraw-Hill

Shier, A., Butler, J., & Lewis, R. (2004). Hole’s Human Anatomy &

Physiology. New York:

McGraw-Hill

Standring, S. (2008). Grays’s Anatomy The anatomical basis of clinical

practice. United

Kingdom: Churchill Livingstone Elservier.

Thibodeau, G. A., & Patton, K. T. (1999). Anatomy & Physiology. Saint

Louis: Mosby,

Von Hoffman Press, Inc.

Tortora, G.J & Derrickson, B (2009). Principles of Anatomy and Physiology

12th Edition,

USA, John Wiley & Sons Inc, USA

Walter, J.B, & Talbot, I. C. (1996). General Pathology. New York: Churchill

Livingstone

Waugh, A. & Grant, A. (2006). Ross and Willson Anatomy and physiology in

Health and

illness. United Kingdom: Churchill Livingstone Elservier

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