The Basic Structure of the Cell in Animals and Plants

Introduction

The cell is the basic functional and structural unit of life. Human beings are multi-cellular animals. What this means is that we humans are made of many cells of cells as opposed to unicellular organisms which are composed of only one cell. The cells in a lot of multi-cellular animals and plants are specialized.

This means that each of them carries out a specific function and when all the cells combine together with their functions, they can share out the processes of life. Each cell is dependent on the other and all of them function collaboratively to support the diverse processes in an organism.

Below are examples of some specialized animal and plant cells, together with their functions and special features.

Types of Animal Cell

1.     Red Blood Cell: The red blood cell has large surface area for oxygen to pass through. It’s major function is to transport oxygen round the body. The red blood cell contains haemoglobin, which reacts with oxygen to form oxyhaemoglobin.

2.     Nerve Cells: Nerve cells transport nervous impulses to various parts of the body. It has a long connection at each end and has the capacity to carry electrical signals.

3.     Female Reproductive Cell: This is also known as the egg cell. The egg cell’s function is to combine with the male cell, and subsequently to make food available for the new cell that was formed  The egg cell is large and contains a lot of cytoplasm.

4.     Male Reproductive Cell: This is also known as the sperm cell. The sperm cell function is to travel up and meet with egg cell for a fusion to form a zygote. The sperm cell has an elongated tail for swimming as well as a head which enables it to get attached with the female egg cell for a fusion.

Types of Plant Cells

1.        Root hair cell: The root hair cell absorbs water and minerals from the soil. It has a large surface area.

2.       Leaf cell: The leaf cell absorbs sunlight for the process of photosynthesis. It has large surface area and lots of chloroplasts

Comparison chart between plant and animal cell

Plant and animal cells have quite a few differences and similarities. For instance, animal cells do not have a cell wall or chloroplasts but plant cells have them. Animal cells are round and irregular in shape whereas plant cells have fixed rectangular shapes.

The table below makes it clearer.

S/NO	Features	Animal Cell	Plant Cell
1	Cell wall	Absent	Present- formed from cellulose; hence it is called cellulose cell wall
2	Shape	Round or irregular shape	Rectangular or fixed shape
3	Vacoule	Contains one or more small vacuoles	Has one central vacuole that occupies about 90% of cell volume
4	Centrioles	Present in all animal cells	Only present in lower plant forms
5	Chloroplast	Absent	Plants have both chloroplasts and chlorophyll because they are autotrophs that manufacture their own food
6	Cytoplasm	Present	Present
7	Endoplasmic Reticulum	Present	Present
8	Ribosomes	Present	Present
9	Mitochondria	Present	Present
10	Plastids	Absent	Present
11	Golgi Apparatus	Present	Present
12	Plasma membrane	Have only cell membrane	Have a cell wall and a cell membrane
13	Microtubules/Microfilaments	Present	Present
14	Flagella	May be found in some animal cells	May be found in some plant cells
15	Lysosomes	Occur in cytoplasm	Usually not present
16	Nucleus	Present	Present
17	Cilia	Present	Very rare

In conclusion, both the animal cells and plant cells contain:

•       Cell membrane

•       Cytoplasm

•       Nucleus

Plant cells in addition to possessing these features also found in
animal cells, has:

•       Chloroplasts

•       Vacuole

•       Cell wall

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Pathogens; Understanding Diseases and How to Prevent Them

Definition

Pathogens are biological agents in form of micro-organisms that causes disease or illness to their host. The white blood cells in animals produce anti-bodies that can destroy these pathogens.  What these pathogens do is to disrupt the normal body processes the moment they gain access to our bodies.

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4 Major Types of Pathogens

* Bacteria

* Virus

* Fungi

* Protozoa

Bacterium Defined

This is a microscopic living organism that can be found everywhere. In human body it can be both beneficial and dangerous. Bacterium helps in food digestion. However, it can cause the human body dangerous diseases.

They are single-cell organisms without a nucleus.

Diseases spread by Bacteria

Staph infection, tetanus, pneumonia, syphilis, typhoid, cholera, tuberculosis, strep throat, food poisoning etc.

Virus Defined: 

This is a microscopic agent that causes diseases to its host by replicating itself. Virus cannot live long or replicate without a host.

   

Diseases Spread by Virus:

HIV/AIDS, Influenza, Hepatistis, Common cold, chicken pox, small pox, genital herpes, genital warts, cold sores, measles, flu, polio, ebola, frequent vomiting etc.

Fungus Defined 

A disease carrying microscopic agent that feeds on organic matter, usually found in moist environment. (Think of the molds in your unwashed plates and pots, athlete’s foot etc). Mushrooms and yeasts are examples of fungi.

        

Diseases spread by Fungi

Athlete’s foot, mushroom poisoning, some types of pneumonia, candidiasis (this can be found in the mouth, throat, vagina or bloodstream), ringworm, eye infection (usually after eye injury), meningitis etc.

Protozoa Defined: 

This is part of the protista family of pathogens. They are single-cell organisms with nucleus

Diseases spread by Protozoa

Malaria, travelers; diarrhea, trypanosomiasis (sleeping sickness) etc.

How diseases are spread

1.     Droplet infection: When you sneeze, cough or talk, you release tiny droplets in the air if you are already infected. Examples of diseases: tuberculosis, flu, common cold

2.     
       Direct contact of the skin: When you have a body contact with an infected skin. Examples of diseases: athlele’s foot, chicken pox, measles etc.

3.     
       Contaminated water/food: Eating food already contaminated by any of the disease-carrying agents. Example of diseases: cholera

4.    Body fluid: having a fluid contact with the blood or semen of the infected person. Example of diseases: hepatitis, HIV/AIDS, others STDs(Sexually-Transmitted Diseases)

5.    Vectors: These are animals that spread disease-causing pathogens: Example of diseases: housefly causing dysentery; mosquito causing malaria; tsetse fly causing (trypanosomiasis) sleeping sickness etc.

Common Disease Preventive Measures

There are many ways we can prevent or attack the various diseases caused by these pathogens. This includes:

a.     Use of vaccination;  b. use of antibiotics and fungicides (let this be taken moderately);  c. food safety;  d. environmental hygiene;  e. water treatment  

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