2.1 Cellular Metabolism

Introduction

Metabolism refers to the chemical reactions that take place within an organism by which complex molecules are broken down to produce energy, and by which energy is used to build up complex molecules. An example of a metabolic reaction is the one that takes place when a person eats a spoonful of sugar.

Metabolism is the set of chemical reactions that occur in living organisms to maintain life. These processes are carried out by the individual cells that make up the organism. As you have learned, the cell is the basic building block of all higher organisms.

All living things are made from one or more cells and as a human; you are essentially the sum of your parts.

 

Cells are tiny compartments that must perform essential tasks such as:

• obtaining food and energy
• converting energy for use inside the cell
• constructing and maintaining cell structures
• carrying out chemical reactions
• eliminating waste
• reproducing
• keeping blueprints for constructing cell structures (chromosomes)

Organisms that exist as single cells are called unicellular and organisms that are made up of groups of cells working together are called multicellular.

 
Unicellular and Multicellular OrganismUnicellular Organism:

An organism with just one (1) cell
Multicellular Organism: An organism made up of more than one (1) cell

All living things are categorized into two groups depending on the features of the cells – prokaryotes and eukaryotes.
Humans are made up of around 100 trillion cells. Watch the video below for more information.

 

 

                                         

Prokaryotes

Prokaryotes are a group of organisms that lack a cell nucleus or any other membrane-bound organelle. Most are unicellular, but a few prokaryotes, such as myxobacteria, have multicellular stages in their life cycles. These organisms were originally thought to live only in inhospitable conditions, such as extreme temperatures, pH, and radiation, but have since been found in all types of habitats. Examples of prokaryotes are bacteria and Archaea. They are as unrelated to human beings as living things can be, but bacteria are essential to all life on planet Earth.

Although prokaryotes are notorious for their role in causing human diseases from tooth decay to the Black Plague, there are beneficial species that are essential to good health. For example, one species that lives symbiotically in the large intestine manufactures vitamin K, an essential blood-clotting factor. Other species can be beneficial indirectly.

Eukaryotes

A eukaryote is any organism whose cells contain complex structures enclosed within membranes. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear envelope, within which the genetic material is carried. Most eukaryotic cells also contain other membrane-bound organelles, such as mitochondria, chloroplasts, and the Golgi apparatus. Almost all species of large organisms are eukaryotes, including animals, plants, and fungi.

In summary, prokaryote cells are smaller and simpler than eukaryote cells, but most importantly the difference is the absence or presence of a nucleus.

 

There are many types of organisms so it helps to classify them.

 

Organelle

Eukaryotic cells contain highly specialized structures called organelles.

In cell biology, an organelle is a specialized part of a cell that has a specific function that is usually separately enclosed within its own thin, flexible membrane.

Organelles work with each other to carry out cell processes. Proteins, lipids, and energy are just a few examples of products the different organelles make that are used in your body on a daily basis. The name organelle comes from the idea that these structures are to cells as an organ is to the body. Below are a few images of organelles and their functions.

 

Electron micrograph of a mitochondrion from mammalian lung tissue showing its matrix and membranes.

 

The mitochondrion is sometimes referred to as the powerhouse of the cell. Within every cell is this small but important structure. Mitochondria are largely responsible for providing the cell with energy from glucose (sugar) through a process called aerobic respiration. These structures produce the energy an organism needs in order to perform all other actions.

 

Cells stained for DNA. The central and rightmost cells are between divisions, thus their entire nuclei are visible.
On the left, a cell is going through cell division and its DNA has condensed and is ready for division.

 

The nucleus is the large, round structure located around the middle of the cell. It is the control center of the cell, directing all of the cell's activities. The chromosomes that contain your DNA are stored in this organelle.

Chromatin is a “thread-like” material inside the nucleus. This material contains genetic information called DNA (deoxyribonucleic acid), a substance that chromosomes are composed of that makes up the genetic code.

 

A cell in late metaphase.

 

Vacuoles are large, “sac-like” structures that help keep plant cells rigid. Unlike animal cells, plant cells do not have muscles to keep their shape. Therefore, the pressure of fluid inside a vacuole causes the plant to stay rigid; when the vacuole becomes empty, the plant is low on water and it wilts. The vacuole also stores water, food, wastes, and other materials for use by the cell.

 

Plant cell with chloroplasts and part of the nucleus against the cell membrane. A large vacuole fills most of the space of the cell.

 

Chloroplasts are the organelles that look like a cucumber structure. They contain the substance called chlorophyll that permits plants to make their own food (energy) from the solar energy of the Sun, through a process called photosynthesis.

 

Chloroplasts visible in the cells of Plagiomnium affine – Many-fruited Thyme-moss.

ePortfolio Submission: Venn Diagram - Prokaryote and Eukaryote Organisms 

For this activity, you will create a Venn Diagram to compare and contrast Prokaryote and Eukaryote Organisms.
Save this study aid and add it to your ePortfolio.  

To learn more about the Venn diagram, please continue reading below.

What is a Venn Diagram? 

A Venn diagram is a visual representation of the similarities and differences between two or more different items. It consists of a series of shapes - usually circles - whose edges overlap.

Below is an example of a Venn diagram comparing a Whale and a Fish 

       

    Title: A Comparison between a Whale and a Fish

How to Make a Venn Diagram