Exploring the Mysteries of Life's Building Blocks
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The Secrets Hidden in Cells
Cells are the fundamental units of life.
Whether they be unicellular or multicellular life forms, all living organisms are composed of and depend on cells to function normally.
Scientists estimate that our bodies contain anywhere from 75 to 100 trillion cells.
In addition, there are hundreds of different types of cells in the body.
Cells do everything from providing structure and stability to providing energy and a means of reproduction for an organism.
The following 10 facts about cells will provide you with well known and perhaps little known tidbits of information about cells.
The different types of cells in the body
The different types of cells in the body
Types of cells in the body: Cells in the human body number in the trillions and come in all shapes and sizes. These tiny structures are the basic unit of living organisms. Cells comprise tissues, tissues make up organs, organs form organ systems, and organ systems work together to create an organism and keep it alive.
Each type of cell in the human body is specially equipped for its role. Cells of the digestive system, for instance, are vastly different in structure and function from cells of the skeletal system. Cells of the body depend on each other to keep the body functioning as a unit. There are hundreds of types of cells, but the following are the 8 most common.
Skin cells
Bone cells
Blood cells
Muscle Cells
Endothelial Cells
Fat Cells
Pancreatic Cells
Nerve Cells
1mm = 1000 µm (Micrometer) - 1µm (Micrometer) - 1000 Nano meter
Cells are too Small to be Seen Without Magnification
Biologists are able to obtain detailed observations of cells with microscopes.
Cells range in size from 1 to 100 micrometers.
The study of cells, also called cell biology, would not have been possible without the invention of the microscope. With the advanced microscopes of today, such as the Scanning Electron Microscope and Transmission Electron Microscope, cell biologists are able to obtain detailed images of the smallest of cell structures
Primary Types of Cells
Primary Types of Cells
The Eukaryotic cells: nucleus is enclosed within a membrane.
Examples: Animals, plants, fungi, and protists
Prokaryotic cells : nucleus is not enclosed within a membrane.
Examples: bacteria and archaeans.
Eukaryotic cells
Eukaryotic cells are the type of cells that make up plants, animals, fungi, and protists.
They are more complex than prokaryotic cells, which are the type of cells that make up bacteria.
Eukaryotic cells have a NUCLEUS, which is a membrane-bound structure that contains the cell's DNA. The DNA contains the genetic instructions that control all of the cell's activities.
Eukaryotic cells also have a variety of other ORGANELLES, which are specialized structures that perform specific functions within the cell.
Some of the most important organelles in eukaryotic cells include:
Mitochondria: The mitochondria are the cell's power plants. They produce energy for the cell by breaking down glucose and other molecules.
Endoplasmic reticulum: The endoplasmic reticulum is a network of membranes that helps the cell synthesize proteins, carbohydrates, and lipids.
Golgi apparatus: The Golgi apparatus is responsible for packaging and shipping proteins and other cellular products to their destinations.
Ribosomes: Ribosomes are found in both the cytoplasm and the endoplasmic reticulum. They are responsible for assembling proteins from amino acids.
Lysosomes: Lysosomes are sacs of enzymes that break down cellular waste and foreign invaders.
Eukaryotic cells are much larger and more complex than prokaryotic cells. This is because they have a nucleus and other organelles that allow them to carry out a wider range of functions.
Eukaryotic cells | More details
Eukaryotic cells have a cell wall, which is a rigid structure that surrounds the cell and provides support and protection. The cell wall is made up of different materials depending on the type of eukaryotic cell. For example, the cell wall of plant cells is made up of cellulose, while the cell wall of fungal cells is made up of chitin.
Eukaryotic cells have a plasma membrane, which is a thin, flexible membrane that surrounds the cell and protects it from the environment. The plasma membrane is also responsible for transporting substances into and out of the cell.
Eukaryotic cells have a cytoplasm, which is the gel-like substance that fills the cell and contains all of the organelles.
Eukaryotic cells have a cytoskeleton, which is a network of protein fibers that provides support and structure to the cell. The cytoskeleton also helps the cell to move and to change shape.
Eukaryotic cells are essential for life. They make up all of the plants and animals on Earth, and they play a vital role in many important processes, such as growth, repair, and reproduction
Prokaryotic Single-Celled Organisms
Prokaryotic cells are the type of cells that make up bacteria and archaea. They are simpler than eukaryotic cells and do not have a nucleus or other organelles.
Prokaryotic Single-Celled Organisms were the Earliest and Most Primitive Forms of Life on Earth
Prokaryotes can live in environments that would be deadly to most other organisms.
For example, live in areas such as hydrothermal vents, hot springs, swamps, wetlands, and even animal intestines.
Prokaryotic cells are essential for life. They play a vital role in many important processes, such as decomposition, nitrogen fixation, and photosynthesis. Prokaryotic cells are also used in many industrial and medical processes
Prokaryotic cells | More details
Prokaryotic cells have a cell wall, which is a rigid structure that surrounds the cell and provides support and protection. The cell wall is made up of peptidoglycan, which is a type of carbohydrate that is also found in the cell walls of plants.
Prokaryotic cells have a plasma membrane, which is a thin, flexible membrane that surrounds the cell and protects it from the environment. The plasma membrane is also responsible for transporting substances into and out of the cell.
Prokaryotic cells have a cytoplasm, which is the gel-like substance that fills the cell and contains all of the organelles. The organelles in prokaryotic cells are not enclosed in membranes, unlike the organelles in eukaryotic cells.
Prokaryotic cells have a single chromosome, which is a circular piece of DNA that contains the cell's genetic information. The chromosome is located in the nucleoid, which is a region of the cytoplasm where the DNA is concentrated.
Prokaryotic cells can reproduce by binary fission, which is a process in which the cell divides into two identical daughter cells. Binary fission is a relatively simple process and can occur very quickly.
The key differences between prokaryotic cells and eukaryotic cells
There are More Bacterial Cells in the Body than Human Cells
Scientists have estimated that about 95% of all the cells in the body are bacteria. The vast majority of these microbes can be found within the digestive tract. Billions of bacteria also live on the skin.
Cells Contain Genetic Material
Cells contain DNA and RNA, the genetic information necessary for directing cellular activities.
DNA and RNA are molecules known as nucleic acids.
In prokaryotic cells, the single bacterial DNA molecule is not separated from the rest of the cell but coiled up in the nucleoid region.
In eukaryotic cells, DNA molecules are located within the cell's nucleus.
DNA and proteins are the major components of chromosomes.
Human cells contain 23 pairs of chromosomes (for a total of 46).
There are 22 pairs of autosomes (non-sex chromosomes) and one pair of sex chromosomes.
The X and Y sex chromosomes determine sex.
DNA
RNA
Organelles Which Carry Out Specific Functions
Organelles have a wide range of responsibilities within a cell that include everything from providing energy to producing hormones and enzymes. for example:
Nucleus - controls cell growth and reproduction.
Mitochondria - provide energy for the cell.
Endoplasmic Reticulum - synthesizes carbohydrates and lipids.
Golgi Complex - manufactures, stores, and ships certain cellular products.
Ribosomes - involved in protein synthesis.
Lysosomes - digest cellular macromolecules
Organelle
Varying Life Spans
Cells within the human body have different life spans based on the type and function of the cell. They can live anywhere from a few days to a year. Certain cells of the digestive tract live for only a few days, while some immune system cells can live for up to six weeks. Pancreatic cells can live for as long as a year.
For example, the lifespan of a mayfly is only a few days, while the lifespan of a Galapagos tortoise can be over 100 years.
Reproduce Through Different Methods
Cells divide and multiply in a process called cell reproduction. This process is essential for the growth and repair of our bodies.
There are two main types of cell reproduction: mitosis and meiosis.
Mitosis is the process of cell division that creates two identical daughter cells. This type of cell reproduction is responsible for the growth and repair of most cells in our bodies.
Meiosis is the process of cell division that creates four daughter cells, each with half the number of chromosomes as the parent cell. This type of cell reproduction is responsible for the production of gametes (sex cells), such as sperm and eggs.
Groups of Similar Cells Form Tissues
groups of similar cells that work together to perform a specific function form tissues. There are four main types of tissues in the human body:
Epithelial tissue covers the body's surfaces and lines its organs and cavities.
Connective tissue provides support and structure to the body.
Muscular tissue allows the body to move.
Neural tissue allows the body to sense and respond to its environment.
Each type of tissue is composed of different types of cells that have specialized functions. For example, epithelial cells are flat and tightly packed together to form a barrier that protects the body from the outside environment. Connective tissue cells are more loosely packed and can vary in shape and size. They can be found throughout the body, providing support, structure, and protection.
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