Cells-Basic Unit of Life
Introduction:
The cell is
the basic structural, functional and biological unit of all known living
organisms. Cells are the smallest unit of life that is classified as a living
thing, and are often called the "building blocks of life".
Cells consist of protoplasm enclosed
within a membrane, which contains many biomolecules such as proteins and nucleic acids.
Organisms can be classified as unicellular (consisting
of a single cell; including most bacteria)
or multicellular (including plants and animals).
While the number of cells in plants and animals varies from species to species,
humans contain about 100 trillion (1014)
cells. Most plant and animal cells are between 1 and 100 micrometres and
therefore are visible only under the microscope.
History:
The cell was discovered
by Robert Hooke in
1665. The cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor
Schwann, states that all organisms are composed of one or more
cells, that all cells come from preexisting cells, that vital functions of an
organism occur within cells, and that all cells contain the hereditary
information necessary for regulating cell functions and for
transmitting information to the next generation of cells. Cells emerged on
Earth at least 3.5 billion years ago.
The word cell comes from the Latin cella,
meaning "small room". It
was coined by Robert Hooke in his book Micrographia (1665),
in which he compared the cork cells
he saw through his microscope to the small rooms monks lived in.
Parts and Functions of the Cell
-click the link to explore the different parts of the cell and function of each part..
Have a short quiz trough this link: http://www.biology4kids.com/files/cell2_main.html.
Hope you enjoy it..
Fun Facts! Did You Know?
1. The biggest cell in the world is the ostrich egg, which can be seen with your naked eye!
2. Many cells make up one tissue, and many tissues make up an organ, and many organs make
up a system!
3. One human cell contains 46 chromosomes, however, some humans have 47 chromosomes,
and therefore these people are diagnosed with Down's Syndrome!
4. Eukaryotic cells are 10 times larger than prokaryotic cells, simply because they
have a nucleus!
5. We have approximately 100 trillion cells in our body! A typical cell is 10 micrometers in
size and 1 nanogram in mass!
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10 Facts About Cells
1. Cells are too
small to be seen without magnification.
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 advance 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.
2. There are two primary types of cells.
Eukaryotic and prokaryotic cells are the two main types of cells. Eukaryotic cells are called so because they have a true nucleus. Animals, plants, fungi and protists are examples of organisms that are composed of eukaryotic cells. Prokaryotes include bacteria and archaeans.
3. 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. They are able to live and thrive in various extreme habitats. Archaeans for example, live in areas such as hydrothermal vents, hot springs, swamps, wetlands, and even animal intestines.
4. 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.
5. Cells contain genetic material.
Cells contain DNA (deoxyribonucleic acid), the genetic information necessary for directing cellular activities. DNA is a type of molecule known as a nucleic acid. In prokaryotic cells, the single bacterial DNA molecule is not separated from the rest of the cell but coiled up in a region of the cytoplasm called 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 gender.
6. Cells contain structures called 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. Eukaryotic cells contain several types of organelles, while prokaryotic cells contain a few organelles (ribosomes) and none that are bound by a membrane. There are also differences between the kinds of organelles found within different eukaryotic cell types. Plant cells for example, contain structures such as a cell wall and chloroplasts that are not found in animal cells. Other examples of organelles include:
2. There are two primary types of cells.
Eukaryotic and prokaryotic cells are the two main types of cells. Eukaryotic cells are called so because they have a true nucleus. Animals, plants, fungi and protists are examples of organisms that are composed of eukaryotic cells. Prokaryotes include bacteria and archaeans.
3. 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. They are able to live and thrive in various extreme habitats. Archaeans for example, live in areas such as hydrothermal vents, hot springs, swamps, wetlands, and even animal intestines.
4. 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.
5. Cells contain genetic material.
Cells contain DNA (deoxyribonucleic acid), the genetic information necessary for directing cellular activities. DNA is a type of molecule known as a nucleic acid. In prokaryotic cells, the single bacterial DNA molecule is not separated from the rest of the cell but coiled up in a region of the cytoplasm called 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 gender.
6. Cells contain structures called 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. Eukaryotic cells contain several types of organelles, while prokaryotic cells contain a few organelles (ribosomes) and none that are bound by a membrane. There are also differences between the kinds of organelles found within different eukaryotic cell types. Plant cells for example, contain structures such as a cell wall and chloroplasts that are not found in animal cells. Other examples of organelles include:
Nucleus
Mitochondria
Endoplasmic Reticulum
Golgi Complex
Ribosomes
7. Different types of cells reproduce
through different methods.
Most prokaryotic cells reproduce by a process called binary fission. This is a type of cloning process in which two identical cells are derived from a single cell. Eukaryotic organisms have a similar type of reproductive method known as mitosis. Some eukaryotes also have the ability to reproduce sexually, which involves the fusion of sex cells or gametes. Gametes are produced by a process called meiosis.
8. Groups of similar cells form tissues.
Tissues are groups of cells with both a shared structure and function. Cells that make up animal tissues are sometimes woven together with extracellular fibers and are occasionally held together by a sticky substance that coats the cells. Different types of tissues can also be arranged together to form organs. Groups of organs can in turn form organ systems.
9. Cells have 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.
10. Cells commit suicide.
Most prokaryotic cells reproduce by a process called binary fission. This is a type of cloning process in which two identical cells are derived from a single cell. Eukaryotic organisms have a similar type of reproductive method known as mitosis. Some eukaryotes also have the ability to reproduce sexually, which involves the fusion of sex cells or gametes. Gametes are produced by a process called meiosis.
8. Groups of similar cells form tissues.
Tissues are groups of cells with both a shared structure and function. Cells that make up animal tissues are sometimes woven together with extracellular fibers and are occasionally held together by a sticky substance that coats the cells. Different types of tissues can also be arranged together to form organs. Groups of organs can in turn form organ systems.
9. Cells have 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.
10. Cells commit suicide.
When a cell becomes damaged or undergoes some
type of infection, it will self-destruct by a process called apoptosis.
Apoptosis works to ensure proper development and to keep the body's natural
process of mitosis in check. A cell's inability to undergo apoptosis can result
in the development of cancer.
Thank You for reading my blog....Hope you have learned something...
