THE CELL AS THE BASIC
UNIT OF LIFE
Presented by:
Joy Maina – 31153
Lincoln Kithaka – 30533
Adrine Wanyoike – 32249
Gerald Njuki - 29994
INTRODUCTION
A cell is the basic membrane-bound unit that contains
the fundamental molecules of life and of which all living
things are composed.
A single cell is often a complete organism in itself, such
as a bacterium or yeast.
Other cells acquire specialized functions as they
mature.
These cells cooperate with other specialized cells and
become the building blocks of large multicellular
organisms, such as humans and other animals.
Cells are the basic building blocks of all living things.
The human body is composed of trillions of cells.
They provide structure for the body, take in nutrients
from food, convert those nutrients into energy, and
carry out specialized functions.
Cells also contain the body’s hereditary material and
can make copies of themselves.
Cells have many parts, each with a different function.
Some of these parts, called organelles, are specialized
structures that perform certain tasks within the cell.
TYPES OF CELL
There are two types of cell namely:
prokaryotic: Small cells in the domains Bacteria and
Archaea that do not contain a membrane-bound
nucleus or other membrane-bound organelles.
eukaryotic: Having complex cells in which the genetic
material is contained within membrane-bound nuclei.
Prokaryotic cell
Eukaryotic cell
WHY THE CELL IS TERMED AS THE
BASIC UNIT OF LIFE
In terms of structure :
Cells are the most basic building units of life, all living things
are composed of cells, and new cells are made from preexisting
cells, which divide into two.
A cell can replicate itself independently. Hence, they are known
as the building blocks of life.
Robert Hooke, one of the first scientists to use a light
microscope, discovered the cell in 1665.
WHY IS THE CELL IS TERMED AS THE
BASIC UNIT OF LIFE
In terms of function:
Cells are the basic units of life capable of doing all the required
biochemical processes that a normal cell has to do in order to
live.
The basic needs for the survival of all living organisms are the
same.
All living organisms need to respire, digest food for obtaining
energy, and get rid of metabolic wastes.
Cells are capable of performing all the metabolic functions of
the body. Hence, cells are called as the functional units of life.
The cell theory
By the late 1830s, botanist Matthias Schleiden and
zoologist Theodor Schwann were studying tissues and
proposed the unified cell theory.
The unified cell theory states that: all living things are
composed of one or more cells; the cell is the basic unit
of life; and new cells arise from existing cells.
CONCLUSION
Cells are one of the characteristics we use to define whether something is
alive or not. Hence life cannot exist without cells.
Cells are the smallest common denominator of life. Some cells are organisms
unto themselves; others are part of multicellular organisms. All cells are
made from the same major classes of organic molecules: nucleic acids,
proteins, carbohydrates, and lipids. In addition, cells can be placed in two
major categories as a result of ancient evolutionary events: prokaryotes, with
their cytoplasmic genomes, and eukaryotes, with their nuclear-encased
genomes and other membrane-bound organelles. Though they are small,
cells have evolved into a vast variety of shapes and sizes. Together they form
tissues that themselves form organs, and eventually entire organisms.
REFERENCES
Agard DA, Hiraoka Y, Shaw P & Sedat JW (1989) Fluorescence
microscopy in three dimensions. In Methods in Cell Biology, vol
30: Fluorescence Microscopy of Living Cells in Culture, part B
(DL Taylor, Y-L Wang eds). San Diego: Academic Press.
Karp G (19 October 2009). Cell and Molecular Biology:
Concepts and Experiments. John Wiley & Sons. p. 2.
Maton A (1997). Cells Building Blocks of Life. New Jersey:
Prentice Hall.
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