BIO 101 – GENERAL BIOLOGY I
BIOLOGY: The study of life or more appropriately the study of living organisms (living things).
WHAT IS A LIVING THING?
A living thing is anything that is capable of reproducing itself and carryout life processes such as
respiration, movement, eat and carryout metabolic processes (nutrition), response to stimuli,
growth, excretion and finally (eventually) die. To carry out these processes a living thing
comprises units and structures that make up the body just as individual a toms combine together
to form matter or substance. The basic unit of life is the cell. Before we discuss the cell, let us
discuss these processes that characterize living things.
RESPIRATION: Respiration is more than exchange of gases but involves the metabolism of
energy sources (food) and the use of these for essential life processes.
MOVEMENT: Movement can be in the form of locomotion as in the case in animals or responses
to environmental stimuli such as tropic (tropism) and tactile (taxism) such as we have in plants.
RESPONSE TO STIMULI: All living things respond to environmental factors such as light,
temperature, water, gravity etc.
GROWTH: All living things are capable of physical increase in size. Growth is due to increases in
the size and number of cells.
EXCRETION: From the smallest of all living things to the largest, all can dispose of unwanted
products from their body.
REPRODUCTION: All living thing can reproduce their kind either vegetative (asexual) or
through sexual means.
NUTRITION: They can take in solid substance, digest or accumulate them for growth.
CELL
A cell is the smallest unit that can carry out all life processes. An organism can be made up of one
or more cells. An organism with a single cell is called a unicellular organism while those with
two or more cells are called multicellular organisms. Examples of unicellular organism are
paramecium, amoeba, euglena etc. The simplest of these are bacterial cells. There are also simple
multicellular organism such as hydra and of course complex o nes such as higher plants and
animals. In human for examples there are different forms (types) of cells and nu mber up to
trillion of cells (10 12).
1
,BASIC STRUCTURE OF A CELL.
Assignment –Prokaryote cell – draw and state features
S/N Prokaryotic Eukaryotic
Kingdoms Bacteria and Archaea Kingdoms Protista, Plantae. Animalia, Fungi
1 Size – about 5um (usually < 10um) >10um
2 Always unicellular Mostly multicellular except some Protists.
3 No organized or membrane enclosed Has membrane bound nucleus
nucleus
4 Single chromosomes in cytoplasm 2 or more in nucleus, arranged in pairs called
homologues (homologous pairs)
5 70S ribosome (50S + 30S) 80s ribosome (60S + 40S)
6 No cytoskeleton Always with cytoskeleton.
7 Division is by binary fission Cell division is by meiosis and mitosis
There are two classes of cells – prokaryotic and eukaryotic. Irrespective of whether microbes,
plants or animals, all are made up of the same basic materials.
A typical cell is made up of;
- An outer covering
- The cytoplasm and
- A nucleus (A nucleoid region in prokaryotes since they do not possess an organized
nucleus)
THE OUTER COVERING
The outer covering of cells of different organisms is made up of different materials. They can be
a cell wall or a membrane.
2
, Cell wall: Cellulose cell wall is a characteristic of plant cells. The cell wall can be made of
carbohydrates such as cellulose pectin, hemicelluloses and wax. This gives a rigid shape to plant
cell. The cell wall of Fungi is made up of chitin, a substance similar to exoskeleton of insects. This
is why it smells like roast insect when put in fire. Bacteria have cell wall of peptidoglycan while
Archaea cell wall is made up of complex lipids that partly accounts for their ability to survive in
extreme conditions.
Plasma membrane is more typical of animal cell although may be present in the inner wall of
plant cell. This extremely thing membrane is variously referred to as plasmalemma, cell
membrane or more commonly plasma membrane.
The plasma membrane is a three- layered structure made up of two dark layers sandwiching a
translucent inner layer. These layers may be made of phospholipids glycoprotein or glycolipids.
It is good to note that cell organelles are also surrounded by plasma membrane. The nucleus is
surrounded by nuclear membrane. The main functions of the outer covering are to give shape
and distinction to each cell and organelle. It also protects the organelles and allows absorption of
useful material and ensure the ejection of unwanted materials.
CYTOPLASM
The cytoplasm is made up of fluid (cytosol – water and dissolved molecules such as amino acids )
in which the organelles are suspended. The cytoplasm can be seen streaming with the various
organelles in constant but random motion. There are other inclusions such as stored food and
secretory substances. The cytoplasmic organelles perform different functions as already seen.
THE NUCLEUS
The nucleus controls all the activities of the cell because it holds most of the genetic materials
(the nuclear genome) while other genetic materials are contained in the mitochondria and
plastids (in plants). The genetic materials carried in the cytoplasmic organelles are usually
transmitted through the egg (maternal inheritance).
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BIOLOGY: The study of life or more appropriately the study of living organisms (living things).
WHAT IS A LIVING THING?
A living thing is anything that is capable of reproducing itself and carryout life processes such as
respiration, movement, eat and carryout metabolic processes (nutrition), response to stimuli,
growth, excretion and finally (eventually) die. To carry out these processes a living thing
comprises units and structures that make up the body just as individual a toms combine together
to form matter or substance. The basic unit of life is the cell. Before we discuss the cell, let us
discuss these processes that characterize living things.
RESPIRATION: Respiration is more than exchange of gases but involves the metabolism of
energy sources (food) and the use of these for essential life processes.
MOVEMENT: Movement can be in the form of locomotion as in the case in animals or responses
to environmental stimuli such as tropic (tropism) and tactile (taxism) such as we have in plants.
RESPONSE TO STIMULI: All living things respond to environmental factors such as light,
temperature, water, gravity etc.
GROWTH: All living things are capable of physical increase in size. Growth is due to increases in
the size and number of cells.
EXCRETION: From the smallest of all living things to the largest, all can dispose of unwanted
products from their body.
REPRODUCTION: All living thing can reproduce their kind either vegetative (asexual) or
through sexual means.
NUTRITION: They can take in solid substance, digest or accumulate them for growth.
CELL
A cell is the smallest unit that can carry out all life processes. An organism can be made up of one
or more cells. An organism with a single cell is called a unicellular organism while those with
two or more cells are called multicellular organisms. Examples of unicellular organism are
paramecium, amoeba, euglena etc. The simplest of these are bacterial cells. There are also simple
multicellular organism such as hydra and of course complex o nes such as higher plants and
animals. In human for examples there are different forms (types) of cells and nu mber up to
trillion of cells (10 12).
1
,BASIC STRUCTURE OF A CELL.
Assignment –Prokaryote cell – draw and state features
S/N Prokaryotic Eukaryotic
Kingdoms Bacteria and Archaea Kingdoms Protista, Plantae. Animalia, Fungi
1 Size – about 5um (usually < 10um) >10um
2 Always unicellular Mostly multicellular except some Protists.
3 No organized or membrane enclosed Has membrane bound nucleus
nucleus
4 Single chromosomes in cytoplasm 2 or more in nucleus, arranged in pairs called
homologues (homologous pairs)
5 70S ribosome (50S + 30S) 80s ribosome (60S + 40S)
6 No cytoskeleton Always with cytoskeleton.
7 Division is by binary fission Cell division is by meiosis and mitosis
There are two classes of cells – prokaryotic and eukaryotic. Irrespective of whether microbes,
plants or animals, all are made up of the same basic materials.
A typical cell is made up of;
- An outer covering
- The cytoplasm and
- A nucleus (A nucleoid region in prokaryotes since they do not possess an organized
nucleus)
THE OUTER COVERING
The outer covering of cells of different organisms is made up of different materials. They can be
a cell wall or a membrane.
2
, Cell wall: Cellulose cell wall is a characteristic of plant cells. The cell wall can be made of
carbohydrates such as cellulose pectin, hemicelluloses and wax. This gives a rigid shape to plant
cell. The cell wall of Fungi is made up of chitin, a substance similar to exoskeleton of insects. This
is why it smells like roast insect when put in fire. Bacteria have cell wall of peptidoglycan while
Archaea cell wall is made up of complex lipids that partly accounts for their ability to survive in
extreme conditions.
Plasma membrane is more typical of animal cell although may be present in the inner wall of
plant cell. This extremely thing membrane is variously referred to as plasmalemma, cell
membrane or more commonly plasma membrane.
The plasma membrane is a three- layered structure made up of two dark layers sandwiching a
translucent inner layer. These layers may be made of phospholipids glycoprotein or glycolipids.
It is good to note that cell organelles are also surrounded by plasma membrane. The nucleus is
surrounded by nuclear membrane. The main functions of the outer covering are to give shape
and distinction to each cell and organelle. It also protects the organelles and allows absorption of
useful material and ensure the ejection of unwanted materials.
CYTOPLASM
The cytoplasm is made up of fluid (cytosol – water and dissolved molecules such as amino acids )
in which the organelles are suspended. The cytoplasm can be seen streaming with the various
organelles in constant but random motion. There are other inclusions such as stored food and
secretory substances. The cytoplasmic organelles perform different functions as already seen.
THE NUCLEUS
The nucleus controls all the activities of the cell because it holds most of the genetic materials
(the nuclear genome) while other genetic materials are contained in the mitochondria and
plastids (in plants). The genetic materials carried in the cytoplasmic organelles are usually
transmitted through the egg (maternal inheritance).
3
