Biology : Term 1 Grade 11
MICRO-ORGANISMS:
Biodiversity and classification of micro-organisms:
● Micro-organisms:Organisms that are too small to see with the naked eye; also
called microbes
● Pathogens:Organisms that cause disease
● Monera:Kingdom that contains all the bacteria; single-celled organisms that
do not have a true nucleus or normal cell wall
● Saprophytic:Feeding on dead or decaying plant or animal matter
● Protista:Kingdom containing all single-celled organisms. Possess a true
nucleus (with both DNA and RNA as well as membrane enveloped organelles).
NOT classified as Fungi, plants or animals.
Group of Kingdom Description
micro-organisms
Viruses Not ● Non-living organisms
classified ● Contain nucleic acid (either DNA or RNA
in any never both)
Kingdom ● Different shapes and sizes
● All are pathogens
Bacteria Monera ● Occur in soil, air and water
● Consist of a SINGLE cell
● Does NOT have a true nucleus
● Some are pathogens
Fungi Fungi ● Plant-like organisms, but LACK chlorophyll
and are UNABLE to photosynthesise
● SAPROPHYTIC or parasitic
● Some are moulds which grow on food
● Some are yeasts that are used in the food
industry
, Protists Protista ● Single-celled and multi-cellular organisms
● Mainly aquatic
● Some are plant-like and can photosynthesise
● Some are animal-like and feed on other
living organisms
Viruses:
Structure and characteristics of virusesThe
structure of a virus (bacteriophage)->
● Smallest micro-organisms.
● Acellular = does not have a nucleus,
cytoplasm or any other organelles and
not considered to be living organisms.
● consist of a protein-coated CAPSID
containing DNA or RNA.
● viruses are pathogenic parasites.
● depend on a HOST. ( can be a plant,
animal or bacteria.)
● A virus that occur outside a host cell is
INACTIVE.
● It cannot grow, reproduce or undergo
any metabolic activities.
● Becomes ACTIVE when it comes into contact with a host cell.
● The virus inserts its genetic material into the host cell, taking over the host
cell’s functions.
=Viral RNA or DNA interferes with the metabolism of the host cell =forcing
the host cell to synthesise viral nucleic acids and protein coats.
= new viruses are formed.
= When enough viruses have replicated, they burst (LYSIS) out of the host cell,
killing the host cell and continue to attack other cells.
, ● Viruses have different shapes: Rod-shaped, spherical and symmetrical.
Diseases caused by viruses
● pathogens and cause infectious diseases in plants and animals.
● The tobacco mosaic virus (TMV): a plant virus that affects agricultural crops.
TMV affects tobacco, tomato, pepper and potato plants. This disease
damages the leaves, flowers and fruit + causes stunted growth. Fruit are
distorted and discoloured. The disease takes its name from the mosaic affect
of the light and dark patches it causes on the leaves. TMV will not kill the
plant completely but it reduces the quantity and quality of the crop.
● Examples of human diseases caused by viruses =the common cold, influenza
(flu), smallpox (chickenpox), measles, mumps, polio, HIV/aids and rabies.
ANTIBIOTICS ARE NOT EFFECTIVE IN TREATING VIRAL DISEASES
AS ONLY BACTERIAL INFECTIONS ARE TREATED WITH
ANTIBIOTICS. Viral diseases can be treated with antiviral medication and
can be prevented by using vaccines.
● Vaccines: Liquid preparations of treated pathogenic microbes that stimulate
the immune system to produce antibodies in the blood.
Rabies:
-contains RNA and is part of the family of viruses called Rhabdoviruses.
-carried in the saliva of infected (rabid) animals.
- transferred to humans by the bite, lick or scratch of an infected animal.
-must penetrate the skin to enter the body.
- Wild dogs, Bats, Black-backed jackal, Yellow mongoose (meerkats), and Bat-eared
foxes can carry rabies to humans.
-Unvaccinated domestic dogs are the usual path of transmission.
MICRO-ORGANISMS:
Biodiversity and classification of micro-organisms:
● Micro-organisms:Organisms that are too small to see with the naked eye; also
called microbes
● Pathogens:Organisms that cause disease
● Monera:Kingdom that contains all the bacteria; single-celled organisms that
do not have a true nucleus or normal cell wall
● Saprophytic:Feeding on dead or decaying plant or animal matter
● Protista:Kingdom containing all single-celled organisms. Possess a true
nucleus (with both DNA and RNA as well as membrane enveloped organelles).
NOT classified as Fungi, plants or animals.
Group of Kingdom Description
micro-organisms
Viruses Not ● Non-living organisms
classified ● Contain nucleic acid (either DNA or RNA
in any never both)
Kingdom ● Different shapes and sizes
● All are pathogens
Bacteria Monera ● Occur in soil, air and water
● Consist of a SINGLE cell
● Does NOT have a true nucleus
● Some are pathogens
Fungi Fungi ● Plant-like organisms, but LACK chlorophyll
and are UNABLE to photosynthesise
● SAPROPHYTIC or parasitic
● Some are moulds which grow on food
● Some are yeasts that are used in the food
industry
, Protists Protista ● Single-celled and multi-cellular organisms
● Mainly aquatic
● Some are plant-like and can photosynthesise
● Some are animal-like and feed on other
living organisms
Viruses:
Structure and characteristics of virusesThe
structure of a virus (bacteriophage)->
● Smallest micro-organisms.
● Acellular = does not have a nucleus,
cytoplasm or any other organelles and
not considered to be living organisms.
● consist of a protein-coated CAPSID
containing DNA or RNA.
● viruses are pathogenic parasites.
● depend on a HOST. ( can be a plant,
animal or bacteria.)
● A virus that occur outside a host cell is
INACTIVE.
● It cannot grow, reproduce or undergo
any metabolic activities.
● Becomes ACTIVE when it comes into contact with a host cell.
● The virus inserts its genetic material into the host cell, taking over the host
cell’s functions.
=Viral RNA or DNA interferes with the metabolism of the host cell =forcing
the host cell to synthesise viral nucleic acids and protein coats.
= new viruses are formed.
= When enough viruses have replicated, they burst (LYSIS) out of the host cell,
killing the host cell and continue to attack other cells.
, ● Viruses have different shapes: Rod-shaped, spherical and symmetrical.
Diseases caused by viruses
● pathogens and cause infectious diseases in plants and animals.
● The tobacco mosaic virus (TMV): a plant virus that affects agricultural crops.
TMV affects tobacco, tomato, pepper and potato plants. This disease
damages the leaves, flowers and fruit + causes stunted growth. Fruit are
distorted and discoloured. The disease takes its name from the mosaic affect
of the light and dark patches it causes on the leaves. TMV will not kill the
plant completely but it reduces the quantity and quality of the crop.
● Examples of human diseases caused by viruses =the common cold, influenza
(flu), smallpox (chickenpox), measles, mumps, polio, HIV/aids and rabies.
ANTIBIOTICS ARE NOT EFFECTIVE IN TREATING VIRAL DISEASES
AS ONLY BACTERIAL INFECTIONS ARE TREATED WITH
ANTIBIOTICS. Viral diseases can be treated with antiviral medication and
can be prevented by using vaccines.
● Vaccines: Liquid preparations of treated pathogenic microbes that stimulate
the immune system to produce antibodies in the blood.
Rabies:
-contains RNA and is part of the family of viruses called Rhabdoviruses.
-carried in the saliva of infected (rabid) animals.
- transferred to humans by the bite, lick or scratch of an infected animal.
-must penetrate the skin to enter the body.
- Wild dogs, Bats, Black-backed jackal, Yellow mongoose (meerkats), and Bat-eared
foxes can carry rabies to humans.
-Unvaccinated domestic dogs are the usual path of transmission.
