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Chapter 2 The Prokaryotes, Viruses, and Protists
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However, some bacteria plays a very positive role on Earth
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There microorganisms convert nitrogen into chemical compounds
that can be used by plants
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We rely on bacteria in the large intestine to produce vitamins K and
B12
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Bacteria are essential for the production of foods such as chesses, yogurt, and chocolate
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A plasmid is a small loop of DNA often found in prokaryotic cells; usually contains a small
number of genes
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A capsule is an outer layer on some bacteria that provides protection for the cell
Bacillus rod shaped
Coccus round shaped
Spirillum spiral or corkscrew shaped

Diplo 2 of them
Strepto chain
Staphylo clump
Inorganic chemical- an
abiotic chemical such as
water, CO2

Prokaryotes normally reproduce asexually
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However, copying errors result in mutations (happen often), there increase the
genetic diversity in populations of bacteria
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Transformation is a process in which a bacterial cell takes in and uses pieces of DNA (a
loose fragment of DNA) from its environment
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Endospore is a dormant structure that forms around the chromosome in response to
stress; can withstand extreme conditions
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Others require oxygen (aerobic)
Their cell membranes contain unusual lipids (fats) that allow then to survive in
these extreme environments
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o swamps, marshes, intestines, sewage disposal
plants
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2 Viruses, Viroids, and Prions
A virus is a small infectious particle containing genetic material in the form of DNA or RNA
within a protein capsule
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Viruses are extremely small parasites that contain genetic material but lack all other cell
structures necessary for metabolism, reproduction and growth
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Instead, new viral
components are synthesized and assembled within
the infected cell

Viruses range from 5 to 300 nm but some may be up
to 0
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An epidemic is a large-scale outbreak of disease;
usually confined to a limited geographic region
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Viruses are classified into orders, families, genera,
and species
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Bacteriophages are viruses that infect bacteria
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Some scientists say that viruses originated as small
infectious cells that lost their cytoplasm and ability
to reproduce without a host cell
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An infectious cycle is the process by which a virus infects a host cell,
replicates, and destroys the host cell
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While
for others, the virus may be constantly changing
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A Viroid is a very small infectious piece of RNA responsible for some serious diseases in
plants (such as Cadang Cadang)
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2
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Endosymbiosis is a relationship in which a single-celled organism lives within the cell(s)
of another organism
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 Present-Day mitochondria and chloroplasts have their own internal chromosomes
 These chromosomes are very similar to prokaryote chromosomes and contain genetic
information used by the organelles
 Mitochondria and chloroplasts reproduce independently within eukaryotic cells by
binary fission, just as prokaryotes do
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They are passed on to new daughter cells when the eukaryotic cells undergo mitosis
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Whole body moves through the use of pseudopods – ‘feet-like’
projections that extend out ; body follows
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Amoeba feeds through – engulfs and digests with enzymes –
Phagocytosis – engulfing food; Pinocytosis – engulfing water and
other nutrients
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 It is unlike an amoeba – because it has a
distinct and permanent shape, it takes food in
differently; movement is different
 Ciliate movement is conducted by cilia
 If it encounters an obstacle, it reverses itself
***** protists are highly organized complex
organisms that do all you do *****
 Feeds through use of oral groove – use of cilia
to move food in; fibrils move food further in for
vacuole formation
 Reproduce – asexually cell division (binary
fission) – also form of sexual reproduction
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They are of interest to scientists because they have
characteristics of both plants and animals
 Euglena lack a rigid cell wall and the ability to store
starch
 If placed in the dark, it loses its green colour and
becomes unable to photosynthesis – and becomes a scary hunter of small single cells
 The pigment spot, the detector of light – allows movement to the light
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that feeds off cytoplasm; makes you very
tired and fatigued; can kill you; passed via an insect vector
(mosquitoes); needs two hosts – us and mosquito
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Spirogyra is a member of the algae family
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Conjugation is a process in which two single cell
exchange DNA; it occurs during certain times of the year
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1
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It can move to the light by using pigment spot to sense light and then
use its flagella to move into light
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This species overwinters (hibernation) by forming a zygospore – and
dropping to bottom of pond
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Haploid is a cell containing half the usual complement of chromosomes (n)
Diploid is a cell containing two copis of each chromosomes (2n)
Zygote is a cell peoduced by the fusion of two gametes
Gamete is a mature haploid male or female germ cell that is able to unite with another of
the opposite sex in sexual reproduction to form a zygote
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Spore a haploid reproductive structure, usuallly a single cell, that is capable of growing
into an individual
Sporophyte is a diploid organism that
produces haploid spores in an alteration
of generations cycle

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