Transcript 3.16.05 - El Camino College

Chapter 28: Microbiology
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Prokaryotes
Prokaryotes
The Prokaryotes
• The bacteria (domain Bacteria) and archaea
(domain Archaea) are prokaryotes.
• Prokaryotes (“before nucleus”) lack a membrane
bounded nucleus. Instead, the chromosome is
in a nucleoid (false nucleus) that lacks an
envelope.
• There are no membranous organelles but they
do have ribosomes; prokaryotes have a cell wall
that may be surrounded by a capsule.
• Some prokaryotes move by flagella, and some adhere to
surfaces by means of small, hairlike appendages called
fimbriae.
Generalized structure of a prokaryote
DNA
motility
Gram + or - stain
Generalized reproduction of a prokaryote
• Prokaryotes reproduce asexually by binary fission, and
some can form endospores (anthrax).
• In order to accomplish genetic recombination (but not
sexual reproduction) bacteria can also reproduce by:
conjugation, transformation, and transduction.
1 binary fission
2 conjugation
One cell passes DNA to another
through a sex “pilus”
3 transformation
A bacteria takes up DNA from its
liquid surroundings
4 transduction
Bacterial viruses carry portions
of DNA from one bacteria to
another
Endospore formation by a prokaryote
• Bacteria can “hibernate” to avoid unfavorable
environmental conditons.
• Hibernation is accomplished
by saving a small portion of
their cytoplasm and a
copy of their DNA, and
letting the rest of the cell
dry out. They are then
encased by three layers
of spore coats.
When conditions are favorable they rehydrate
and form a full bacterial cell again!
Prokaryotes, In General
• Most bacteria are aerobic, requiring a
constant oxygen supply for cellular
respiration.
• Obligate anaerobes are unable to grow in
the presence of oxygen; facultative
anaerobes are able to grow in the
presence or absence of oxygen.
• Bacteria are saprotrophs which externally
digest organic compounds and absorb
nutrients.
Prokaryotes, In General
• Bacteria are the decomposers in ecosystems.
• Some bacteria are symbiotic and live in
association with other organisms.
• The bacteria that reside in the human intestinal
tract are mutualistic (both benefit); commensalistic
(no harm, no benefit) bacteria reside on our skin;
and parasitic (only they benefit, we suffer) bacteria
cause a wide variety of diseases.
• The cyanobacteria are photosynthetic in the
same manner as plants.
Your Basic Bacteria:
• Bacteria occur in three
basic shapes:
rod (bacillus),
round (coccus),
or spiral (spirillum).
• Based on a dye test, bacteria are
either Gram-positive or Gramnegative: Gram-positive bacteria
have a thick layer of peptidoglycan
on their cell wall; Gram-negative
bacteria have a thin layer.
Prokaryotes
Domain Archaea:
The Extremophiles
Domain Archaea
Adapted to extreme conditions:
1. Plasma membrane contains
special lipids to tolerate super high
temperatures, as well as modified
cell walls compositions.
2. Archaea are NOT photosynthetic. Most
gain nutrition through “chemosynthesis”.
That is, they can “eat” sulfur. Some excrete
methane gas, which is a large contributor to
the greenhouse effect (global warming).
3. Archaea have been found living in the great salt lake and dead
sea (WAY HYPERTONIC!), hot springs or even submarine
thermal vents ( over 200 degrees F!)
Chapter 29: Plants
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Prokaryotes
MONERA
ANIMALS
PLANTS
FUNGI
PROTISTA
Characteristics of Plants
• Plants are multicellular, photosynthetic
organisms adapted to a land existence with
features such as a waxy cuticle.
• Plants resemble algae in using
chlorophylls(green) a and b and
carotenoid(red) pigments for photosynthesis.
• But unlike algae, land must plants protect the
developing embryo from drying out by
creating a protective coat around them…...
(ahhhh, the beginning of seeds and fruit!)
• The many divisions of plants can be grouped
into three main groups:
Nonvascular
plants
Seedless vascular plants
Vascular plants
with seeds
“Vascular” refers to the tissues and structures that
transport water and minerals from the roots to all the
tissues.
Nonvascular
plants
Seedless vascular plants
Vascular plants
with seeds
“Vascular” refers to the tissues and structures that
transport water and minerals from the roots to all the
tissues (namely, the Phloem and Xylem).
Nonvascular plants
(phylum: Bryophyta)
Seedless vascular plants
(phylum: Trachophyta)
Vascular plants
with seeds
(phylum: Trachophyta)
Nonvascular Plants
• PHYLUM: Bryophyta
• Nonvascular plants include the liverworts,
hornworts, and the mosses.
• Nonvascular plants lack vascular tissues
throughout their life cycle; they lack true
roots, stems, and leaves.
• Sperm require water to swim to the egg.
Liverworts (a bryophte)
• The liverwort has a flattened, lobed body known as thallus.
• Rhizoids (rootlike hairs) project from the lower surface into the
soil.
• Can reproduce asexually by forming gemmae, groups of cells
in gemmae cups on the upper surface of thallus.
• In sexual reproduction, umbrella-like gametophores produce
gametes (star-shaped for female, disc-like for males).
Mosses (a bryophyte)
•
•
Following
fertilization,
the
dependent
moss
sporophyte
consists of
a foot,
stalk, and a
capsule or
sporangium
within
which
spores are
produced
by meiosis.
They are
dispersed
by the wind.
In the moss life cycle, antheridia produce swimming sperm that use external
water to reach the eggs in the archegonia.
Life-Style of Nonvascular Plants
• Mosses are usually found in moist habitats
because the sperm are flagellated.
• However, mosses can live in shady cracks of
hot, exposed rocks.
• Liverworts can only live in a moist
environment.
Adaptations and Uses of
Nonvascular Plants
• Sphagnum is bog or peat moss that is
used to hold water in garden soil.
• Dried peat is sometimes used as fuel.
“Vascular” refers to the tissues and structures that
transport water and minerals from the roots to all the
tissues.
Nonvascular plants
(phylum: Bryophyta)
Seedless vascular plants
(phylum: Trachophyta)
Vascular plants
with seeds
(phylum: Trachophyta)
Seedless Vascular Plants
(phylum: Trachophyta)
• Vascular plants have vascular tissue: xylem
(conducts water and minerals from the soil)
and phloem (transports organic nutrients
within the plant).
• Vascular plants have true roots, leaves,
and stems.
• Waxy cuticles prevent leaves from drying
out.
Seedless Vascular Plants
(phylum: Trachophyta)
Ferns
• Whisk ferns, club mosses, horsetails, and ferns are the
seedless vascular plants that were prominent in swamp forests
during the Carboniferous period.
• Their incomplete decomposition formed much of the coal we
burn today.
Whisk fern, Psilotum
Club moss, Lycopodium
Horsetail, Equisetum
• Ferns
• Ferns have very large fronds (leaves) that grow
from a rhizome; ferns have vascular tissue and
have true roots, stems and leaves (leaflets).
• Sporangia are within sori on the underside of
the leaflets of a frond; meiosis occurs within a
sporangium, producing spores.
• A windblown spore develops into a separate
gametophyte, a heart-shaped prothallus, that
bears both egg-producing archegonia and
sperm-producing antheridia.
Fern Life-Cycle
Fern diversity
“Vascular” refers to the tissues and structures that
transport water and minerals from the roots to all the
tissues.
Nonvascular plants
(phylum: Bryophyta)
Seedless vascular plants
(phylum: Trachophyta)
Vascular plants
with seeds
(phylum: Trachophyta)
Vascular Seed Plants
• Phyllum: Tracheophyta (Contain Xylem and Phloem)
• Both gymnosperms and angiosperms disperse
by seeds.
• A seed has a seed coat and contains an
embryonic sporophyte and stored food that
supports growth when the seed germinates.
• Gymnosperms have exposed or “naked” seeds.
• In angiosperms (flowering plants), seeds are
enclosed by a fruit.
Gymnosperm diversity
(naked-seed plants)
Gymnosperms
• This group includes cycads, the ginkgo, and
conifers.
• Cycads are palm-like, tropical and subtropical plants
that flourished during the era of dinosaurs.
• Ginkgo is planted in parks because it does well in
polluted areas. Also used in Japanese art.
• Conifers are the largest group of gymnosperms
and include cone-bearing pine, spruce, fir, and
redwood trees.
Pine life cycle
fertilized “pinecones” scales
fly on the wind with wings!
“pinecones” are
female!
• Life Cycle of a Conifer
• The gymnosperm microspore develops into a
pollen grain which develops in a pollen cone.
• The megagametophyte develops within an
ovule located on the scale of a seed cone.
• Following wind pollination and fertilization that
do not require external water, the ovule
becomes a winged seed that is dispersed by
wind.
• Adaptation and Uses of Conifers
• Conifers supply much of the wood used for
construction of buildings and production of paper.
• Many valuable chemicals are extracted from resin, a
substance that protects conifers from fungi and
insects.
• The oldest trees in the world, at 4,500 years old,
are bristlecone pines in Nevada.
Impressive!!!! Trees can live longer than any other organism!
They were around 2500BC, during the time of
TROY…..Pharoh’s age!
Some trees today were around to see King Tut, Jesus,
Mohammed
Angiosperms
(enclosed-seeds)
• Angiosperms are flowering plants and include
tropical and subtropical trees.
• All hardwood trees are angiosperms.
• Angiosperms are divided into moncots (such as
the grass family) and dicots (such as the maple
and rose families).
Flowering plant life cycle
The fruit you eat, is a plants ovary.
The seeds inside are fertilized!
• Life Cycle of Angiosperms
• Like conifers, angiosperms produce sperm and
eggs, except angiosperms do so within their
flowers (instead of a pinecone).
• The ovules (eggs – usually a lot!) develops into
seeds, each one consisting of a seed coat,
stored food, and an embryo. The ovary and
adjacent parts of the flower develop into a fruit.
• Fruits aid in seed dispersal.
• The Flower
• The flower accounts for the success of angiosperms.
• The flower both attracts animals that aid in pollination
and produces seeds enclosed by fruits that aid
dispersal.
Summary
• Plants resemble algae in using chlorophylls a
and b and carotenoid pigments for
photosynthesis, BUT unlike algae, plants protect
the embryo (seed) to keep it moist so that it can
live on land existence.
Summary
• Nonvascular plants are low-growing and lack a means
of water transport and internal support, whereas
vascular plants have a system that transports water and
also provides internal support.
• In nonseed plants, spores disperse the species; in seed
plants, seeds disperse the species.
• In seed plants, a pollen grain transports sperm to the
egg.