Transcript Microbes PowerPoint

Morphology
Unit 1
Microbes, Protists, and Fungi
Ch 23 Bacteria
 Prokaryotes - single cell organisms without a
membrane bound nucleus and organelles.
 All bacteria are prokaryotic and are the
earliest known group of living organisms.
 There are 2 branches of bacteria
 Eubacteria - What we think of when we hear the
word bacteria
 Archaebacteria - (archaea) bacteria that lives in
extreme conditions.
Archaea
 Structure
 Cells walls do not contain peptidoglycan (a
protein carbohydrate compound that
makes up most cell walls).
 Have different amino acids and lipids than
other bacteria.
Archaea
 3 major archaeal groups  Methanogens - convert hydrogen gas and
carbon dioxide into methane. Oxygen is
poisonous to them, so they live in anaerobic
(oxygen free) environments
 Swamps, bottom of water, cow intestines
 Halophiles - salt loving archaea
 Great salt lake, dead sea
 Thermoachidophiles - acidic environments
with high temperatures
 Hot springs, ocean floor vents
Bacteria
 Structure
 Three basic shapes
 Rod shaped - bacilli
 Sphere shaped - cocci, in chains - streptococci
(strept throat), clusters - staphylococci (staph
infection)
 Spiral shaped - spirilla
Bacteria
 Types
 Proteobacteria - Nitrogen Fixing bacteria
 Gram-positive - use to make antibiotics and other
medicines, can kill people, makes milk sour.
 Cyanobacterias - use photosynthesis, give off
oxygen, offer food to freshwater ecosystems
 Spirochetes - Gram negative, spiral shaped,
causes diseases
 Chlamidia - Gram negative coccid pathogen,
depend and live on animal cell for survival.
Bacteria Structure and Function
 Cell wall - for shape and protection
 Cell membrane - lipid bilayers (selectively permeable),
many metabolic functions occur here
 NO membrane bound organelles
 DNA - single closed loop attached to one point in the
cell membrane
 Has plasmids - small circular self replicating DNA
loops
 Endospore - thick coated resistant structure contains
DNA to help survival
 Capsules - polysaccharides (sugars) to bind to cell wall
and protect against chemicals and drying out
 Pili - hair-like proteins on surface to help to connect to
other objects
 Move by: flagella, slime or corkscrew rotations
Bacteria cont.
 Bacteria gets its food
Ch 24 Viruses
 Virus - a nonliving particle made up of a
nucleic acid and protein/lipid-protein
coat.
 Causes many disease in living organisms
 Useful tools for genetic research which
started in the late 1800s
 Appeared after living cells.
Viral Characteristics
 Lack all organelles and a cytoplasm
 Cannot carry out cellular functions
(metabolism and homeostasis)
 Do not grow by dividing
 Cannot reproduce outside of host cell (do
have DNA or RNA)
 Use host cell’s ribosomes, ATP and enzymes to
reproduce
 Usually contains a protein coat and a nucleic
acid core.
Viral Structure/Size
 Some of the smallest particles able to cause
diseases
 Capsid: (protein coat) is the only covering of
most viruses, acts as protection
 Helix - rabies, measles
 Icosahedrons - 20 triangular faces and 12
corners (adenovirus)
 Spherical - influenza virus
 Envelope: bilipid membrane that surrounds
the capsid (AIDS, chicken pox, HIV)
Classification and Replication
 Viruses are classified by
 DNA or RNA
 single stranded or double stranded DNA/RNA
 linear or circular DNA/RNA
 Membrane bound envelop or not.
 Replication
 Spread by air, water, food, or body fluids
 Lifeless with no control over its movement without a host
 Envelopes act as lock and key with hosts
 Attaches and then takes over cell
 Provirus - insertion of viral DNA to create viral proteins
 Insertion of viral RNA infects cells RNA (retroviruses)
 Bacteriophages - viruses that infect bacteria
Lytic and Lysogenic Cycles
 Lytic Cycle - a virus invades a host cell,
produces new viruses and ruptures the
host cell when releasing newly formed
viruses.
 Lysogenic cycle - an infection that
allows viruses to hide in their host for
days, months or years.
 Viruses that only reproduce by the
lysogenic cycle are called Temperate
viruses.
Viroids and Prions
 Viroids - smallest known particle able to
replicate, infect plants, and do not have
a capsid. Only contains RNA
 Prions - infectious protein particles that
don’t have a genome, convert normal
brain proteins into prion particles. (only
contains a protein.)
 Causes a number of degenerative brain
diseases
 Creutzfeldt-Jakob, mad cow disease
Ch 25 Protista
 Protists – single celled or simple
multicellular eukaryotic organisms that
generally do not fit in any other
kingdom.
 Some of the oldest eukaryotic cells are
protists.
Protist Characteristics
 Unicellular or multicellular
 Most protists are unicellular (amoeba) with few
being multicellular (brown algae).
 Nutrition
 Most protists are autotrophs (can make their own
food) the same way plants are, but some are
heterotrophs (eating other organisms or their
byproducts and remains).
 Motility/Movement
 Flagella dinoflagellates use flagella), cilia,
pseudopodia, extending structures 9amoebas use to
move.
Reproduction
 Most reproduce asexually
 Binary fission –a single cell divides into two
 Multiple fission – produces more than two
offspring
 Some reproduce sexually
 Conjugation – two individuals join and
exchange genetic material stored in a small
second nucleus.
Animal-like Protists
 Animal like protists are sometimes
called protzoa the move about
capturing and consuming prey.
 Pseodopodia – a large, rounded
cytoplasmic extension that function both in
movement and feeding.
 Hundreds of species in freshwater, marine
environments, soil, and inside humans.
Animal-like Protists cont.
 Others are called Paramecium, found in
ponds and streams feeding on decaying
organic matter, bacteria, algae, and
other small organisms.
 Mouth pore –sucks in food into the gullet
(stomache)
 Undigested material exits through the anal
pore, excess water gets released from the
contactile vacuoles.
 Macronucleus contains the DNA
 Micronucleus participates in the exchange
of genetic material during conjugatoin.
Plantlike Protists
 Many plantlike protists are called algae and
are autotrophic.
 Reproduction-have single-celled gamete chambers
(gametangia) instead of multicellular.
 Have chlorophyll and undergo photosynthesis
 Unicellular aglae- one single cell that are freeliving aquatic organisms (phytoplankton)
 Colonial Algae – groups of cells working in a
coordinated manner. Some cells become
specialized.
 Filamentous algae – Multicellular, slender, rodshaped with celled joined end to end.
 Multicellular algae (kelp and seaweeds)- unusually
large and complex, look most like plants.
Algae
 The most well known
plantlike protist
 Algae are autotrophic
protists. (make their own
food)
 Can be found in salt water
 Can be found in fresh
water.
 Can have specialized
structures for
reproduction, movement
and anchoring itself.
Plantlike Protists cont.
 Other organelles that help perform
life’s functions:
 Cell walls made of cellulose
 shells
 Chlorophyll and other Pigments to help
with photosynthesis
 Some have high resistant cysts allowing
them to live in extreme environments
 Some are plantlike and animal like
 Euglena - have chlorophyll but no cell wall,
have a vacuole, have a cell membrane. In light
they have chloroplasts (autotrophic) but in the
dark they don’t and are heterotrophic.
Fungus-like Protists
 Slime molds
 Is a mass of cytoplasm that oozes around
obstacles.
 Move as independent organisms (move like
amoebas)
 The feeding stage of slime molds have multiple
nuclei and is known as a multinucleate.
 Some look like slugs and leave slime behind them.
 Water molds
 Parasitic
 Undergo sexual reproduction as well as asexually
reproduction
 Cell walls
 Similar enzymes and biological pathways
Examples of Protists
Kelp forest
Seaweed
Kelp
amoeba
Ch. 26 Fungi
 Fungi - eukaryotic, nonphotosynthetic
organisms. Most are multicellular and
heterotrophs.
 Main types
 Molds - can grow on bread and are tangled
masses of filaments of cells (known as
Zygomycota)
 Yeasts -unicellular fungi whose colonies
resemble bacteria (make bread rise)
Fungi Obtaining Nutrients
 Fungi get their nutrients by absorbing
organic molecules (usually from dead
organisms) from their environment
through their cells walls. (outside to
inside)
 They store nutrients in the form of
glycogen.
 Known as the recyclers of organic
material in nature.
Structure of Fungi
 Hyphae –individual filaments of fungi
that make up a mycelium.
 Cell walls that contain chitin (same
thing that makes up exoskeleton of
insects).
 Most fungi have the ability to exist in
two different forms. (dimorphism)
 They do not have chloroplasts
 The do not produce their own food
Fungi Reproduction
 Asexual – reproduce thousands of
genetically identical haploid cells.
 Can reproduce with protective sacs
(sporangiophores) This is where the
spores form. (plural = sporangia)
 Can reproduce from spores without sacs
(conidia).
 Can also reproduce by hypha drying and
shattering to spread and release spores
(fragmentation)
 Budding- part of a yeast cell pinches itself
off to produce a small offspring cell
Fungi Reproduction cont.
 Sexual reproduction
 Many fungi can reproduce both asexually
and sexual.
 Sexually- when two different mating types
of the same breed come in contact fungi
will reproduce sexually for genetic
variation, and increased survival ability.
 Being able to reproduce both ways is
extremely advantageous. Whatever the
environment conditions are, the fungi can
reproduce.
Fungi Evolution
 Fungi were first thought to be
unicellular and clung together after
mitosis.
 Scientists believe Fungi evolved from
prokaryotes.
 Fungi are probably as old as plants.
640mya.
Examples of Fungi
Molds
Yeasts