UNIT II A- BAFPAVH Flashcards
Proposed by Carl Woese
Phylogenetic relationship
Phylogenetic relationship
Provides information on shared ancestry but
not necessarily on how organisms are similar
or different
evolutionary history and relationship of an
organism or group of an organisms
phylogeny
phylogeny
another such as which organisms thought to
have evolved from which species it is closely
related to
bacteria
single-celled organisms
- lack organelles, such as chloroplast and
mitochondria
- do not have true nucleus found in eukaryotic
cells
- a double stranded DNA that is continuous
and circular is located in a nucleoid
an irregular-shaped region that
does not have a nuclear membrane
Nucleoid
Bacterial cell membrane and cell wall is made
of
peptidoglycan
cell membrane+ cell wall
cell envelope
Binary fission
-bacterial reproduction
splitting of a bacterial cell after
reaching a certain size
bacterial reproduction. sexual/ asexual?
reproduce asexually hence the two
daughter cells, result from the binary fission,
have the same DNA as the parent cell
horizontal gene transfer or
transformation, conjugation and
transduction
bacterial exchange of genetic
material among one another
bacterial shape: Coccus: define and examples.
- spherical/ovoid in shape
- some remain attached after binary fission
even forming separate cells
examples: Streptococci – cocci in chains - Staphylococci – clusters of multiple
cocci - Tetrads – square arrangements of
four cocci - Sarcinae – cubes of eight cocci
bacterial shape: bacillus: define and examples.
-Rod-shaped bacteria
- Can be solitary or arranged together
Example:
o Diplobacilli – 2 bacilli arranged next
to each other
o Streptobacilli – chains of bacilli
bacterial shape: spiral: define and examples.
Spiral in shape Example: o Spirillum - thick, tough spirals o Spirochetes – thin, flexible spirals o Vibrious – comma-shaped rods with a small twist
State other bacterial shape.
- Filamentous – long and thin
- Square
- Star
- Stalk
what makes gram staining of bacteria possible?
cell wall
define gram staining
- A method of staining bacteria involving
crystal violet dye, iodine, and the
counterstain safranine - Used for general identification of bacteria or
detect the presence of certain bacteria - Cannot be used to identify bacteria in the
species level - Can be used for grouping bacteria, gram-positive or gram-negative
Appearance of gram-positive bacteria and why?
Violet – due to the thick
cell wall that trapped the crystal violet iodine
complex
Appearance of gram-negative bacteria and why?
appear red due to the thin cell wall not holding the violet iodine complex but can hold safranine
Selectively permeable barrier, mechanical boundary of cell, nutrient and waste transport, location of many metabolic processes (respiration, photosynthesis), detection of environmental cues for chemotaxis
Plasma
membrane
Gas
vacuole
An inclusion that provides
buoyancy for floating in aquatic
environments
Ribosomes
Protein synthesis
Storage of carbon, phosphate,
and other substances
Inclusions
Localization of genetic material
DNA
Nucleoid
In typical gram-negative bacteria, contains hydrolytic enzymes and binding proteins for nutrient processing and uptake In typical gram-positive bacteria, may be smaller or absent
Periplasmic
space
Cell wall
Protection from osmotic stress,
helps maintain cell shape
Capsules
and slime
layers
Resistance to phagocytosis,
adherence to surfaces
Fimbriae
and pili
Attachment to surfaces, bacterial
conjugation and transformation,
twitching and gliding motility
Swimming and swarming motility
Flagella
Endospore
Survival under harsh
environmental conditions
Archaea
delineated from Eukarya, Eubacteria. -Lack a nucleus and consist of the extremophiles or ‘ancient’ bacteria (e.g. methanogens, thermophiles, halophiles)
arkhaios
primitive
Examples of members of archaea
• Pyrolobus fumarii - holds the upper temperature limit for life at 113 °C and found living in hydrothermal vents • Picrophillus – isolated from acidic soils in Japan; most acid-tolerant organisms; known capable of growth at around pH 0 • Methanogens – produce methane gas as a metabolic by-product and found in anaerobic environment such as in marshes, hot springs, and animal guts
Common Characteristics of Archaea
• Presence of tRNA and rRNA
• Absence of peptidoglycan cell walls;
replacement by largely proteinaceous coat
• Occurrence of ether-linked lipids built from
phytanyl chains in extreme environments
(Bacteria has esther-linked lipids)
Fungi
- eukaryotic, non-vascular, non-motile and
heterotrophic organisms - may be unicellular or filamentous
- reproduce by means of spores
- exhibit the phenomenon of alternation of
generation - lack chlorophyll and hence cannot perform
photosynthesis - store their food in the form of starch
- Biosynthesis of chitin occurs in fungi.
- nuclei are very small.
- fungi have no embryonic stage; develop
from the spores - mode of reproduction is sexual or asexual
- fungi are parasitic and can infect the host
- produce a chemical called pheromone
which leads to sexual reproduction in fungi
Examples of fungi
mushrooms, moulds, yeast
Alternation of
Generations/Metagenesis/Heterogenesis
- important characteristic of fungi
- asexual phase of the life of an organism
- has 2 generations which are often
morphologically or chromosomally distinct
Fungi classification: Mode of Nutrition: Saprophytic
feeding on dead organic
substances
Examples: Rhizopus, Penicillium
and Aspergillus
Fungi classification: Mode of Nutrition: Parasitic
living on other living organisms (plants or animals); absorb nutrients from their host Examples: Taphrina and Puccinia
Fungi classification: Mode of Nutrition: Symbiotic
interdependent relationship association with other species in which both are mutually benefited Examples: Lichens (algae synthesize carbs & fungi provides shelter) and mycorrhiza
Fungi classification: Spore formation: Zygomycetes
formed by the fusion of two different cells sexual spores – zygospores asexual spores – sporangiospores The hyphae are without the septa
Fungi classification: Spore formation: Ascomycetes
sac fungi; coprophilous (live on dung), decomposers, parasitic or saprophytic sexual spores - ascospores Asexual reproduction – conidiospores Example: Saccharomyces
Fungi classification: Spore formation: Basidiomycetes
Mushrooms are the most commonly found basidiomycetes and mostly live as parasites Sexual reproduction occurs by basidiospores Asexual reproduction occurs by conidia, budding or fragmentation Example: Agaricus
Fungi classification: Spore formation: Deuteromycetes
imperfect fungi-do not follow the regular reproduction cycle do not reproduce sexually Asexual reproduction by conidia Example: Trichoderma.
Fungi classification: Reproduction:
Vegetative
By budding, fission and
fragmentation
Fungi classification: Reproduction:
Asexual
-Anamorph
-This takes place with the help of
spores called conidia or
zoospores or
sporangiospores
Fungi classification: Reproduction:
Sexual
-Teleomorph
-ascospores, basidiospores, and
oospores
Protozoa
- eukaryotic, unicellular microorganisms
which lack cell wall - do not have cell wall but some possess a
flexible layer called pellicle, a rigid shell of
inorganic materials outside the cell
membrane - move by locomotor organelles or by a
gliding mechanism - have heterotrophic mode of nutrition
Protozoan forms
Free-living forms - ingest particulates, such as
bacteria, yeast and algae
Parasitic forms - body fluids of their hosts
- reproduce primarily by asexual means,
although in some groups sexual modes also
occur
Protozoa classification: Sarcodina
Motility: streaming of ectoplasm, producing protoplasmic projections called pseudopodia (false feet) Examples: Free-living form like Amoeba proteus* and parasitic form like Entamoeba histolytica*
Protozoa classification: Mastigophora
Locomotion: one or more whip-like, thin structures called flagella Examples: Free-living forms like Euglena viridis*, Cercomonas longicauda*, Heteronema acus* Parasitic forms like Trichomonas vaginalis, Trypanosoma gambiense*, Giardia lamblia*
Protozoa classification: Ciliophora
Locomotion: cilia, short hairlike projections whose synchronous beating propels the organism Examples: Free-living forms like Paramecium caudatum*,Stentor polymorpha*, Vorticella campanula* Parasitic form like Balantidium coli*
Protozoa classification: Sporozoa
do not have locomotor organelles in their mature stage however, in immature form, they exhibit some type of movement; All the members of this group are parasites. Examples: Plasmodium, the malarial parasites of animals and human beings.
algae
belongs to Protista
- a group of predominantly aquatic,
photosynthetic organisms of the kingdom
Protista
can photosynthesize like plants
- possess specialized structures and cell
organelles like centrioles and flagella, found
only in animals
either unicellular or multicellular organisms
- lack a well-defined body; structures like
roots, stems or leaves are absent
- found where there is adequate moisture
- Reproduction: asexual and sexual forms
- Asexual reproduction: spore formation
- free-living; some can form a symbiotic
relationship with other organisms
Types of Algae:
Red Algae
-Rhodophyta
-Distinctive species found in
marine and freshwater
ecosystems; has chlorophyll a
but lack chlorophyll b or beta-carotene
-Pigments responsible for red
coloration: phycocyanin and
phycoerythrin
Types of Algae:
Green Algae
Large informal grouping of algae having the primary photosynthetic pigments, chlorophyll a and b, and auxiliary pigments like betacarotene; can have symbiotic relationships with other organisms; members are uni/multicellular, colonial, and flagellates Example: Spirogyra, Ulothrix, & Volvox
Why are Blue-green Algae/Cyanobacteria not algae?
- they are prokaryotes hence not an algae
- lives in moist or aquatic environments
- obtains energy through photosynthesis
- fixes nitrogen in the soil
Example: Nostoc, and Anabaena
Viruses
- Infectious, acellular pathogens
- Obligate intracellular parasites with host and
cell-type specificity - DNA or RNA genome (never both)
- Genome is surrounded by a protein capsid
and, in some cases, a phospholipid
membrane studded with viral glycoproteins - Lack genes for many products needed for
successful reproduction, requiring
exploitation of host-cell genomes to
reproduce - Have living (can mutate) and non-living
characteristics (acellular – no cellular
organelles) - Don’t grow and divide; new viral
components are synthesized within the
infected host cell - Vast majority of viruses have RNA genomes
DNA virus – has DNA
RNA virus – has RNA
Plant viruses – have single-strand RNA
genome
Bacteriophages – have double-stranded DNA
genome
Example:
• Coronavirus
• Bacteriophage – a virus that infects a
bacteria; bacteria-eater
Viral Replication Process
- Begins when a virus infects its host
- Touching to the host cell, penetrating the
cell wall/membrane - The virus genome is uncoated from the
protein and injected into the host - The viral genome hijacks the host cells’
machinery forcing it to replicate the viral
genome and produce viral proteins to make
new capsids - the viral particles are assembled into new
viruses - New viruses burst out of the cell in the host
cell during the process of lysis which kills the
host cells - Some viruses take a portion of the host
membrane during the lysis process to form
an envelope around the capsid
Helminths
Not a group of microorganisms but are included in studying microbiology - Parasitic worms that feed on a living host to gain nourishment and protection while causing poor nutrient absorption - Cause weakness and disease to the host - These worms and larvae live in the small bowel and are referred to as intestinal parasites - Nematodes or roundworms - Trematodes, which includes flukes or flatworms - Cestodes or tapeworms - Monogenans, also members of the flatworm phylum - Share similar morphology - Multicellular organisms that are visible to the naked eye The worms are usually caught when treading on contaminated soil in warm, humid countries that have poor sanitation and hygiene - Can grow up to 13ml in length - Can penetrate human skin
Features of Helminths:
Trematodes /
flatworms
flat, leaf-shaped and
unsegmented; hermaphroditic
Features of Helminths:
Nematodes
cylindrical and have lips, teeth
and dentary plates; either male
or female
Features of Helminths:
Cestodes or
tapeworm
segmented and hermaphroditic;
have a sucker and a projecting,
hooked rostellum
Diseases caused by Helminths: Hookworm
disease
common worm infestation in the developing countries Cause: Ancylostoma duodenale or Necator americanus Illness lead to anemia and malnutrition
Diseases caused by Helminths: Dracunculiasis
Cause: ginny worm, Dracunculus medinensis transmitted through contaminated water; lies burrowed within skin causes severe inflammatory reactions
Diseases caused by Helminths: Loiasis or
African eye
worm disease
Cause: filaria Loa loa worm contracted through Deer fly or Mango fly bites and the adult worms move through subcutaneous tissue towards the subconjunctiva of the eye Illness: red, itchy swelling in the skin “Calabar swelling”
Diseases caused by Helminths: Cysticercosis
Cause: tapeworm Taenia solium Symptoms are not present for a year but painless bumps develop in the skin and muscles or cause neurological problems
Diseases caused by Helminths: Echinococcosis
Cause: Echinococcus tapeworms liver is usually affected first, followed by the lungs and brain; liver disease may cause abdominal pain and jaundice; lung disease leads to breathlessness and coughing
