Download VIRUS - C. Shirley Science EJCHS

VIRUS
Viruses are nonliving particles that can only
reproduce within a HOST CELL (living cell).

Can NOT carry out life-sustaining functions.
Viral Structure:
1. Nucleic Acid – DNA or RNA

encodes for the synthesis of proteins – making new viruses
2. Capsid – protein coat surrounding nucleic acid; arrangement determines shape
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protects the nucleic acid from digestive enzymes
contains special sites on its protein surface that allow the virus to attach and penetrate the host cell
membrane
3. Envelope – membrane surrounding capsid; NOT found in all viruses
Viral Replication – Capsid proteins on virus must match proteins on host cell.
Lytic cycle:
1. virus attaches to host cell and injects viral
DNA
2. viral DNA uses host cell to create new
viruses
3. new viruses assemble –destroying host
VIRAL DISEASES
Mumps
Rabies
Influenza Herpes
Lysogenic cycle:
Smallpox
Chickenpox
Measles
AIDS
Polio
Hepatitis
1. virus attaches to host cell and injects viral
DNA
2. viral DNA integrates with host DNA creates
provirus
3. provirus is replicated along with host cell’s
DNA
4. virus may become active, switching to the
lytic cycle, destroying host
TREATMENT:
Antiviral drugs – treat symptoms or
suppress the virus
o your immune system has to kill
the virus
Vaccine – preparation of weakened
or killed virus/viral particle
 stimulates immune system to
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prevent infection by “teaching” it
to recognize virus
Edward Jenner created smallpox
vaccine
Jonas Salk created polio vaccine
Extras-- Oncogenic viruses – cause cancer; genes disrupt cell
cycle
 Retrovirus – contains RNA; produces a DNA copy of the
viral RNA and inserts viral DNA into host cell
 Prion – protein particle with no nucleic acid;
accumulation of proteins in an area kills cells
 Viroid - small naked single-stranded RNA molecules
that cause plant diseases
Domain Archae
Domain Bacteria
Kingdom Archaebacteria
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prokaryotes
cells walls lack peptidoglycan
May be ancestors of eukaryotes - DNA
sequences of key genes are more like
eukaryotes
live in extremely harsh environments
Classification based on environment:
1. Methanogens – all anaerobes and
produce methane; live in marsh mud, etc.
2. Halophiles – live in extreme salt
environments; Great Salt Lake
3. Thermoacidophies – live in acidic/hot
places; volcanic vents, hot springs
Bacterial Structure
o
o
o
o
Kingdom Eubacteria
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prokaryotes
cell walls contain peptidoglycan (sugar &
amino acid molecule)
live almost everywhere
cause diseases
Classification based on:
1. shape and cell arrangement
 arrangement: staphylo(clusters) or
strepto(chains) or diplo (pairs)
 shape: coccus(round) or bacillus(rod) or
spirillum(spiral)
2. movement - flagella, cilia or use vectors
3. Heterotrophic (use endocytosis/exocytosis) OR
Autotrophic (photosynthesis – use light energy
or chemosynthesis – use inorganic compounds)
4. O2 requirements – obligate anaerobe (can’t
survive in O2) OR obligate aerobes (must have
O2 to survive)OR facultative anaerobe (live with
or without O2)
5. Gram Stain lab test: Gram positive (+) turns
purple, more peptidoglycan; Gram negative (–)
turns pink, less peptidoglycan
 Gram– are more resistant to antibiotics
Capsule – sticky protective layer that helps evade immune system and adhere to substances
Plasmids - accessory rings of DNA; can be used as vectors to carry foreign DNA into bacteria during
genetic engineering procedures; can carry resistant genes
Endospore – thick internal wall that encloses the DNA; formed so bacteria can remain dormant during
harsh environmental conditions.
Pili – allow bacteria to stick to surfaces
BACTERIAL Reproduction
1. Binary fission – grows, replicates DNA, and divides; (asexual) – identical daughter cells
2. Conjugation – pili form bridge, exchange DNA then split; (sexual) – diversifies population
3. Transformation – bacteria taking up free pieces of DNA secreted by live bacteria or released
by dead bacteria (sexual
BACTERIA – Good or Bad??
HELPFUL
 decomposers – break down dead matter and recycle nutrients
 nitrogen fixation – convert atmospheric nitrogen into soil nitrogen form
 denitrification – convert excess soil nitrogen form into atmospheric nitrogen
 photosynthesis – produces oxygen
 human uses – food, digest petroleum, remove waste from H2O, synthesize drugs, bacterial
enzymes used in genetic engineering
 mutualistic relationships – both organisms benefit; ex. bacteria in human colon
HARMFUL
 pathogens – cause disease by breaking down tissue or release toxins
BACTERIAL DISEASES
Strep throat
Syphilis
Tuberculosis
Lyme disease
Typhoid fever
Pneumonia
Tetanus
Gonorrhea
Treatment –
Antibiotics – destroy bacterial cells by inhibiting cell wall growth or protein synthesis
 Alexander Fleming created first antibiotic – penicillin
Vaccine (prevention) – stimulates immune response
Controlling Bacteria –
1. Sterilization – kill bacteria by heat or chemical action

Joseph Lister created the first antiseptic to disinfect instruments before surgery (1860).
2. Refrigeration – bacteria grows at a slow rate in cold temperatures
Kingdom Protista
 Eukaryotes
 Mostly Uni- or Some Multicellular
 First Eukaryotic organism on Earth – appeared
about 1.5 billion years ago
 Most live in watery habitats
CLASSIFIED according to the way they obtain
nutrients:
1. Animal-like protist - heterotroph
2. Plant-like protist - autotroph
3. Fungi-like protist – heterotroph
ANIMAL-LIKE PROTIST (AKA: PROTOZOANS)
1.
2.
3.
4.
Zooflagellates – use flagella
Ciliates – use cilia
Sarcodines – use pseudopods
Sporozoans - parasitic
Amoeba
Protozoans  Unicellular
 Contractile vacuole – regulate water level
 Some live symbiotically within organisms – termite and
zooflagellate
Paramecium
Disease
Malaria
Giardiasis
African Sleeping Sickness
Amebic Dysentery
Protozoan
Plasmodium species – carrier Anopheles mosquito
Giardia species – carrier beavers; contaminated H2O
Trypanosoma species – carrier Tsetse fly
Entamoeba species – contaminated H2O
PLANT-LIKE PROTIST (AKA: ALGAE)
Unicellular Algae 1. Euglena
2. Dinoflagellates – algal blooms
produce red tide
3. Diatoms – cell walls rich in silicon
Multicellular Algae (aka: seaweed) –
red, brown, green algae
 Pigments vary to efficiently harvest light energy
for photosynthesis
 Phytoplankton – population of photosynthetic
organism
 Cell walls composed of cellulose
 when waste is excessive, algae grows into masses
called algal blooms; depletes nutrient in H2O
which kills aquatic organisms
Human uses of Algae –
 much of Earth’s O2 is produced by algae – uses photosynthesis to produce oxygen
 chemicals in algae – medicines(treat ulcers, arthritis), make plastics, deodorants, paints etc.
 food --nori wraps in sushi, ice cream, candy bars, syrups, etc.
FUNGI-LIKE PROTIST
 Multicellular, decomposers, produce spores, cell walls made of cellulose
 Includes slime molds & water molds
 Can be parasitic to plants - cause diseases such as blight, mildews
Kingdom Fungi
Fruiting body
Eukaryotes
Heterotrophs – Decomposers
All fungi are multicellular, except for yeast
STRUCTURE –
 Cell walls – contain chitin (carb)
 Hyphae – thin filament
 Mycelium – thick mass of hyphae
 Fruiting bodies – reproductive structure
How do fungi spread?
 fungi need proper
temperature, moisture & food
or they remain dormant in
soil
 spores are scattered by wind,
water or animal
REPRODUCTION –
1. Budding (asexual) – cells break off and grow new fungus
2. Spores (asexual) – reproductive cell germinates into new fungus
3. Sexual reproduction – Two mating types (+ & -) fuse nuclei then divide to produce haploid
spores germinate into new fungus – produce genetically diverse spores
ECOLOGICAL ROLES –
1. Saprophytes (decomposer) - absorb nutrients from dead organic matter.
2. Parasites - absorb nutrients from body fluids of host organism causing plant and human
diseases. (wheat rust, corn smuts, ringworm, yeast infection, thrush, etc)
3. Used to produce medicines - penicillin, cortisone, antibiotics, vitamins
4. Fermentation process to produce food – cheese, bread, etc.
5. Mutualistic symbionts - both reciprocate with some beneficial function.
 Mycorrhiza – special roots and fungi association (fungi increase absorption of
water/minerals and fungi release enzymes to free nutrients in the soil & plant provides
product from photosynthesis)
 Lichen – fungus and green algae association (algae carries out photosynthesis,
providing the fungus with a source of energy & fungus provides water, minerals and
protect the algae)
KINGDOM PLANTAE
Characteristics of Plants –
 cell walls – composed of cellulose
 eukaryotes
 autotroph
 multicellular
Green algae are believed to be the
ancestors of plants.
Survival NEEDS:
invasion of plants –
 sunlight
occurred about 430
 gas exchange
million years ago
 water & minerals
 movement of water and nutrients
Adaptations – Evolutionary trend was to move from water to land, plants had to adapt……
Adaptations for attainment of resources
Land plants evolved methods to gain vital minerals from the soil. Green algae absorb nutrients they
need directly from the water they live in. Land plants have to live without being suspended in water.
o Roots developed as a structure that allowed plants to obtain minerals and water from the soil.
o Some plants developed vascular tissue (xylem & phloem) that act as a transport system to
bring water and other substances such as minerals up the plant body, allowing for increased
plant size.
o All plants contain lignin which binds to cellulose fibers to harden and strengthen the cell walls
of plants to support growth.
o Stems developed to store and transport water & nutrients.
o Leaves are modified to maximize photosynthesis.
Adaptations to reduce water loss
Strategies to catch and retain water were vital for the survival of land plants. Once removed from
moist, swampy areas, plants risk desiccation, or drying out.
o To prevent desiccation, many plants developed a cuticle (a thick, waxy, watertight barrier)
that covers the plant and prevents loss of moisture to the air.
o The stomata are openings in the cuticle that allow for gas exchange and transpiration of
water as the plant photosynthesis.
Adaptations for reproduction
The reproductive processes of the earliest plants to evolve from green algae still required an
aquatic environment. Consequently, these primitive land plants could live only in highly moist, swampy
areas. Plants evolved the ability to reproduce without water and began to populate drier
environments.
o The seed allowed safe dispersal of plant embryos by supplying it with nutrition and protection
against hostile conditions. Seeds can remain dormant during unfavorable conditions.
o Pollen grains containing the male gamete could be dispersed without water.
o Flowers developed to attract pollinators and allow for greater dispersal of the pollen.
o Fruits developed to protect the embryo and allow for greater dispersal of the plant.
Can plants DEFEND themselves?
Mechanical defense -incorporated into the physical structure of the organism. -- thorns, spines and stiff
hairs that repel a predator
Chemical defense - occurs when the plant produces stinging sensations, paralysis, poisoning, or just a
bad taste.
Camouflage - the organism blends into its environment or appear to be something they are not
Classification –
Xylem – transports H2O
Phloem – transports dissolved
nutrients
Nonvascular Plants: Bryophytes
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nonvascular – instead uses rhizoids for movement of minerals & water via diffusion
produces spores (reproductive cells) – sperm require water for fertilization
habitats and size of plant is limited due to lack of vascular tissue
Vascular Plants: Tracheophytes
1. Seedless vascular – reproduce with spores
2. Gymnosperms – produces seeds in cones
3. Angiosperms – produces flowers and seeds in fruit
TROPISMS ~plants adjust growth in response to environmental stimuli
o Gravitropism or Geotropism– a growth response to gravitational forces
o Phototropism— when stems/leaves adjust the direction of growth in response to light
o Thigmotropism— plants shift a direction of growth as they contact objects
How do plants control their growth in response to environmental stimuli?
 Most plants do this by way of chemical messengers known as hormones.
 A hormone is a chemical that is produced in one part of an organism and transferred to another
part to affect the activities of that part of the plant.
 Auxins – hormone responsible for regulating phototropism in a plant by stimulating the
elongation of cells & helps promote the growth of fruit…during fall auxin levels decrease causing
ripened fruit to fall and plants will lose their leaves
 Abscisic Acid – inhibits plant growth during times of stress such as cold temperature or drought
 Gibberellins – growth hormones that cause plants to grow taller & increase the rate of seed
germination and bud development
KINGDOM ANIMALIA
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All animals are multicellular, eukaryotes and
most have tissues, organs, and organ systems.
They have no cell walls.
Animals are aerobic heterotrophs that ingest
other organisms or withdraw nutrients from
them.
Animals reproduce sexually; many also
reproduce asexually. Their embryos usually
develop through a series of stages.
Most animals are motile; they actively move
about during all or part of the life cycle.
MAJOR ANIMAL GROUPS
Phylum Porifera - sponges
Phylum Cnidaria – hydras, jellyfish
Phylum Platyhelminthes (flatworms) – flukes, tapeworms
Phylum Nematoda (roundworms) – pinworms, hookworm
Phylum Annelida (segmented worms) – leeches, earthworms
Phylum Arthropoda – crustaceans, spiders, insects
Phylum Mollusca – snails, slugs, clams, squids, octopi
Phylum Echinoderms – starfish, sea urchins
Phylum Chodata
Invertebrate chordates – tunicates, lancelets
Vertebrate chordates – fish, amphibians, reptiles, birds, mammals
Animal Behaviors
Behavior – anything an organism does in response to a stimulus in its environment. Behaviors develop
through interactions between genes and environmental inputs.
Behavior is ADAPTIVE –
adapting allows animals
TYPES of behaviors:
to survive!!!
1. Innate Behavior – inherited behaviors (You are pre-wired to recognize
stimuli before being born!)
 Reflexes
circadian rhythm – occur in daily patterns
 Instincts
migration – periodic movement from one place to
 territoriality
another
 aggression
hibernation – dormancy during winter
 submission
estivation –dormancy during summer
 courtship
 behavioral cycles
2. Learned Behavior – these behaviors are acquired or learned over time. Organisms can alter
their behaviors as a result of experience.
 Habituation – organism decreases or stops its response to a repetitive stimulus that neither
rewards nor harms the animal
 Imprinting – when an organism forms an attachment to an object or other organism after
birth and copies it. For example, sparrows have an innate ability to recognize their own
species’ song. To sing the complete version, the young birds must first hear it sung by the
adults.
Adaptations for DEFENSE
 Mechanical defense occurs when an animal uses its physical structures such as claws, tusks, stingers
and shells. Other examples of mechanical defense include camouflage, cryptic coloration, disruptive
coloration, counter shading, etc…
 Chemical defense occurs when the animal produces stinging sensations, paralysis, poisoning, or just
a bad taste.