Bacteria, viruses, protists, and fungi

Taxonomy

The science of classifying organisms

-developed by Carolus Linnaeus

-groups organisms by physical and structural similarities

Two word naming system

Binomial nomenclature

-Genus species

-written in italics, G s

Genus Species

Genus refers to a group of organisms that are very closely related

Species is used to describe the organism and can be based on location, physical attributes, or the person that discovered the species

H. habilis=man of skill

H. erectus=upright man

H. sapien=wise man

7 levels of classification

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Domain classification

Archaea- Archaeabacteria

Bacteria- Eubacteria

Eukarya- Anamalia, Plantae, Fungi, and Protista

Phylogeny

the evolutionary history for a group of species

Cladistics

method used to make phylogenic trees, traces evolutionary history of a group by using shared traits

clade

a group of species that shares a common ancestor

derived characters

traits that can be used to figure out evolutionary relationships among a group of species are those that are shared by some species but are not present in others

node

each place where a branch splits on a cladogram

Bacteria

-eubacteria

-living

-unicellular

-cell wall (peptidoglycan)

-heterotrophic

-autotrophic (photosynthesis and chemosynthesis)

Protist

-Eukarya

-Living

-Eukaryotic

-Unicellulr and multicellular

-cell wall made of cellulose

-heterotrophic and autotrophic

-motile(move) or sessile(attatched)

Fungi

-Eukarya

-Living

-Eukaryotic

-Multicellular(except yeast)

-cell wall made of chitin

-heterotrophic

Plant

-Eukarya

-living

-eukaryotic

-multicellular

-cell wall made of cellulose

-autotrophic (photosynthesis)

Animal

-Eukarya

-living

-eukaryotic

-multicellular

-heterotrophic

Cytosol, cytoplasm, and protoplasm

cytosol- just jelly like substance

cytoplasm- jelly like substance and organelles

protoplasm- jelly like substance, organelles, and nucleus

Pathogen

An organism that causes disease, could be virus, bacteria, or fungi

Bacteria (domain characteristics)

-single celled prokaryotes

-no specialized intracellular structures

-found in large numbers everywhere on earth

Archaea (domain characteristics)

-single celled prokaryotes

-no organelles

-extremophiles, live in harsh environments such as sea vents, hot geysers, and salt lakes

Eukarya (domain characteristics)

-eukaryotes

-can be single-celled or multicellular

-contain special intracellular structures called organelles

Prokaryotic structure

-unicellular but some live in colonies

-Can be spheres (cocci), rods (bacilli), or spirals (spirilla)

-archaea vary more in shape than bacteria do

Cell walls

Eukaryotic cell walls are made of cellulose (plants or protists) and chitin (fungi)

Bacterial cell walls contain peptidoglycan (network of sugar and polypeptides)

Archaea cell walls do not have peptidoglycan

Gram stain

-helps scientists classify bacteria

-gram-negative bacteria have less peptidoglycan and stain lighter than gram-positive bacteria

Prokaryotic mobility

most move using a flagellum and pili

plasmids

small circular DNA molecules

Prokaryotic reproduction

asexually through binary fission, and exchange genetic material through conjugation

binary fission

A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size

Conjugation

the process where genetic material is transferred between bacterial cells

-increases genetic variation

Prokaryotic classification

obligate aerobes- require oxygen for cellular respiration (most bacteria)

obligate anaerobes- are poisoned by oxygen and use fermentation or anaerobic respiration

facultative anaerobes- can survive with or without oxygen

How do bacteria survive in harsh conditions

they can produce and endospore, a specialized thick and protective wall that is formed around DNA

Ecological roles of prokaryotes

-recycling of nutrients (recycling chemical elements, decomposing bacteria)

-nitrogen fixation (convert nitrogen in soil for plants to use)

-bioremediation (used to break down pollutants like oil)

-photosynthesis (cyanobacteria can make oxygen)

pathogenic bacteria

-cause illness by invading tissues or making toxins

Antibiotics

-work by interfering with the peptidoglycan cell walls of bacteria

How does antibiotic resistance occur

-overuse: creates selective pressure that favors the bacteria is was intended to destroy

-underuse: not completing a dose of antibiotics will only cause the weak ones to die and allows the strong ones to multiply

-misuse: mixing antibiotics with livestock food may cause bacteria within the food to become resistant

What are viruses?

-not cells

-particles made of nucleic acid enclosed in a protein coat

-they cannot reproduce on their own or carry out metabolic processes

-NOT LIVING OR INCLUDED IN LINNAEAN CLASSIFICATION SYSTEM

Virus structure

-capsid: protein shell that encloses the DNA

-viral envelopes: surround capsids of some viruses and help infect hosts

-surface proteins: aid in infecting host cells

Capsid shapes

rod shaped, polyhedral, complex (bacteriophages)

how does a virus identify its host

By fitting its surface proteins to receptor molecules on the surface of the host cell

Bacteriophages

A virus that infects bacteria; also called a phage.

-elongated capsid head that encloses their DNA

-protein tail piece attaches to the host and injects the phage DNA

The lytic cycle

A type of viral (phage) replication cycle resulting in the release of new phages by lysis (and death) of the host cell.

-the virus uses the hosts machinery and digests the hosts wall to create more viruses

ACTIVE

Lysogenic cycle

a viral reproductive cycle in which the viral DNA is added to the host cell's DNA and is copied along with the host cell's DNA

-DNA is incorporated into host cell and called a prophage

-dormant

DNA and RNA virus

DNA can be replicated and used for protein synthesis (DNA ->RNA->Protein)

RNA can be replicated and used for protein synthesis (RNA-> Protein)

Retroviruses

use reverse transcriptase to copy their RNA genome into DNA

-RNA->DNA->RNA->Protein

-Ex: HIV

Provirus

the viral DNA that is integrated into the hosts genome

Vaccines

harmless derivatives of pathogenic microbes that stimulate the immune system to mount defenses against the actual pathogen

Smaller less complex entities that cause disease in plants and animals

viroids (RNA molecules that infect plants and disrupt their growth) and prions (slow-acting, virtually indestructible infectious proteins that cause brain disease in animals)

What is Protista compared to?

a kitchen junk drawer

Ameboid motion

motion with the use of pseudopods (cytoplasmic extensions)

Cilia motion

short and numerous, used like oars on a boat

flagella motion

long, 1-2 per cell, wavelike or propeller motion

How do protists reproduce?

-many use mitosis which can limit genetic diversity

-some can preform conjunction

-many protists have life cycles where they switch between sexual and asexual reproduction depending on the conditions (alternation of generations)

Autotrophic protists

They can perform photosynthesis and mainly consist of unicellular algae. they form the base of the food chain in aquatic enviornments

mutualistic protists

-many protists are involved in mutualistic symbiosis where both they and their host benefit

parasitic protists

-responsible for causing some of the worlds most dangerous diseases

-Malaria, Sleeping sickness, Ameobic Dysentery

Ameobas

use false feet to move, pseudopodia, heterotrophic

Paramecium

use cilia to move, heterotrophic

Euglenoids

use flagella to move, both autotrophic and heterotrophic

How do fungi differ from plants

plants contain chlorophyll and photosynthesize which fungi do not photosynthesize and absorb their energy from the environment

plants have true roots while fungi do not

plant cell walls are made of cellulose while fungi cell walls are made of chitin

anatomy of fungi

hyphae- long filaments that make up the bodies of fungi

mycelium- hyphae that grow together into a tangled mass found underground

fruiting body- reproductive structures found above ground

How do fungi obtain nutrients?

by secreting chemicals that break down food and then absorbing it

-hyphae extend into the food source and release enzymes that break down food that is then absorbed across cell walls

-high surface area= larger amounts of nutrients taken in

classifying fungi

they are classified by their mode of sexual reproduction

Sac fungi (Ascomycota)

-during sexual reproduction they form a sac called an ascus that contains spores for reproduction

-include yeast, certain molds, morels, and truffles

Bread Mold (Zygomycota)

-during sexual reproduction they form a structure called an zygospore that gives rise to a sporangium which releases spores

-most spoil food

-ex mycorrhizae

club fungi (basidiomycota)

-during sexual reproduction they form structures called basidia that contain spores for reproduction

-ex: mushrooms, puffballs, and bracket

Fungi reproduction

-reproduce in vast numbers

-usually haploid except when they are in the sexual reproduction stage and they are diploid

-sexual reproduction requires the fusion of two haploid cells followed by meiosis

-sexual reproductions during favorable conditions and asexual reproduction when conditions are harsh

ecological roles of fungi

-decomposers: decompose the dead and decaying organic matter, return nutrients back into the soil

-pathogens: illnesses in humans such as ringworm and athletes food, illnesses and plants such as Dutch elm disease

Relationships in fungi

-Mutualists:

Mycorrhizae, symbiotic relationship- where fungus transfer minerals to a plants roots and plant roots supply carbohydrates to fungus

Lichens, symbiotic relationship- fugus protects photosynthetic partner providing minerals, and photosynthetic partner provides carbohydrates to fungus

ameoba

animal like

Phytoplankton

plant-like

water molds

fungi like

zooplankton

animal-like

stentor

Paramecium

euglena

spyrogyra

Derived characteristics

characteristics that arise as lineages evolve over time