[2.1] BIOL 191L: Lab Quiz 2: Bacteria and Protists

Bacteria

small, simple, single celled organisms, existed for more than 3.5 bya

found almost everywhere, but each type has a limited range of where it will grow

studied the most = cause diseases

autotroph

capable of living exclusively on inorganic materials and other sources (like sunlight) rather than carbon sources

ex: cyanobacteria and plants

heterotrophic

obtain organic nutrients from their surrounding environment

most bacteria

saprotrophic

send out digestive enzymes into the environment and afterward pick up the resulting nutrients from the environment

aka Decomposers, digest remains of dead organisms and return inorganic nutrients to a biologically useful form

Cell structure of a bacteria

cytoplasm filled with jelly like cytosol

circular dsDNA (double stranded DNA) and chromosome wound around protein, making a dense areas called the nucleoid

ribosomes are smaller and less dense, still synthesize protein

cell wall - made of peptidoglycan

plasma membrane - lies between the cell wall and cytoplasm and regulates what enters and leaves the organism

prokaryotic characteristics

circular, double stranded DNA

no true nucleus

no membrane bound organelles

pili

finger like projections on the surface of the cell

attachment and transfer of genetic material

can attach to teeth, rocks, root, etc.

flagella

bacteria can have one or more, for locomotion

spherical bacteria

cocci

may occur in pairs - diplococci

groups of 4 - tetracocci

bunches - staphylococci

bead like chain - streptococci

cubical arrangement of eight or more - sarcinae

rod like bacteria

bacilli

occur singly but may occur in

pairs - diplobacilli

chains - streptobacilli

spiral shaped bacilli

spirilla

short, incomplete spirals are called vibrios or comma bacteria

Gram staining bacteria

division is based on how bacteria react when stained using the gram stain and is due to cell wall chemistry between the two groups

most common differential stain used in microbio

gram stains are important because doctors and scientists can determine which antibiotics are effective against a specific species of bacteria

few visible differences among most bacteria - so biochemical tests are needed

Gram positive bacteria

APPEAR PURPLE AFTER STAINING

have a cell wall composed of 60-90% peptidoglycan

multiple layers of peptidoglycan cause cell wall to be 20-80 mm thick

THICK CELL WALL/PEPTIDOGLYCAN

Gram negative bacteria

APPEAR PINK AFTER STAINING

have a cell wall composed of only 10-20% peptidoglycan

THIN CELL WALL/PEPTIDOGLYCAN

Penicillin works by

attaching the peptidoglycan of GRAM POSITIVE CELLS, but is ineffective against GRAM negative cells

Handwashing results

Most effective - antibacterial soap and water

hand sanitizer

non antibacterial soap and water

least effective - water only

Making a wet mount (w/ cyanobacteria)

place your specimen on a glass slide'

if not a suspension, add a drop of water to the slide

gently lay a coverslip over your specimen (45° angle)

use scanning objective to focus, switch to low power

protists

eukaryotic organisms

most closely resemble the earliest eukaryotes

found in wet or damp environments such as soils, oceans, ponds, and lakes

ALL PROTISTS REPRODUCE ASEXUALLY WHILE SOME PRODUCE SEXUALLY

Eukaryotic characteristics

have a nucleus containing linear DNA

membrane bound organelles

unicellular

3 broad groups of protists

plant like autotrophs (algae)

animal-like heterotrophs (protozoa)

fungus like absorptive heterotrophs (slime molds)

3 structural arrangements

unicellular, colonial, filamentous

unicellular

live as single cells, such as Amoeba and Paramecium

colonial

cells attached to each other but each cel remains metabolically independent, such a Volvox

filamentous

chains of cells attached end to end, such as Spirogyra

slime molds

fungus like heterotrophs

phagocytic predators meaning the organisms hunt for and physically engulf their prey

found in leafy forests where plenty of food (bacteria)

multinucleated

also eat fungi, spores, and dissolved organic compounds. if food becomes scares, can aggregate and form a large visible mass (plasmodium) which can crawl farther and faster - uses cytoplasmic streaming to move (directed flow of cytoplasm)

when plasmodium reaches a nice location, transforms into a stalked fruting body, which ruptures and releases spores

cellular slime molds vs. acellular slime molds

in plasmodium of cellular - individual amoebas retain their cell membranes, creating a community of cells

plasmodium of acellular - individual cell membranes break down, making the entire plasmodium 1 large multinucleated cell

Green algae are probably the ancestors of today's land plants because

an increase in the size and occurrence of cell differentiation - within a group of cells, certain cells have functions (multicellularity - different cells perform specific functions and operate together)

appearance of sexual reproduction - 3 types: isogamy, heterogamy, and oogay

isogamy

motile male and female gametes look exactly alike

heterogamy

motile male and female gametes look alike except that the EGG IS LARGER

oogamy

male gamete is small and motile and female gamete is LARGE AND NON-MOTILE

Green algae characteristics

primarily aquatic

photosynthetic using chlorophyll a and b pigments

store starch in plastids, organelles used in storage

many have a cell wall very similar in structure to land plants

Bacillus megaterium

Domain: bacteria

Genus: Bacillus

Species: megaterium

Shape: bacilli (rod shaped)

POSITIVE (purple)

Rhodospirillum rubrum

Domain bacteria

Genus: Rhodospirillum

Species: rubrum

Shape: spirilla (spiral shaped)

NEGATIVE (pink)

Micrococcus luteus

Domain bacteria

Genus: Micrococcus

Species: luteus

Shape - Cocci (spherical)

POSITIVE (purple)

Physarum

Domain: Eukarya

Kingdom: Protista

Genus: Physarum

Protist group: slime mold (fungus like absorptive heterotroph)

CYTOPLASMIC STREAMING (sol state)- allow movement and direct of nutrients

firmer cytoplasm around edge - gel

interior fluid - sol

Amoeba

Domain: Eukarya

Kindgom: Protista

Genus: Amoeba

Protist group: protozoa (animal like heterotrophs)

Structures: PSEUDOPODIA (lobe-shaped cytoplasmic extensions) used for locomotion and engulfing prey, nucleus

only reproduce asexually

penicillin WON'T WORK

Paramecium

Domain: Eukarya

Kindgom: Protista

Genus: Paramecium

Protist group: protozoa (animal like heterotrophs)

structures: pellicle - outer layer, contains alveoli at base of cilia, cell membrane, trichosysts (defensive organelle shot outwards)

CILIA - used for locomotion, more precise, can make rapid retreat, fastest protists

CONTRACTILE VACUOLE - live in freshwater and are hypertonic to environment (osmosis causes water to move into organism), holds and later excretes excess water, prevents taking in too much water and exploding

2 NUCLEI - micronucleus (reproduce)

macronucleus - day to day

both have dna

Euglena

Domain: Eukarya

Kindgom: Protista

Genus: Euglena

Protist group: protozoa (animal like heterotrophs)

Structures: unicellular, have FLAGELLA on anterior end for locomotion

CHLOROPLASTS and photosynthesize

LIGHT SENSITIVE EYESPOT NEAR THEIR ANTERIOR (photoreceptor that senses light level)

not in light = can obtain nutrition by phagocytosis (switch b/w auto and hetero feeding.= mixotrophic)

flexible outer layer (pellicle) - instead of cell wall = can change shape

Volvox

Domain: Eukarya

Kindgom: Protista

Genus: Volvox

Protist group: algae (plant like autotrophs)

Structures: colony is shaped like a sphere with cells on outside and gelatin substance in the center

each cell has 2 flagella facing outward (beat in coordinated pattern)

have special functions for both asex and sex reprod and dev of eyespots

oogamous sexual reproduction - free swimming sperm fertilize large eggs, cells are thick walled zygospores, remain inside colony

eventually colony breaks down, releasing zygospores that undergo meiosis to produce haploid cells, multiply using mito to form a new colony

a sex reproduction - cells in parent colony repeat mitosis and form new DAUGHTER COLONY (retained inside parent colony until breakdown and release)

Spriogyra

Domain: Eukarya

Kindgom: Protista

Genus: Spirogyra

Protist group: algae (plant like autotrophs)

Structures: aka water silk because they form long thin strands (feel silky due to mucus secretion)

named for SPIRAL CHLOROPLAST

isagomous sexual reproduction (conjugation) - when 2 haploid filaments line up side by side, each grows a projection toward the other, fuse into a single CONJUGATION TUBE

cell contents from one filament moves through tube into other

zygote that forms as a result = zygospore = thick cell wall

old filament breaks down and releases zygospore into the environment where it undergoes meiosis and produces new haploid filaments