(2.1) morphology

Ch 2 - Bacteria

what are the misconceptions of bacteria?

1. bacteria were only found on or in things that had gotten contaminated somehow

TRUTH- bacteria is everywhere, even in clean houses and outside, found on skin and digestive system

2. bacteria are always bad

TRUTH- bacteria on skin, digestive system, foods, nitrogen cycle and ecosystems are good

HOWEVER bacteria can still be pathogens

antibiotics

important for destroying bacterial infections but some broad spectrum antibiotics can harm some of the “good” bacteria as well

do antibiotics work for viruses?

no bcz viruses are pathogens that are not made of cells at all

• but there are vaccines which can prevent many types of both bacterial and viral infections

shapes of bacteria

1. coccus (cocci)= sphere-shaped

2. bacillus (bacilli)= rod-shaped

3. spirillum (spirilla)= spiral shaped

autotroph vs heterooph in bacteria

• heterotroph= consume or feed on some organic matter

• autotroph= they can make their own food (plants aren’t the only autotrophs)

bacterium

• prokaryotic cell which are generally much smaller than eukaryotic cells

• no nucleus

• no membrane-bound organelles

• DO have ribosomes, cytoplasm, cell membrane, cell wall

• DO have bacterial DNA

• can also have flagellum to help with movement

• can have capsule→ gives them extra protection or attachment abilities

• can have pilli→ help w/ attaching to surfaces, including each other

bacterial DNA

• double stranded

• arranged in a circular shape

• some bacteria have plasmids (it’s like extra DNA)

what are abilities that bacteria have that are diff from human body cells?

• bacteria undergo binary fission (not mitosis, cytokinesis)

binary fission

type of fast asexual reproduction when the bacteria can easily divide to make a copy of themselves

are daughter cells identical to parent cells in binary fission?

yes! unless there is a mutation

conjugation

• process where bacteria can share plasmids with each other

• the pili can be used to share this genetic information with each other

bacterial transformation

process where bacteria take in DNA from their environment

bacterial transformation in a lab

scientists use stimuli like heat shock to induce bacteria in a lab setting to pick up genetic material

endospore

produced by bacteria, allow bacteria to be survivors in all kinds of hostile environments (lack of nutrients, freezing temp, dorught)

extremophiles

some archaea and bacteria can be extremophiles, can live in extreme environments where there may be excessive heat, chemicals that our cells would find toxic, or radiation

magnetotactic bacteria

they tracj the earth’s magnetic field to find the perfect spot in their watery homes

how do magnetotactic bacteria build their mini-compasses?

• the bacteria take in iron from their surroundings and transport it to special compartments called magnetosomes

• inside each compartment grows a small, near-perfect crystal of magnetite (type of iron oxide)

• microbes chain up the crystals, combining them into one long, strong magnet and that’s what acts as a compass needle, detecting the earth’s field and rotating accordingly

magnetite

has north and south poles and is the most strongly magnetic natural mineral we know of

why do bacteria use magnetism?

use it to stay in their comfort zone

• if there isn’t enough oxygen at the bottom of the ocean, they follow the magnetic field towards the surface where is more and if there’s too much oxygen then they just move in opposite direction

nanomagnets from bacteria

they are small and bind readily to other substances and can be easily retrieved from a mix of other particles

• this can make them useful for medical technology (might show up in our pills one day)

• might treat infected blood by delovering drugs to targeted parts of the body, speeding up treatment and reducing side-effects

• making nanomagnets in the lab results in many shapes and sizes but magnetotactic bacteria craft their nanomagnets to precisely the same specs, every time

  • if u know which bacteria can make which shape of crystals then that can help you make nanomagnets in whatever shape you want

morphology of bacterial cells

1. bacteria can take many different shapes (or morphologies)

2. bacteria can also assume multicellular organizations

3. size of bacteria can vary greatly

4. there are exceptions to the general size of bacterial cells

what do bacteria look like?

1. spherical (singlular→ coccus, plural→ cocci)

2. rod-shaped (s. bacillus, pl. bacilli)

3. comma-shaped (s. vibrio, pl. vibrios)

4. spiral-shaped (s.spirillum, pl. spirilla)

5. pleiomorphic (varied shapes)

example of spherical shaped bacteria

• staphylococcus aureus

• streptococcus pyogenes

example of rod shaped bacteria

• escherichia coli

• bacillus anthracis

example of comma shaped bacteria

• vibrio cholerae

example of spiral shaped bacteria

treponema pallidum

example of various shaped bacteria

• pleiomorphic

what type of structures or “multicellular organizations” can bacteria form?

1. hyphae (branchinf filaments of cells)

2. mycelia (tufts of hyphae)

3. trichomes (smooth, unbranched chains of cells)

size of bacteria

usually smaller than eukaryal cells (bacteria are often 0.5- 5 µm in length)

size of small eukaryal cells

usually > 5 µm in diameter

exceptions to the general size of bacterial cells

1. thiomargarita namibiensis: up to 700 µm in diameter

2. epulopiscium fishelsoni: 200 to 700 µm x 80 µm!

3. some mycoplasma cells are only 0.2 µm in diameter

what happens when u go from smallest end of scale to largest for bacteria size?

smallest is 0.2 to largest 750 µm

• that’s a 3,750-fold difference

• comparing average length of baby equivalent to 3.4 CN towers

• this is the variation when it comes to bacteria in terms of cell size

2.1 checkpoint