microorganisms (incl fungi + yeast)

microorganism definition

tiny living organism that cannot be seen by the naked eye

pathogen

disease causing microorganism

microorganism kingdom

eubacteria

microorganism domain

bacteria

notable features of bateria

microscopic, unicellular, prokaryotic

cellular nature of bacteria ?

prokaryotic

prokaryote

organism whos cells do not have a nucleus/membrane bound organelles

things that are always present in structure of bacteria ?

cell membrane, storage granule, cell wall, ribosomes, dna

what is sometimes present in the structure of bacteria

capsule, flagellum, plasmid, mesosome

what is nuclear material in bacteria

single chromosome of dna

whats a plasmid

contains dna that enables resistance

cell wall of bacteria is mostly composed of..

peptidoglycan

capsule

slime layer made of polysaccharides outside the cell wallneeded for protection

what does the flagella do

allows movement

bacteria groups

round, rod, spiral

nutrition def

way in which organism obtains food

two overarching types of nutrition in bacteria

heterotrophic, autotrophic

four ways bacteria can get nutrients

saprophytic, parasitic, photosynthetic, chemosynthetic

saprophytic

feed on dead sources

parasitic

takes food from living host

photosynthetic

use light to make food

chemosynthetic

use energy from chemical reactions to make food

how do microorganisms reproduce

binary fission

whats an endospore

in unfavourable conditions, bacteria chromosome develops an endospore, or a tough outer wall allowing it to remain dormant for a long time

factors effecting rate of growth of bacteria

ph, nutrients, temperature, presence of antibacterial chemicals, water/external solute concentration, oxygen concentration

how does ph affect growth rate of bacteria

each species has an optimum ph

how do nutrients affect growth of bacteria

in nutrient rich conditions, bacteria divides rapidly

how does temperature effect rate of growth of bacteria

bacteria grows more rapidly in optimum temperature, too high temps can denature enzymes

how does the presence of antibacterial chemicals affect growth rate of bacteria

chemicals may damage cell wall/membrane, inhibit enzyme activity or prevent reproduction

how does water/external solute concentration affect the growth of bacteria

if external solution has low solute concentration, cell will swellif external solution has high solute concentration, water leaves cell, causing cell to shrink (growth stops)

osmosis definition

movement of water from area of high water concentration to an area of low water concentration across a semi permeable membrane

if water enters bacterial cell by osmosis, cell swells, why doesnt it burst?

presence of cell wall

how does oxygen concentration affect microbial growth

some bacteria require oxygen, some respire with/without it, some may need it absent

aerobic organisms

require oxygen for respiration

anaerobic organisms

organism doesnt require oxygen for respiration

facultative anaerobes

respire with/without oxygen

obligate anaerobes

only survive in absence of oxygen

phases of growth curve of microorganisms

lag/log/stationary/dead

lag phase of growth curve of microorganisms

no increase in numbers - bacteria adjust to environment

log phase of growth curve of microorganisms

numbers increase very rapidly - optimum conditions allow optimum growth

stationary phase of growth curve of microorganisms

no increase in numbers - birth rate balances with death rates (resources become limited and waste builds up)

decline phase of growth curve of microorganisms

rapid fall in numbers - not enough resources to support growth. Endospores may form

survival phase of growth curve of microorganisms

some bacteria survive as endospores

why is bacteria used in food processing

to produce many types of food products/to maximise product yield

examples of bacteria used in food processing

lactobacillus - yoghurt yeast - bread/beer

types of methods of food processing using microbes

batch culture / continuous flow culture

batch culture

a certain amount of nutrient is added, the batch is maintained in the lag log stationary stages and then stopped, the process is restarted after the bioreacter is sterilized

continuous flow culture

nutrients are continuously added whilst conditions are kept constant, bacteria is maintained in the log phase where growth and product formation is greatest

is batch culture or continuous flow culture used more often

batch culture used more frequently - easier to control, lower risk of containation

antibiotics

chemicals produced by microogranismsthat stop the growth of/kill other microorganisms without damaging human tissue

example of antibiotic

penicillin (produced from fungus penicillium)

what are antibiotics used for

to control fungi/bacteria NOT VIRUSES

describe antibiotic resistance

when antibiotic used - sensitive bacteria die, resistant bacteria survive resistant bacteria - have less competition, and reproduce rapidly

definition of antibiotic resistance

when a random mutation might give one bacterium resistance to an antibiotic

multiresistant bacteria

accumulated multiple resistant genes and are now resistant toseveral antibiotics

examples of misuse of antibiotics

taking antibiotics when not needed/ not completing a full course of bacteroa

microbiome

community of microorgnisms living in a particular environment

human microbiome

microorganisms living on/inside the human body

microorganisms help the body to

• break down food humans cant digest on our own

• product vitamins (eg vit k)

• prevent pathogenic bacteria growing by competing for space and nutrients

how does the human microbiome aid digestion

break down substances like complex carbs into nutrients that we can absorb, in return, the microorganisms receive a constant supply of food and a warm stable environemtn

Explain one effect of antibiotics on the human microbiome

The use of antibiotics can reduce the diversity of microorganisms in the gut, which may lead to digestive problems. A balanced microbiome is important for maintaining good health.

role of fungi

decomposers, food producers, pathogens

why are fungi classed seperately from plants

differ in structure, nutrition, reproduction

fungi domain

eukarya

fungi kingdom

fungi

notable features of fungi

• eukaryotic

• heterotrophic

• cell wall of chitin

• body made of hyphae

• reproduce both sexually and asexually

cellular nature of fungi

fungi are eukaryoric

eukaryote

organism whos cells have a nucleus and membrane bound organelles

what are rhizopus

genus of fungi

whats rhizopus made of

many hyphae which form a mycellium

labels youd include in the structure of a rhyizopus diagram

• sporangium

• columella

• apophysis

• sporangiophore

• spores (+spores blown away)

• stolon

• hyphae

• rhizoids

• mycelium

• substrate

are the nuclei of rhizoids haploid of diploid

haploid

what are stolon

hyphae that spread over the surface

rhizoids

hyphae that anchor the fungi and release digestive enzyme into the food, and absorb digested food

what are sporangiophores

hyphae that enlarge at the tip to form sporangiums

sporangium

swelling at tip of sporagiophore that contains spores

columella

dome shaped structure that supports the sporangium and distributes spores when sporangium bursts

apophysis

swelling below sporangium

spores

small, black, light asexual reproductive structures

advantage of spore structure ?

they’re light - can be carried and distributed easily by the wind

are fungi hetero or auto trophic

heterotrophic - feed by external digestion

whats external digestion

• digestive enzymes released into food source

• soluble nutrients then absorbed through the hyphae

3 modes of nutrition of fungi

saprophytes, symbionts and parasites

what are saprophytes

feed on dead organic matter - act as decomposers, breaking down complex substances and recycling nutrients

what are parasites

feed on living host, cause harm to the host

symbionts

Live in close association with another species where at least one organism benefits

Symbiosis

relationship between two different species living in close proximity where at least one benefits

Why are fungi described as decomposers?

because they break down complex substances and recycle nutrients

whats rhizopus’s reproduction called

sporulation

describe sporulation

sporangiophore grows up from mycelium

sporangium forms at tip

mitosis occurs inside sporangium, producing spores

in dry conditions, sporangium bursts and releases spores

if a spore lands on a suitable substrate, it germinates to form new mycelium

does sexual reproduction happen in rhizoids often?

it may occur under unfavourable conditions and increases genetic variation

Why is asexual reproduction advantageous for fungi such as Rhizopus?

rapid

4 benefits of fungi

• yeast used to make bread/drink

• source of nutrition

• antibiotics

• produce enzymes

4 harmful things about fungi

• can attack crops (blight)

• causes dry rot, mildew and structural damage

• infect animals, cause human disease (athletes foot)

• some mushrooms are poisonous

what is yeast

general term to describe unicellular fungi

cell nature of yeast

unicellular

what does a yeast cell contain

single haploid nucleus, large central vacuole and thin cell wall

how do yeast reproduce, describe the process

• budding (asexually)

• bud forms on cell

• nucleus undergoes mitosis

• new nuclei moves into the bud

• bud continues growing and may separate from parent cell

Aseptic

minimising unwanted organisms

Sterile

all microorganisms destroyed – nothing living