Microbiology Test Flashcards
How are the two types of prokaryotes, archaea and bacteria similar and different?
Both archaea and bacteria and very similar and differ only in molecular structure. Bacteria have cell walls composed of pepitdogylcan and archaea’s are made up of membrane lipids.
Look at picture of prokaryote.
How can prokaryotes survive in a variety of environments?
Structures that help ensure survive in hostile environments
-capsule (slime layer) help evade immune systems & adhere to surfaces
- pili which is hair-like structures used for anchorage and ‘docking’
- endospore is a protective coating formed when conditions are unfavorable
- flagellum is a tail-like structure used for movement
- plasmid DNA is a small rings of extra-chromosomal DNA carrying non-essential genes which are copied independently of the chromosome inside the cell. They can be transferred to other prokaryotes spreading genes that are beneficial to survival (antibiotic resistance)
Describe the different processes of reproduction in prokaryotes. From an evolutionary standpoint which would be the most beneficial and why?
- as the simplest living organisms, prokaryotes can reproduce in a variety of ways
- Asexual Reproduction
- most common form of reproduction = binary fission, 1 organism divides into 2, both genetically identical to the parent (clones) it can do this every 20 minutes if conditions of food and space are ideal
= warmth, moisture and prefer darkness - Sexual Reproduction
a) Conjugation
:2 cells line up side by side & exchange nuclear material before dividing
= offspring have new genes (and new traits)
b) Transformation
: living bacteria absorb & integrate genes from dead bacteria into their own DNA
= gain new characteristics
c) Transduction
: a virus attacks a bacterial cell & enters it
: the bacterial cell incorporates the new gene
the virus is carrying
: this method is used in biotechnology to create bacteria to produce valuable products (ie. insulin)
Sexual reproduction is better for evolution to take place.
How are prokaryotes classified?
Prokaryotes are Currently identified using DNA but historically identified and named based on:
Respiration, Nutrition, Shape and Arrangement
1. Respiration
- prokaryotes can be grouped based on their need for oxygen
a) obligate anaerobes = cannot live in the presence of O2 (poisoned by it)
b) obligate aerobes = need O2 (obligated to use it)
c) facultative aerobes = can live without O2
- Nutrition
a) Autotrophic [create their own food]
- photosynthesizers = use sunlight to convert C02 & H20 to 02 & glucose
- chemosynthesizers = change inorganic materials into organic materials
b) Heterotrophic [ ingest food via absorption]
- saprophytes = feed on dead plant and animal matter [decomposers] - parasites = feed on living cells [pathogenic organisms] - Shape and Arrangement Shape:
- Coccus (plural cocci) - spherical
- Bacillus (plural bacilli) - rod-shaped
- Spirillum (plural spirilla) – twisted / spiral
Arrangement = use Prefixes
diplo = two eg. Dipplococcus
staphyl= clusters eg. Staphylococcus
strepto = chains eg. Streptococcus
How are obligate anaerobes similar, yet different from facultative aerobes?
Obligate anaerobes cannot live in presence of O2 and will get poisoned by it. Faculties anaerobes can live with and without O2.
What is the dif between autotroph and heterotroph?
Autotrophs create there own food
Heterotrophs ingest good via absorption.
What is the dif between photosynthesizers and chemosynthesizers?
photosynthesizers = use sunlight to convert C02 & H20 to 02 & glucose
Chemosynthesizer = change inorganic materials into organic materials
What is the dif between saprophytes and parasites?
saprophytes = feed on dead plant and animal matter [decomposers]
parasites = feed on living cells [pathogenic organisms]
How would staphylococcus bacteria differ from streptococcus bacteria?
Staphyl= clusters Coccus=spherical
Therefore it would have clusters and be spherical
Strepto=chains Coccus=spherical
Therefore it would have chains and be spherical
Why would determining if a bacteria is gram positive or gram negative be a matter of life or death?
all bacteria can be classified as Gram Positive or Gram Negative based on whether it absorbs Gram’s Dye
: thicker peptidoglycan cell wall will absorb the Gram’s Dye
= determines which antibiotic to use against it
List and describe the 3 divisions of archaea.
a) Methanogens
- decompose sewage, garbage dumps, etc.
producing methane gas = obligate anaerobes
b) Halophiles
= salt loving bacteria (the Dead Sea) - photosynthetic
c) Thermoacidophiles
= heat and acid loving bacteria (deep ocean volcanoes) - chemosynthetic
In what ways are bacteria helpful and harmful?
Benefits of Prokaryotes
-make vitamins in humans
- fix nitrogen for plants [Nitrogen cycle]
- produce oxygen and food [yogurt, cheese, vinegar]
- recycle dead things and wastes (bioremediation)
- genetically engineered to make drugs, antibiotics and hormones
Harmful Effects of Prokaryotes
-de-nitrogen fixing bacteria
- tooth decay
- decomposers [spoil food, etc]
- damage crops
- cause diseases and illness in all organisms [ie. Tetanus, Food Poisoning]
: can be treated with antibiotics
Explain how the use of antibiotic can result in resistant bacteria.
As you humans use antibiotics, they work inside your body to disrupt the reproduction of bacteria and kill them. But sometimes a bacteria developed a mutation that allows them to withstand the anti biotic. When this happens that mutated bacteria will survive in the body and reproduce passing down the resistant trait.
What is the dif between viruses, vroids, prions, and retroviruses.
Viruses
- does not grow, respire, or respond to stimuli but it does reproduce
= non-living particles which infect every form of life, in every kingdom - the word Virus comes from Latin meaning poison - are classified by the type of nuclear material they contain
- are named after the disease they cause (ex: Rabies virus) or for the
organ or tissue they infect (ex, Meningitis)
Viroids
- RNA molecules with no protein capsid or fatty envelope - disease causing
- only infect plants
- ie. Potato spindle tuber
Prions
- naked pieces of proteins molecules; no nucleic acids involved - normally exist in cells and are shaped like a coil
- when mutated prions are shaped like a piece of paper folded
many times = cause disease
- ie. Mad Cow disease, Chronic Wasting Disease
Retroviruses are infectious particles consisting of RNA genome packages by a protein capsid surrounded by a lipid envelope. The lipid envelope holds receptor binding proteins which link it so the membrane receptors of the host cell initiating infection.
