Lecture 13 Flashcards
Biologists classify living things into WHAT?
a few large groups
called DOMAINS
How many domains are there?
3 distinct domains
name all 3
Bacteria
Archaea
Eukarya
Which one(s) are part of Prokaryotes?
Bacteria & Archaea
Between Bacteria & Archaea, which one is closer to Eukarya?
Archaea
Are prokaryotes (B & A) mostly unicellular or multi?
uni
Do they have a nucleus?
NO
How is their chromosome?
A simple genome -> usually one circular chromosome
Do they all mostly have a CW or no?
yes, mostly
Is their ribosome structure the same as eukaryotes?
NO, it’s different
Reproduce sexually or asexually?
Asexually
Prokaryotes (2 Domains: Bacteria & Archaea) have 6 main characteristics, name them all
- most are unicellular
- lack nucleus
- simple gnome = one circular chromosome
- CW (differs from that of plants & fungi)
- Ribosome structure (different than that of eukaryotes)
- Reproduce Asexually (no meiosis)
Where can I find Prokaryotes? ()
- Air
- Soil
- Water
- On plants
- On/in Animals
- Polar ice caps
- Deep sea hydrothermal vents
Present pretty much everywhere
According to what are the prokaryotes extremely varied (metabolically wise)?
According to the source of ENERGY or CARBON
What are the 2 types of energy in Sources of Energy?
Chemotrophs & Phototrophs
What do you know about Chemotrophs?
Energy from chemical bonds
*These can be organic compounds (carbohydrates, hydrocarbons, etc)
* or inorganic substrates (H2S, NH4, NH4 …)
What do you know about phototrophs?
Radiant energy from the sun (light)
photo = photosynthesis
What are the 2 types of energy in Sources of Carbon?
Autotrophs & Heterotrophs
What do you know about autotrophs?
Atmospheric CO2 (i.e. from the AIR)
What do you know about heterotrophs?
Organic compounds such as Sugars, Fats, Amino-Acids and proteins
What do you get when combining Energy and Carbon? (name all combinations)
you get different nutritional modes:
- Photoautotrophs
- Photoheterotrophs
- Chemoautotrophs
- Chemoheterotrophs
What do you know about photoautotrophs?
Most plants, some prokaryotes, and some
protists
= Energy from the sun, carbon from atmospheric CO2
What do you know about photoheterotrophs?
Energy from the sun, carbon in organic form =
organic carbon (i.e. other living or things)
What do you know about chemoautotrophs?
Energy from chemical bonds (organic or
inorganic compounds), carbon from atmospheric CO2
What do you know about Chemoheterotrophs?
Energy from chemical bonds (organic or
inorganic compounds), carbon in organic form =
organic carbon (i.e. other living or things)
Which nutritional mode can only be prokaryotes?
Photoheterotrophs & chemoautotrophs
Which one is all animals and fungi?
Chemoheterotrophs
Which one is mostly plants?
Photoautotrophs
Prokaryotic metabolism also varies with
respect to WHAT?
to oxygen
What are the 3 different metabolisms concerning oxygen?
- Obligate aerobes
- Facultative anaerobes
- Obligate anaerobes
Which prokaryotic metabolism is Poisoned by O2?
Obligate anaerobes
Which one will use O2 if present but can also grow by fermentation?
Facultative anaerobes
= Can grow with or without air
Which one REQUIRES O2 for cellular respiration?
Obligate aerobes
Through which process do prokaryote cells reproduce?
Binary fission
What is the result of Binary fission?
Each daughter cell receives a copy of the parental DNA
Is it more similar to mitosis or meiosis?
Mitosis
Some bacteria can survive hostile conditions by
producing WHAT?
endospores
What are endospores? (main function)
- remain dormant and can hydrate and revive in more hospitable conditions
How are you able to kill endospores
Heat at high temperatures 120ºC
Name all 5 varieties of shapes in Domain Archaea
- rods
- cocci
- spirilla
- filaments
- square
We say that many groupings within Archaea are Extremophiles, what does this mean?
typically found in extreme environments
Name all 3 types of extremophiles
- methanogens
- Extreme Halophiles
- Extreme Themophiles
What are Methanogens?
Found in anaerobic environments, releases methane as a waste product of cellular metabolism. (maybe in mud, lakes, swamps (areas where it lacks Oxygen) + some in intestinal tracts of animals)
Relate definition to correct type:
(a) grow in hot environments (45 to 104ºC). Found in deep-sea vent areas and hot springs
(b) Found in the Dead Sea and other extremely saline (salty) lakes
(a) Extreme Thermophiles
(b) Extreme Halophiles
How does Domain Archaea differ from Bacteria? (3 main characteristics)
1) lack of peptidoglycan in CW
2) cell membranes differ
3) DNA and RNA structures differed from those of Bacteria
TRUE OR FALSE:
*No archaea are known to cause disease in humans
TRUE
Name 3 cell shapes
i) sphere (cocci)
ii) rods (bacilli)
iii) spirals (spirilla)
Name 3 colony shapes
i) strepto (chain)
ii) staphylo (clumps)
iii) spirilla (squiggly/spiral)
Where do you find/locate DNA in prokaryotes?
located in the cytoplasm; not surrounded by a membrane in the nucleoid region
Most bacteria also have 1 or more plasmid(s), what are they?
smaller circular fragments of DNA
Do they carry genes essential for survival?
NO, they do not
Plasmids can be transferred b/w bacterial cells through what process?
Conjugation
What is specifically conjugation?
- bacterial “ sex ” transfers genetic material between two bacterial cells that are temporarily joined
=> - the transfer of DNA between cells in physical contact (via sexual pilus)
If plasmids are not essential to survival, why carry plasmids in addition to the main genome?
Plasmids constitute an extra pool of genes for a
population (Comes in useful only in special situations)
Plasmids carrying antibiotic-resistance genes enable bacteria to do what?
enable bacteria to evolve resistance rapidly (b/c bacteria multiplies quickly)
What then happens to the resistant bacteria?
it spreads through direct contact with a person/animal with that infection
What happens when an antibiotic is given?
it kills the sensitive bacteria
Does it kill every bacteria?
NO, any resistant ones can survive and multiply.
Many plasmids in bacteria contain genes for what?
for antibiotic resistance
Antibiotic use creates selective pressure, favoring what? (2)
favoring the survival and reproduction of resistant bacteria
TRUE OR FALSE: Antibiotics cause resistance
FALSE, they don’T cause resistance
They create an environment favorable for them, what does this mean?
where resistant bacteria thrive by killing non-resistant ones
How do the resistance variants of bacteria come about?
they exist naturally or can arise through genetic mutations
What is the MAJOR role of the bacteria?
they are decomposers (saprophytes)
so, decomposition of dead organic material + recycling of nutrients
After the decomposers break down organic matter, what are the 2 next steps?
Minerals and other nutrients released into soil + plant growth
What are symbionts?
2 organisms that live together (can be beneficial, harmful, or neutral)
What is a mutualistic symbiotic relationship?
A mutualistic symbiotic relationship is when both animals benefit
What do Herbivores eat?
they eat plants
What do they contain in their CW?
Cellulose
Do Herbivores produce enzymes?
NO, so they can’t breakdown cellulose
So, what is needed to have the enzymes to break down cellulose?
House bacteria in their digestive system and the bacteria have the enzymes
