Chapter 27- Bacteria and Archaea

What are the additional structures of a prokaryote?

-A capsuli -pili -fimbriae, -flagella, -internal plasmid DNA

What characteristics enable prokaryotes to reach huge population sizes and thrive in diverse environments?

-Small size and rapid reproduction which leads to mutation -Diverse adaptations to the environment that lead to rapid evolution.

How often does binary fission occur?

1-3 hours

How many bacteria are estimated to be on Earth?

2-12 million

How many mutualist type bacteria are estimated to live inside the human body.

30-39 trillion

Describe where prokaryotes are found in the environment

Prokaryotes, which include both bacteria and archaea, are found almost everywhere - in every ecosystem, on every surface of our homes, and inside of our bodies! Some (such as Archaea) live in environments too extreme for other organisms, such as hot vents on the ocean floor.

Describe the ecological impact of prokaryotic organisms.

Prokaryotic organisms are important to ecology because they can play a role in oxygen production, agriculture, antibiotic production, and food production.

What are the functions of the cell wall? (Think..wall)

Protection, maintains the cell's shape, prevents lysis (cell wall rupture) in hypotonic environments

We've established that rapid reproduction leads to increased mutation. Why does that happen exactly?

Rapid divisions mean that adaptive mutations appear more quickly and accumulate more rapidly.

Since endospores are survival mechanisms, they can withstand high temperatures and can't be killed through usually methods of boiling. How do we kill endospores?

We use autoclave, which is a combination of high temperature and pressure.

Describe how prokaryotes are used in research as well as for commercial uses.

We use prokaryotes in bioremediation to break down harmful pollutants and waste, help up study the origin of eukaryotes, and use their heat-tolerant enzymes in biomedical research.

What is a microbiome?

An example of human-prokaryote mutualism

Explain how antibiotics are effective against bacteria.

Antibiotics target the cell wall. They specifically prevent the crosslinking of the peptidoglycan layer to prevent new cell wall formation. Without that cell wall, unfortunately bacteria is left exposed to outside water and pressure and will quickly die :(

Describe Domain Archaea and Bacteria. Why were the two domains split, they're both prokaryotes aren't they?

Archaea Primitive structed prokaryotes. Typically only live in extreme conditions. Bacteria Prokaryotic organisms that lack a membrane, nucleus, and organelles. (Both are prokaryotic btw) These classifications were created because Bacteria and Archaea have distinct differences. Archaea are more closely related to eukaryotes. Ribosomal RNA was analyzed and it was found that the ribosomal RNA genes of Archaea was more similar to Eukaryotes than Prokaryotes and thus the classification needed to be split.

Fill in the blank! The larger prokaryote that engulfed the smaller one during endosymbiosis was likely a(n) _______________

Archaean

What is binary fission?

Asexual reproduction by a separation of the body into two new bodies

Describe the difference between basic conjugation and that involving an Hfr (high frequency of recombination) cell.

Basic conjugation is just the direct sharing of DNA between cells whereas conjugation involving a Hfr cell the Hfr cell is the recipient and the F- cell is always the donor. Frequency of recombination is very high but frequency of transfer of whole F-factor is very low.

Describe the three main mechanisms of genetic variation: Conjugation, transformation, and transduction. (Hint: kissing, radioactive spider bite, lovesickness)

Conjugation- Direct sharing of DNA between cells. Transformation- When bacteria absorb free DNA from their surroundings and can result in the acquisition of advantageous traits. Transduction- Viruses that infect bacteria accidentally from one host cell to another (indirect).

All living organisms need what two things to survive? What are those two things used for?

Carbon and energy Carbon is used to build organic molecules and energy is used to make ATP

Describe what F-factors and R-plasmids are

Cells who share the F-factor through conjugation share the ability to conjugate with other cells. R-plasmids that are shared give cells resistance to antibiotics.

Name all examples of bacterial phyla.

Chlamydia, spirochetes, cyanobacteria, and gram-positive bacteria.

Give a characteristic of each group in bacterial phyla.

Chlamydia- all parasitic, responsible for the most common STD Spirochetes- have spiral-like movement, Not all are pathogenic but some are incredibly pathogenic to humans (Lyme disease, syphilis) Cyanobacteria- The origin of chloroplast and hugely important to the environment (produces oxygen) Gram-positive bacteria- Very diverse. Some are pathogenic but others have been used to derive antibiotics so that's cool.

Which Domain of prokaryotes does these things for us? (We use prokaryotes in bioremediation to break down harmful pollutants and waste, help up study the origin of eukaryotes, and use their heat-tolerant enzymes in biomedical research.)

Domain Archaea.

List all the differences between prokaryotes and eukaryotes (DNA, nucleus, cell membrane, cell wall, cytoplasm, ribosomes, membrane bound organelles)

Eukaryotes -Have linear DNA -Have nucleus -Have a cell membrane -Only SOME have a cell wall -Have a cytoplasm -Have ribosomes -Have membrane bound organelles Prokaryotes -Have circular DNA -Have no nucleus -Have a cell membrane -Have a cell wall -Have a cytoplasm -Have ribosomes -Have no membrane bound organelles

What form of adaptation is the evolution of flagella called?

Exaptation, where structures adapted for one function take on new functions through descent with modification.

How did flagella likely evolve?

Existing proteins were added to an ancestral secretory system

While it is true that Archaea can thrive in extreme conditions, which two have been the most intensely studied?

Extremophiles and Methanogens

Protists are a polyphyletic group of organisms, which means...?

Prokaryotes include two separate clades (Bacteria and Archaea), but excludes their common ancestor.

Describe what fimbriae and pili are and what they do.

Fimbriae are adhesive structures. They allow bacteria to bind to structures so that they can colonize specific surfaces. Pili on the other hand allows the transfer of DNA between bacteria. This is related to conjugation because conjugation is the process of direct exchange of DNA between cells (Think of kissing).

Describe the main purpose/function of prokaryotic flagella. Why is taxis important?

Flagella's main purpose is to provide motility. Taxis are important because it creates movement within an organism in response to stimulus, whether that be light, food, etc. This can help bacteria get away from danger as well as lead them to nutrient sources.

Describe why Gram + bacteria stain purple and Gram - bacteria stain pink.

Gram positive bacteria stain violet due to the presence of a thick layer of peptidoglycan in their cell walls, which retains the violet color these cells are stained with. Alternatively, Gram negative bacteria stains pink, which is attributed to a thinner peptidoglycan wall, which does not retain the violet color as easily.

Explain the difference between gram positive and gram negative bacteria. (Gram negatives are a little fancy)

Gram-positive bacteria have simpler walls with a large amount of peptidoglycan whereas gram-negative bacteria have less peptidoglycan and are more complex with an outer membrane that contains lipopolysaccharides

What are the two sub categories of extremophiles?

Halophiles- can live in environments with high salt concentration like the Great Salt Lake in Utah Thermophiles- can live in extreme temperatures (hot or cold) (ex. Hot springs, geysers, etc)

Describe why prokaryotes are good model organisms to study evolutionary change.

Prokaryotes undergo rapid evolutionary and are highly adaptable.

What are internally folded membrane in prokaryotes for?

Metabolic machinery such as for aerobic respiration or photosynthesis.

We mentioned before that Archaea lack the ability to create endospores in reproduction. What are endospores and why are they so cool?

Metabolically inactive endospores are created when water or nutrients are lacking. The cell will copy its chromosome and surround it with a multilayered structure. Endospores can withstand extreme conditions and remain viable for centuries. (Think of like freezing your eggs!)

What do methanogens do and what is their relationship with ruminants like cows or humans?

Methanogens produce methane as a metabolic byproduct. They reside in the gut of cows and help them digest cellulose. They can help humans break down food as well and aid with sewage treatment.

What is binary fission similar to meiosis or mitosis?

Mitosis

Describe how mutation and horizontal gene transfer are major sources of prokaryotic genetic variation.

Mutation and horizontal gene transfer are major sources of genetic variation! Mutation occurs rapidly in bacteria due to how fast they reproduce. These mutations can be deleterious but they can also be advantageous. Horizontal gene transfer is the sharing of DNA which can spread beneficial genes, as well as genetic parasites across populations creating genetic variability.

What are the three types of symbiosis?

Mutualistic - both benefits Commensal - one benefits and the ether neither benefits or is caused harm Parasitic - one benefits and the other is caused harm

We can categorize bacteria based on their ability to tolerate oxygen: What are the 3 types of aerobes and anaerobes?

Obligate aerobes- MUST have oxygen; must be in oxygen rich environment Obligate anaerobes- Require the absence of oxygen Facultative anaerobes -Can use oxygen, but can also survive without (can switch between aerobic and anaerobic respiration)

What molecule makes up a cell wall?

Peptidoglycan

Describe the difference between photoautotrophs, heterotrophs and mixotrophs

Photoautotrophs- Organisms that make their own food; usually by fixing carbon Heterotrophs- organisms that other consume organic substances (All organic substances have carbon as a backbone so heterotrophs do be needing a lil carbon too) Mixotrophs- organism that can use a mix of different sources of energy and carbon, instead of having a single trophic mode

Bacteria include 3 different types/species. What are they?

Photosynthetic species- those that absorb carbon dioxide and produce oxygen Decomposers- breakdown dead organic matter and recycle nutrients Mutualists- species that live inside our bodies

Describe the beneficial and harmful impacts of prokaryotes on humans.

Prokaryotes can benefit our nutrition, help with immunity, protect us from infection, maintain protective barriers, help develop our organs and more! However they can be harmful too. Some bacteria can be pathogenic, causing Lyme disease, Syphilis, Food poisoning, Tuberculosis, Cholera and more

List the characteristics of a prokaryotic cell (Remember prokaryotes usually have less than eukaryotes.

Prokaryotes have less DNA and produce fewer proteins than the eukaryotes •Prokaryotes have one circular chromosome; eukaryotes have multiple linear chromosomes •Prokaryotes lack a nucleus; the chromosome is located in the nucleoid, a region with no membrane

Describe the effect endosymbiosis had on protistan diversity (secondary endosymbiosis). (Start by defining what secondary endosymbiosis is)

Secondary endosymbiosis- when a eukaryotic cell engulfs a cell that has already undergone primary endosymbiosis Secondary endosymbiosis gave rise to an increase in plastid diversity.

Explain what the capsules of bacteria are made of. What does it do?

The capsules of bacteria have a sticky external layer of polysaccharides or proteins-Capsules can assist with colony formation (adhesive) and may also protect against dehydration or help cells evade host immune system.

What is the structure of genomic prokaryotic DNA and how does it differ from plasmid DNA? (Genomic general, plasmid plus)

The genomic DNA provides all the information for regular well-being of the cell, whereas Plasmid DNA provides extra characteristics like antibiotic resistance.

Wait a second, so why aren't our human cells absolutely flatlined when we take antibiotics?

The peptidoglycan layer is not present in human cells and that is the structure that antibiotics target!