The Microbial World Flashcards
What is a microorganism?
- bacteria
- microbial eukaryotes
- archaea
When do we use the term ‘microbe’?
When we want to refer to microorganisms AND viruses
What did Robert Hooke discover and what didn’t he discover? (options: microorganisms, bacteria, archaea, viruses)
- Discovered Microorganisms
- Did not discover bacteria, archaea, viruses
Who is the first to see and describe bacteria?
Antoine van Leeuwenhoek
Who is credited as the father of Microbiology?
Antoine van Leeuwenhoek
What are some examples of microbial importance for humans?
- Making essential amino acids and vitamins
- Aiding digestion
- Fixing Nitrogen
- Breaking down organic material
- producing food and drink
- making Oxygen
- Biotechnology
If all microbes were to disappear tomorrow, which of the following would NOT be a consequence that humans would notice?
A. Problems w digestion B. Problems with breathing C. Wastewater treatment plant failures D. Fermented food supply issues E. Crop failures
B. Problems with breathing
What makes microorganisms excellent model systems for experimentation?
- short generation times
- inexpensive/easy to grow
- small number of genes makes it easier to sequence and assemble genomes and study functions of genes
What are the 6 requirements for microbial life?
- Metabolism
- Growth
- Reproduction
- Genetic Variation/Evolution
- Adaptation to external environment
- Homeostasis
What is the dry weight of polypeptides in a cell (%)?
50-55%
What is the dry weight of DNA in a cell (%)?
2-5%
What is the dry weight of RNA in a cell (%)?
15-20%
What is the dry weight of lipids in a cell (%)?
10%
What is the dry weight of sugars in a cell (%)?
6-7%
What are polypeptides?
building blocks for enzymes + other proteins
What is one function of proteins within a cell?
To catalyze chemical reactions
Arrange the following in order from least to most abundant in a cell by dry weight:
- Polypeptides
- Lipids
- RNA
- Polysaccharides
- DNA
DNA, Polysaccharides, Lipids, RNA, Polypeptides
What are the nucleic acids?
DNA and RNA
What is the purpose of nucleic acids?
- DNA stores genetic information
- RNA is important for gene expression
What does mRNA do?
encodes for proteins and is involved in transcription and translation
What does rRNA do?
assists ribosomes with structural and catalytic properties
What is the purpose of a lipid bilayer? What is it often embedded with and for what reason?
- separates cell interior from exterior
- often embedded w polysaccharides + polypeptides who serve as transporters for materials in and out of the cell
Which is the true statement?
A. Most molecules pass freely through the plasma membrane.
B. Transporter proteins are embedded in the plasma membrane.
C. The plasma membrane does not contain proteins.
D. Lipids comprise approximately 50% of cell mass by dry weight.
B. Transporter proteins are embedded in the plasma membrane.
What is the purpose of polysaccharides?
- Provide structural and energy storage compounds within the cell
All microorganisms can be classified into 2 groups. What are the names of these groups?
- Prokaryotic
- Eukaryotic
What are the two subgroups of Prokaryotes?
Bacteria and Archaea
What is the definition of a Prokaryotic cell?
A cell with no nucleus
What is the definition of a Eukaryotic cell?
A cell with a nucleus
What is “the tree of life” based on?
rRNA sequences
What are the three domains of life?
Bacteria, Archaea, Eukarya
What did Carl Woese discover?
Arhaea
Which of Bacteria, Archaea, Eukarya have a nuclear membrane?
Eukarya
Do Bacteria have membrane bound organelles?
No
Why are viruses not considered to be alive?
Because they don’t hjave RNA
T/F: Viruses can replicate outside a host cell
False. Virsues can’t replicate outside a host cell
T/F: Viruses have little to no biochemical activity outside a host cell
True
T/F: Viruses are reactive outside a host cell
False. Viruses are inert outside a host cell.
Which of the following have a nuclear membrane?
Bacteria
Archaea
Eukarya
Eukarya
Do bacteria have membrane-bound organelles?
Rarely, but exist in a few species
Do archaea have membrane-bound organelles?
Rarely, but exist in a few species
Do eukarya have membrane-bound organelles?
Yes, in all species. Have multiple distinct types.
What is the plasma membrane of bacteria similar to?
The plasma membrane of eukarya
What is the plasma membrane of eukarya similar to?
The plasma membrane of bacteria
What is the plasma membrane of archaea similar to?
Nothing, it is unique from bacteria and eukarya
Do bacteria have a cell wall? If so, what is it made of?
Nearly all species do. Made of peptidoglycan.
Do archaea have a cell wall? If so, what is it made of?
Nearly all species do. Made of various materials.
Do eukarya have a cell wall? If so, what is it made of?
Some species do. Made of various materials.
What are the polymerase differences among bacteria, archaea, and eukarya
Bacteria: Single polymerase
Archaea: Single polymerase + RNA pol II
Eukarya: RNA pol I, II, and III
What are the histone differences among bacteria, archaeam and eukarya?
Bacteria: Histone-like proteins
Archaea and Eukarya: have Histones
Which of the following is NOT a characteristic of Bacteria?
Nuclear membrane Cell wall Having a single RNA polymerase Histone-like proteins DNA within a nucleoid
Nuclear membrane
Which of the following is NOT a characteristic of Archaea?
Nuclear membrane Cell wall Having a single RNA polymerase Histones Cytoplasmic membrane
Nuclear Membrane
Which of the following is NOT a characteristic of Eukarya?
Nuclear membrane Cell wall in some species Having DNA replication enzymes similar to Archaea Histones Single polymerase
Single Polymerase
Organisms that lack a membrane-bound nucleus, including bacteria and archaea:
Viruses
Eukaryotes
Fungi
Prokaryotes
Prokaryotes
Which of the following is NOT a characteristic that distinguishes all living organisms from most/all nonliving entitities?
Cellular maintenance
Metabolism
Growth
Motility
Motility
Describe the experiments of Miller and Urey.
Simulated the spark that might have started forming organic molecules (amino acids) from primordial soup
What are the requirements for early life?
- genetic information storage
- ability to catalyze biochemical reactions
- way to separate cell interior from external environment.
What are the essential components for LUCA
Proteins, DNA, RNA, Ribosomes
Why is DNA a superior information-storing molecule compared to RNA?
DNA is more stable than RNA
If you are ever asked, “what is the central dogma of biology?” what do you say?
DNA -> RNA -> Proteins. Because all life does this, and has been doing it since LUCA
DNA to RNA is ___________, and RNA to protein is ___________.
Trancription, Translation
Transcription is RNA _________ from DNA _____________
Transcription is RNA synthesis from DNA template
DNA provides a __________ for __________ with respect to information flow within a cell.
DNA provides template for transcription
Earliest microbes would have been ….
- able to metabolize iron and/or sulfur (mineral breathers)
- heat-loving (thermophiles)
- anaerobic
- photosynthetic
- consumers of inorganic carbon
When were the first microorganisms formed?
About 4.5 billion ybp About 3.8 billion ybp About 2.7 billion ybp About 1 million ybp About 4000 ybp
About 3.8 billion ybp
Which of the following is NOT likely to be true of many primitive microbes?
They were aerobic
They were photosynthetic
They had a plasma membrane
They were thermophilic
They were aerobic
How did the atmospheric O2 concentration rise initially to 21%?
via cyanobacteria
Cyanobacteria were the first organisms to generate free _________ by their __________.
First organisms to generate free oxygen by their metabolism
What is the likely origin of eukaryal mitochondria and chloroplasts?
Endosymbiosis of bacteria within archaea
Engulfment of other eukaryal cells by eukaryotes
Endosymbiosis of archaea within bacteria
No evidence supports any of these theories
Endosymbiosis of bacteria within archaea
Which of the following is NOT evidence for endosymbiosis?
DNA sequences of mitochondria and chloroplasts
Size of organelles
Large size of eukaryal cells
Organelles that contain their own genomes
They divide like bacteria
Large size of eukaryal cells
Endosymbiosis:
Primitive __________ microbes ingested other microbes.
It was a __________ relationship.
It formed the first basic _________.
- Primitive prokaryotic microbes ingested other microbes
- symbiotic relationship
- formed the first basic eukaryotes.
What is an autotroph?
An organism that can produce its own organic molecules from inorganic carbon (e.g CO2).
What is a heterotroph?
an organism that ingests organic carbon as a food source
Which metabolic pathway is the most energy yielding?
Fermentation
Glycolysis
Aerobic respiration
Anaerobic respiration
Aerobic respiration (yields much much more ATP)
Who disproved the theory of spopntaneous generation?
Louis Pasteur
Who developed postulates for identifying the causative agents of disease?
Robert Koch
What are the primary mechanisms used to prevent infection
Antimicrobial compounds
Sanitation improvements
What are the differences in membrane-bound organelles among bacteria, achaea, and eukarya
B, A: Rare, a few types in a few species
E: Found in ALL SPECIES, multiple distinct types
What are the differences in plasma membrane among bacteria, achaea, and eukarya
B, E: Similar to eachother
A: Unique from B,E
What are the cell wall differences among bacteria, archaea, and eukarya?
B: Nearly all species have one, constructed of peptidoglycan
A: Nearly all species have one, constructed of various materials
E: Some species have one, constructed of various materials