Chapter 1 - Introduction to Microbiology Flashcards
In what year did the CDC begin recording flu deaths for children?
2003
What are two reasons this year’s flu season is “odd”?
- The flu started earlier and does not seem to have reached its peak
- The flu is dominated by influenza B, which usually occurs later and at lower rates; this version is known to be deadlier for children and adolescents
Who received the Nobel Prize for discovering pencillin and even warned about antibiotic resistance?
Alexander Fleming
What is a microbe or microorganism?
An organism that is too small to visualize with the naked eye
Most microorganism are ____________________ and include all life forms other than plants and animals.
Microscopic
What is the average size of a microorganism?
Approximately 0.2 mm
True or false: all microbes are unicellular.
False. Most microbes are unicellular, but they can be multicellular; however, when multicellular, they lack highly differentiated tissues
What seems to have been an evolutionary invention of plants and animals alone?
Tissue differentation and organ specialization
When did microbal life originate?
Shortly after the formation of earth
How old do cosmologists believe earth to be?
Approximately 4.5 bilion years old
When did the earth become habitable for life?
Approximately 4.0 billion years ago once the earth cooled to temperatures less than 100 degrees celsius
How old are the oldest rocks?
3.8 billion years old
How old are the earliest known microbial fossils?
Approximately 3.4 to 3.5 billion years ago
What is the study of microscopic fossils called?
Micropaleontology
In Western Australia, rocks as old as ___________ billion years old were found, and it was believed that fossilized microbes were present in the rock; however, more recently, in the _________ ___________ _________ in Western Australia, it is believed that earliest life arose around 3.43 billion years ago.
3.46 billion years ago
Strelley Pool Formation
Why did researchers believe that the earliest signs of microbial life arose earlier than previously thought (i.e., the Strelley Pool Formation in Western Australia)?
Researchers outlined in “Microfossils of sulphur-metabolizing cells in 3.4-billion-year-old rocks of Western Australia” that microbial cells had been found based on “indicators of biological affinity,” including hollow cell lumens, carbonaceous cell walls enriched in nitrogen, taphonomic degradation, organization into chains and clusters, and δ13C values of −33 to −46‰ Vienna PeeDee Belemnite (VPDB).
Currently, research suggests that the earliest evidence of microbial life is _____________ billion years ago.
3.43 billion years ago
There are two fundamentally different types of cells: prokaryotic and eukaryotic. How does one distinguish them?
Eukaryotic cells have a membrane-bound nucleus whereas prokaryotic cell; it is the absence or presene of a membrane-bound nucleus is the only true defining feature
Which group of cells are generally specialized for rapid growth and maximal use of nutrients for increasing biomass? Prokaryotes and eukaryotes?
Prokaryotes
Which cell types are generally and intially specialized for predation on existing biomass? Prokaryotes or eukaryotes?
Eukaryotes
Although there are many exceptions, it is probably fair to think of the ____________________ as specialists at rapid growth at the expense of nutrients dissolved in the water that surrounds them. This has entailed the evolution of small, relatively simple cells with highly effective permease systems to take nutrients from a dilute solution, and a highly effiecient, tightly regulated _______________ to make the most of them.
Prokaryotes
Metabolism
What likely drove the multicellularity and complexity of eukaryotes?
Predartion of smaller, simpler prokaryotes
Are microbes rare or ubiquitous?
Ubiquitous
There are approximately 10__ human cells on the human body but approximately 10__ microbial cells!
1013 human cells
1014 microbial cells
What is the difference between a microbiota and a microbiome?
A microbiome is the collection of genomes from all the microorganisms found in a particular environment. Humans, plants, and other animals all have microbiomes; these can be generalised to their entire organism, or broken down into specific microbiomes for different locations on them. Microbiota, on the other hand, usually refers to specific microorganisms that are found within a specific environment. Microbiota can refer to all the microorganisms found in an environment, including bacteria, viruses, and fungi. This means that there are localised differences in the microbiota of each person, depending on where in the body the microbiota is collected from. In each person, their gut microbiota can be radically different to their skin microbiota – care needs to be taken when talking about where microbiota come from.
Collectively the microbal biomass is greater than or lesser than the macroscopic biomass by mass on earth.
Greather than
Bacteria, fungi, and viruses outnumber human cells in the body by a factor of ___ to ___.
10 to 1
In the human lungs, there are ____+ microbial species; in the gastrointestinal tract, there are _____ microbial species; and in the urogenital tract, there are ____ species of microbial species.
600
1,000
60
The tree of life is almost entirely ______________.
Microbial
There are three major lineages of life on earth. What are they?
Eubacteria
Archaea
Eukarya
Eukarya are most biochemically similar to Eubacteria or Archaea?
Archaea
A ______________ __________ is a diagram that represents evolutionary relationships among organisms. They are hypotheses, not definitive facts.
Phylogenetic tree
In a phylogenetic tree, more closely related species are closer or farther away from each other?
Closer
Is Chlamydia more closely related to Escherichia or Clostridium?
Clostridium
How are most phylogenetic trees constructed via modern technology?
Genome sequencing
__________ is most often found in the human mouth; it is the primary colonizer of teeth, creating a biofilm that recruits more bacteria and ultimately leads to cavities.
Streptococcus
What is “next generation” or “next gen” sequencing?
Next-generation sequencing (NGS), also known as high-throughput sequencing, is the catch-all term used to describe a number of different modern sequencing technologies. These technologies allow for sequencing of DNA and RNA much more quickly and cheaply than the previously used Sanger sequencing, and as such revolutionised the study of genomics and molecular biology
Different areas of the body have different microbiomes, and it is believed that disruptions to these microbiomes can lead to ______________.
Illness
Do the microbes in the gut of a premature infant change radically from day to day?
Yes, the microbes in the gut of a premature infant change radically from day 10 to days 16 through 21
Prokaryotes inhabit a wide range of habitats. In what temperature and pH ranges can they be found?
Temperature range: -10 degrees to 120 degrees celsius
pH range: less than 1 to more than 10
What probably defines the limits of life based on the kind of chemistry that characterizes life on earth?
The range in which prokaryotes can survive
What is one of the biggest - if not the biggest - driving force for diversity among the microbes?
The immense range of the habitats in which they reside; ultimately this has resulted in evolutionary changes where prokaryotes have genes that lead to their ability to live in such environments
Would removing all plants and animals destroy life on earth?
No; although the ecosystem would be affected, microbes are sufficient to maintain a sustainable global ecosystem as they did for several billion years
Why are prokaryotes essential to all life on earth?
Because some catalyze transformations of chemical compounds essential to the sustainability of life
What two specific reactions can prokaryotes accomplish that most eukaryotes are unable to do?
Fixation of inorganic nitrogen into organic nitrogen and denitrification of nitrate (organic nitrogen) into nitrogen gas (inorganic nitrogen)
Briefly explain the nitrogen cycle.
____________ ____________ is the process in which N2 in the atmosphere breaks and combines with other compounds to form organic molecules.
Nitrogen fixation
_________________________ is the process in which organic nitrogen (e.g., nitrate) is broken down into nitrogen gas.
Denitrification
Like all cells, microbes are mostly ____________.
Water
Approximately how much water makes up microbes?
70%
The dry weight of microbial cells consists mainly of _______________________ and ______________.
Macromolecules
Lipids
What are macromolecules?
They are very large molecules with molecular weights above 10,000 Daltons with a polymeric structure
What are lipids?
Lipids are smaller molecules with molecular weights under 1,000 Daltons; they are not polymeric in structure, and they are highly hydrophobic
What are the three macromolecules?
Carbohydrates
Proteins
Nucleic Acids
Macromolecules constitue more than ____% of the dry weight of microbial cells.
85
Lipids constitute about ___% of the dry weiight of microbial cells.
10%
Among the macromolecules, _________________ are the largest and most diiverse category.
Proteins
There is something wrong with this figure. What is it?
The composition of a microbial cell is 70% water and 30% dry weight
According to the textbook, there are four major macromolecule categories. What are they?
Proteins
Nucleic acids
Polysaccharides
Heteropolymers
What are heteropolymers?
Macromolecules in which two different types of monomers are covalently combined
What is the principle heteropolymer in E. coli?
Murein
What is murein?
A heteropolymeric structure found in the cell wall of bacteria like E. coli that is composed of many short peptides and a polysaccharide core
Another complex macromolecule or heteropolymer found in the cell walls of E. coli combines a polysaccharide with a lipid to form a ___________________________________.
Lipopolysaccharide
The cytoplasm is a dense suspension of ______________________.
Ribosomes
Why are there so many ribosomes in the prokaryotic cell?
- Because about 54% of the dry mass of the cell is protein
- Protein synthesis is slower than that of other macromolecules
Approximately how many ribosomes are present in the average E. coli cell?
18,000
The average E. coli cell has approximately ___ million proteins.
2 million
What are most of the small molecules of a microbial cell?
Intermediates in biochemical pathways or monomeric precursors of macromolecules
Why are small molecules so abundant if they make up only 5% of the dry weight of microbial cells?
Because they are so much smaller than the macromolecules, a very small mass of them consists of a very large number of molecules
