Chapter 1: The Microbial World Flashcards
A scientist discovers a small particle that can replicate and examines it in the lab. What finding would indicate that the particle is not a living cell?
It has an RNA genome with no DNA
LUCA is ______________
the last common ancestor of Bacteria and Archaea
What is a reason that the term prokaryote may be confusing?
Archaea and Bacteria both have prokaryotic cells but are very different domains.
What is the difference between transcription and translation?
Transcription produces various types of RNA, and translation produces proteins.
What best describes why microbes have been so important in answering general questions about how genetic material is copied?
Many microbes are easy to grow in a test tube or in a dish in the lab, making them easy to study.
If you performed a Gram stain on a gram-negative cell but forgot to add safranin, the cell would appear _____________
unstained
Eukaryotic cells can be distinguished from prokaryotic cells by _________________
having linear chromosomes
What are types of macromolecules?
Ribosomal protein, DNA
Compared with a large cell, a small cell has a surface area-to-volume ration that is _________
larger.
If you wanted to determine whether intercellular communication was occurring between bacteria, what would be the best thing to study?
How some bacteria produce toxins only when their population density is high
A cell with an unusually thick cell wall is most likely ____________
able to resist pressure well.
What observation would be consistent with classifying a newly discovered microbe within Domain Archaea?
It produces methane.
Why is it important that rRNA used to construct phylogenies is highly conserved?
Genetic material with a high mutation rate would change too quickly to allow the detection of gradual evolutionary change.
A researcher obtains a sample of water from a lake. He immediately analyzes the sample to detect all bacterial DNA and then adds the sample to culture to see what species will grow. What do you predict that he will find?
There will be many more species of bacteria identified through DNA than in the cultures
You are able to view a specimen at very high magnification using a bright-field microscope, but the resolution is very low. What will the specimen look like?
The specimen will be large but blurry, and it will be difficult to distinguish features.
The name for the technique used to prevent contamination of cultures is called ______________
aseptic technique
If you are given a micrograph, what characteristic would let you know that it was taken using scanning electron microscopy compared with another type of microscopy?
It shows 3D outer structures
The researcher who developed rigorous criteria for identifying the causative agent of a disease was ____________
Robert Koch, Koch’s postulates.
What is one reason that a particular bacterium may develop antibiotic resistance very quickly?
It receives an antibiotic resistance gene through horizontal gene transfer.
Stains are used because _________________
they increase contrast and can be used to distinguish between types of structures or cells.
-bright background
-differential stains- gram -/+
Over many generations, a small group of bacteria has been separated from others of its species. This small group appears to be thriving even though it has much less access to water than others of its species. What do you predict to be true of these bacteria compared with others of the same species?
The cells will have adaptations to conserve water
Microbial medium can be ______________
solid or liquid
While analyzing fungal DNA, a researcher detects a gene that is almost identical to a common bacterial gene but not similar to any genes previously detected in well-studied fungi. What is the most likely explanation?
The gene was transferred horizontally from the bacterium to the fungus.
What is one reason that a researcher might prefer to use a dark-field microscope rather than a bright-field microscope to view a cell?
Cell motility can be observed more easily without a stain
Dark-field= easier to view LIVING cells without stains that may kill the cells
What best describes any microorganism that can cause disease?
pathogen
Louis Pasteur
disproved spontaneous generation- sterilization technique- swan neck.
-rabies vaccine
-pasteurization
Sergei Winogradsky
defined chemolithotrophy- obtain energy and carbon from inorganic sources
Carl Woese
used rRNA to examine evolutionary relationships and developed a tree of life.
