Microbiology and Properties of Cellular Life Flashcards
What is microbiology?
The study of microorganisms
What are 5 study areas in microbiology?
- Microbial physiology (structure and function)
- Diversity and evolution of microbes
- Environmental roles of microbes
- Effects of microbes on other living things
- How we can use microbes in industrial processes
What are microorganisms?
Microscopic organisms that you can’t see with the naked eye. Includes prokaryotes, single-celled eukaryotes, and acellular microbes
What is a cell?
Simplest collection of matter that can live
What are some things all cells have and do?
- Plasma membrane
- Genetic material
- Ribosomes
- Distinct internal environment in the form of the cytoplasm
- Use and transform energy in the form of ATP
- Respond to external stimuli
- Replicate
- Relatively small
- Do the central dogma
What are 6 properties of cellular life?
- Have a catalytic metabolism and produce and use energy
- Have genetic metabolism and do DNA replication, transcription, and translation
- Growth
- Evolution
- Exchange genetic information
- Communicate through chemical signals
What are 2 things only some cells can do?
Differentiation and motility
What are 6 differences between prokaryotes and eukaryotes?
- Eukaryotes have membrane bound organelles and a nucleus
- Transcription and translation are coupled in prokaryotes, separate in eukaryotes
- Single circular chromosome in prokaryotes, multiple linear chromosomes in eukaryotes
- Plasmids in prokaryotes, none in eukaryotes
- More complex and varied metabolism in prokaryotes
- No cytoskeleton in prokaryotes
Why are prokaryotes a paraphyletic group?
Archaea are more closely related to eukaryotes than they are to bacteria
What traits do we know the last universal common ancestor had?
A cell membrane, DNA, ribosomes, and a metabolism. All cells today have them, ancestral traits
Why doesn’t grouping microbes by morphology work for determining phylogenetic relationships?
They all look the same under a microscope
What is a better way to determine phylogenetic relationships among microbes than morphology?
Genetic methods, using 16S rRNA sequences
What is 16S rRNA? Why is it good to use for determining phylogenetic relationships among microbes?
Is a piece of ribosomal rRNA. It’s good to use because everything has ribosomes and they are highly conserved. Ribosomes evolve very slowly because they’re so essential, so every sequence change in the ribosome is the result of species divergence
What is endosymbiosis?
A smaller bacterial cell got engulfed by a larger archaean cell and didn’t get destroyed. Instead it just kept doing its metabolism, kept living, and the two eventually become a single organism
What is the advantage for the smaller cell in endosymbiosis?
Protection from the environment
What is the advantage for the larger cell in endosymbiosis?
Metabolic products of the small cell
Why do we think endosymbiosis happened twice?
All eukaryotes have mitochondria, but only some have chloroplasts. Happened the first time in the ancestral eukaryote to form mitochondria, and then happened again in a group of eukaryotes to form chloroplasts
What are the two hypotheses for the origins of the nucleus in eukaryotic cells?
- The nucleus came before mitochondria
2. The mitochondria came before the nucleus
What is the evidence that the endosymbiosis forming the mitochondria happened before the origin of the nucleus in eukaryotic cells?
If the nucleus came first, it would have been formed from archaeal lipids, which are extremely different from bacterial and eukaryotic lipids. If the mitochondria formed first and kept producing bacterial lipids, the larger cell could have used those to form the nuclear envelope
What are 6 pieces of evidence that mitochondria and chloroplasts originated from bacteria?
- Mitochondria and chloroplasts have a single circular chromosome with no histones
- Genes that look like bacterial genes are found in the eukaryote nuclear DNA, and are involved in mitochondria and chloroplast function
- 70S ribosomes
- Are susceptible to attack from antibiotics that attack 70S ribosomes
- The inner mitochondrial/chloroplast membranes look like bacterial membranes, the outer membranes look like the plasma membrane
- Replicate by binary fission
How are mitochondria and chloroplasts similar to bacteria in terms of DNA?
Single circular chromosome with no histones
How are mitochondria and chloroplasts similar to bacteria in terms of gene structure?
They look like bacterial genes. Eukaryotic nuclear DNA also has genes involved in mitochondria and chloroplast function that look like bacterial genes
How are mitochondria and chloroplasts similar to bacteria in terms of ribosomes?
Have 70S ribosomes, unlike eukaryotes that have 80S ribosomes
What’s the difference between 70S and 80S ribosomes?
Size. 80S is larger
How are mitochondria and chloroplasts similar to bacteria in terms of antibiotic specificity?
Antibiotics that attack 70S ribosomes will also attack mitochondria and chloroplasts
How are mitochondria and chloroplasts similar to bacteria in terms of membrane structure?
Have a double membrane structure. The inner membrane looks like a bacterial membrane and the outer membrane looks like the outer plasma membrane
How are mitochondria and chloroplasts similar to bacteria in terms of division?
Replicate by binary fission rather than mitosis
What is the difference between bacteria and archaea?
Evolutionary history
How are the cell walls of bacteria and archaea different?
Bacterial cell walls are always made of peptidoglycan, archaeal cell walls are made of other stuff
How are the membrane lipids of bacteria and archaea different?
Archaeal lipids have ether linkages and bacterial lipids have ester linkages
How is the DNA of bacteria and archaea different?
It isn’t. DNA is in a single circular chromosome in both
How are the DNA packaging proteins of bacteria and archaea different?
Some archaea use histones, no bacteria do. Bacteria only use looping and supercoiling
Why is living in an extreme environment not a trait of the archaea?
Most archaea don’t live in environments any different than bacteria
What does it means when it says Pseudomonas sp.?
One species in the genus
What does it means when it says Pseudomonas spp.?
Multiple species in the genus
