Week 2 Flashcards
Differences in the cell walls of archaea and bacteria
bacteria
- separation between the inside and outside of cell
-facilitate what enters and leaves the cell
-hydrophilic front end and a hydrophobic interior
-bacterial cell walls always contain peptidoglycan
Archaea
-no peptidoglycan in the cell walls
-lipid tails are branched and sometimes linked
-This creates rigidity and stability, good for warm environments
-Continuous monolayer
Endospore
Only made by gram positive bacteria
Endospores can remain dormant for YEARS, have multiple coats
When the spore germinates is releases neurotoxins
Difference between gram + and gram - bacteria
gram-positive have thick cell wall
gram-negative have thin cell wall
-Have evolved many times
-Have periplasmic space (in between area)
-Can protect itself with this buffer region- detoxifying environment
-Nutrient processing/acquisition
Which is associated with human disease, bacteria or archaea
Bacteria
Are archaea common in extreme environments?
YES
How do prokaryotes reproduce
By binary fission
Chemoheterotrophic prokaryotes function as ____
decomposers
Chemoheterotrophs can perform aerobic respiration, or aerobic respiration (fermentation)
Oxygen is the ideal electron acceptor
What kind of chlorophyll does cyanobacteria have
Chlorophyll A
What became the key selective pressure driving the evolution of aerobic metabolism and enabling the diversification of oxygen-utilizing organisms, favouring multicellular organisms with specialized respiratory and circulatory systems, this supports the high metabolic demands associated with aerobic respiration
oxygen
What has helped prokaryotes to succeed
adaptability and versatility
adapt to diverse environments (extreme conditions)
facilitates their fast reproductive rates, short generation times and metabolic versatility
metabolic diversity
photosynthesis, chemosynthesis, fermentation, nitrogen fixation and biodegradation
occupy diverse ecological niches and play a crucial role in nutrient recycling
abundance and ubiquity
symbiotic relationships
evolutionary resilience
possess high levels of genetic diversity and exhibit rapid rates of genetic mutation, recombination and horizontal gene transfer
Explain the term exaptation
The concept to explain the evolution of new adaptive traits by modifying structures that had different ancestral functions
Evidence for the serial endosymbiosis theory
Mitochondria and chloroplasts have double membranes, and also resemble bacteria
Cells could phagocytosize things for food, could do this but with other cells/materials
Pressures would have favoured use of oxygen and production of ones own energy
The two theories of the formation of the nucleus
Autogenous: infolding of the plasma membrane to form the ER and nuclear membrane
Endosymbiosis
- host archaean and bacteria combined DNA
Differences between eukaryotic and prokaryotic cells
- Almost the same at the chemical level
- Eukaryotic cells are much larger than prokaryotic cells
- In eukaryotic cells there are membrane bound organelles, DNA is contained in a nucleus
○ More order= more complexity
○ Little differentiation in prokaryotic cells
explain the fundamentals of evolution by natural (and sexual) selection
Genetic variation makes evolution possible
- mutations, deletions/duplications, deletion/addition, genetic recombination/crossing over
Selection altering allele frequencies
sexual selection: inter/intra
What is the significance of horizontal gene transfer in the tree of life
early eukaryotes evolved by a complex process involving gene transfers from both bacterial and archaeal ancestors
gene transfer between archaea and bacteria have been ongoing since they evolved
the tree of life is a web at its earliest ancestral levels because of extensive horizontal gene transfers
no single point at the bottom of the tree, likely an ancestral colony
how does sexual reproduction create diversity within the eukarya
Meiosis
-new gametes and diversity
Multiple alleles in a population
-evolution acts on allele frequency
Dominant/recessive alleles
Hybridization
two species bring interbreed by bringing their haploid gametes together
promotes genetic divergence from the parents as well as reproductive isolation
How does polyploidy impact diversity?
increases genetic redundancy and buffering capacity, providing organisms with greater resilience to deleterious mutations and environmental stress
creates new, reproductively isolated species
increases genetic stability
Autoploidy vs Allopolyploidy
Auto: Duplicates and doesn’t actually split apart 4n new species
Allo: two species interpreted and produce hybrid offspring and the gametes don’t divide 4n new species
70% of plants
Allopatric vs Sympatric speciation
Allopatric: reproductive isolation caused by geographic barriers
Sympatric: speciation within same geographic area
- can come from ploidy (division creates extra sets of xsomes)
Zygotic Meiosis, Alternation of Generations and Gametic Meiosis
Zygotic: zygote directly undergoes meiosis, the dominant phase is the haploid stage
Alternation: multicellular haploid and diploid phases
Gametic: gametes produced directly by meiosis
Dominant diploid phase
