Week 2

Question 1

Differences in the cell walls of archaea and bacteria

Answer 1

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

Question 2

Endospore

Answer 2

Only made by gram positive bacteria
Endospores can remain dormant for YEARS, have multiple coats
When the spore germinates is releases neurotoxins

Question 2

Difference between gram + and gram - bacteria

Answer 2

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

Question 2

Which is associated with human disease, bacteria or archaea

Answer 2

Bacteria

Question 2

Are archaea common in extreme environments?

Answer 2

YES

Question 3

How do prokaryotes reproduce

Answer 3

By binary fission

Question 4

Chemoheterotrophic prokaryotes function as ____

Answer 4

decomposers

Question 5

Chemoheterotrophs can perform aerobic respiration, or aerobic respiration (fermentation)

Answer 5

Oxygen is the ideal electron acceptor

Question 5

What kind of chlorophyll does cyanobacteria have

Answer 5

Chlorophyll A

Question 5

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

Answer 5

oxygen

Question 6

What has helped prokaryotes to succeed

Answer 6

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

Question 6

Explain the term exaptation

Answer 6

The concept to explain the evolution of new adaptive traits by modifying structures that had different ancestral functions

Question 7

Evidence for the serial endosymbiosis theory

Answer 7

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

Question 7

The two theories of the formation of the nucleus

Answer 7

Autogenous: infolding of the plasma membrane to form the ER and nuclear membrane

Endosymbiosis
- host archaean and bacteria combined DNA

Question 8

Differences between eukaryotic and prokaryotic cells

Answer 8

• 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

Question 9

explain the fundamentals of evolution by natural (and sexual) selection

Answer 9

Genetic variation makes evolution possible
- mutations, deletions/duplications, deletion/addition, genetic recombination/crossing over

Selection altering allele frequencies

sexual selection: inter/intra

Question 9

What is the significance of horizontal gene transfer in the tree of life

Answer 9

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

Question 10

how does sexual reproduction create diversity within the eukarya

Answer 10

Meiosis
-new gametes and diversity

Multiple alleles in a population
-evolution acts on allele frequency

Dominant/recessive alleles

Question 10

Hybridization

Answer 10

two species bring interbreed by bringing their haploid gametes together
promotes genetic divergence from the parents as well as reproductive isolation

Question 11

How does polyploidy impact diversity?

Answer 11

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

Question 11

Autoploidy vs Allopolyploidy

Answer 11

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

Question 11

Allopatric vs Sympatric speciation

Answer 11

Allopatric: reproductive isolation caused by geographic barriers

Sympatric: speciation within same geographic area
- can come from ploidy (division creates extra sets of xsomes)

Question 12

Zygotic Meiosis, Alternation of Generations and Gametic Meiosis

Answer 12

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