Lecture 4 Flashcards
What is exaptation?
when a new additional pressure comes along (selective pressure) which results in a modification of the gene coding
Are archae or bacteria more common in an extreme environment?
archae
What are the principle differences between archaea and bacteria?
- rRNA nucleotide sequences
- cell wall and membrane lipids differ
are bacteria or archae more diverse in forms of energy and aquisition? provide a simple example
bacteria are more diverse
* some are able to photosynthesize
What is the bacterial plasma membrane structure?
- hydrophilic front end
- hydrophobic interior
- semi-permeable
What do bacterial cell walls always contain?
always contain peptidoglycan, but in differing amounts
What are the two major groups of bacteria?
gram positive and gram negative
What color do gram negative stain?
pink
Why do gram negative bacteria stain pink?
they have a very thick peptidolgkycan cell wall
What is the trait of gram negative bacteria that gives rise to many functions?
- it is the evolution of the peroplasmic space, between the inside and outside of the cell wall and outer membrane
- gives it many functions
- the bacteria can be in an environment and protect itself
- this is an evolutionary advantage
What is the signifigance of the gram stain response?
common quick medical diagnostic tool
What type of group is a gram positive group?
a monophyletic group
What are key characteristics of a gram positive bacteria?
- very resistent to osmotic stress
- can form endospores
- usually chemoheterotrophs
- non-motile and without appendages
What are key characteristics of gram negative bacteria?
they utilize their periplasmic space for:
* nutrient aquisition
* nutrient processing
* detoxifying environment (including against antibiotics)
What can gram positive bacteria form when entering dormancy? What is the term?
- they can form highly resistent forms
- endospores
What are endospores?
- gram positive only
- form many coats
- highly resistent to UV, high temperatures, chemical disinfectants, desiccation
- very resistent to the environment
- must have evolved to be this way, as this form is very advantageous in their lifecycle
- results in severe health and food concerns
What happens when an endospore germinates?
- produces neurotoxins
- this is to protect the growing bacteria to the environment
- this can cause serious infection
What are the characteristics of the cell wall of archae?
- no peptidogylcan
- may or may not retain G stain, depending on wall thickness
how are the plasma membrane lipids for archae distinctive from both bacteria and eukarya?
that lipid tails are branched and sometimes linked
is archae transcriptional machinery more similar to bacteria or eukarya?
eukaryotes
Why is the different structure of the plasma membrane advantageous for them?
- the branching on the tails gives rise to more potential for hydrogen bonding, making the membrane a lot less fluid
- this causes it to be more viscous
- this can be beneficial in warm environments
- can help lead to more stability due to rigidity
*if the membrane breaks down they’re dead, so we need to make sure it is stable, which is what this does
Many of the organisms that are photoheterotophs can also do ___________?
chemoheterotrophs
Wha does oxygen availability determine in terms of metabolism?
oxygen availability determines metabolic energy yield
what is the ideal electron acceptor?
oxygen
