5. Properties of living things Flashcards
1
Q
what is metabolism?
A
- catabolism + anabolism
2
Q
what is important about metabolism?
A
- all living organisms require carbon and energy to carry out metabolic process
- classed according to carbon sources
– autotroph
– heterotroph - organisms require energy, hydrogen and electrons for growth
– use radiant energy (phototrophs)
– oxidation of organic/inorganic compounds (chemotrophs) - bacteria relying on inorganic energy sources and organic can be called mixotrophic
– combine autotrophic and heterotrophic metabolic processes
3
Q
give the different nutritional types, energy sources, carbon sources, and examples
A
- photoautotrophs
– light
– CO2
– microalgae - photoheterotrophs
– light
– organic compounds
– microalgae - chemoautotrophs
– chemicals
– CO2
– few bacteria, many archaea - chemoheterotrophs
– chemicals
– organic compounds
– most bacteria, some archaea, fungi, yeasts
4
Q
explain the differentiation of the bacterial endospore
A
- number of gram +ve bacteria form special resistant dormant strucute (endospore) in response to stress
– bacillus, clostridium, sporocarcina - resilience explained by unique structure
5
Q
how is the strucutre of an endospore unique?
A
- resistant to heat, UV radiation, chemical disinfectants, desiccation
- important because not readil killed
– antimicrobial treatments
6
Q
what is the structure of an spore?
A
- spore
– can survive advers conditions for years - core
– DNA, ribosomes, glycolitic enzymes - cytoplamsic membrane
- spore wall
– normal peptidoglycan - cortex
– thick layer of less cross-linked peptidoglycan - keratin spore coat
– protein
7
Q
what is differentiation in swarmer and stalk cells?
A
- single-celled bacterium undergoes cellular differentiation
– Caulobacter crescentus - it differentiates into two cell types that do not co-operate
– motile swarmer
– stalk cells
8
Q
what are the functions of the motile swarmer and stalk cells?
A
- motile swarmer
– find nutrient-rich place to attach and grow
– loses flagellum, replacing with stalk that attaches to detritus in the pond - stalk cell
– divides, then divides forming 2 daughter cells (a swarmer and a cell with original stalk)
– swarmer cells swims to find nex location avoiding competitions with left stalk cell
9
Q
how do cells communicate?
A
- chemicals released and taken up
10
Q
what is quorum sensing?
A
- process of cell-to-cell communication allowing bacteria to share information about cell density and adjust gene expression accordingly
11
Q
what does QS involve?
A
- production, detection and response to extracellular signaling molecules
– autoinducers (AIs)
12
Q
how do AIs function?
A
- accumulate in environment as population density increases
- bacteria monitor this to track changes in cell number
- collectively alter gene expression
13
Q
what are the three basic principles of QS?
A
- members of community produce AIs
– at LCD AIs diffuse away
–at HCD AIs lead to local high concentration enabling detection and response - AIs detected by receptors that exist in cytoplams or in membrane
- in addition to acitivating gene expression, detection also results in activation of AI production
14
Q
what is an example of QS?
A
- Vibrio fischeri Lucl/LuxR QS circuit
15
Q
how do squid use bioluminescent bacteria for survival?
A
- bobtail squid has symbiotic relationship with bioluminescent Vibrio fischeri
- V.fischeri colonises light producing organ
– fed a sugar and amino acid solution by squid
– serving as source of light - squid stay buried in sand during day
– swim looking for food at night using organ on underside
