CLASSIFYING BACTERIA AND REPRODUCTION (lesson six) Flashcards
what are prokaryotes?
a cell that does not have its chromosomes surrounded by nuclear envelop and lacks membrane-bound organelles
characteristics of bacteria
- are unicellular
- are prokaryotic
- have a single chromosome in the form of a loop of DNA called a plasmid
- most reproduce asexually by binary fission some reproduce sexually by conjugation
- thrive in moist environments
Ways to classify bacteria
- if they cause disease
- Gram-positive vs gram-negative
- shape
- configuration
- oxygen requirements
- nutrition
if they cause diseases
- non-pathogenic
- pathogenic
what is Gram-positive?
- stain purple
- Cell wall contains peptidoglycan (protein)
what is Gram-negative?
- stain pink
- cell wall does not contain peptidoglycan
If the bacteria is spherical?
cocci
if the bacteria is rod-shaped?
bacilli
if the bacteria is spiral?
spirilla
Configuration
- after division, many bacteria stay together in groups called colonies
- colonies are visible growths of microorganisms that contain millions of cells
- in colonies, bacterial cells stay together in typical arrangements
in clumps add what prefix? (configuration?)
staphyllo
in chains add what prefix (configuration?)
strepto
in pairs add the prefix (configuration?)
diplo
oxygen requirements
- aerobes: need lots of O2
- anaerobes: cannot survive in the presence of O2
Nutrition
can be autotrophic, heterotrophic, photosynthetic, or chemosynthetic
when will bacilli bacteria go into a dormant?
Under unfavorable environmental conditions, bacilli bacteria will go into a dormant or resting state called an endospore.
what is endospore?
It is resistant to heat and other extreme conditions.
what are the 2 types of Reproduction?
asexual reproduction (binary fission) and sexual reproduction ( conjugation)
what is Asexual Reproduction?
Binary fission is another name for it.
-only one parent is needed
- offsprings are identical to parent and to each other
what is Sexual Reproduction?
conjugation is another name for it.
- two parents are involved
- offsprings are different from parents and to each other
Advantages of asexual reproduction?
- simple: only 1 parent
- offspring are fully formed (no maturation needed)
- very fast
Disadvantages of asexual reproduction?
- no genetic variety (DNA is identical to parent)
- one unfavorable environmental condition can wipe out the whole population
Advantages of sexual reproduction?
- genetic variety i.e. some are able to adapt to unfavourable conditions (ex: antibiotic resistance)
Disadvantages of sexual reproduction?
- more complex: slower because must find a compatible partner
- no new individuals produced
why are no new individuals produced?
no NEW individuals are produced because the donor cell is inserting plasmids into an already existing cell. therefore not creating a new cell but instead changing the old cell by inserting plasmid.
Factors that affect bacterial growth
- Temperature
- Nutrients
- Oxygen availability
- Salt concentration
- pH
