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Flashcards in Microbes Deck (44)
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1

Archaea

Definition: A domain of single celled organisms

Cell membranes:
fatty acids linked to glycerol by ether linkages, no peptidoglycan

2

Asexual reproduction

offspring arise from a single organism

3

Autoinducer

- bacteria and archaea communicate with chemical signals (autoinducers) that are species specific or universal
- initiate group behavior genes once concentration is high enough

4

Bacteria

Definition: A large domain of prokaryotic microorganisms

Cell membrane: They have a peptidoglycan layer in their cell walls (gram+ or gram-)

5

Binary Fission

1) asexual, rapid division
2) no cell cycle
3) no membrane-bound organelles

6

Biofilm

communities of organisms that are irreversibly bound to a substrate; they secrete extracellular polymers (slime)

It works as a means of communication between prokaryotic cells; enables them to function like a multicellular organism

Key features:
1. Extracellular polysaccharide matrix
2. Surface attachment
- solid surface OR
- soft tissues in living organisms
3. Structural heterogeneity AND diversity (bacteria, archaea, protists, fungi, algae, etc.)

7

Chloroplast

An organelle bounded by a double membrane containing the enzymes and pigments that perform photosynthesis. Chloroplasts occur only in eukaryotes.

Also, organelles that work to convert light energy of the sun into sugars that can be used by cells

Origin: derived from endosymbiotic cyanobacteria

8

Conjugation

Bacteria and Archaea can directly exchange parts of their genome through a conjugation pilus (like a bridge). The transferred DNA is a plasmid.

9

Cyanobacteria

- Photolithoautotrophic
- Many can fix nitrogen
- contain internal membrane system

10

Diploid

2n; 2 sets of chromosomes

11

Endosymbiosis

Explains the origins of eukaryotic cell organelles such as mitochondria and chloroplasts

evidence:
1. mitochondrial/chloroplast size
2. mitochondrial/chloroplast structure and presence of DNA; their DNA is similar in structure, size and shape to bacterial DNA

12

Eukarya

Nucleus present, linear DNA, haploid or diploid or more, membrane-enclosed organelles present, cytoskeleton, mitosis
features: metabolically limited,

13

Extremophile

organisms that can live in extreme conditions. freezing/boiling temperatures, acidic environments
also called halophiles, thermophiles, acidophiles

14

Gram Stain

reveals the complexity of bacterial cell walls & separates bacteria into two distinct groups.
gram negative= thin cell walls and an outer membrane
gram positive= have dense cell wall consisting of primarily peptoglycan

15

Halophile

a microorganism that grows in or can tolerate high salty conditions.

16

Haploid

n; has a single set of chromosomes

17

Heterotrophy

Carbon source is organic

18

Lateral Gene Transfer LGT

1. Conjugation - Bacteria and Archaea can directly exchange parts of their genome
2. Transformation - Bacteria and Archaea can pick up DNA from their environment
3. Transduction - Viruses can transmit DNA between hosts.

Similarities:
- both create new genetic combinations
- both may involve recombination

Differences (LGT):
- only involves small part of genome
- not reproduction
- multiple mechanisms
- can occur across large phylogenetic differences

19

Mitochondria

Facilitates aerobic cellular respiration in the cell.

Mitochondria arose from alpha-proteobacterium; all these bacteria are gram-

20

Meiosis

cell division that results in a reduction of ploidy

21

Nitrogen Fixation

Some cyanobacteria are able to fix atmospheric nitrogen and can convert it into a molecule to make available to other living organisms.

22

Mitosis

cell division that results in no reduction of ploidy

23

Peptidoglycan

bacteria membrane, cell wall; a special polymer of amino sugars

- gram+: peptidoglycan is outside of cell wall
- gram-: peptidoglycan is between plasma membrane and outer membrane of cell wall

only bacteria have peptidoglycan

24

Phagocytosis

The ingestion of bacteria or other material by phagocytes and amoeboid protozoans.

25

Photoautotroph

Organisms that carry out photosynthesis

26

Pathogenicity

• Pathogens are infectious agents that cause a disease
(can be considered a subclass of parasites)
• Pathogenicity = ability to enter a host and cause disease
• Virulence = degree of pathogenicity
• Note - not all parasites are pathogens but all pathogens
are parasites

Pathogenicity in Bacteria has evolved multiple times independently.

27

Photosynthesis

process where organisms use sunlight to synthesize foods from carbon dioxide and water.
- generally involves green pigment chlorophyll and generates oxygen and carbohydrates as byproducts

28

Plasmid

a small DNA molecule that can replicate independently; and it is a small, circular chromosome distinct from main chromosome of a bacteria

29

Prokaryote

a microscopic single-celled organism that does not have a distinct nucleus with a membrane or membrane-bound organelles. Prokaryotes include bacteria and cyanobacteria.

30

Quorum Sensing

expression of group behavior genes as a result of density dependent interactions
- seen in biofilms

Group Behavior Genes:
- Virulence
- Antibiotics Production
- Sporulation
- Conjugation