Prokaryotes Basics Flashcards

1
Q

Types of microorganisms

A

Bacteria
Archaea
Microeukaryotes
Viruses

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2
Q

What features do bacteria have

A

-plasmids
-70s ribosomes
-one rna polymerase
-Cell wall muramic acid
-ester bonds in the cell membrane that act as lipid linkage
-sensitivity to chloramphenicol,streptomycin,kanamycin

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3
Q

Examples of eukaryotes

A

Microeukaryotes
Protists
Parasites
Fungi

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4
Q

Features that archaea have

A

-plasmids
-70 s ribosomes
-Several rna polymerases
-ester bonds in the cell membrane that act as lipid linkage

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5
Q

Features in an eukarya

A

-membrane enclosed nucleus
-80 s ribosomes
-3 rna polymerases
-ester bonds in the cell membrane that act as lipid linkage

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6
Q

Prokaryote cell division

A

-process called binary division
-3 stages:cell elongation,septum formation,completion of septum formation,formation of walls and cell separation

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7
Q

What is DNA

A

DNA is a double helix containing unique distribution of TA and GC nucleotide pairs for every gene.

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8
Q

Heredity

A

Transmission of properties from a mother cell to daughter cells during cell divisions

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9
Q

Role of dna replication

A

Makes possible existence of heredity

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10
Q

Semi conservative replication

A

Every dna strand serves as a template for the synthesis of the complementary strand

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11
Q

Process of gene expression

A

-DNA gets replicated by dna polymerase
-dna gets transcribed to rna by rna polymerase
-rna gets translated into a protein by tRNA and ribosomes
-the protein then gets folded ans modified to have a biological activity

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12
Q

4 main classes of compounds

A

proteins
- structural components of the cell, enzymes and regulators; encoded by genes; synthesised in ribosomes;
Nuclei acids
-Genetic material
Lipids
Components of cellular membranes,cell wall and storage granules
Polysaccharides
-components of cell wall and capsule

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13
Q

Metabolism

A

Uptake of nutrients from the environment,their transformation within the cell and elimination of wastes into the environment.It is an open system

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14
Q

Reproduction

A

1)Chemicals from the environment are turned into new cells under the direction of pre-existing cells

2)It is a process based on
-replication of dna
-equal distribution of replicated dna into two cells after division of the initial cell

3)it’s a core way of colonisation of a host by pathogenic microbes causing diseases

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15
Q

Differentiation

A

Formation of a new cell structure such as a spore,usually as a part of a cellular life cycle

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16
Q

Communication

A

-Cells communicate or interact primarily by means of chemicals that are released or taken up
-one of the consequences is quorum sensing mechanism.It allows a population to sense critical amount of cells and stop divisions

17
Q

Quorum sensing mechanism

A

Process of cell-cell communication that allows bacteria to share information about cell density and adjust gene expression accordingly

18
Q

Movement

A

Living organisms are capable of self-propulsion(ability to move using their own power)

However motility is not compulsory property of all microbes

19
Q

Evolution

A

Cells contain genes and evolve to display new biological properties

20
Q

What does closed system mean

A

Limited amount of nutrients

21
Q

5 phases of microbial growth in a closed system

A

Lag phase
Log phase
Stationary phase
Death phase
Long term stationary phase

22
Q

Lag phase

A

Metabolic activity but no growth/adaptation period

23
Q

Log phase

A

Cells doubling through binary fission
Exponential phase

24
Q

Stationary phase

A

Growth ceases but cells remain metabolically active

25
Death phase
-Waste builds up and nutrient rich media is depleted -living cells stop metabolic functions and begin to process of death
26
Long-term stationary phase
Birth and death rate are balances
27
Dna in prokaryotic cells
-bacterial chromosome as main molecule of dna;considered to encode for essential genes -located in cell cytoplasm -bacterial plasmids as smaller molecules of dna: considered to encode for accessory genes
28
Pathogenic traits/ virulence factors
-contributed or directly cause damage in host eg • pili formation • biofilm production • spore formation • toxin production • capsule production
29
Stages in infection
Adhesion Colonisation Invasion Evasion
30
Adhesion
Adhesive molecules expressed on bacteria surface bind to host surface receptors
31
Colonisation
-Bacteria on the surface doesn’t cause disease yet -virulence factors such as biofilm(A biofilm is an assemblage of surface-associated microbial cells that is enclosed in an extracellular polymeric substance matrix)
32
Invasion
Dissemination of a pathogen through local tissues or the body Pathogens may produce enzymes/toxins that act as virulence factors
33
Invasion
Dissemination of a pathogen through local tissues or the body Pathogens may produce enzymes/toxins that act as virulence factors
34
Evasion
-pathogens can bypass of evade the immunogenicity response of hostscells and continue its growth and transmission into the new host
35
Tag dna polymerase
-found in all cells -synthesis complementary dna strand to dna template -extremphile(heat stable)
36
Function of dna polymerase
In the cell: Replication of the genome through by binding to single strand (template) and incorporation of nucleotides on synthesising strand using Okazaki fragment to bind initially - Nobel prize won in 1956 In Polymerase Chain Reaction: Binds to denatured template strain with guide of primer to bind to initially and extend from. - PCR was Nobel prize won in 1993
37
Other properties of dna polymerases
• Processivity – affinity for DNA template = speed • fidelity - synthesis accuracy and proof reading ability (not all have) • substrate nucleotide selectivity –
38
T4 DNA ligase -gene engineering
-dna ligases are essential for dna replication,repair and recombination -The bacteriophage T4 infects E. coli. -The T4 DNA ligase seals the nicks between Okazaki fragments during replication of the phage genome. -The T4 DNA ligase is ATP- dependant and catalyses the formation of new phosphodiester linkages in DNA. -Has ability to perform “blunt”-end ligation – not a nick but two ends of DNA molecule together but also “sticky” ends with overhangs -Used in cloning for insertion of cloned section (e.g. PCR product or restriction product) into the vector (plasmid).