Prokaryotes Basics

Question 1

Types of microorganisms

Answer 1

Bacteria
Archaea
Microeukaryotes
Viruses

Question 2

What features do bacteria have

Answer 2

-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

Question 3

Examples of eukaryotes

Answer 3

Microeukaryotes
Protists
Parasites
Fungi

Question 4

Features that archaea have

Answer 4

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

Question 5

Features in an eukarya

Answer 5

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

Question 6

Prokaryote cell division

Answer 6

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

Question 7

What is DNA

Answer 7

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

Question 8

Heredity

Answer 8

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

Question 9

Role of dna replication

Answer 9

Makes possible existence of heredity

Question 10

Semi conservative replication

Answer 10

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

Question 11

Process of gene expression

Answer 11

-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

Question 12

4 main classes of compounds

Answer 12

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

Question 13

Metabolism

Answer 13

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

Question 14

Reproduction

Answer 14

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

Question 15

Differentiation

Answer 15

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

Question 16

Communication

Answer 16

-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

Question 17

Quorum sensing mechanism

Answer 17

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

Question 18

Movement

Answer 18

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

However motility is not compulsory property of all microbes

Question 19

Evolution

Answer 19

Cells contain genes and evolve to display new biological properties

Question 20

What does closed system mean

Answer 20

Limited amount of nutrients

Question 21

5 phases of microbial growth in a closed system

Answer 21

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

Question 22

Lag phase

Answer 22

Metabolic activity but no growth/adaptation period

Question 23

Log phase

Answer 23

Cells doubling through binary fission
Exponential phase

Question 24

Stationary phase

Answer 24

Growth ceases but cells remain metabolically active

Question 25

Death phase

Answer 25

-Waste builds up and nutrient rich media is depleted
-living cells stop metabolic functions and begin to process of death

Question 26

Long-term stationary phase

Answer 26

Birth and death rate are balances

Question 27

Dna in prokaryotic cells

Answer 27

-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

Question 28

Pathogenic traits/ virulence factors

Answer 28

-contributed or directly cause damage in host eg

• pili formation
• biofilm production
• spore formation
• toxin production
• capsule production

Question 29

Stages in infection

Answer 29

Adhesion
Colonisation
Invasion
Evasion

Question 30

Adhesion

Answer 30

Adhesive molecules expressed on bacteria surface bind to host surface receptors

Question 31

Colonisation

Answer 31

-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)

Question 32

Invasion

Answer 32

Dissemination of a pathogen through local tissues or the body

Pathogens may produce enzymes/toxins that act as virulence factors

Question 33

Invasion

Answer 33

Dissemination of a pathogen through local tissues or the body

Pathogens may produce enzymes/toxins that act as virulence factors

Question 34

Evasion

Answer 34

-pathogens can bypass of evade the immunogenicity response of hostscells and continue its growth and transmission into the new host

Question 35

Tag dna polymerase

Answer 35

-found in all cells
-synthesis complementary dna strand to dna template
-extremphile(heat stable)

Question 36

Function of dna polymerase

Answer 36

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

Question 37

Other properties of dna polymerases

Answer 37

• Processivity – affinity for DNA template = speed
• fidelity - synthesis accuracy and proof reading ability (not all have)
• substrate nucleotide selectivity –

Question 38

T4 DNA ligase -gene engineering

Answer 38

-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).