Unit 1 Exam Terms

Question 1

Nucleus

Answer 1

A membrane enclosed organelle containing a cell’s primary genetic material

• Prokaryote = before a nucleus
• Eukaryote = new nucleus

Question 2

Chromosome

Answer 2

A genetic element carrying genes
essential to cellular function

Question 3

Plasmid

Answer 3

An extrachromosomal genetic element that is non essential for growth

Question 4

Genome

Answer 4

The complete set of genes within an organism

Question 5

Bidirectional Replic.

Answer 5

Two replicating forks moving in opposite directions away from the origin

Question 6

Gram Stain

Answer 6

Crystal violet forms a complex with iodine that cannot ‘escape’ from thick cell wall - identifies bacteria

Question 7

Promoter

Answer 7

site on DNA where RNA polymerase binds

Question 8

Activator

Answer 8

proteins bind to DNA @ sequence specific sites promoting RNA polymerase function

Question 9

Conjugation

Answer 9

Transfer of genes from one prokaryotic cell to another by a mechanism involving cell to cell contact
- VERY FAST and efficient

Question 10

Transformation (via competence)

Answer 10

Naked or free DNA naturally taken up from the environment and assimilated into the genome

Question 11

Infection

Answer 11

Successful invasion of an animal or plant by a pathogen

Question 12

Pathogen

Answer 12

an organism that causes disease

Question 13

Disease

Answer 13

• the condition of being at unrest or
  uncomfortable
• Injury to a host that impairs host
  function

Question 14

Transduction

Answer 14

the process by which a virus transfers genetic material from one bacterium to another. Viruses called bacteriophages are able to infect bacterial cells and use them as hosts to make more viruses.

Question 15

opportunistic pathogens

Answer 15

microorganisms that are usually harmless in healthy, immunocompetent persons but may become virulent in compromised hosts such as the immunocompromised, or people with underlying disease.

Question 16

intracellular pathogens vs extracellular pathogens

Answer 16

Extracellular bacteria do not have to enter host cells to reproduce, whereas intracellular bacteria do.

Question 17

Virulence factor - Extracellular enzymes

Answer 17

Bacterial Secreted Lipases and
Proteases
– Target surface molecules (lipids and
proteins) on host cells
- Alter cellular receptors and cause cell and tissue damage

Question 18

Virulence factor - Exotoxins

Answer 18

Toxins are often soluble proteins that have cytotoxic (i.e. cell killing) activity on host cells
– Secreted from the bacteria, remain stable and soluble in extracellular milieu
- toxins can have activity even in the absence of infection
or colonization
- Natural infections and toxigenic diseases

Question 19

The AB toxin - an exotoxin (virulence factor)

Answer 19

It inhibits protein synthesis in the host cell through phosphorylation of the eukaryotic elongation factor 2, which is an essential component for protein synthesis.

Question 20

Lateral gene transfer

Answer 20

Package DNA from one organism and insert it into another

Question 21

antibiotic resistance

Answer 21

ability of an organism to grow and/or exist in presence of a compound known to exhibit growth inhibiting properties (anti-biotic)

Question 22

Colicins (or holins)

Answer 22

• small proteins that poke holes in membranes of other cells
• bind to bacterial membrane
  proteins then get internalized

Question 23

Capsule (& Biofilms)

Answer 23

• Dense, well defined polysaccharide or protein layer closely surrounding a cell
• hydrophobic sticky covering to cells
• cells can stick together and form a biofilm that is very impermeable to external agents
• bacteria are ‘protected’ from antibiotics or might be
  exposed to sub-lethal (sub-inhibitory) concentrations
• promote adherence to host cell surfaces (promoting colonization) & resist phagocytosis

Question 24

Efflux Pumps

Answer 24

Multicomponent protein channels located in the bacterial membrane that serve to expel toxic compounds from the cytoplasm

Question 25

Flagellar Genetics

Answer 25

• Over 50 genes are involved in flagellar
  biogenesis and function in most bacteria Salmonella/E. coli
• Flagellar gene expression is linked to the cell cycle, nutrient availability
• genes are co-transcribed from
  multiple locations on the chromosome
• Gene expression is hierarchical
  based on ‘morphogenesis

Question 26

Endospores

Answer 26

• Differentiated cells that are highly resistant to heat, chemicals and radiation
• Generated to survive in difficult times
• easily dispersed by wind, water or animals
• exist in soils (over winter) or in abiotic environments
• dormant yet viable biological body

Question 27

Sanitation

Answer 27

Set of conditions that allow for clean drinking water and safe disposal of animal (human) bodily excretions

Question 28

Sterilization

Answer 28

• The killing or removal of all living organisms and viruses
• Inert, devoid of life, yet sample may contains nutrients and compounds to support life.