food microbiology exam 1

What organisms are prokaryotes?

Bacteria

What organisms are eukaryotes?

Fungi, plants, animals, protozoa

How many cells do prokaryotes have?

One

How many cells do eukaryotes have?

One or more

Do prokaryotes have a nuclear membrane?

Absent

Do eukaryotes have a nuclear membrane?

Present

Do prokaryotes have mitochondria, lysosomes, Golgi complex, and endoplasmic reticulum?

Absent

Do eukaryotes have mitochondria, lysosomes, Golgi complex, and endoplasmic reticulum?

Present

Where are ribosomes found in prokaryotes?

Dispersed throughout the cytoplasm

Where are ribosomes found in eukaryotes?

Attached to the endoplasmic reticulum

How do prokaryotes reproduce?

Asexually

How do eukaryotes reproduce?

Sexually

What is the function of DNA in a bacterial cell?

Controls everything in the cell

What is the function of plasmids?

Carry genes that influence cell traits (extra genetic material)

What is the function of ribosomes in bacteria?

Protein synthesis

What is the function of the cytoplasm?

Where chemical reactions occur

What is the function of the glycocalyx?

Protection

What is the function of the cell wall?

Provides shape and protection

What is the function of the plasma membrane?

Selective transport of substances in and out of the cell

What is the function of fimbriae?

Adhesion to surfaces

What is the function of flagella?

Movement

What are the four phases of the bacterial growth curve?

Lag phase, Log (exponential) phase, Stationary phase, Death phase

What happens during the lag phase?

Population constant, cells increase in size

What happens during the log (exponential) phase?

Cell number increases rapidly due to cell multiplication

What happens during the stationary phase?

Nutrient shortage and waste accumulation cause the population to become stable

What happens during the death phase?

Cell death rate exceeds cell multiplication

What is a biofilm?

A community of microorganisms attached to a surface and surrounded by an extracellular matrix

How do bacteria form a biofilm?

Bacteria attach to the surface, produce extracellular material, and form microcolonies

What happens when a biofilm matures?

Cells stick tightly together and develop resistance to cleaning and antimicrobials

What happens when a biofilm disperses?

Cells detach and spread to new areas

What is sporulation?

Process by which some bacteria form spores when the environment is not favorable for growth

Which types of bacteria can sporulate?

Only certain species can form spores (e.g., Bacillus, Clostridium)

What are intrinsic factors affecting microbial growth?

pH and water activity

What are extrinsic factors affecting microbial growth?

Temperature and humidity

How does pH affect bacterial growth?

Bacteria grow best in foods with a near-neutral pH

How does water activity affect bacterial growth?

Bacteria grow best in foods with high water activity (above 0.90)

What are nutrients needed for microbial growth?

Sources of nitrogen, carbon, and minerals

What is the function of buffering in growth media?

Keeps pH neutral to support microbial growth

What is a selective medium?

Medium that only allows certain microorganisms to grow

What is a non-selective medium?

Medium that allows all microorganisms to grow

What is a differential medium?

Medium that differentiates microorganisms based on visible characteristics or biochemical reactions