BIOL Chap 3

What is the smallest unit of life?

The cell.

What are the three main parts of cell theory?

Cells are the fundamental units of life; all cells come from pre-existing cells; and the biochemical reactions of life occur within cells.

What structures are shared by all cells?

Nucleic acids, ribosomes, and a plasma membrane.

How do bacterial cells differ from eukaryotic cells?

Bacterial cells are smaller, lack a nucleus, lack membrane-bound organelles, and usually have one circular DNA molecule.

How do eukaryotic cells differ from bacterial cells?

Eukaryotic cells are larger, have a nucleus, have membrane-bound organelles, and store DNA in chromosomes.

Where is DNA found in bacterial cells?

In the nucleoid region.

Where is DNA found in eukaryotic cells?

Inside the nucleus.

Why are cells so small?

Small cells have a higher surface area-to-volume ratio, which allows more efficient exchange with the environment.

What happens to surface area-to-volume ratio as a cell gets smaller?

The ratio increases.

What distinguishes Eubacteria from Archaea?

Eubacteria have peptidoglycan in their cell walls; Archaea do not.

What do plant cells have that animal cells usually lack?

A cell wall and chloroplasts.

What is the plant cell wall made of?

Cellulose.

What is the fungal cell wall made of?

Chitin.

Do animal cells have cell walls?

No.

What does bacterial morphology mean?

The shape of bacterial cells.

What are cocci?

Round bacterial cells.

What are bacilli?

Rod-shaped bacterial cells.

What are spirilla?

Spiral-shaped bacterial cells.

What are vibrios?

Slightly curved or comma-shaped bacterial cells.

What is the bacterial cell envelope?

The protective outer structure surrounding bacteria.

What are the three main layers of the bacterial cell envelope?

Cell membrane, cell wall, and glycocalyx.

What is the bacterial cell membrane made of?

A phospholipid bilayer with proteins.

What is the function of the cell membrane?

It is a selectively permeable barrier that controls what enters and exits the cell.

What does selectively permeable mean?

The membrane allows some substances to cross while limiting others.

What is the bacterial cell wall made of?

Peptidoglycan.

What does the bacterial cell wall do?

It maintains cell shape and helps prevent the cell from rupturing due to osmotic pressure.

Why is the bacterial cell wall a good antibiotic target?

Because bacterial cell walls contain peptidoglycan, which eukaryotic cells do not have.

Which antibiotics discussed target bacterial cell wall formation?

Penicillin and vancomycin.

What is antibiotic resistance?

When bacteria develop mechanisms that make antibiotics less effective or ineffective.

What is the glycocalyx?

A viscous outer covering made of polysaccharides and proteins.

What are the two main forms of glycocalyx?

Slime layer and capsule.

What is a slime layer?

A loosely organized glycocalyx layer that can be washed away easily.

What is a capsule?

A highly organized glycocalyx layer firmly attached to the cell wall.

What are major functions of the glycocalyx?

Attachment, biofilm formation, protection from drying out, and hiding from immune cells.

What is a biofilm?

A community of bacteria attached to a surface, often helped by glycocalyx slime layers.

How can a capsule increase bacterial virulence?

It can hide bacteria from immune cells and make disease more severe.

What does virulence mean?

The degree to which a pathogen causes disease.

What are bacterial appendages?

Protein structures extending from the surface of some bacterial cells.

What are the two main functions of bacterial appendages?

Motility and adherence.

Which appendage is mainly used for bacterial motility?

Flagella.

Which appendages help bacteria adhere to surfaces or other cells?

Fimbriae and pili.

What is a bacterial flagellum?

A long hair-like projection that helps bacteria move.

How do bacterial flagella move?

They rotate like a propeller.

What are the main parts of a bacterial flagellum?

Basal body, hook, and filament.

What does monotrichous mean?

One flagellum on one side.

What does amphitrichous mean?

One flagellum on both sides.

What does lophotrichous mean?

A tuft of flagella on one side.

What does peritrichous mean?

Flagella all around the cell.

What is bacterial run-and-tumble movement?

A movement pattern where bacteria move quickly in one direction, then stop and reset before moving again.

What is taxis in bacteria?

Movement in response to a stimulus.

What is positive taxis?

Movement toward a stimulus.

What is negative taxis?

Movement away from a stimulus.

What is chemotaxis?

Movement in response to chemical signals.

What are fimbriae?

Small bristle-like protein appendages that help bacteria attach to surfaces or each other.

What are pili?

Long tubular protein structures involved in bacterial conjugation.

What is conjugation?

A process where one bacterial cell transfers genetic material, often a plasmid, to another cell.

Why are pili important for antibiotic resistance?

They can help transfer plasmids containing antibiotic resistance genes between bacteria.

What are bacterial endospores?

Hardy dormant structures that help some bacteria survive harsh conditions.

What is sporulation?

The formation of endospores.

What is germination?

The return from an endospore state to active vegetative growth.

What does vegetative growth mean for bacteria?

Active growth and cell division.

Which bacterial genera commonly produce endospores?

Bacillus and Clostridium.

What is the function of ribosomes?

Protein synthesis.

What are ribosomes made of?

Protein and rRNA.

How do bacterial ribosomes compare to eukaryotic ribosomes?

Bacterial ribosomes are smaller.

What is the bacterial chromosome like?

A single circular double-stranded DNA molecule in the nucleoid region.

What are plasmids?

Small circular double-stranded DNA molecules that can replicate independently of the bacterial chromosome.

What helpful genes can plasmids carry?

Antibiotic resistance genes, metabolic genes, or virulence genes.

What is bacterial cytoplasm mostly made of?

Water, about 70–80%, plus dissolved sugars, amino acids, and salts.

What are inclusions or granules in bacterial cells?

Storage bodies for materials the cell may use later.

How can photosynthetic bacteria perform photosynthesis without chloroplasts?

They use thylakoid-like membrane structures with chlorophyll.

What kingdoms are part of Domain Eukarya?

Protista, Fungi, Plantae, and Animalia.

What major structures are found inside eukaryotic cells?

A nucleus, membrane-bound organelles, ribosomes, cytoplasm, and cytoskeleton.

Which eukaryotic groups have cell walls?

Plants, fungi, and some protists.

What is the function of a eukaryotic cell wall?

It provides strength, rigidity, and protection against osmotic pressure changes.

Does the plant cell wall control what enters and leaves the cell?

No, the cell membrane controls passage of molecules.

What is exocytosis?

The release of cellular contents to the outside of the cell.

What is endocytosis?

The uptake of material from outside the cell into the cell.

What is phagocytosis?

Endocytosis of solid particles or other cells; cell eating.

What is pinocytosis?

Endocytosis of fluid; cell drinking.

What is receptor-mediated endocytosis?

Specific endocytosis triggered when molecules bind to receptors on the cell surface.

How can viruses use receptor-mediated endocytosis?

They can bind to cell receptors and trick the cell into bringing them inside.

What are vacuoles?

Membrane sacs of fluid used for storage, transport, and regulation.

How are animal vacuoles usually described?

Small and numerous, often involved in transport.

How are plant vacuoles usually described?

Large, often one central vacuole filled with water.

What is the tonoplast?

The large central vacuole in plant cells, especially involved in water regulation.

What are lysosomes?

Specialized vacuoles containing digestive enzymes.

What do lysosomes do?

They break down and recycle organic material through hydrolysis reactions.

What is cytosol?

The fluid portion inside the cell.

What is cytoplasm?

All contents of the cell between the nucleus and the plasma membrane.

What is the nucleus?

The command center of the eukaryotic cell that contains DNA.

What surrounds the nucleus?

A double-layered nuclear membrane, also called the nuclear envelope.

What are nuclear pores?

Openings in the nuclear envelope that allow certain substances, like mRNA, to leave the nucleus.

Why can mRNA leave the nucleus but DNA cannot?

mRNA is small enough to pass through nuclear pores; DNA is too large.

What is chromatin?

Genetic material made of DNA and associated proteins inside the nucleus.

Where can eukaryotic ribosomes be found?

Free in the cytoplasm or attached to the rough ER.

Are ribosomes membrane-bound organelles?

No.

What structures are part of the endomembrane system?

Endoplasmic reticulum, Golgi apparatus, and lysosomes.

What is the endoplasmic reticulum?

Membrane channels around the nucleus involved in transport and synthesis.

What are the two types of endoplasmic reticulum?

Rough ER and smooth ER.