Bacterial and Archaeal Cell Structure

Flashcards covering key vocabulary and concepts from the lecture notes on bacterial and archaeal cell structure.

Prokaryote

Term used to describe cells lacking a membrane-bound nucleus, cytoskeleton, and internal membraneous structures.

Bacilli

Rod-shaped bacteria.

Cocci

Spherical-shaped bacteria.

Vibrio

Comma-shaped bacteria.

Spirillum & Spirochetes

Spiral-shaped bacteria.

Fimbriae

Attachment to surfaces; bacterial conjugation + transformation, twitching motility.

Capsule

Resistance to phagocytosis, adherence to surfaces.

Cell Envelope

Plasma membrane and all the surrounding layers external to it.

Macronutrients

Nutrients needed in relatively large quantities.

Micronutrients

Nutrients (trace elements) used in very small amounts.

Passive Diffusion

Substance moves through the membrane on its own, down the concentration gradient, without energy input.

Facilitated Diffusion

Substances move across the plasma membrane with the assistance of transport proteins, without metabolic energy required.

Group Translocation

Type of active transport in which bacterial cells transport organic molecules while modifying them.

Endotoxin

Lipid A portion of LPS; release into the human body can lead to septic shock.

Capsules, Slime layers, and Glycocalyces

Layers of material lying outside the cell wall, protecting cells from environmental conditions and host defenses.

S-layers

External-most layer in some bacteria, composed of proteins or glycoprotein, with a geometric shape.

Nucleoid

Area within the cytoplasm where the genetic material of bacterial cells is located.

Plasmids

Extrachromosomal DNA found in many bacteria, encoding traits that confer a selective advantage.

Fimbriae

Hairlike appendages functioning primarily in attachment to surfaces.

Flagella

Threadlike, locomotory organelles.

Swarming

A behavior in which bacterial species move as a group, mediated by flagella on moist surfaces.

Twitching Motility

Jerky movement brought about by type IV pili.

Gliding Motility

Smooth movement.

Chemotaxis

Motile cells respond to gradients of attractants and repellents.

Endospores

Dormant structures resistant to heat and desiccation, formed within so-called mother cells.

Germination

Breaking of endospores' dormant state.

Archaeal Cell Envelopes

Archaeal cell envelopes consist of only the plasma membrane & cell wall contains no peptidoglycan,only S-layer.

Pili

Similar to bacterial type IV pili.

Archaella

Archaeal flagella, rigid helices that rotate.

What are the three main domains of life?

Bacteria, Archaea, and Eukarya

Who discovered microorganisms with a microscope?

Antony Van Leeuwenhoek

What did Pasteur’s swan-neck flash experiment demonstrate?

That microbes do not arise from non-living matter spontaneously

What is the RNA World Hypothesis?

The idea that RNA was the first genetic and catalytic molecule

What is LUCA?

Last Universal Common Ancestors shared by all cellular life

Why are SSU rRNA genes useful for classification?

Because they are conserved across all forms of life

Name two acellular infectious agents

Viruses and prions

How did Reid disprove spontaneous generation?

By showing maggots didn’t appear in sealed meat jars

What is the role of ribozymes?

RNA molecules that catalyze reactions, supporting RNA world

What are the basic shapes of bacteria?

Coccus, bacillus, and spiral forms

What is a glyococalyx?

A polysaccharide coating that helps with protection and adhesion

What do pilli do?

Aid in attachment and DNA transfer

What distinguishes Gram (-) from Gram (+) bacteria?

Thin vs thick peptidoglycan and presence of other membrane

What are inclusions?

Storage granules for nutrients or enzymes

What is group translocation?

Transport mechanism where the substance is chemically modified during uptake

What do endoscopes do?

Help bacteria survive extreme conditions

What is the function of the S-layer?

Protection and adhesion

What causes a bacterium to be peritrichous?

Flagella distributed over entire surface

What are L-forms?

Bacteria that lack a cell wall

What type of bacteria lacks a cell wall and is resistant to penicillin?

Mycoplasma

What enzyme breaks the bond between NAG and NAM?

Lysozyme

What is the function of dipicolinic acid in endospores?

Help stabilize DNA and confer heat resistance

What are volutin granules?

Inclusions that store inorganic phosphate

What is the function of porins?

Passive transport of small molecules across the outer membrane

What triggers sporulation in bacteria?

Nutrient depletion

How does the flagellar motor work?

It rotates using the proton motive force

What causes bacteria to “tumble” during chemotaxis?

Clockwise rotation of flagella

What is the purpose of the periplasmic space?

It contained enzymes and binding proteins crucial for nutrient uptake

How do gas vacuoles function?

They regulate buoyancy in aquatic bacteria

What makes archaeal membranes unique?

Ether-lined lipids and isoprenoid chains

Do archaeal have peptiodoglycan

No

What is an archaellum?

A thinner, ATP-powered flagellum unique to Archaea

What do hami do?

Allow cells to attach like grappling hooks

Do archaea use group translocation

Some do

What is the main archaeal cell wall structure?

S-layer made of protein

Why are archaeal ribosomes antibiotic-resistant?

Different r-protein composition

What are cannulae?

Tube-like structures connection daughter cells (found in archaea)

Do archaea have histones?

Yes, to organize DNA (unlike bacteria similar to euks)

Where do archaea commonly live?

Extreme environments like hot springs and salt lakes

Which of the following transport mechanisms require energy?

Primary active transport, secondary active transport, and group translocation