MicroBio Lec: Chapter4-6

What are the main components of a Prokaryotic cell?

Ribosomes, cytoplasm, plasmids, cell walls (thick & thin), flagella, pili(fimbriae)

How are multiple pili used?

Attach to other organisms/environments for the purpose of colonization or biofilm formation.

What are sex pili?

Specialized pili used for mating to exchange genetic material between cells

What are the basic shapes/structure of a prokaryotic cell?

Bacillus(rod), Coccus (spherical), Spiral (spirillum, vibrio, spirochete)

Monomorphic Bacteria

Bacteria that remains the same shape and doesn’t change

Pleomorphic Bacteria

Bacteria that changes shape after infection (one shape before infection, changes to better attack the host cells)

What arrangements can bacteria be found in?

Pairs (diplococci, diplobacilli), Clusters(staphylococci), Chains (streptococci, streptobacilli)

What is the purpose of flagella?

Senses the environment and provides movement either towards or away

Chemotaxis

Movement towards/away from chemical signals (negative move away from toxins/antibiotics) (positive move towards food)

Phototaxis

Movement toward/away from light (negative move away from light) (positive move toward light)

Peritrichous Flagella Arrangement

Many flagella, moves in any direction

Monotrichous & Polar Flagella Arrangement

Single flagella, moves in one direction

What does the word polar mean when discussing flagella arrangements?

Only moves in one direction, if polar is not used the bacteria can move in multiple directions

Lophotrichous and Polar Flagella Arrangement

Clustered flagella in one corner/area of the bacteria, moves in many directions

Amphitrichous and Polar Flagella Arrangement

Flagella enters from one end and goes through to the other, moves in many directions

Endoflagella Bacrteria Flagella Arrangement

Axial filaments that remain inside the cell, rotation of filaments create movement

How many attachment pili vs. sex pili can a bacteria have?

Conjugation pili can only have 1-2, attachment can be few to hundreds

How can fimbriae help bacteria/cause disease?

Help to attach to the host cells better allowing for contamination

What is glycocalyx?

Carb-rich outer coating that is sticky, creating a slime layer/biofilm

What is organized glycocalyx?

Tightly bound outer layer that forms a capsule

How does the glycocalyx capsule help bacteria?

Shields bacteria from chemicals/harmful toxins and phagocytes

What is unorganized glycocalyx?

Loose, diffused outer layer that forms biofilms/slime layers (cells ill undergo cell death to create film)

What are the characteristics of a gram-positive cell?

Thick wall, made of peptidoglycan (polysaccharides are NAG & NAM), layers joined by teichoic acids

What are the characteristics of a gram-negative cell?

Thin wall, very little peptidoglycan, no teichoic acids NAM & NAG join directly to peptide bond

Which type of gram-bacteria is harder to kill?

Negative, the additional outer membranes help to stop antibiotics/toxins

What is LPS and why is it important in gram-negative bacteria?

Lipid polysaccharide that protects the cell from harmful environments/antibiotics

How does LPS negatively affect humans?

When bacteria in our gut is attacked/broke/destroyed Lipid A is released causing a massive immune response (high fever, sepsis, inflammation). LPS is not naturally occurring or introduced to our systems so when exposed it compromises our cells/systems

Atypical cell walls

Acid-fast cell walls, unique wall patterns that do not match the typical gram-pos/neg staining techniques

Mycoplasmas

Smallest genus that lacks cell walls (cannot be gram-stained)

Mycobacteria

Genus with waxy-cell walls, has mycolic acids

What is the plasma membrane’s function?

Has selective permeability to control what comes in/out of the cell (controls osmolarity equilibrium)

Isotonic solution

Equal concentration between inside and outside the cell

Hypotonic solution

Water moves into the cell, bursts the cell (osmotic lysis)

Hypertonic solution

Water moves out of the cell, shrinks the cell (plasmolysis)

How is transcription & translation different in bacteria?

There is no nucleus so they occur at the same time

Nucleoid

Membrane-free region that holds the bacterial genetic material (one chromosome)

Plasmids

Small DNA molecules that can replicate independently (carry genes that can be used for drug resistance, toxin production, etc.)

Ribosomes

Primary site for protein synthesis

What are the ribosomal subunits of a Prokaryotic ribosome?

70S (consists of 30S & 50S)

What does -mycin mean?

Antibiotics that are ribosome inhibitors or a protein synthesis inhibitors

What are spores and thier function?

Created by gram-positive bacteria in response to stress

How do spores form and what happens during the process?

Outer coating forms when there is poor living conditions, metabolism is close to zero but DNA is still intact so when conditions become favorable they can go back to reproducing and being active

What type of fungi are single celled?

Yeasts

What type of fungi are multi-celled?

Molds

What is the difference between eukaryotic flagella and prokaryotic?

Euk have a wipe like movement

What are the characteristics of the cell wall in fungi?

thick inner layer of chitin/cellulose and a thin outer layer of mixed glycans

What are the characteristics of the cell wall in algae?

Varies, may contain cellulose, petin, mannas, and minerals

Function of rough & smooth ER?

rough contains ribosomes and is the site of protein synthesis, smooth contains no ribos and site of lipid synthesis

Function of the golgi apparatus

Site of protein modification and shipment, after ships off condensed vesicles to lysosomes or out of the cell

Function of lysosomes

A cell containing a pathogen is engulfed by a phagosome and fused to a lysosome, enzymes will then break down the microbes and pathogens

What are the ribosoal subunits for eukaryotes?

80S (contains 40S + 60S)

Cytoskeleton

Flexible proteins that provides structure, movement and shape changes within a cytoplasm (microfilaments & microtubules)

For bacteria, is it easy to kill, spore forming, multicellular?

Hard to kill, spores only form on gram-positive bacteria (non-spore= vegetative), and unicellular

For fungi, is it easy to kill, spore forming, multicellular?

Easy to kill, most/all form spores, uni & multicellular

For protozoa, is it easy to kill, spore forming, multicellular?

Intermediate to kill, form spores(non-spores= trophozite), unicellular

Pros and cons of fungi function

Con; allergies, disruption of crops, toxin production Pros: decomposers, source of antibiotics, used in foods

Characteristics of algae

Multi-cellular plant-like organisms that contain chlorophyll and can do photosynthesis

What is T. brucei (African sleep sickness)?

A parasitic black fly that bites its host, crossing the blood brain barrier and creating neurological issues

What is amoebiasis?

When drinking contaminated water with the amoebia spores it introduces new bacteria into your immune system

What is T.cruzi?

CO2 released while breathing (typically while sleep) attracts bugs that then bite the host, parasite is transferred through their feces

What is toxoplasmosis?

In which a parasite found in cat urine affects and crosses the placenta of a pregnant women

What is malaria?

When an infected (female) mosquito bites its host

Parasitic helminths

Microscopic worms that live in and feed on their host (flat worms & roundworms;nematodes) through ingestion

Characteristics of viruses?

NO cells (acellular), are non-living outside of a host, goal is to create more proteins & viral particles (create their own mRNA)

Can a virus single/double DNA &RNA?

They carry either DNA or RNA, single DNA and double RNA is possible & vice versa

How can viruses be classified?

Through morphology (shape&structure), infected host (animal,plants,bacteria?), genetic composition (single,double), and pathology (how deadly, contagious,transmission)

What is a naked capsid virus?

A virus with no membrane but will gain one once it infects a host, it gathers genetic material from the host and forms a membrane

What is the genetic material in retrovirus?

They use RNA as the material and reverse transcriptase as their enzyme

What is the lytic cycle?

Immediate destroys the host cell upon infection by rapidly reproducing and bursting itself open to release partials (lysis)

What is the lysogenic cycle?

Silently and slowly infects viral DNA into the host cell without killing itself, over time host DNA will replicate with the viral DNA, stressors/toxins can trigger the release of the viral DNA

What are the outcomes of cellular infection?

There is no straightforward outcome and multiple outcomes are possible; the cell can die to eliminate the pathogen, survive with replication and release at lytic infection, transform into growth/cancer, and an asymptomatic clearance where the host immune system clears the pathogen with minimal injury to the host.

What is the endosymbiotic theory?

The belief that the key organelles in eukaryotic cells were once evolved from free-living prokaryotic bacteria which were later engulfed by a larger ancestral cell

What is florescent microscopy?

the process in which light wavelengths excite/charge up proteins or florescent dyes within a sample creating a dark background illuminating each cell

What is the cell wall of archaea made of?

Pseudomurein