Microbial Structure and Function Lecture Sep 6 Flashcards

Question

What is LPS comprised of? What part is the endotoxin?

Answer 1

Lipopolysaccharide is comprised of Lipid A and O-antigen. THe lipid A is a complex lipid that is covalently attached to a polysaccharide. This is the endotoxin and it's extremely toxic to us. THe lipid portion of LPS is attached to the outer membrane by hydrophobic bonds. THe polysaccharide chain of releatin gunits is called the O antigen, which is exposed to the outside of the cell. THis is antigenic.

Answer 2

They are the smallest free-living organism. They DON"T HAVE A CELL WALL! The only barrier is the cytoplasmic membrane, but the membrane contains sterols required for growth (but aren't synthesized by the bacterium) They often cause walking pneumonia

Answer 3

THey don't have a cell wall-no peptidoglycan

Answer 4

They contain mycolic acid in the cell wall, which prohibits gram staining. You have to use acid fast staining to visualize. They contain small amounts of peptidoglycan and large amounts of glycolipids including LAM and mycolic acids which make the cell walls impermeable.

Answer 5

Staining with red carbolfuschin and then destaining with acid alcohol. THe mycolic acid will hold onto the stain stronger than the alcohol could, so only acid fast bacteria will retain the stain after the decolorizing step.

Answer 6

This is how a bacteria exchanges is proteins with the surrounding environment. They transport proteins or nucleic acids to the outside fo the cell, periplasm, or the inside of host cells (can transport adhesins or toxins) There are 7 types (6 in gram negative and 7 in gram positive). This plays a major role in determining a bacteria's pathogenicity. Some consist of transporters, outer membrane factors, and membrane fusion proteins, while others involves a transmembrane structur called an injectosome

Answer 7

An endospore is a version of a bacteria that is highly resistant to heat, desiccation and chemical changes. They are produced by baccilus and clostridium species in nutrient limiting conditions and dehydration.

Answer 8

1. Spore wall (exosporium) contains normal peptidoglycan and will ve the cell wall of the germinating bacterium 2. SPore coat contains keratin-like protiens which are very impermeable to chemicals 3. Cortex is the thickest part of the spore envelope and contains peptidoglycan with fewer cross-links 4. The core cotains calcium dipicolinate (which is what confers the endospore with heat resistance) and all the nucleic acid for later growth

Answer 9

Viruses that infect prokaryotes = bacteriophage Viruses that infect eukaryotes

Answer 10

1. They are obligate intracellular parasites (need a host) 2. The viral particle is either DNA or RNA (ds or ss) in a protein coat with or without a membrane 3. THe outer coat protects the genetic material and facilitates adhesion and infection 4. Contains almost no enzymes, no organelles or other biosynthetic machinery 5. the nucleic acids code for proteins needed for viral replication

Answer 11

They both have nucleic material with a coat ot capsid around it, but envelopes have an additional membrane that surrounds the capsid. They acquire the membrane when they bud out from the host--so the membrane is basically a plasma membrane. Naked viruses are more durable in the environment because the membrane of enveloped proteins can be broken down easily

Answer 12

It protects nucleic acids A capsomere is a subunit of capsid structure dapsid structures can be polyhedral, helical, isodecahedral, etc.

Answer 13

Viroids are very small single-stranded circles of RNA. THey cause disease in plants Hepetitis D is similar to a viroid

Answer 14

A misfolded PrP protein (PrPsc) that can induce the same conformational change in other PrP proteins Even though PrPc and PrPsc have the same protein sequence, they are shaped differently The PrPsc is resistant to autoclaving, radiation, and nucleases But they can be inactivated by detergents, urea, phenol, erc. Examples include scarpies, Kurur, Creutsfeldt-Jakob disease, spongiform encephalopathy

Answer 15

They catalyze the formation of new beta sheets within the protein conformation

Answer 16

Erogsterol

Answer 17

Yeasts, molds, and mushrooms Yeasts and molds can directly product disease in humans Mushrooms cause disease indirectly by the toxins they produce

Answer 18

Single celled fungi Reproduce by budding some strains produce psuedohyphae

Answer 19

They grow in filamentous forms called hyphae Many species produce cross walls of hyphae called septae (some nonseptate hyphae do exist) Masses of hyphae are called mycelia

Answer 20

Dimorphic fungi can exist as a yeast or a mold form The form is controlled by environmental conditions like temperature and nutrients Yeast form is found in the body and the mold form is found in the environment (or lab culture)

Answer 21

Conidia -- asexual spores of molds Arhtoconidia--formed from joints in hyphae and then fragmentation Blastoconidia--yeast cell buds

Answer 22

THey are single celled eukaryotes that can exist as trophozoites (motile form) and as cysts (resting stage). Some move by flagella

Answer 23

Trematodes (flukes) Cestodes (tapeworms) Nematodes (roundworms) Infection usually involves ingestion of larval or cyst form