MICRO EXAM 4

Which of the following items would be chemoattractant for phagocytic cells?

-C5a -chemokines -products of invading microorganisms -phospholipids released by injured host cells

Which contribute to antibody and TCR diversities?

-combinatorial association -imprecise joining of segments -rearrangement of gene segments -somatic hypermutations

Peptides that can be presented on an MHC class I molecule for possible interaction with a T cell receptor on a cytotoxic T cell include ___________.

-endogenous abnormal self peptides from cancerous cells -viral intracellular pathogen peptides -endogenous normal self peptides

Adaptive immunity has two main divisions. They are

Humoral immunity and cell-mediated immunity

Which statement DOES NOT describe activation of innate immune responses by PRRs?

Recognition triggers cleavage of existing mRNA

Why are vaccines so important for protecting people against exotoxin-induced diseases such as botulism and tetanus?

-they induce production of specific antibodies that will immediately bind the toxin if encountered later, providing fast protection -following initial exposure to exotoxin, antibody production takes time during which the exotoxin may cause extensive damage or even death

Humoral immunity is generally used to deal with extra cellular antigens such as

-toxins -viruses in tissues fluids -bacteria outside of cells

Place the steps of animal virus infection in the correct order

1. Attachment 2. Penetration and unloading 3. Synthesis of viral protein and replication of the genome 4. Assembly 5. Release

Which gene is likely transferred to other bacteria during specialized transduction?

A gene adjacent to phage integration site

First line of defense

Are generally barriers such as skins and mucous membranes

Pattern recognition receptors

Bind to compounds unique to microbes yet common on them

More toxin may be produced from treatment with bactericides of which bacteria?

Endotoxin-producing Gram - bacteria

What are prions?

Infections proteins

What are viroids?

Infectious naked RNA

A macrophage kills by ___, while a neutrophil kills by ___?

Ingesting microbes and destroy them internally, phagocytosis and releasing toxic granule component.

During the process that leads to a lysogenic infection, which of the following inserts the phage DNA into a bacterial chromosome?

Integrase

Which is not a step shared by the replication of temperate and lytic phages?

Integration of page DNA to host genome

A_____ phage can either cause a lytic infection or can incorporate its DNA into the host genome as a prophage

Lysogenic

Viruses with dsDNA genomes and replicating via ssRNA intermediates are

Pararetroviruses

Activation of lymphocytes are tightly regulated. The second signal required by lymphocytes to become fully activated is usually provided by

T helper cell or dendritic cells

Innate immunity is

The body's defense against any kind of pathogen

Retroviruses may lead to latent infection because

They integrate a DNA copy of their genome into host chromosome

The complement system is a series of _____ that circulate in the ____

proteins; blood and extracellular fluid

When microbes enter through a minor skin wound, resident ______ in the tissues destroy them. If these microbes are not rapidly cleared, the resident cells secrete _______ to recruit _______ for extra help.

macrophages; cytokines; neutrophils

What definitely set viruses apart from other organisms?

-Viruses replicate by assembly -Viruses are not made of cells

The innate immunity and adaptive immunity are closely linked. Which cell types pass on information from the innate immunity to adaptive immunity?

-activated macrophages -dendritic cells

Which are true of antigen processing and presentation in B cells?

-antigen and BCR complexes are brought into the B cell -peptide fragments are loaded into MHC class II molecules for presentation to helper T cells -antigens are broken down into peptide fragments

Which viruses carry an RNA-dependent RNA polymerase in their virions?

-double stranded RNA viruses -(-) strand RNA viruses

Which of the following events occur after T cell activation?

-formation of memory cells -differentiation of the activated cells into effector cells -proliferation of newly activated cells

A human baby acquires normal microbiota

-from passage through birth canal -from breastfeeding and contact with another human -from ingested food and from environment

A T-cell receptor is

-is similar (but not identical) in function to a B cell receptor -is found on the surface of T cells -only recognizes antigen that is presented by another cell

TRLs (toll-like receptors) in endosomes and phagosomes detect

-long molecules of double stranded RNA -peptidoglycan fragments from bacterial cell walls -nucleotide sequences that are relatively common in bacterial DNA

When complement is activated via the classical pathway, which of the following outcomes are likely to occur?

-membrane attack complex will form -inflammation will be stimulated -pathogens will become opsonized

For a productive viral infection in a host cell, which of the following activities are needed?

-replication of viral genome -transcription of viral genes -translation of viral genes

Which of the following statements regarding all cases of symbiosis is true?

-symbiosis refers to different organisms living together -at least one member must benefit in a symbiotic relationship

Which of the following are a part of Koch's postulates?

-the microbe must be present in every case of disease -the microbe must be grown in pure culture from diseased host -the same disease must be produced when pure culture is inoculated into susceptible hosts

Which of the following statements about viruses are true?

-the viral capsid is composed of proteins -viruses contain RNA or DNA but not both

Normal microbiota provide protection from infection in that

-they change the pH of the environment -they make the chemical environment unsuitable for nonresident bacteria -they compete with pathogens for nutrients -they produce antibacterial chemicals

What is the correct sequence of events for activation of a B cell by T-dependent antigen?

1. B cell receptors recognize and bind the antigen 2. B cells internalize the antigen and digest it to fragments 3. An antigen fragment in complex with MHC II is displayed on the B cell's surface 4. The MHC antigen complex binds a receptor on a Th cell 5. The Th cell secretes cytokines that activate the B cell

Put the following steps that result in directed uptake of Salmonella species in intestinal epithelial cells in order

1. Bacteria adhere to the host cells 2. Bacteria use a type III secretion system to deliver proteins to host cells 3. Bacterial proteins cause rearrangement of actin molecules in host cells 4. Characteristic membrane ruffling occurs on the host cell's surface 5. Host cell's membrane encloses around and engulfs the bacterial cells

Place Koch's postulates in the correct order

1. The organism must be present in every case of the disease 2. The organism must be isolated from the host with the disease and grown in pure culture 3. The specific disease must be reproduced when a pure culture of the organism is inoculated into a healthy susceptible host 4. The organism must be recoverable from the experimentally infected host

Positive selection take place in T cells but not in B cells because

B cells don't need to have peptides presented to them on an MHC molecule, so it doesn't matter if they can bind MHC or not

Protection of lysogens from infection by the same phage is called

Immunity to superinfection

The clonal selection theory states that there are

Many lymphocytes produced, but each has only one specific epitope it will react with