Diversity Exam 3

The immune system protects against:

viruses; bacteria; fungi; animal parasites; rogue cells which cause cancer

what does blood contain?

plasma, red and white blood cells, and platelets

what does lymph contain?

contains fluid from the blood and the tissues as well as white blood cells and blood platelets

examples of the immune (white blood) cells:

macrophages; dendrite cells; B lymphocytes; T lymphocytes

what are macrophages?

engulf and digest microorganisms; activate T cells

dendrite cells def:

present antigen to T cells

B lymphocytes def:

differentiate to form antibody-producing cells and memory of cells

T lymphocytes def:

kill virus-infected cells or cancer cells; regulate activites of other white blood cells

types of immune system:

innate (non-specific) and adaptive (acquired or specific)

characteristics of innate immune system:

fast
first encountered
always present/quickly activated
found in all animals

characteristics of adaptive immune system:

slow
encountered last
has to be activated
very specific
found in some invertebrates/vertebrates

barrier of the immune system examples:

skin, mucus, nasal hairs, cilia, acids, tears and saliva

Other innate responses:

• Fever
• Coughing/sneezing
• Inflammation
• Phagocytosis by macrophages and neutrophils
• Natural killer cell lysis
• Complement response
• Mobilize acquired defenses
• Stimulation of inflammation by toll-like receptors

Path of inflammation:

1) damaged tissues attract mast cells which release histamine, which diffuses into blood vessels
2) histamine causes vessels to dilate and become leaky; complement proteins leave the vessels and attract phagocytes
3) blood plasma and phagocytes move into infected tissue from the vessels
4) phagocytes engulf bacteria and dead cells
5) histamine and complement signaling cease; phagocytes are no longer attracted
6) growth factors from white blood cells and platelets stimulate cell division in skin cells, healing wound

types of adaptive (acquired) immunity:

humoral and cell-mediated

characteristics of humoral immunity:

antibodies released into the fluid; B lymphocytes; requires APCs

characteristics of cell-mediated immunity:

cell-to-cell contact and T lymphocytes; require APCs

adaptive immunity features:

specificity
distinguish self from not self
diversity
memory

Path of humoral immunity:

antigens (cell with surface antigen) -\> antigen-presenting cell binds -\> T-helper cell stimulates -\> B cells bind free antigen to its antibody receptors -\> antibodies made by B cells bind to free antigen and to antigen on the surface of pathogen cells and antigen-presenting cells

path of cellular immunity:

cell with surface antigen -\> antigen-presenting cell binds -\> T-helper cell stimulates -\> Cytotoxic T cell kill all cells with antigen exposed

antigen def:

a molecule, typically foreign, that elicits an immune response; promotes production of antibodies

antibody def:

peptide molecules that are produced by B lymphocytes; bind antigens at epitope sights

what do B cells make?

antibodies

heavy chains are \________ and light chains are \_________

identical

antibodies react with \_____ \_______

antigenic determinants

the functions of antibodies:

agglutination
precipitation
neutralization
opsonization
stimulation of complement response

agglutination def:

binds antigens and clumps them

precipitation def:

binds antigen and it loses solubility

neutralization def:

binds antigens, eliminating the antigen's function

opsonization def:

an antibody binding antigen promotes macrophages phagocytosis

clonal selection process

each naïve B cell makes a different, specific antibody and displays it on its cell surface
1) one B cell makes an antibody that binds specific antigen
2) this binding along with signals from Helper T cells stimulates the B cell to divide, resulting in a clone of cells
3) primary immune response: some cells develop into plasma cells (effector B cells) that secrete the same antibody as the parent cell)
4) potential secondary immune response: a few cells develop into non-secreting memory cells that divide at a low rate, perpetuating the clone

how are antibodies encoded?

antibodies are made by shuffling different domains which are encoded by genes?

the shuffling and jointing of the domains for encoding antibodies occurs in...

embryos

loss of DNA in B-lymphocytes makes choices of antibody \_______

irreversible

What activates Helper T lymphocytes?

APCs

what do Helper T lymphocytes activate?

cytotoxic T and B cells

what do cytotoxic T lymphocytes do?

bind to and kill virally infected cccells

regulator T lymphocytes def:

bind and inactivate, alter, or kill other immune cells

antigen presenting cells def:

macrophages dendritic cells and microglial that engulf antigens, present on their surface

what are T cell receptors?

glycoprotein; 2 polypeptide chains; each chain has constant/variable regions; bind to specific fragments of antigens displayed on cell

any cells can present ... (MHC protein table)

any cell can be present...intracellular protein fragment on...Class I and they present to...cytotoxic T cells with...co-receptor CD8 that binds with Class I

macrophages, dendritic cells, and B cells can present... (MHC protein table)

macrophages, dendritic cells, and B cells can present...fragments from extracellular proteins on...Class II and they present to...Helper T cell with...Co-receptor Cd4 that binds Class II

path of Antigen-presenting cells:

1) the APC takes up an antigen by phagocytosis
2) the cell breaks down the antigen into fragments in the phagosome
3) a class II MHC protein binds an antigen fragment
4) the MHC presents the antigen to a Helper T cell

how do Helper T cells activate other cells?

travel through lymph and blood;
can then activate B lymphocytes and cytotoxic T cells which are specific for the antigen

cytotoxic T cell activates...

apoptosis of virally infected cell

positive selection for T cells that...

interact with proper MHC protein

negative selection against T cells that...

bind to self-antigens

autoimmune diseases \_____ in frequency with age

increase

what is the first organ to senesce?

thymus

HIV emerge surrounded in \___ from cell membrane

bud (envelope)

what are inserted into the phospholipid bilayer?

envelope glycoproteins encoded by the virus

HIV is what kind of virus?

retrovirus

with HIV, the error rate for replication is...

very high

why do some AIDS counselors recommend two infected partners still practice safe sex?

- reduces the chance of swapping variants which are resistant to different meds
- reduces chances of recombination of these two resistances into one HIV strain

what do envelope glycoproteins bind to?

CD4 co-receptor molecule on Helper T-lymphocytes, macrophages, microglia, and dendritic cells

pathway of HIV

1) amount of virus in blood increases quickly and then symptoms occur
2) antibodies are secreted and viral load decreases
3) long asymptomatic period (5-10yrs)

how does HIV virus evade immune system?

antigenic variation
latency of proviral state
over time, abolishes immune system

Where do HIV viruses replicate?

within helper T lymphocytes

in the asymptomatic period HIV, what happens?

helper T-lymphocytes are produced, some become infected; virus replicates and variants of the virus are generated by mutation

when does symptomatic phase of HIV begin?

when [] and diversity of Helper T-cells is too low (CD4 count below 200)

what happens during symptomatic phase?

immunity collapses due to lack of Helper T-lymphocytes to stimulate cytotoxic T-cells; AIDS patients are unable to fight off infections and die due to other infections

antibodies increase and stay stable until immune system collapses
-true or false

true

example of animal that does asexual reproduction (mitosis only)

hydra

characteristics of parthenogenesis:

-development of offspring from unfertilized eggs
- involves meiosis
- some species sex is determined this way
-sexual behavior may still be required

compare and contrast asexual reproduction and parthenogenesis

parthenogenesis occurs in mammals
-true or false

false

to develop properly with parthenogenesis, what does the mammalian embryo need?

wild type alleles of certain genes with maternal or paternal imprint

spermatogenesis pathway

male germ cell (2n) -\> (mitosis) -\> spermatogonium (2n) -\> (mitosis) -\>primary spermatocyte (2n) -\> (first meiotic division) -\> 2 secondary spermatocytes (n) -\> (second meiotic division) -\> 4 spermatids (n) -\> 4 sperm (n)

Oogenesis pathway

female germ cell (2n) -\> (mitosis) -\> oogonium (2n) -\> (mitosis) -\> primary oocyte (2n) -\> (first meiotic division) -\> second oocyte (n) and first polar body -\> (second meiotic division) -\> Ootid (n) and second polar body -\> Ovum (egg) (n) and polar bodies degrade

early events of sea urchin fertilization

-sperm and outer coat of egg interact
- digestive enzymes are released
- outer coat near sperm is digested allowing recognition process between sperm and egg surface

later events of sea urchin fertilization

- membrane of the egg depolarizes briefly (called fast block of polyspermy)
- sperm and egg membrane fusion and the engulfment of sperm nucleus
- Ca+ released from stores in the ER into cytoplasm

what is fast block polyspermy?

membrane of egg depolarizes briefly; prevents more than one sperm from fertilizing egg

what is a calcium wave?

sperm acting through a signal cascade pathway containing a G-protein, inositol triphosphate, and a tyrosine kinase initiate calcium release

what do calcium waves trigger?

- activation of a sodium-proton exchanger (protons pumped out of cell, pH rises, DNA/protein synthesis activated)
- exocytosis of granules form fertilization envelope (slow block to polyspermy)
- nuclear fusion and first mitosis

what is a slow block to polyspermy?

fertilization envelop from calcium wave

what happens in sodium free water with sodium-proton exchanger?

- protons not pumped out and pH doesn't rise (protein synthesis not activated)
- activating nH3 with no sperm can raise egg pH and activate protein synthesis
- so pH rise (not Na inflow) is necessary and sufficient for protein synthesis activation)

things mammals have that sea urchins don't

-capacitation
- presence of cumulus
- no significant membrane depolarization
-species specific interaction on zona pellucida
- exocytosis of granules results in changes in zona pellucida which lowers affinity for sperm
- no nuclear fusion prior to first mitosis

definition of capacitation

a special structure surrounding the sperm head must be removed by interactions with the female reproductive tract

zona pellucida def:

in mammals, a species-specific protein in the zona pellucida binds a sperm and triggers acrosomal reaction

external vs internal fertilization

oviparous def

viviparous def

ovoviviparous def

birth control def

reproductive technology and infertility

deuterostomes after fertilization process:

- cleavage
- change in form (gastrulation)
- emergence of pattern
- differentiation of cells
- growth

cleavage def

special mitoses which begin immediately after fertilization

emergence of a pattern in frogs:

- inhibition of a degrading protein (inhibitor)
- localization of molecular players already in the egg prior to fertilization and then the changes that occur after fertilization

steps in emergency of a pattern in frogs:

1) fertilization
2) cortical rotation
3) dorsal enrichment inhibitor
4) dorsal inhibition of GSK-3
5) dorsal enrichment of B-catenin

characteristics of cleavage:

- frequent and usually synchronous at first
- embryo hasn't had chance to grow so cells become greater in \#, but small in size
- little to no G1 or G2, just DNA synthesis and Mitosis
- later slows down and becomes non-synchronous
- forma solid ball of cells (morula), then a blastula

initially, the \_______ axis is already established in egg prior to fertilization
-anterior/posterior
- dorsal/ventral
- right/left

anterior/posterior

\________ axis appear during or after fertilization
- anterior/posterior
- dorsal/ventral
- right/left

-dorsal/ventral
- right/left

what are the germ layers formed by gastrulation?

ectoderm, endoderm, mesoderm

ectoderm is the future what?

epidermis and nervous system

endoderm is the future what?

linings of gut, blood vessels, urethra

mesoderm is the future what?

bones and other connective tissue and muscles

cell movements during gastrulation:

invagination
involution
epiboly
passive envelope

invagination def:

a layer of cells buckles inward together; cells are attached to one another

involution def:

individual cells not connected with one another stream inward

epiboly def:

multiple layers of cells reorganize and stretch to fewer layers