Bio Notes Q-Cards Flashcards
what is an immune system?
defense which enables animals to avoid or limit many infections.
what is innate immunity?
a defense that is active immediately upon infection and is the same whether or not the pathogen has been encountered previously
what is adaptive immunity (acquired immune response)?
a defense found only in vertebrates. Animals with adaptive immunity produce a vast arsenal of receptors, each of which recognize a feature typically found only on a particular pathogen
when is adaptive immune response used?
it is activated after the innate immune response and develops more slowly
Innate immunity (rapid response) contains?
Barrier defenses: -skin -mucous membranes -secretions Internal Defenses: - phagocytic cells - natural killer cells - antimicrobial proteins -inflammatory response
adaptive immunity (slower response) contains what?
Humoral Response:
-Antibodies defend against Infection in body fluids
Cell-mediated Response:
-cytotoxic cells defend against infection in body cells
what is a lysozyme?
an enzyme that breaks down bacterial cell walls, further protects the insect digestive system
what is phagocytosis?
cellular ingestion and digestion of bacteria and other foreign substances
Cellular Innate Defenses include what?
- TLR
- Neutrophils
- Macrophages
- Dendritic Cells
- Natural Killer Cells
what are Toll-like Receptors?
bind to fragments of molecules characteristic of a set of pethogens
what are neutrophils?
they circulate in the blood, and are attracted by signals from infected tissues and then engulf and destroy the infecting pathogens
what are macrophages?
“big eaters” , they are large phagocytic cells
some migrate through the body and other reside permanently in organs and tissues where they are likely to encounter pathogens
what are dendritic cells?
mainly populate tissues, such as skin, that contact the environment.
They stimulate adaptive immunity against pathogens they encounter and engulf
what are natural killer cells?
these cells circulate through the body and detect the abnormal array of surface proteins characteristic of some virus-infected and cancerous cells
-they dont engulf, they RELEASE CHEMICALS THAT LEAD TO CELL DEATH
what is the process of innate cell immunity response?
- interstitial fluid in tissues, along with white blood cells in it, enter lymphatic vessels
- fluid inside the lymphatic system flows through lymphatic vessels throughout the body
- within the lymph nodes pathogens and foreign particles in the circulating lymph encounter and activate macrophages and other cells to carry out defense actions
- lymphatic vessels return lymph to the blood via two large ducts that drain into veins near the shoulders
what are internefrons?
proteins that provide innate defense by interfering with viral infections
what is an inflammatory response?
the changes brought about by signaling molecules released upon injury or infection
what is a histamine?
one important inflammatory signaling molecule, which is stored in the granules of mast cells, found in connective tissue
cell adaptive immune response relies on what?
T cells and B Cells, which are types of white blood cells called lymphocytes
where are lymphocytes made?
lymphocytes are made in the bone marrow, but where they mature is what defines what type of cell they will become
lymphocytes that mature in the thymus gland become?
become T cells
lymphocytes that mature in the bone marrow become?
become B Cells
what is an antigen?
any substance that elicits a response from a B cell or a T Cell
in adaptive immunity recognition occurs when?
occurs when a B cell or a T cell binds to an antigen via a protein called an ANTIGEN RECEPTOR
each B cell receptor is ?
is a Y-shaped molecule consisting of four polypeptide chains: two identical HEAVY CHAINS and two identical LIGHT CHAINS
The binding of a B cell receptor to an antigen leads to what?
leads to the secretion of a protein called an antibody.
what are antibodies?
anitbodies are Y-shaped like B cell receptors and they help defend against pathogens
what are the steps in adaptive immune response?
- antigens bind to the antigen receptors of B cells
- The selected B cell proliferates, forming a clone of identical cells bearing receptors for the antigen
- some daughter b cells develop into memory b cells that can respond rapidly upon subsequent exposure to the same antigen
- other daughter b cells develop into plasma cells that secrete antibodies specific for the antigen
what is a helperT cell?
triggers both humoral and cell-mediated immune responses.
They themselves do not carry out those responses
what are the two requirements that must be met for a T cell to be activated?
- a foreign molecule must be present that can bind to the antigen receptor of the helper T cell
- this antigen must be displayed on the surface of an antigen-presenting cell
what us an antigen-presenting cell?
it can be a dendritic cell, macrophage, or a B cell
what are cytotoxic T cells?
in cell-mediated immune response, cytotoxic t cells are the effector cells. they use toxic gene products to kill infected cells
what are plasma cells?
antibody secreting effector cells
what are the two types of immune responses present in adaptive immunity?
- Humoral immune response
2. Celll-mediated Immune response
what is a summary of what happens during a Humoral Immune response?
- antigens 1st exposure
- it is then engulfed by an Antigen-presenting cell
- this process then activates the helper T cells, they signal for B cells to be produced and mature into memory T cells
- B cells release antibodies that fight the antigens. then the B cells mature and develop into memory B cell and Plasma cells
- In the case of a 2nd exposure memory T and B cells recognize antigen immediately signaling for Plasma B cells to be activated
- Plasma B cells secrete antibodies which are specific to the antigen to kill them off quicker via phagocytic cells
what is a summary of what happens during a cell-mediated immune response?
- antigens 1st exposure to the cell
- this stimulates antigen-presenting cells to engulf the antigen
- This activates helper T cells, which then send out a signal, activating Cytotoxic T cells and giving rise to memory helper T cells
- cytotoxic T cells bind to and lyse infected of cancerous cells
- In the case of a 2nd exposure memory helper T cells remember the antigen and activate memory cytotoxic T cells
- memory cytotoxic T cells give rise to active T cells, which defend against antigens by binding to and lysing infected cells
what is fertilization in plants?
the fusion of gametes, results in diploid zygotes, which divid by mitosis and form new sporophytes
what are the two types of reproduction for plants?
- sexual reproduction
2. asexual reproduction
what are microspores?
each microsporocyte undergoes meiosis forming four haploid microspores, each of which eventually give rise to a haploid male gametophyte
what is a pollen tube?
a long cellular protuberance that delivers sperm to the female gametophyte
what is an embryo sac?
the female gametophyte
what are megaspores?
four haploid megaspores. only one survives the others degenerate
what is the process of the development of a male gametophyte?
- Each of the microsporangia contains diploid microsporocytes (microspore mother cells)
- each microsporocyte divides by meiosis, producing 4 haploid microspores, each of which develops into a pollen grain
- within a pollen grain the male gametophyte becomes mature when its generative nucleus divides two sperm. this occurs after a pollen grain has landed on the stigma of carpel
what s the process of development of a female gametophyte?
- within the ovule’s megasporangium is a large diploid cell called the megasporocyte(mother cell)
- the megasporocyte divides by meiosis and gives rise to 4 haploid cells, but in most species only one survives
- three mitotic divisions of the megaspore form, the embryo sac, a multicellular female gametophyte. the ovule now consists of the embryo sac along with the surroundings integuments (protective tissue)
most angiosperm species rely on what as a pollinating agent?
they rely on biotic(living) or abiotic(nonliving pollinating agent that can move pollen from the anther of a flower to the stigma of another flower
what is abiotic pollination by wind?
20% of all angiosperm species are wind-pollinated
- since their reproductive success does not depend on attracting pollinators
- no selective favour over colourful or sweet smelling flowers
- the inefficiency of wind-pollinating is compensated by by over production ofpolen
what is biotic pollination by bees?
about 65% of all flowering plants require insects for pollination
- Bees are the most important insect pollinators, Bees are attracted to bright colours, primarily yellow and blue
- many flowers have “nectar guides” that help insects locate the nectaries to insects
what is pollination?
the transfer of pollen from an anther to a stigma
what is coevolution?
The joint evolution of two interacting species each in response to selection imposed by the other
what is the process of double fertilization of plants?
- if a pollen grain germinates, a pollen tube grows down the style towards the ovary
- The pollen tube discharges two sperm into the female gametophyte(embyro sac) within an ovule
- One sperm fertilizes the egg, forming the zygote. The other sperm combines with the two polar nuclei of the embryo sac’s large central cell, forming a triploid cell that develops into nutritive tissue called endosperm
what is an endosperm?
a food-storing tissue of the seed
what is double fertilization sexual reproduction?
The union of two sperm cells with different nuclei of the female gametophyte
what is imbibition?
germination depends on imbibition, the uptake of water due to the low water potential of the dry seed
what is asexual reproduction?
offspring are derived from a single parent without fusion of egg and sperm. the result would be a clone, an asexually produced genetically identical organism
