Quiz 6.4-51.4 Flashcards
where are ion channel linked receptors found?
found in the plasma membrane
what do ion channel linked receptors do?
convert chemical signals into electrical signals
what causes ion channel linked receptors to open or close?
the response to the binding of the signaling molecule (ligand)
what is an example of an ion channel linked receptor?
acetylcholine binding to and opening a ligand gated sodium ion channel
what are G-protein-linked receptors?
transmembrane proteins with an outside binding site for a signaling molecules, and an internal binding site for a specific G protein
what is the relationship between G-protein-linked receptors and transduction pathways?
couple signaling molecules transduction pathways in the cell
why are G-protein-linked receptors possibly important to the medical world?
more than 400 are potential targets for pharmaceutical interventions
what are enzyme-linked receptors?
transmembrane proteins with a binding site for a signaling molecules outside the cell and an enzyme component inside the cell
what do enzyme-linked receptors do?
bind hormones such as insulin and growth factors
what is the enzyme-linked receptor tyrosine kinase?
an enzyme that catalyzes transfer of phosphate groups (phosphorylation) from ATP to a specific tyrosine that is part of a protein
where are intracellular receptors located?
the cytosol or nucleus
what are most intracellular receptors?
transcript factors like the estrogen receptor (ER) that binds estrogen and is involved in some breast cancers
what is the relationship between intracellular receptors and membranes?
signaling molecules diffuse across the membrane of target cells
what ways do intracellular receptors diffuse across the membrane?
by combining with receptors in the cytosol and moving to the nucleus or binding to receptors already bound to DNA inside the nucleus
what is the first step of signal transduction?
regulatory molecules activate membrane proteins, which then transduce the signal
what is the second step to signal transduction?
a signaling molecule binds with a cell-surface receptor and activates it by changing the shape of the receptor tail which extends into cytoplasm
what is the third step to signal transduction?
a signal is relayed through protein kinases, creating a signaling pathway that amplifies the signal
how do signaling molecules acts as molecular switches?
each component in a signaling pathway can be active (on) or inactive (off)
what are molecular switches regulated by?
phosphorylation/dephosphrylation
how does protein kinase regulate molecular switches?
adding phosphate to typically activate a target
how does protein phosphatase regulate molecular switches?
catalyzes the removal of a phosphate group
when do closed ion channel gates open?
when a ligand binds to the receptor
what do GABA receptors bind to?
neurotransmitter GABA
what are GABA receptors?
ligand gated chloride ion channels
what does GABA do when chloride enters the cell?
inhibits neural signaling which inhibits transmission of neural impulses
what do G protein linked receptors initiate?
signal transduction
what inactive the G protein subunit is linked to?
guanosine diphosphate (GDP)
what replaced GDP when a signaling molecules binds to the receptor?
guanosine triphosphate (GTP)
what does GTP release?
energy
what are second messengers?
intracellular signaling agents
what is the first messenger and how does it relate to the second messenger?
the signaling molecule is the first messenger and information is relayed by the G protein to a second messenger
what does the second messenger do?
amplify signals inside the cell and relay to other signaling/target proteins
when receptors are activated how do they affect second messengers?
second messengers are produced in large quantities
what is the last molecule in the signaling chain and what does it do?
the second messenger, activates the final response
what is cyclic AMP?
a second messenger
what does adenylyl cyclase do?
convert ATP to cyclic AMP
what do some G proteins use as second messengers?
phospholipid components
what does phophoplipase (PIP) split into?
IP3 or DAG
what are calcium ions used for?
neural signals
how do calcium ions work?
by binding to certain proteins which then activate certain enzymes
How does calmodulin regulate calcium?
helps to regulate metabolism, muscle contraction, memory, inflammation, and apoptosis
what are many activated intracellular receptors called?
transcription factors
what do transcription factors do?
regulate gene expression
for transcription factors, what does the binding of a ligand receptor complex to a specific region of DNA do?
activate/repress specific genes
Activated genes produce?
messenger RNA
what dies messenger RNA carry?
the code for synthesis of a particular proteins into the cytoplasm
what are the three types of cellular response?
ion channels open/close, enzymes activity is altered, and specific gene activity turned on/off
how does one signaling molecule create a cascade?
by leading changes in millions of molecules at the end of a signaling cascade
what must happen to signals in the end?
they must be returned to their inactive state
what are some things found in signaling pathways of most organisms?
G proteins, protein kinase, and phosphates
how are some bacteria similar to eukaryotes?
they contains similar signal transduction pathways
where did cell communication first evolve?
unicellular organisms
what does development include?
all the changes that take place in an individual during its life, from fertilization until death
how is an embryo formed?
the zygote divides by mitosis
in animals, how does growth occur?
by the increase in the number of cells (mitosis)
what contributes to the development of form?
cell determination, cell differentiation, pattern formation, and morphogenesis
what happens in cell differentiation?
certain cells become biochemical and structurally specialized to carry out specific functions
cell differential is the result of?
cell determination
what is cell determination?
activities of certain genes are altered to progressively commit a cell to a particular differentiation pathway
as cells become gradually committed what happens?
certain genes are activated or inactivated
of cell determination and differentiation which comes first?
cell determination
what is morphogenesis?
the creation od shape/form (arms, legs, hands, etc)
during development what happens to differentiated cells?
they become progressively organized into multicellular animals
how does morphogenesis proceed?
through the processor pattern formation
what is pattern formation?
a series of steps requiring signaling between cells, changes in cell shapes, precise cell migrations, interactions with the extracellular matrix, and apoptosis (the blueprint of the body (front and back))
what is the principle of nuclear equivalence?
all somatic cells of an animal contains the same genetic information
what does each cell type express?
different subset of the information
what is differential gene expression responsible for?
variations in chemistry, behaviors and structure among cells
which cells remain undifferentiated?
stem cells, giving them to ability to give rise to various cell types
what happens in fertilization?
a motile sperm fuses with a ;large immotile ovum to produce a zygote
what are the three important genetic consequence of fertilization?
restores diploid chromosome number, combines genetic information interactions from parents, and determines sex of offspring
what does fertilization do to the egg?
activation, initiating reactions that permit development
what are the four processes of fertilization?
sperm contacts egg, sperm or sperm nucleus enters the egg, egg becomes activated, and sperm and egg nuclei fuse
what are the components of the sperm structure?
head, midpiece, ad tail
what are components of the sperm head?
acrosome and nucleus
what is a zone pellucida?
a noncellular layer (cell covering)
what is an egg surrounded by?
a plasma membrane and one or more external coverings
what is the purpose of egg coverings?
to offer protection and ensure fertilization of sperm of the same species
what is the egg morphology? (contact and recognition)
jelly coat, vitelline envelope, plasma membrane, and cortical granules
what two layers cover sea urchin eggs?
a vitelline envelope and a glycoprotein jelly coat
what happens when sperm contacts the jelly coat?
an acrosome reaction where proteolytic enzymes digest through the jelly coat
what are the last few stages of contact and recognition?
enzymes continue to digest through the jelly coat, binding to vitelline envelope, and membrane fusion
what is the fertilization cone?
formed by the plasma membrane and draws the sperm into the egg
what is polyspermy?
fertilization of the egg by more than one sperm causing an extra set of chromosomes, lethal
what is fast block?
the egg plasma membrane depolarizes to prevent fusion with addition sperm causing electric shock
what happens during fast block?
the egg is negatively charged, ion channels in the egg membrane open, and ion diffusion depolarizes the egg
what is slow block?
calcium is release form the ER to trigger the release of cortical granules and the vitelline envelope lifts and forms the fertilization envelope as a physical barrier
what happens during egg activation?
the release if calcium ions into the egg cytoplasm stimulates the cortical reaction and triggers the activation program, a series of metabolic changes in the egg; including the completion of meiosis
what happens during egg and sperm fusion?
the completion of meiosis I the eggs forms the female pronucleus and the sperm nucleus swells to form the male pronucleus
what happens to sperm in mammals?
it first undergoes capacitation, a maturation process in the female reproductive tract
what is different for fertilization in mammals?
bindin-like proteins, cortical reaction alters “binding” sperm receptors so no more sperm can attach, and no fertilization envelope
