unit 4 study guide Flashcards
autocrine
(same cell): Some cancer cells release their own growth hormone
juxtacrine
(direct contact): Gap junctions, plasmodesmata - plant cells
paracrine
(local distance): Growth factors, neurotransmitters
endocrine
(long distance): Hormones
reception
Detection of a signal molecule (ligand) coming from outside the cell
transduction
Convert signal to a form that can bring about a cellular response
response
Cellular response to the signal molecule
plasma membrane receptors works with
water soluble ligands
intracellular receptors work with
hydrophobic or small ligands
how receptors work
Ligand binds to receptor protein -> protein changes shape -> initiates transduction signal
gpcr
7 transmembrane segments in membrane
G protein + GTP activates enzyme -> cell response
tyrosine kinase
Attaches (P) to tyrosine
Activates multiple cellular responses at once
ligand gated ion channels
Signal on receptor changes shape
Regulate flow of specific ions (Ca2+, Na+)
phosphorylation cascade is used to
enhance and amplify signal
protein kinase
Enzyme that phosphorylates and activates proteins at next level
Attached a phosphate group (PO4) to a protein to activate
only what amino acids can be phosphorylated
Threonine (Thr), Serine (Ser), and Tyrosine (Tyr)
secondary messenger
Small, non-protein molecules/ions that can relay signal inside cell
Ex: Cyclic AMP (cAMP), calcium ions (CA2+), inositol triphosphate (I3)
sequence of events for cAMP
GPCR-> adenylyl cyclase (convert ATP -> cAMP) -> activate protein kinase A
chromosome
structure of 2 chromatids held together by the centromere (chromosomes in anaphase)
chromatin
what DNA and chromosomes are made of
chromatids
one side a chromosom-e
centromere
connects the 2 chromatids
centrioles
make mitotic spindles
centrosomes
region near nucleus that’s considered a “microtubule organizing center”
homologous chromosomes
pair of chromosomes with the same gene sequence
somatic cells
body cells
gamete cells
sex cells
zygote
fertilized egg
proteins kinase
enzyme that phosphorylates and activates proteins at next level
cyclin
proteins which attach to kinases to activate them; levels fluctuate in the cell cycle
CDK
proteins enzyme controls cell cycle; active when connect to cyclin
MPF
(maturation promoting factor) specific cyclin-cdk complex which allows to pass from G2 to M phase
haploid
1 type of each chromosome (gametes)
diploid
types of each chromosome (somatic cells)
kinetochore
Proteins associated with DNA at centromere
How do the daughter cells compare to the parent cells at the end of mitosis?
They are the same (Parent cells were duplicated then split)
G0 state
adult and nerve cells are in this nondividing state
G1 phase
Cell grows and carries out normal functions
S phase
Duplicated chromosomes
G2 phase
Prepares for cell division
M (miotic) phase
mitosis and cytokinesis
mitosis
nucleus divides
cytokinesis
cytoplasm divides
cell cycle process
G1 -> S -> G2 -> mitosis -> cytokinesis
checkpoint
control point where stop/go signals regulate the cell cycle
G1 checkpoint
most important
Controlled by cell size, growth factors, and environment
“Go” - Completed whole cell cycle
“Stop” - Cell enters nondividing state (G0 phase)
Adult nerve and muscle cells stay at G0: Liver cells called back from G0
G2 checkpoint
Controlled by DNA replication completion, DNA mutations, and cell size
m-spindle checkpoint
Check spindle fiber (mircotubule) attachment to chromosomes at kinetechores (anchor sites)
internal regulatory factors
kinases
cyclins
mpf
kinases
protein enzyme controls cell cycle; active when connected to cyclin
cyclins
proteins which attach to kinases to activate them; level fluctuate in the cell cycle
mpf
Specific cyclin-CDK complex which allows cells to pass G2 and go to M phase
external regulatory forces
growth factor
density-dependent inhibition
anchorage dependence
growth factor
Proteins released by other cells to stimulate cell division
density dependent inhibition
Crowded cells normally stop dividing; cell-surface protein binds to adjoining cell to inhibit growth
anchorage dependence
Cells must be attached to another cell or ECM to divide
what happens after cyclin dependent kinases are used
becomes unactivated and just stays in the cell until reactivated
what is MPF made of
Specific cyclin-Cdk complex which allows cells to pass G2 and go to M phase
what phase does the cell spend most of its time
interphase
prophase
Chromosomes become visible
metaphase
Alignment of chromosomes at the equator
anaphase
Separation of sister chromatids
telophase
Form two daughter cells
what happens with animal cells during the cell cycle
cleavage furrow
what happens with plant cells during the cell cycle
cell plate forms
density dependent inhibition
Crowded cells normally stop dividing; cell-sruface protein binds to adjoining cell to inhibit growth
anchorage dependence
Cells must be attached to another cell or ECM to divide
anchorage dependance in cancer cells
loses regulatory processes
apoptosis
programmed cell death
Cell is dismantled and digested
what is apoptosis triggered by
Cell is dismantled and digested
benefits of apoptosis
protect neighboring cells from damage
Animal development and maintance
May be involved in some diseases (Parkinson’s, Alzheimer’s)
how does cancer cells escape apoptosis
by not responding to the cell signals (like anchorage dependence and density-dependent inhibition)
proto oncogenes
gas pedal- promote cell growth
what happens when proto oncogenes and tumor suppressor genes have mutations
overproduction of cells
tumor suppressor genes
break pedal- stop cell growth
negative feedback
brings the body back to homeostasis
Lowers a temperature during a fever
positive feedback
increases stimulus and “goes over” homeostasis
Blood clotting
Can have bad effects if not brought back to homeostasis
