Unit 4 Flashcards
signal transduction
process of a signal activating a certain response in another or the same cell
autocrine signal
chemical messages that affect the same cell they originated from
paracrine signal
chemical messages that affect local cells
endocrine signal
chemical messages that target cells over a long distance by traveling through the bloodstream
cell to cell contact
sending and receiving important information through direct contact (ex: signal to tell nearby cells to stop dividing)
local regulators
signals over small distances (ex: neurotransmitters)
endocrine system
coordinated activity of the body by releasing hormones that circulate blood stream to organs and tissues across the body (ex: pancreas, insulin and glucagon)
reception
protein receives signal (could be ligand or physical change)
transduction
transmission of signal throughout the cell through secondary messengers and proteins
response
action carried out because of the signal, depends on what the signal is, what kind of cell it is, and the external environment
what occurs when the protein binds to the ligand?
a conformational change that travels through hydrophobic part of membrane and into the cell (this starts transduction)
phosphorylation cascade
starts with the creation of a second messenger that activates thousands of enzymes throughout the cell
secondary messenger
spreads signal throughout the cell and activates enzymes leading to cellular response, non protein and water-soluble
what are the two types of receptors
membrane proteins and intercelluar proteins
g-protein coupled receptors (GPCR)
membrane bound protein that goes through membrane seven times and start the phosphorylation cascade
what is the function of protein kinases?
they transfer phosphates from ATP to a proteins to activate it
protein phosphatases
enzymes that remove phosphate from a protein to deactivate it
dimerization
when a growth factor binds to a cellular receptor domain
competitive inhibitors
block active site so substrate can’t enter
noncompetitive inhibitors
bind to another spot but prevent catalysis
uncompetitive inhibitors
bind to substrate enzyme complex
activators
activate pathway
interphase
the chromosomes duplicate and two centrosoles will organize the spindle fibers in preparation of chromosome seperation
prophase
centrosoles migrate to opposite poles of cell, the nuclear envelope begins to break down and seek out the centrosomes of each chromosome
metaphase
chromosomes line up on metaphase plate where chromatids begin to separate
anaphase
chromatids fully seperate into individual chromosomes and chomosomes are pulles to poles of cell, the chromosomes don’t rip apart, they walk away from each other
telophase
nuclear envelope reforms around each nucleus and cleavage furrow begins to form and starts to pinch cell into two
cytokenesis
full separation of cells, not a part of mitosis
positive feedback mechanisms
process that starts or continues a cellular process
negative feedback mechanisms
process that stops or slows a cellular process
negative feedback system
operate to maintain a specific setpoint (ex: homeostasis)
positive feedback system
employed when a process needs to proceed a certain threshold so a greater action can be employed (ex: childbirth)
S Phase
synthesis phase, new strands of DNA are synthesized by DNA polymerase, DNA is being replicated
G1 Phase
cell metabolizes energy and creates new protiens/lipids, growth
G2 Phase
cell continues growing, replicates important organelles, and replicates other cellular components in preparation for division
G0
cell isn’t working to grow or divide, just functioning (ex: nerve cells)
Mitosis
cell separates DNA into two cells and process restarts
binary fission
used by bacteria in order to divide
meiosis
sexual reproduction, gametes must duplicate
G1 checkpoint
cell checks if size is appropriate, if there is enough nutrients for both daughter cells, and checks DNA to make sure there there is no damage. If cell fails then it goes into G0, signals activate proteins that sens cascade
G2 checkpoint
DNA replication has completed and checked for damage, if it passes the test it goes into mitosis and if it doesn’t then APOPTOSIS CELL DEATH. if the cell is okay then there is a chemical release to start mitosis.
M checkpoint
during metaphase, ensures that chromosomes are equally divided and both cells have a full genetic code
chromatin
loosely coiled/compacted (interphase = chromatin)
chromosome
tightly coiled chromatins
internal regulators
Cyclins, CDKs, and checkpoints
external regulators
growth factor, density dependent, anchor dependent
growth factor
protein that stimulates cells to divide (can be autocrine)
density dependent
crowded cells stop dividing in healthy tissue
anchorage dependent
healthy cells must be attached to a substratum to divide
pro-oncogenes code
code for proteins that stimulates normal cell growth and division “the gas”
oncogenes
cancer causing genes
2 types of genes associated with cancer genetics
tumor suppressor genes and pro-oncogenes
tumor suppressor genes
encode proteins that inhibit abnormal cell divisions, “the break”
p53 gene
encodes of tumor suppressor gene, “guardian angel”, it’s the spell check of DNA and pauses to see if cell should correct mistakes or apoptosis.
cyclins
group of related proteins that progress the cell cycle, they vary in concentration based on cell’s phase
CDK
enzymes involved in cell cycle regulation that require cyclin binding for activation, they phosphorylate substrates and promote certain cell activities.
