Exam 2 Flashcards
signal transduction
converts information from signal into cellular response
ligand
binds to receptor protein making the cell respond; the signaling molecule
Animal cell signals
- Hormones, peptide (insulin) or steroid (estrogen)
- Neurotransmitters (catecholamine)
- Cytokines (interleukins)
Plant cell signals
- Hormones (auxin, gibberellin, brassinosteroid)
- Red light
- Blue light
intracellular receptor
- steroid hormones
- cytoplasm
- nonpolar; bind to lipid-soluble ligands (hydrophobic)
- can easily cross plasma membrane and bind to a cytoplasmic protein
cell surface/membrane receptor
3 types:
- channel linked- ion channel that opens in response to a ligand
- enzymatic- an enzyme activated by ligand
- G protein-coupled- bound to GTP and assists in transmitting signal
- water soluble; cannot cross membrane
- outside cell (cytoplasm + environment)
How to turn receptors on/off
- On: Add a phosphate from ATP (Kinase)
Off: Remove a phosphate (phosphatase) - On: add GTP (GEF trades GDP for GTP)
Off: release P (GAP)
second messenger
alter behavior of cellular proteins by binding to them and changing their shape
- cyclic-AMP(cAMP)
- calcium/calmodulin
Steroid receptor’s 3 domains
- hormone-binding
- DNA- binding
- a domain that can interact with coactivators to affect the level of gene transcription
substrate
molecule that undergo reaction
active site
region of the enzyme that binds to substrate
allosteric enzymes
possess allosteric site where molecules other than the substrate can bind
-active or inactive site
cofactor
usually metal ions that bind to a protein to make it active
coenzyme
- non-protein organic molecules
- electron donor or acceptor in redox reaction
biochemical pathway
a series of reactions in which a product of one reaction becomes the substrate for the next
feedback inhibition
the end product is an allosteric inhibitor of an earlier enzyme in the pathway
anabolism
chemical reactions that expend energy to make new bonds (synthesis)
catabolism
chemical reactions that harvest energy when bonds are broken (breakdown) (to make ATP)
Cellular respiration
- process by which energy is harvested (process of making ATP)
- exergonic
- leads to redox, moves electrons, makes ATP
aerobic respiration
final electron receptor is O2 and produces H2O
(each step is lower energy than the next)
Delta G= negative
-everything we learned
chemiosis
using a proton gradient to make ATP
thylakoid membrane
internal membrane arranged in flatten discs containing chlorophyll
antenna complex
- captures photons from sunlight
- reaction center and accessory pigments
photosystem
photosynthetic pigments are clustered together in the thylakoid membrane
cyclic phosphorylation
- photons added exciting electrons then electrons are returned back
- ATP (only product) made by chemiosis (gradient)
- electrons come from pigments
photorespiration
- when hot storm openings close cutting off CO2 causing it to bind to rubisco
- no glucose; not useful; CO2 lost
- chloroplast-> peroxisome-> mitochondrion
cytokinesis
splitting of the cells
condensin
protein for super coil
histones
proteins that cluster in 8 to make a nucleosome
chromatin
DNA and protein
kinetochore
attachment point for spindle
cohesin
protein that holds chromosomes together
cyclins`
proteins produced in sychrony with cell cycle
-regulate passage of cell through check points
CDK
- cyclin-dependent kinases
- enzymes that drive cell
- activate only when bound by a cyclin
how to activate CDK
-kinases add 2 phosphate
-phosphatase clips off one phosphate
(kinase cascade)
kinase cascade
- phosphates are added to kinase that goes to receptor turning it on
- one signal protein gets phosphorylated then transfers phosphate to next signal protein
protein gradient
ATP synthase- protons move back into matrix to make ATP (h+) (oxygen is needed)
phragmoplast
formed by microtubules; makes cell plate (new cell wall)
