AP BIO UNIT 4

Signal Transduction Pathway (4.1)

series of steps in which a signal on a cell's surface is converted into a specific cellular response

Cell Junctions (4.1)

gaps that directly connect the cytoplasm of adjacent animal cells (plant cells have plasmodesmata)

Local Signaling (4.1)

animal cells send signals by direct contact

Local Regulators (4.1)

messenger molecules animal cells use to communicate w/ by traveling short distances

Long Distance Signaling (4.1)

plants and animals use hormones to send signals long distances

Reception (4.2)

a signal molecule (ligand) binds to a receptor protein on the surface or inside of the cell, altering its shape

Membrane Receptors (4.2)

receptors on the surface of a cell, have polar ligands (ex

Cytosolic/Intracellular Receptors (4.2)

receptors inside the cell, has nonpolar ligands that can diffuse through the bilayer

Transduction (4.2)

change in shape of the receptor starts a molecular relay of the signal into the cell until it activates the protein that starts a response

Amplification (4.2)

a few molecules can produce a larger cellular response due to multistep pathways (cascade of protein phosphorylations)

Protein Kinases (4.2)

proteins that transfer phosphates from ATP to a protein

Second Messengers (4.2)

small non protein water soluble ions that spread through a cell by diffusion participating in pathways initiated by GPCRs (ex

Response (4.2)

cell's response to a signal (ex

Nuclear Responses (4.2)

regulates the synthesis of enzymes/proteins by turning on and off genes in the nucleus

Cytoplasmic Responses (4.2)

regulates activity of the enzymes not it's synthesis

G Protein Coupled Receptors (GPCR) (4.2)

ligand binds to the GPCR altering the receptor's shape, G protein is activated and released, GDP is displaced by a GTP, when done with transduction, G protein dephosphorylates its GTP into GDP inactivating itself and the ligand dissociates from the receptor deactivating GPCR

Ligand Gated Ion Channels (4.2)

ligand binds to a receptor, opening the gate allowing specific ions to channel into the cell and then closes

Receptor Tyrosine Kinases (RTKs) (4.2)

a receptor protein that forms a dimer when activated by ligands, ATP phosphorylates tyrosine on the dimer relaying the signal to proteins

Phenotypes (4.3)

manifestation of an organism’s appearance

Apoptosis (4.3)

programmed cell death if cell is damaged or during embryonic/fetal development

Caspases (4.3)

main proteases (enzymes that cut up proteins) carry out apoptosis

Juxtacrine signaling (4.1)

cells in direct contact with each other to exchange signals through surface proteins

Paracrine signaling (4.1)

cells do not touch but are in the same local area by sending signaling molecules to be received by a target cell’s receptor

Endocrine signaling (4.1)

hormone producing cells send signals in endocrine glands to be received by cells far away in the body

Autocrine signaling (4.1)

the cell secretes a hormone or chemical messenger that binds to the receptors of that SAME cell, leading to changes in the cell

Negative Feedback (4.5)

a stimulus causes an organism to migrate away from their homeostasis level, this work to RESTORE homeostasis

Insulin and glucagon (4.5)

pancreatic hormones that work to maintain blood sugar levels

Positive Feedback (4.5)

a stimulus causes an organism to migrate away from homeostasis level, this AMPLIFIES the response (ex

Cell Cycle (4.6)

the life of a cell from formation to its own division (self replication or development, growth and repair)

Genome (4.6)

all of the cell’s dna can either be prokaryotic (one strand of DNA) or eukaryotic (multiple strands of DNA)

Chromosomes (4.6)

dna molecules packaged into a cell

Chromatin (4.6)

Eukaryotic chromosomes contain this complex of DNA and protein that condenses during cell division

Somatic Cells (4.6)

non reproductive cells that have 2 sets of chromosomes (diploid) (46 chromosomes)

Gamete Cells (4.6)

reproductive cells, have half the chromosomes of somatic cells, haploid (23 chromosomes)

Sister Chromatids (4.6)

joined copies of the original chromosome (2 create one chromosome) and later separate to move into 2 separate nuclei

Centromere (4.6)

narrow waist of the duplicated chromosome (2 sister chromatids connect the most here)

Meiosis (4.6)

how gametes are produced, variation of cell division yielding non identical daughter cells with only 1 set of chromosomes

Interphase (4.6)

cell growth and copying chromosomes (S) to prepare for division (G1, S, G2)

G1 (Gap 1)

the size of the cell increases, cellular contents except the chromosomes are duplicated

S phase

all 46 chromosomes are duplicated

G2 (Gap 2)

the cell double checks the duplicated chromosomes for errors and pauses to make repairs

Mitosis (4.6)

division of genetic material in the nucleus

Prophase (Step 1 of Mitosis)

centrosomes duplicate and migrate to opposite poles where spindle starts to form and chromosomes start to condense, nuclear envelope disintegrates

Metaphase (step 2 of mitosis)

chromosomes align in the middle and spindle fibers attach to them

Anaphase (step 3 of mitosis)

spindle fibers shorten, pulling the sister chromatids apart to the opposite poles, the cell elongates

Telophase (step 4 of mitosis)

chromosomes cluster in the center of each new cell, nuclear membrane forms, cells begin to separate

Cytokinesis (4.6)

division of the cytoplasm into 2 new cells, each has the same # of chromosomes as the original parent cell

G0

phase of the cell cycle where cells do not divide (don't pass the checkpoint or just don't divide)

mdm2

protein in humans that inhibits/negatively regulates p53 (tumor suppressor), can speed up cell division

p53

tumor suppressors, induces cell cycle arrest and apoptosis, slows down cell division checking for mutations and DNA damage

G1 Checkpoint

checks for nutrients, growth factors and DNA damage, transitions to the S phase or put into G0

G2 Checkpoint

checks for cell size and dna damage, transitions to Metaphase when fixed

Metaphase Checkpoint

checks to make sure the chromosomes are attached to the spindle correctly

Maturation Promoting Factor (MPF)

a cyclin-cdk complex that regulates the passage of a cell from G2 to M phase at a G2 checkpoint (ensures DNA replication)

ProtoOncogenes

a group of genes that encode cyclin proteins that work to control cell growth (accelerator), green light to go

Tumor Suppressors

group of genes that prevent cell division, produces proteins that repair DNA or regulate apoptosis (brakes)

Retinoblastoma protein (RB)

a tumor suppressor gene that prevents cells from entering S phase when there is no signal from growth factors

ATM and BRCA1

ataxia telangiectasia mutated protein and Breast Cancer 1 protein.... tumor suppressors that halt the cell cycle and repair breaks/cell death

Malignant tumors

invade surrounding tissues and metastasize (export cancer cells to other parts of the body) forming additional tumors

Benign Tumor

abnormal cells that remain at the original site only (lump)