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Bio unit4 (11/12/13)
| Question | Answer |
|---|---|
| what is a signal transduction pathway? | series of steps that converts an external signal into a cellular response |
| paracrine signaling | a cells releases signaling molecules that effect nearby target cells (ex: growth factors) |
| synaptic signaling | occurs in nuestras, an electrical signal triggers release of neurotransmitters that cross a synapse to a target cell (ex: dopamine) |
| long-distance vs local signaling | long distance- hormones travel through bloodstream local-nearby cells |
| 3 stages of a signal transduction pathway | reception transduction response |
| reception stage of cell signaling | ligand binds to a receptor protein, receptor changes shape |
| transduction stage of a signal signaling | signal from ligand binding to receptor is relayed and amplified through a cascade |
| response stage of a signal signaling | cell signaling leads to a response (gene expression or protein activity) |
| what is a ligand | a signaling molecule that binds to a receptor |
| what happens in a G protein coupled receptor process | ligand binds to receptor, changes its shape, activates G protein, GTP replaces GDP, activated G protein activates enzyme, triggers a cellular response. |
| What is a receptor tyrosine kinase? | receptors that dimerize and phosphorylate each other to activate signaling pathways |
| what happens in ion channel receptors? | ligand binding opens/closes a channel receptor, allows ions to flow, the flow triggers a cellular response |
| where are intracellular receptors found | cytoplasm or nucleus, they bond to small/non polar molecules |
| explain the function of transcription factors in the cell | regulate gene expression by binding to specific DNA and controlling transcription of genes into Mrna. |
| 2 benefits of multi step pathways | a few molecules can amplify the response quickly, more opportunities for coordination and regulation of the cellular response |
| explain the role of protein kinases in transduction | the enzyme transfers phosphates from ATP to proteins (tags), phosphorylation |
| explain the role of protein phosphates in transduction | removes phosphates from proteins (untags), dephosphorylation |
| What is the difference between a first messenger and a second messenger? | first- signal outside of cell second- internal molecule that spreads signal |
| explain role of cAMP | adenylyl cyclase converts ATP into cAMP acts as a 2nd messenger that activates protein kinase amplifies signals cAMP = BROADCASTS |
| Where are Ca+2 ions typically stored in cells? what do they do when their released into the cell? | a secondary messenger calcium is stored in the ER, its release into the cytoplasm increases CA2+ which activates proteins that trigger a cellular response |
| What is apoptosis? | programmed or controlled death, proteins are involved in this process |
| How is apoptosis utilized in embryonic development in humans? | used to remove unnecessary cells (ex- webbing between fingers, tails) |
| adenylyl cyclase | an enzyme that converts ATP to cAMP in response to an extracellular signal (is a second messenger) |
| hormone receptor complex | a ligand and intracellular receptor complex act as a transcription factor, turning on specific genes in the nucleus |
| gap junctions | protein-lined channels connecting the cytoplasm of adjacent animal cells |
| plasmodesmata | crucial microscopic channels that pass through plant cell walls, directly connecting the cytoplasm of adjacent cells for intercellular transport and communication, |
| meiosis, prophase 1 | crossing over occurs homologous chromosomes pair |
| meiosis, metaphase 1 | independent assortment homologous chromosomes line up randomly |
| meiosis anaphase 1 | homologous pairs are separated |
| meiosis telophase 1 / interkinesis | 2 haploid cells are created interkinesis= rest before meiosis 2 |
| meiosis, prophase 2 | spindle forms, chromosomes condense |
| meiosis, anaphase 2 | sister chromatids are separated |
| meiosis, telophase 2 /cytokinesis | 4 unique haploid cells form |
| mitosis prophase | nuclear membrane breaks down nucleolus breaks down DNA/chromatid is condensed into chromosomes centrioles separate + produce spindle microtubules centromere begin to move to poles |
| mitosis prometaphase | chromosomes attach to spindle microtubules at kinetochore |
| mitosis metaphase | chromosomes line up in the middle of cell at metaphase plate (like the equator of the cell) |
| mitosis anaphase | spindle MT shorten @kinetochore, pulls sister chromatids apart to separate poles |
| mitosis telophase/cytokinesis | nuclear membrane and nucleolus reaper, spindle microtubules disintegrate, chromosomes decondense cytokinesis occurs - cytoplasm divides into 2 identical diploid cells (1 chromosome in each cell) both new cells enter interphase |
| differences between gametes and somatic cells | gametes are sperm or egg, - haploid somatic cells are any cells other than a gamete (23 chromosomes are somatic cells)- diploid |
| sexual vs asexual reproduction | sexual- 2 parents give ride to offspring, genetic variation asexual- a single individual passes genes to its offspring without fusing a gamete (faster, produces more offspring), identical offspring |
| homologous chromosomes | same type of chromosomes from mom and dad |
| sister chromatids | joined copies of the original chromosome, separate during cell divison |
| centromere | is a crucial constricted region on a chromosome that acts as the attachment point for spindle fibers during cell division, ensuring that replicated chromosomes (sister chromatids) are accurately pulled apart into two new daughter cells |
| chiasmata | point where homologous chromosomes exchange DNA during crossing over (x shaped regions that each chromosome has) |
| autosomes (how many in somatic and sex cells) | non sex chromosomes (human somatic cells- 22 pairs) |
| diploid vs haploid | diploid- 2 sets haploid - 1 set |
| why do sex cells have half the number of chromosomes as somatic cells/ why is meiosis important in sexually reproducing organisms | prevents chromosome number doubling after ferlization |
| crossing over | genetic rearrangement between non sister chromatids (during prophase 1) homologous chromosomes exchange corresponding segments of DNA. |
| independent assortment | during meiosis 1 homologous chromosomes pairs line up randomly at the metaphase plate. this means maternal and paternal chromosomes are assorted independently into gametes producing many combos |
| chromosomes vs chromatids | chromosomes are DNA packaged and chromatin are DNA unwound. (chromatids separate and become chromosomes as cell division occurs) |
| cytokinesis (animals vs plants) | division of the cytoplasm animals- cleavage furrow plants- cell plate |
| what happen in G0 phase of mitosis | cells exits the cell cycle, does not divide, usually specialized cells going to differentiate |
| kintetochore | protein complex at the centromere of each chromatids, where spindle fiber attach |
| binary fission and how its different from mitosis | replication of bacterial chromosomes, different from mitosis because it occurs in prokaryotes and doesnt include spindle or nucleus. |
| check points / diff ones in the cell cycle | where the cell cycle stops until a go ahead signal is received m, g2, g1 (most important) |
| cyclins | regulatory proteins |
| cdks | enzymes that are activated by cyclins they activate cell cycle proteins and drive the cell cycle |
| mpf | cyclin cdk complex that triggers mitosis |
| growth factors | proteins released by certain cells that stimulate other cells to divide |
| what is density dependent inhibition | crowded cells stop dividing (cancer cells cant exhibit this) |
| anchorage dependence | they must be attached to a substation in order to divide (cancer cells cant exhibit this) |
| what characteristics do cancer cells exhibit | ignore checkpoints divide uncontrollably avoid apoptosis |
| difference between benign and malignant tumor. | benign- abnormal cells remain at original site malignant- invade surrounding tissues/ can metastasize (move)/ form more tumors |
| what does it mean when cells differentiate | cells stop dividing and become specialized in structure and function by turning genes on/off |
| cell cycle regulators | molecular signals that may stimulate or half cell division, instruct cell to differentiate or initiate cell death. |
| stimulating proteins | proteins that promote cell division (from proto-oncogenes) |
| inhibitory proteins | protein that stop cell division- tumor suppressors |
| tumor suppressor genes | are essential genes that act as the "brakes" for cell growth, preventing uncontrolled division, repairing DNA damage, and triggering programmed cell death (apoptosis). |
| kinase | enzymes that add a phosphate to other proteins to activate or inhibit it |
| G1 (events, checkpoints, regulatory processes) | events- cell grows, checkpoint- is there damage in dna? |
| S phase (events, checkpoints, regulatory processes) | dna replication checkpoints- make sure DNA is fully replicated |
| G2 phase (events, checkpoints, regulatory processes) | final prep for mitosis check if DNA damage/ incomplete replication duplicate organelles, make proteins |
| to cause cancer what is required of tumor suppressors and proto oncogenes | proto oncogenes require 1 allele to be mutated (dominant) which results in a gain in function OR a tumor suppressor genes requires 2 alleles to be mutates (recessive) which results in a loss of function. |
| explain impact of 1 mutated tumor suppressor genes vs 2 mutated tumor suppressor genes | 1 copy mutate- cell cycle can still function 2- cell cycle proceeds inappropriately, loss of control |
| explain impact on the cell cycle of a proto oncogene vs an oncogene | Proto-oncogenes- normal genes, promote controlled cell growth/division, when mutated, are oncogenes, causing uncontrolled cell proliferation, bypassing checkpoints, leading to tumor formation, promoting excessive cell division/ inhibit normal apoptosis. |
| p53- role | encoded by a tumor suppressor gene stops cycle when things are damaged while they get fixed |
| negative feedback | returns the system back to steady state end product decreases the pathways |
| positive feedback | moves the system further away from its set point end product increases the pathway (ex: labor, ripening fruit) |
| synapsis | pairing of homologous chromosomes in prophase 1 at the start of meiosis. |
| Phosphorylation cascade | is a signal transduction pathway where one protein kinase activates the next by adding a phosphate group, creating a chain reaction that amplifies a small initial signal into a large cellular response |
| how do bacteria communicate | quorum sensing (cell-density signaling) |
| meiosis metaphase 2 | chromosomes line up singly |
Created by:
Lilyhowes