Untitled Flashcards Set

Signal Transduction Pathway

The process by which a signal on a cell's surface is converted into a specific cellular response.

What are the three common characteristics of cell signaling?

Signal, receptor, signal cascade, and response.

What type of signals are heat and light signals classified as?

Environmental signals.

What does allosteric regulation refer to?

The binding of a molecule to a protein that affects the function of the protein at a different site.

Which type of molecules can diffuse easily across the membrane?

Small non-polar molecules.

Name the four types of receptors.

Intracellular receptors, membrane (G protein) receptors, ion channel receptors, protein kinase receptors.

What is the function of kinase receptors after activation?

They modify proteins (change shapes) by adding phosphate groups.

What is signal termination?

The process by which the signal molecule detaches from the receptor and various enzymes break down signaling molecules to terminate the signal pathway.

What happens to existing cAMP in the cell during signal termination?

cAMP needs to be broken down by cAMP phosphodiesterase.

What characterizes autocrine signals?

Autocrine signals affect the same cells that release them.

What is the first step of the epinephrine signaling pathway?

Epinephrine binds to the receptor.

What is juxtacrine signaling?

Juxtacrine signaling requires direct contact between the signaling and responding cells.

What is an example of positive feedback?

Childbirth and blood clotting.

What is the role of sensors in control systems?

Sensors detect the current level or state of the controlled variable.

What occurs during G1 phase of the cell cycle?

The cell grows and performs its normal functions.

What is the purpose of the G1 checkpoint?

To check for DNA damage, correct cell size, growth factors, environmental conditions, and sufficient ATP.

What happens during telophase of mitosis?

DNA begins to condense, the nuclear envelope and nucleus reappear, spindle fibers break down, and chromosomes become less compact.

What is the consequence of no more cAMP in the cell?

There is no more activated Protein Kinase A (PKA).

What happens in cytokinesis in animal cells?

The cell membrane pinches in between the nuclei, and a contractile ring causes the pinch due to myosin, forming a cleavage furrow.

What is the S phase of the cell cycle?

The synthesis phase where DNA is replicated and centrioles are duplicated.

What is the significance of the M checkpoint?

To ensure everything is lined up in the center and that spindle fibers are attached before proceeding to anaphase.

Signal cascade and response involves

Second messagers, sequence of events involving protien protien interactions, signal is amplified, protiens are activated or deactivated, long term affect that affects ge

An intracellular receptor would need a what type of molecule?

Small and non polar so it can easily diffuse through the membrane

An intracellar receptor has what 2 parts?

Ligand binding domain (top)and catalytic domain (bottom)that interact with the ligand and trigger a response.

Epinephrine receptor (intracellular) first step

Epinephrine binds to receptor

2nd step of Epinephrine receptor

Now change in shape due to the binding ( change in shape occurs in catalytic domain)activates the catalytic domain

3rd step Epinephrine receptor

Catalytic domain activates effector protiens (gdp to gtp)

4th step in Epinephrine receptor

Effector protien activates CAMP

5th step of Epinephrine receptor

Camp activates pka

PKA then

Activates the phosphlayse of a molecule (glucose released from gylcogen) or pka stops a molecule from being made (pka inhibits glucose synthesis, prevents glycogen from being made)regulates metabolic pathways, influencing energy production.

Ion channel or Ligand Gated Ion Channel

A type of membrane protein that opens or closes in response to the binding of a ligand, allowing ions to flow across the membrane and influence cellular activity.

kinase receptor

a type of mebrane receptor, They undergo a change in shape that activates the cytoplasmic protein kinase domain, modify protien by adding phosphoate groups to target proteins, which can alter their activity or function.

What is an example of protein kinase that is not a receptor

PKA

What is signal termination

The signal molecule detaches from the receptor; phosphatase can dephosphorylate the kinase in the transduction pathway; enzymes break down cAMP; G protein hydrolyzes GTP into GDP. All of these will terminate a signal pathway

What is the first step of epinephrine signal termination?

The ligand comes off the receptor due to non-covalent weak bonds.

what are autocrine signals?

Autocrine signals affect the same cells that release them.

what are paracrine signals?

Paracrine signals diffuse to and affect nearby cells.

What is juxtacrine signaling?

Juxtacrine signaling requires direct contact between the signaling and responding cell.

How do hormones function in chemical signaling?

Hormones travel to distant cells.

Cells can alter the balance of enzymes in two

ways

• Synthesis or breakdown of the enzyme

• Activation or inhibition of the enzymes by

negative feedback loop

hormonal activy that decareses function, reducing the out put of a situtaion ,miantains homeostatisis and helps stabalize

postive feedback loop

increasing fucntion amplyfying output until a specific outcome is achived

g2

cells continue to grow and produce the proteins necessary for cell division

g2 checkpoint

Big enough to divide, no muratations in dna, all 46 chromosomes replicated well

prophase

Nuclear envelope, dissolves chromatids, condense into chromosomes centrosome start moving to polls and create spinal fibers chromosomes become visible

Metaphase

Kinetecore spindle fibers attach to centroile on chromosomes. They tgen line up in the middle at cell equator. 46 chromosomes lineup

M checjpoint

Everything is lined in the center spindle fibers are attached

Anaphase

Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell. This is due to the central splitting, causing the separation of sister chromatids

Telophase

DNA begins to condense, nuclear evelope + nuclueus reapersrs, spindle fibers breakdown, chromosomes become less compact