Untitled Flashcards Set

3 common characteristics of cell signaling

Signal, receptor, signal cascade and response

Heat and light signals are

Environment

Chemicals ligands

Allosteric regulation

allosteric regulation

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

What molecule can diffuse easily across membrane?

Small non polar

Name 4 receptors

Intracellular, membrane (g protein), ion channel, protein kinase receptors

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 genes

intracellular receptors

receptors located inside the cell

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)

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)

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)

Ion channel or Ligand Gated Ion Channel

When ligand binds to receptor gate is opened

A gate being open allows..

Ions to flow through

What happens to kinase receptors when they are activated?

They undergo a change in shape that activates the cytoplasmic protein kinase domain.

What is the function of kinase receptors after activation?

They modify proteins by adding phosphate groups.

Are all protein kinases considered receptors?

No, not all protein kinases are receptors.

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 happens to the catalytic domain during epinephrine signal termination?

The catalytic domain is no longer active, thus the effector protein is also inactive.

What is the effect of the effector protein being inactive in epinephrine signal termination?

cAMP is no longer produced.

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

cAMP needs to be broken down by cAMP phosphodiesterase.

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

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

What does Protein Kinase A (PKA) stop activating during epinephrine signal termination?

PKA stops activating phosphorylase kinase.

What is the result of phosphorylase kinase being inactivated?

Glycogen synthase is inactivated.

signal transduction pathway

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

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.

How does the cell discard the ligand

Weak covalent bond allows it to fall off

Whats the goal of receptors

To produce cellular responses (short term or long term)

Cells can alter the balance of enzymes in two

ways:

• Synthesis or breakdown of the enzyme

• Activation or inhibition of the enzymes by

other molecules

What is a controlled variable in a control system?

The characteristic that is being controlled, such as body temperature.

What is the role of sensors in control systems?

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

What are effectors in a control system?

Tissues or organs that can change the level of the controlled variable, such as shivering muscles.

What are Control mechanism in an control system 

uses information from sensors to determine which effectors to activate to modify the controlled variable

negative feedback system

A reaction that causes a decrease in function in response to some kind of stimulus.

negative feedback loop

stabilizing influence and is often involved in maintaining homeostasis.

example of negative feedback

body temperature regulation

postive feedback loop

Destabilizing feedback which will tend to amplify changes and drive the system toward a tipping point where a new equilibrium is adopted.

Positive feedback examples

childbirth and blood clotting

How can signal celled prokaryotes reproduce

binary fission

Single-celled eukaryotes can reproduce by

mitosis and cytokinesis

somatic cells

body cells

G1 phase

stage of interphase in which cell grows and performs its normal functions (longest in interphase)

G1 check point

Check for:

Any DNA damage, correct cell size, and growth factors, environment check and enough atp

S phase

The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated and centrisomes

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

aster microtubules

connect spindle poles to cell membrane

polar microtubules

separate two poles

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

Cytokines in animals

Cell membrane pinches in between the nuclei, contractile ring caused pinch due to mycin. Cleavage furroe develops

cytokinesis in plants

Golgi apparatus sends vesicles that transport cell while materials such as cellulose carbs and other proteins this creates a cell plate or cell wall