ANSC 452 Exam 1

Define hormone

a molecule that travel through the blood to affect distant targets

Define growth factor

implies that a molecule has a positive effect on cell growth

ligand

a hormone, growth factor, or other compound that binds a receptor or binding site.

Agonist

a ligand that activates a receptor

Antagonist

a ligand that blocks/inhibits a receptor

Receptor

a protein or complex that transmits a signal once a ligand is bound

What are the minimum requirements of a cell to respond to a growth factor.

1. effective concentration of GF

2. receptor activity

3. Intracellular signaling is activated

what dose effective concentration refer to

There needs to be enough of the GF present for the cell to be able to realize it is there

• concentrations are very low for GF

• half-lives are short for GF

What does the receptor actively refer to

For a GF to have an effect if must have a receptor

• receptor must be present

• must be in a location where the GF can reach it

• must be a functional receptor

what does intracellular signaling refer to

A pathway or sequence of events is needed to translate the growth factor
message into a cellular response.

what is the overall outcome of intracellular signaling

– changing protein form and function

or
– changing the amount/types of proteins present.

how two cells exposed to the same growth factors can respond differently.

• GF are pleiotropic (meaning that they can have different effects depending on the situation) so they can send different signals

  • if the concentration of the GF is different, it can trigger different receptors and effects

  • if there are different receptors on the cells

Describe the paracrine mode for GF signaling

When one cell sends a ligand out and through diffusion, it connects with a receptor on an another cell near by

what mode of GF signaling is used mostly during early development and organogenesis

paracrine and juxtacrine signaling

Describe the endocrine mode for GF signaling

GF travel through the blood and reacts with cells that are separated by long distance

Describe the autocrine mode for GF signaling

when a cell releases a GF that reacts with a receptor on its self

Describe the neural mode for GF signaling

Growth factor transported via axon to
distant target cell or blood, diffuses from
endplate.

Describe the Juxtacrine mode for GF signaling

The GF is anchored to the membrane of the cell and must physically touch the receiving cell to transmit a signal

what happens to the GF signaling throughout development

they change, starting with paracrine and Juxtacine and developing into endocrine

What does protein confirmation influence

the protein function

what causes a change in protein shape

the addition of functional groups (typically ones with a charge)

what can conformation changes alter

• the polarity of the protein

• interactions with other proteins

• enzyme activity

what does the confirmation change of polarity effect about the protein

changes where the protein can be in the cell (ex: cytosol,nucleus)

what is phosephorylation

The addition of a high-energy phosphate group

what is a kinase

Proteins that phosphorylate other proteins

what does the additon of a phosphate group cause a protein to change its configuration

because phosphate groups carry a large charge that will interact with other functional groups on the protein

what amino acids does phosphorylationW occur

serine and threonine

what does confirmation change allow proteins to interact

can allow for protein binding and then carry out new functions

what are the purposes of phosphorylation

• may activate or inhibit a target protein

proteins and be phosphorylated at multiple sites, with each phosphorylation____

changing the shape a little more

what is a phosphatase

removes phosphate group

what is a protease

enzyme that cleave proteins

what is a ligases

enzyme that joins proteins together

what is a polymerase

and enzyme that builds structures

which membrane receptor is located on the cell surface

membrane

what is interesting about the signals membrane receptors have to understand

1. have to sense the outside of the cell

2. but translate info into the inside of the cell

what kind of ligands do membrane receptors need

proteins - which are polar and they cant pass through the cell membrane

what do membrane receptors rely on

intracellular secondary messenger to take action in the cell

which membrane receptor is located in the cytoplasm

intracellular receptor

what kind of ligands do intracellular receptors need

non-polar ligands - which will freely cross the cell membrane

signaling pathways use what type of receptors

intracellular

hormones and growth factors use what type of receptors

extracellular

What are the type of membrane receptors

1. ion channel linked receptors

2. enzyme receptors

3. G-protein linked receptors

How are ion linked receptors in relation to growth and development

they are not often involved in growth and development (they are present for nerve pulses and muscle contractions) but other growth effects can occur in response to signal receptors

example of an ion channel linked receptor

acetylcholine with the sodium potassium channel

explain how g protein receptor work

G protein receptors act INDIRECTLY to regulate the activity of another membrane-bound target protein

What is the relationship between the receptor and the target proteins in the G protein pathway

The interactions between them are mediated by another protein, a GTP-binding regulatory protein (G-protein)

describe the physical features of a G- protein receptor

7-transmembrane proteins

what cells are G-protein linked receptors in

Eukaryotes

what is an example of an G-protein linked receptors

Beta- adrenergic receptors which bind to epinephrine

What is the ultimate general result of a G-protein linked receptor pathway

activation of downstream signalers like PKA

what is typicaly the protein state in a balanced cell

Proteins are being synthesized and degraded at the same time at equal rates

Protein accretion also means

an anabolic protein state

an anabolic state means

that is more protein synthesis than protein degradation

a catabolic state means

there is more protein degradation than protein synthesis

what are the two fundamental cell types in animals

epithelial and mesenchymal

what kind of junctions of epithelium cells form

tightly joined structures

what do the epitheliam cell layers look like

2D layers wh

what type of polarization do epithelial cells have

apical basolateral polarization

what does it mean when cells have apical basolateral polarization

the top side of the cell is different from the bottom side

what type of structure do mesenchyme cells have

more of a 3D shape

Describe the polarization of mesenchyme cells

little polarization

where are epithelial cells are found

skin, intestines, lungs, blood vessels, repro tract

what is the function of epithelial cells

forms a barrier to the outside world

where are mesenchymal cells found

everywhere else where epithelia cells are not

how does the structure of mesenchymal cells support their function

they have the ability to move, morph, and change so that they can specialize

what type of adhesion do epithelial cells use

cell-cell adhesion

what type of adhesion do mesenchymal cells use

cell-matrix adhesion

what happenes when cells loose their adhesion

apoptosis called anoikis

what types of proteins are cadherins and integrins

transmembrane

what do cadherins and integrins rely on

they are calcium- dependent

what molecule is used for cell-cell adhesion

cadherines

what molecule is used for cell-matrix adhesion

integrins

what are the two types of enzyme linked receptors

1. receptor with enzymatic activity

2. receptor that is closely linked with an enzyme

how can you change the amount of growth factor present

making changes in production or in degradation of the GF

how to change the production of growth factor in a cell

alter the transcription and translation of GF

how to alter the degradation of GF

a. alter the activity of the proteases by other GF

b. alter the access of proteases to the GF

how do most GF circulate the body

bound to large binding proteins

what is the role of a binding protein to a GF

protect the GF from getting destroyed from proteases

what do binding proteins do to the amount of GF available to bind to receptors

They increase the amount of growth factors activity because they are protecting them from getting destroyed from proteases

what ways can you change the properties of the receptor for GF

a. receptor inactivation

b. inactivation of signaling proteins

c. production of inhibitory proteins

d. change the number of receptors

e. alter the affinity of the receptor

f. alter confirmation of the receptor

Describe how receptor inactivation will affect GF

the GF can bind but there will be no subsequent steps in the cell for the affect of the GF

Describe how inactivation of signaling proteins will affect GF

the receptor will work but if one of the proteins is turned off then the pathway can not be complete to have its affect

Describe how production of inhibitory proteins will affect GF

producing a protein to block the signaling pathway will inhibit the effects of the signal

how can you change the number of receptors present for a GF

• make more or less receptors

• change the location of the receptors

• change the degradation rate of a receptor

how can you change the confirmation of a receptor

by phosphorylation

what is the most important way that cells can control the amount of active protein in a cell

transcriptional control

what are some ways that cells can control the amount of active protein in a cell

• transcriptional control

• processing RNA

• degrading mRNA

• translation process of mRNA

• microRNA

what molecule does transcription require

RNA polymerase

define gene expression

the information of a gene is made into a functional product

what is true about all cells in relation to the genes they possess

all cells have all the DNA to make every protein

what causes changes in gene expression

responses to growth factor signaling, which allows the cell to respond to its environment

how does a cell make its self unique

only expresses a particular set of genes to gain a specific function

what are the two elements needed for transcriptional control of gene expression

1. cis- acting agent

2. trans- acting agent

where is the cis- acting agent in relation to the gene

very close to the gene being regulated

where is the trans- acting agent in relation to the gene

no located close to the gene being expressed

what is a cis- acting agent commonly called

response element

what is a cis- acting agent made of

DNA

what form do cis acting agents commonly come in

a binding sequence and arrange into clusters or modules

how many genes can a cis acting agent regulate

one cis- acting agent can regulate many genes