Cell Communication & Mitosis

The 4 steps of Cell Communication

The 4 steps of Cell Communication

Stimulus—>Signal release—>signal reception—>response

Ligands

They bind to specific receptor proteins when there is a complementary between molecular shape and distribution of charge. (Only affects cells that have that specific build up)

Quorum sensing

Occurs in prokaryotes in a density dependent matter. Leads to bioluminescence, DNA uptake, etc

Adrenaline (ex. Chemical)

Achieves cell communication in fight/flight response. It binds to receptors in heart and many other areas to create this response.

Endocrine signaling

Takes place over long distances and relies on the blood system for transport of signaling molecules.

Paracrine signaling

Takes place over short distance between neighboring cells and relies on diffusion.

Autocrine Signaling

When a cell signals itself.

Sensors

Are components in a homeostatic system that are stimulated when a variable is altered from it’s set point

Effectors

Components in a homeostatic system that help restore the set point

Hydrophilic, polar signaling molecules

Can produce rapid biochemical responses

G-protein

Upon binding signals they change conformation and use membrane-bound proteins called ______ to trigger a signal transduction cascade in which second messengers drive the response mechanisms in target cells. Really hard to get through the membrane

Kinases

Can tell 100s of messenger molecules messages

Receptor Protein Kinases

Have a signal-binding function and an enzyme function that is activated upon binding the signal. Responses are terminated by release ending the enzyme’s activity.

Ligand-gated ion channels

Proteins that have both signal-binding and ion channels that can open or close to alter ion movements across the membrane.

Hydrophobic, nonpolar signaling molecules

Can turn genes on or off, can cross through the membrane, target cells that respond have receptor proteins inside.

Receptor agonists

Activate signal transduction pathways and receptor antagonists inhibit them (food and drugs can be sources)

Exogenous ligands

Can disrupt the usual activity of a signal transduction pathway—alters responses of target cells

Genetic mutations

Can disrupt signal transduction pathways, a change in genetic material

Positive feedback

Self-reinforcing and amplifies

5 phases of cell (3 main), a circular life

Interphase, mitosis, Cytokinesis

Pair of Chromosomes

EACH COPY MUST BE THERE FOR A CELL TO FUNCTION (humans have 23

Gametes

Sex cells that are haploids and pair up with other half in fertilization

Centromeres

Hold sister cells together during prophase and metaphase

Sister chromatids

Duplicated chromosomes attached by centromere

Centrioles

Organise spindle microtubules

Spindle microtubules

Also referred to as spindle fibers

Chromosomes

After anaphase when sister chromatids separate

Interphase G1 stage

Cells mature by making more cytoplasm and organelles

Interphase S stage

DNA is copied or replicated

Interphase G2 stage

All cell structures need for division are made

Mitosis

Division of the nucleus (has 4 stages: prophase, metaphase, anaphase, telophase)

Prophase

Chromatin condenses to form visible chromosomes and nuclear membrane and nucleus are broken down

Metaphase

Chromosomes move to the center of the cell and become lined up

Anaphase

Occurs rapidly, sister chromatids are ripped apart to different ends of cells

Telophase

Sisters at opposite ends, nuclear envelope forms around each set, nucleus reappears

Cytokinesis

Division of the cytoplasm, divides into 2 daughter cells

Daughter cells

Have the same number of chromosomes and are identical

Mitosis

Growth, asexual reproduction, tissue repair, embryonic development

Cyclins

A family of proteins that control the progression of cells through the cell cycle