ap bio unit 4 lock in

3 steps of cell communication

• reception

• transduction

• response

intracellular receptors

• found inside the cell

• ligand enters the cell and binds to the receptor inside the cell

• doesnt need secondary messangers

cell surface receptor

• located outside of the cell

• binds to hydrophillic ligands

why would aptosis happen

• damaged or infected cells

• removing unnessasary cells

reception

-ligand binds to receptor protein

-causes conformational shape change

why does reception cause conformational shape change

because when something binds to a protein it changes shape

ligand

-signaling protein

-can either be a steroid hormone or protein hormone

Steroid hormone

-goes through simple diffusion

-intracellular

-examples: testosterone, estrogen

Protein hormone

• goes through exocytosis

• extracellular

• example: insulin

Transduction

• signals are amplified and relayed from receptors to cell targets

• steps of phosphorylation cascade and secondary messangers

secondary messangers

• small molecules inside the cell(Ca²⁺ and cAMP) that carry the signal from a receptor to the inside of the cell

• causes phosphorylation cascade

Phosphorylation cascade

• domino effect where one protein activates another by adding a phosphate over and over again

• uses enzymes called kinases to do this

can intracellular receptors skip the secondary messanger step of transduction

yes

Response

-the final outcome

• cell growth

• secretion

• gene expression

• aptosis

• others

phases of the cell cycle

interphase

mitosis

• cells are in interphase most of the time

steps of interphase

G1 phase

• cell grows and performs normal functions

• ensures conditions are ok for DNA replication

S phase

• DNA is replicated

G2 phase.

• cell grows and prepares for division

• ensures DNA replication is complete and free of error

steps of mitosis

• prophase

• metaphase

• anaphase

• telophase

• cytokenesis

prophase

• chromosones condense

• spindle fibers form

metaphase

chromosones align at the metaphase plate

Anaphase

-chromosones are seperated and pulled to opposite poles of the cell.

telephase

• nucleus reforms around chromosones

• chromosones condense

cytokenesis

• cytoplasm is divided

• forms a cleavage furrow to divide into two indentical daughter cells

cleavage furrow

Chromatin

-loose unpacked DNA

-like 🍝 spaghetti

-turns into chromosones

-also contains histone proteins (help package the DNA)

chromosone

-Tightly coiled DNA

-like a📦 packed box

sister chromatids

-Duplicated DNA strands

-like 👯 twins

centromere

• Holds chromatids together in center

• like a 🎀 ribbon or belt

cyclins/ CDKs

proteins that regulate progression throught the cell cycle

kinase

enzymes that cause phosphorylation

what can cause cancer

• mutations in oncogenes or tumor suppression genes

oncogenes

genes that promote cell division

tumor suppresion genes

genes that inhibit cell division

caspases

enzymes involved in aptosis

feedback mechanisms

used to maintain homeostasis

• negative and positive feedback mechanisms

negative feedback

• reverses change to return to a stable state

• examples: Sweating, shivering, blood sugar

positive feedback

• amplyfies a response to a change

• example: blood clotting

3 types of signals

-autocrine

-paracrine

-endocrine

autocrine

signals effect the same cell that released them

paracrine

signals act on nearby cells

endocrine

signals act on distant target cells with hormones that travel through the bloodstream

🦠 What are antigens and how do they relate to cell communication?

Antigens are foreign molecules (like from viruses) that trigger an immune response.
They bind to receptors on immune cells and start cell communication, leading to a response like making antibodies or attacking the invader.

🔔 Antigen = Alarm → 🧬 Receptor hears it → 💥 Cell responds