AP Bio Unit E (4)

types of cell communication

cell-to-cell, short distance, and long distance

steps of communication

generation, transmission, and reception

signals

broad chemical molecules that are sent between cells

signal transduction pathways

pathways involved in communication

ligand

specific type of molecule that acts as a chemical message

receptor protein

protein that must be compatible to ligand to receive message

stages of cell signaling

reception, transduction, and response

kinase

enzyme that phosphorylates molecules (usually proteins)

reception

detection of a ligand from outside the cell, highly specific binding between ligand and receptor to change shape and initiate response

types of receptors

plasma/cell membrane (hydrophilic) and intracellular (hydrophobic)

transduction

converts signal reception into cellular response through cascades to amplify signals with kinase

secondary messengers

small molecules that relay signal inside cell (cAMP)

response

regulation of one or more cellular activities in nucleus or cytoplasm, usually creating more enzymes or proteins

feedback mechanism

maintain or amplify chemical systems, negative or positive feedback

negative feedback

decreases stimulus back to homeostasis

positive feedback

amplifies response further away from homeostasis

cells divide to

grow and repair

main stages of cell cycle

interphase and mitosis

interphase

G1, S, G2

mitosis

prophase, metaphase, anaphase, telophase (cytokinesis)

G0

temporary or permanent stage when cells don’t have enough nutrients or are in a certain stage of development

chromosomes

have their own centromere

chromatids

share a centromere

G1

cellular contents (not DNA) are duplicated

G1 checkpoint

checks for cell size, nutrients, growth factors, and DNA damage

S

the 46 chromosomes are duplicated

G2 and G2 checkpoint

double checks DNA duplication for errors

passes all checkpoints

enter mitosis

prophase

chromosomes condense and spindle fibers form

metaphase

chromosomes line up in middle of cell

anaphase

chromatids pulled toward opposite poles by spindle fibers

telophase

nuclear envelope reforms

cytokinesis

cytoplasm splits, cleavage furrow for animals and cell plant for plants

cyclin

core cell cycle regulators for each specific phase (G1 needed throughout)

cyclin dependent kinase

drives the cycle with Cdk based on phases

p53

tumor suppressor that limits replication of damaged DNA by stopping cycle at G1, blocking Cdk cyclins, and activate DNA repair enzymes

growth factors

stimulus released by certain cells to have other cells divide

anchorage dependence

need to be attached to a surface to divide, regulating growth

density-dependent inhibition

crowded cells will stop dividing, regulating growth

cancer cells

don’t need growth factors to grow and divide

proto-oncogene

signals cell division to start, normal when controlling cell growth

oncogene

mutated proto-oncogene that is always active, so cells grow uncontrollably

tumor suppressor gene

slows cell division, when mutated with two inactivation mutations, they don’t stop cell division

types of tumors

benign and malignant

benign

tumor that stays in original area of body

malignant

tumor that spreads to new tissues and rapidly replicates

metastasis

when cancer cells spread from the original site to another location