cells: cycle, communication, receptors, ect.

G1

is the first growth phase of the cell cycle, where the cell grows, synthesizes proteins, and prepares for DNA replication.

S

phase (Synthesis) is the part of the cell cycle where DNA is replicated, resulting in two copies of each chromosome

Interphase

is the stage of the cell cycle where the cell grows, copies its DNA (DNA replication), and prepares for cell division.

G2

phase (Gap 2) is the final growth phase of interphase, where the cell prepares for mitosis by producing additional proteins and organelles

mitosis

is the process of cell division where a single cell divides to produce two identical daughter cells, ensuring that each daughter cell receives an identical set of chromosomes.

prophase

the first stage of mitosis, characterized by the condensation of chromatin into visible chromosomes, the dissolution of the nuclear envelope, and the formation of the mitotic spindle.

metaphase

is the stage of mitosis where chromosomes align along the metaphase plate in the center of the cell, ensuring equal distribution to daughter cells.

anaphase

is the stage of mitosis where sister chromatids separate and move to opposite poles of the cell

telophase

the final stage of cell division where chromosomes reach the cell's opposite poles and nuclear envelopes reform around them, creating two separate nuclei

cytokinesis

the cytoplasmic division of a cell at the end of mitosis or meiosis, bringing about the separation into two daughter cells.

p53

tumor suppressor gene/protein that is activated by DNA damage in order to repair DNA damage or initiates apoptosis in case of irreplaceable damage

Cyclins

Cyclin-dependent kinases (CDKs) are activated when they bind to which of the following molecules? These molecules are a group of proteins that help to regulate the cell by activating other proteins

Growth factors

external regulator that affects the cell cycle and cause the activation of cyclin dependent kinases (CDKS) to promote progression through the cell cycle

G1 checkpoint

The cell enter G0 phase and temporarily stops dividing in order to check for DNA damage and the correct cell size

S checkpoint

check if DNA doubled correctly and that there is no damage

G2 checkpoint

Make sure it has all components for division

M checkpoint (between metaphase and anaphase)

are all the chromatids attached to spindle fibers

density dependent inhibition

when cells are surrounded by other cells there is no growth

positive feedback

Increase stimulus until you get response (ex: blood clotting, birth, fever)

negative feedback

stop/decrease stimulus to decrease homeostasis (ex. salt, sugar, water levels, blood pressure, temp)

autocrine

self signaling (ex. apoptosis)

juxtacrine

touching signaling (ex. density dependent inhibition, T-cells)

paracrine

all nearby cells get signal (ex. neuron signals,inflammatory response)

endocrine

signal sent through circulatory system/blood (ex. pituitary gland in brain to femur)

ligand

=signal and it must match the shape of receptor (some are large, polar, can’t pass through

first step in signal transduction pathway

reception: ligand must match receptor, receptor will change

second step in signal transduction pathway

transduction: amplify signal, bring it deep into the cell

third step in signal transduction pathway

response: DNA replication, controsome copied, release sugar

G-protein coupled receptor

Ligand binds to receptors which then the GTP connected to G-protein breakers in order for it to be used to activate adenylyl cyclase, and after another protein is activated

Tyrosine kinase receptor

after ligands reach each receptor they connect to each other to phosphorylate/add a phosphate to other molecules

Ligand gated ion channel

ligand opens ion channel to let molecules like Na+ to pass through to inter membrane

Intracellular receptor

is inside where the cell where a steroid passes through the membrane to the receptor in the cell

second messengers

Small intracellular molecules (like cAMP or Ca²⁺) that rapidly amplify and spread a signal inside the cell after a receptor is activated.

phosphorylation cascades

Enzymes inside the cell (kinases) activate through phosphorylation by activating one another by adding phosphate groups, ultimately producing a specific cellular response.

Depolarization

A rapid change in membrane charge (negative to positive) caused by positive ions rushing into a cell, creating an electrical signal (such as an action potential).