Unit 4 - Cell Communication and Cell Cycle

cells must use energy and information transmission to communicate and replicate

Cell Communication

Cell Communication

critical for the function and survival of cells; responsible for growth and development of multicellular organisms

Direct Communication

communication through cell junctions

Animal Direct Communication

communication through gap junctions

Plant Direct Communication

communication through plasmodesmata

Local Regulators

a secreting cell will release chemical messages that travel a short distance through the extra

Paracrine Signaling

a type of local signaling where local regulators are released via exocytosis to adjacent cells

Synaptic Signaling

a type of local signaling where neurons in animal nervous systems secrete nerotransmitters

Long Distance Signaling

animal and plants use hormones; Animals use endocrine signaling and plants use the vascular tissue

Reception Stage

first stage; detection and receiving of a ligand by a receptor in the target cell to activate and initiate transduction signals

Transduction Stage

second stage; conversion of an extracellular signal to an intercellular signal that will bring about a cellular response and amplify the signals

Response Stage

third stage; molecules in signaling pathways convert the signal to something that will alter a cellular process

Receptor

macromolecule that binds to a signal molecule

Phosphorylation

enzyme protein kinase relays signal inside cells

Dephosphorylation

enzyme protein phosphatase shuts off pathways

Second Messengers

small non-protein molecules and ions that relay messages and amplify the response

Ligand Molecule

the actual “signal” being transducted in a signal transduction pathway

G Protein Coupled Receptors (GPCRs)

the largest category of cell surface receptors that intiates GTP; inactive till ligand is binded on extracellular side to cause the cytoplasmic side to change shape

Ligand Gated Ion Channels

locate din the plasma membrane and used in the nervous system to close out ions depending on if the ligand is binded to the receptor

Homeostasis

state of relatively stable internal conditions to detect and respond to stimuli and balance theusing feedback loops

Positive Feedback Loop

increases the effect of the stimulus

child labor, blood clotting, fruit ripening

Negative Feedback Loop

most common and reduces the effect of the stimulus

sweat, blood sugar, breathing rate

Stimulus

a variable that will cause a response

Receptor/Sensor

senosry organs that detect a stimulus to be sent to the control center

Effector

muscle or gland that will respond

Response

increases or decreases the effect of the stimulus

Cell Cycle

life of a cell from its formation until it divides; alternate between interphase and mitosis

Cell DIvision

integral part of life which allows for reproduction of cells, growth of cells, and tissue repair

Nucleosomes

DNA associates with and wraps around proteins known as histones

Chromatin

strings of nucleosomes; non-condensed when not dividing but condensed to form chromosomes

Sister Chromatids

Chromosome copies joint together

Centrome

reign on each sister chromatid where they are most closely attached

Kinetochore

proteins attached to the centromere that link each sister chromatid to the mitotic spindle

Genome

all the cell’s genetic information

Somatic Cells

body cells which are diploids and divide by mitosis

humans have 46, 23 from each parent

Gametes

reprodcutive cells which are haploids and divide by meiosis

humans have 23

Interphase

consists of G1, S, and G2

G1 Phase

cell grows and carries out normal functions

S Phase

DNA replication and chromosome duplication occurs

G2 Phase

final growth and preparation for mitosis

Mitosis

nucleus divides and paired with cytokinesis, 2 identical diploid cells are formed

Cytokinesis

cytoplasm divides and paired with mitosis, 2 identical diploid cells are formed

Animals have a cleavage furrow formed and Plants have vesicles produced by the Golgi that ravel to the middle

Prophase

chromatins condense, nucleoli disappear, dublicated chromatids, mitotic spindles begin to form, and centrosomes move away from each other

Prometaphase

nuclear envelope fragments, microtubules enter nuclear area, and some attach to kinetochores

Metaphase

cenrosomes are at opposite poles, chromosomes line up at the center, and microtublules are attached to each kinetochore

Anaphase

sister chromatids seperate and move to opposite ends of the cell due to the microtublules shortening, and the cell elongates

Telophase + Cytokinesis

two daughter nuclei form, nucleoli reappear, and chromosomes become less condensed

Cell Checkpoints

control points that regulate the cell cycle; stop and go signals are recieved

G1 Checkpoint

checks for cell size, growth factors, and DNA damage

Go - cell completes while cell cycle

Stop - cell enters a nondividing phase and enters G0

G0 Phase

some cells stay here forever or can be called back into the cell cycle

G2 Checkpoint

checks for completion of DNA replication and damage

Go - cell proceeds to mitosis

Stop - cell cycle stops and the cell will attempt the repair damage or undergo apoptosis if severe

M (Spindle) Checkpoint

checks for microtubules attached to chromosomes at the kinetochores

Go - cell proceeds to anaphase and completes mitosis

Stop - cell will pause mitosis to allow for spindles to finish attaching to chromosomes

Cyclin Proteins

concentration of cycling varies to regulate internal control systems

Cyclin-Dependent Kinases Enzymes

concentration remains constant through each phase of the cell cycle to regulate internal control systems

Growth Factors

hormones released by cells that stimulate cell growth

Contact Inhibition

cell surface receptors recognize contact with other cells

Anchorage Dependence

cells rely on attachment to other cells or the extracellular matrix to divide

Cancer Cells

do not follow checkpoints, divide infidefinily, “immortal”, and evade appotosis

Tumors

lead by uncontrollable growth of cancer cells; mass of tissue formed by abnormal cells

Benign Tumor

abnormal cells, but not cancerous and only remain at the site

Maligant Tumor

mass of cancerous cells losing their anchorage and can leave the site through Metastasis