Cellular Signals

1 - 8 Basics 9 - 15 How it Works 16 - 19 Signalling Molecules 20 - 25 Animal Hormones 26 - 33 Plant Hormones 34 - 44 Endocrine Glands 45 - 48 Nerve Cells 49 - 52 Pheromones 53 - 54 Immune system

Cellular Signals

Sources/transmission of signalling molecules to target cells

Apoptosis

Regulatory process of cell death to prevent malfunction

Cell Communication

Cells receive/send signals from other cells/the environment

Hydrophobic molecules

Don’t dissolve in water/blood, transported in a vesicle

Hydrophilic molecules

Dissolve and transported by water/blood

Homeostasis

The ability to maintain internal stability

Negative Feedback

Loop producing hormones, adrenaline stops after threat

Positive Feedback

Continues to produce hormones, prolactin when feeding a baby

Stimulus Response Model

The three step process of signal transduction

Reception

Protein molecules bind to chemical signals

Intracellular Receptors

In cytoplasm, binds to hydrophobic molecules

Intercellular Receptors

On cytoplasm, binds to hydrophilic molecules

Transduction

Amplifies and converts the signal into a cellular response

Cellular Response

Changes in gene activity/effector proteins for specific jobs

Effector protein jobs

Cell migration, Metabolism changes, Cell division and Apoptosis

Signal Molecules

Classified by effect distance, bind to receptor on target cell

Endocrine signalling

Long distances, transported by blood, hormones

Paracrine signalling

Short distances by diffusion, neurotransmitters

Autocrine signalling

Cells produce/react to their own signals, growth/immune system

Animal hormones

Made in endocrine glands, transported by blood, long lasting

Amino-Acid derived hormones

Hydrophilic, thyroxine and adrenaline

Lipid derived hormones

Hydrophobic, testosterone and cortisol

Peptides

Hydrophilic short hormones, insulin

Proteins

Hydrophilic and long, growth hormones

Hormone regulation

Plant hormones

Made in growing areas of the plant, transported by phloem vessels

Phloem tissue

Made of cells with holes, water and food, two way, transports hormones

Xylem vessel

Thick walls, water and minerals, one way

Auxins

Bends plants towards life by growing shaded areas

Cytokinin

Promote cell reproduction in shoots, roots and fruits

Gibberellins

Stem/fruit growth, no seed dormancy, seedless fruit development

Abscisic acid

Closes stomata and induces dormancy, in winter

Ethylene

Influences the lifecycle of the plant, ripens fruit, drops leaves

Pineal gland

Secretes melatonin for the circadian cycle

Thalamus

The body’s information relay system

Hypothalamus

Makes releasing/inhibiting hormones to direct the Pituitary gland

Pituitary gland

Directs the thyroid, adrenal glands, and reproductive organs

Thymus

Produces/matures immune cells

Thyroid gland

Regulates metabolism, growth and development

Parathyroid glands

Regulates calcium, phosphorus and magnesium in bones/blood

Adrenal glands

Regulates metabolism, immune system, blood pressure, fight/flight

Pancreas

Makes insulin to control blood sugar levels

Uterus/Ovaries

Makes estrogen/progesterone for girlie stuff

Testes

Makes testosterone and sperm

Neurons act on

Acts on nerve or muscle cells

Action potentials

Electrical signals made by the movement of sodium/potassium ions moving in/out of the neuron

Neuron Communication

Uses action potentials to transmit a nerve impulse along the axon

Neurotransmitters

Diffuse across the synaptic cleft between neurons/muscle cells

Pheromones

Chemical signals released/received by animals of the same species

Pheromone messages

Warnings, food trails, territory, mating

Volatile pheromones

Disperse rapidly by air, insect sex pheromones

Localised pheromone

Disperse slowly, marking territory

Cytokines

Peptide signals made by immune cells to move towards inflammation, infection and trauma

Modulators

Molecules that directly influence other molecules