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21 Cards in this Set

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What is Apotosis?

Programmed cell death

What cells produce the signalling molecules, and what cells receive them?

Signalling cells produce signals, and target cells receive them.

What is recognition in cell signalling?

Recognition occurs when the signal binds to a specific site on the receptor because it is a complimentary shape.

What is transduction in cell signalling?

Transduction occurs when the signal molecule attaches to the receptor and is converted into another chemical form so that it can produce a cellular response.

What is direct cell communication?

When cells are in direct contact. Protein channels connect the two adjoining cells.

How do animal cells send direct signals?

They use gap junctions.



How do plant cells send direct signals?

They use plasmodesmata (a narrow thread of cytoplasm that passes through the cell walls of adjacent cells to allow for communication)

What is indirect cell communication? Give examples of the systems that use it.

When a signal travels from a signalling cell to a target cell that aren't in direct contact. For example, the endocrine and nervous systems.

What are the types of signalling molecules?

Plant hormones, hormones, neurotransmitters, pheromones.

What are the types of chemical messengers?

Paracrines, autocrines, neurotransmitters, hormones and neurohormones.

What are neurohormones?

Hormones released in to the bloodstream by neurosecretory neurons. They're distributed through blood to distant target cells.

What is paracrine signalling?

A form of cell to cell communication in which a cell produces a signal to induce changes in nearby cells. The signal will only have an effect on neighbouring cells in the immediate environment of secretion.

What is autocrine signalling?

A form of cell signalling in which a cell secretes a hormone or chemical messenger that binds to autocrine receptors on the same cell.

What are the types of plant growth factors?

Auxins, gibberellins, ethene/ethylene, cytokinins and Abscissic Acid (ABA).

What do gardeners use plant hormones for?

Growing cuttings, killing weeds and ripening fruit.

What is photoperiodism?

The physiological response of plants to the length of day and night. Long day plants need more that 12 hours of daylight/day, short day plants need less than 12 hours daylight/day and day-neutral plants are unaffected by the length of day/night.

What do auxins do?

-Promote cell growth


-Inhibit the growth of side shoots


-Inhibit leaf abscission (leaf fall)


-Involved in photoperiodism



What do gibberellins do?

Promote seed germination and stem growth

What does ethyne/ethylene do?

Promotes fruit ripening and leaf abscission (leaf fall).

What does cytokinins do?

Promotes cell division.

What does ABA do?

ABA (abscissic acid) inhibits seed germination and growth, and causes stomatal closure for water conservation.