Ch. 39.1—Plant Responses to Internal & External Signals Flashcards
________ ________ ______ link signal reception to response
-Signal transduction pathways.
morphological adaptations for growing in darkness, collectively called ______;
-etiolation.
________ is characterized by: long, weak stems; smaller and sparser leaves due to longer internodes; pale yellow color (chlorosis).
-etiolation.
After exposure to light, a potato undergoes changes called _________, in which shoots and roots grow normally
-de-etiolation
Signal processing in plants occurs in three stages:
- Reception
- Transduction
- Response
Internal and external signals are detected by receptors, proteins that change in response to specific stimuli: In de-etiolation, the receptor is a _________
capable of detecting light.
-phytochrome
In transduction, _____ ________ transfer and amplify signals from receptors to proteins that cause responses.
-Second messengers.
Two types of second messengers play an important role in de-etiolation:
- Ca2+ ions &
- Cyclic GMP (cGMP)
The phytochrome receptor responds to light by:
Opening Ca2+ channels, which increases Ca2+ levels in the _______.
-Cytosol.
The phytochrome receptor responds to light by:
Activating an enzyme that produces ______.
-cGMP.
Response:
A signal transduction pathway leads to regulation of one or more cellular activities; In most cases, these responses to stimulation involve increased activity of enzymes—this occurs by: _____ ______ or ______ ________.
- Transcriptional Regulation
- Post-translational Modification
Post-translational modification involves modification of existing proteins in the signal response;
Modification often involves the
________ of specific amino acids by ______ _______.
- Phosphorylation.
- Protein kinases.
The second messengers cGMP and Ca2+ activate protein kinases directly:
______ ________ “switch off” the signal transduction pathways by dephosphorylating proteins
-Protein Phosphatases.
