{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

4-25 arabidopsis genetics-hormones and growth

4-25 arabidopsis genetics-hormones and growth - ARABI DOPS...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
ARABIDOPSIS GENETICS: HORMONES AND GROWTH LIFE 37 37.1 How does plant development proceed? - Four factors are involved in regulating plant growth : Environmental cues to which a plant responds Receptors that allow a plant to sense environmental cues, such as photoreceptors , molecules that absorb light Hormones , chemical signals that mediate the effects of the environmental cues including those sensed by receptors The plant ’s genome , which encodes enzymes that catalyze the biochemical reactions of development 37.1.1 Several hormones and photoreceptors play roles in plant growth regulation - Hormones are regulatory compounds that act at very low concentrations at sites often distant from where they are produced. Unlike animals, which produce each hormone in a specific part of the body, plants produce hormones in many cell types. Each plant hormone plays multiple regulatory roles, affecting several different aspects of plant development -Like hormones , photoreceptors are involved in many developmental processes in plants . Unlike plant hormones , which are small molecules , plant photoreceptors are pigments ( molecules that absorb light) associated with proteins . 37.1.2 Signal transduction pathways are involved in all stages of plant development - Plants , like other organisms , make extensive use of signal transduction pathways , sequences of biochemical reactions by which a cell generates a response to a stimulus . Cell signaling in plant development involves a receptor (for a hormone or for light) and a signal transduction pathway , and concludes with a cellular response. Protein kinase cascades amplify responses to signals in plants , as they do in other organisms 37.1.3 The seed germinates and forms a growing seedling - If all developmental activity is suspended in a seed , even when conditions appear to be suitable for its growth , the seed is said to be dormant . Cells in dormant seeds do not divide, expand, or differentiate. - As the seed begins to germinate —to develop into a seedling—it takes up water. The growing embryo then obtains chemical building blocks—monomers—for its development by digesting the polysaccharides , fats , and proteins stored in the seed . The embryos of some plant species secrete hormones that direct the mobilization of these reserves. Germination
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
is completed when the radicle (embryonic root ) emerges from the seed coat. The plant is then called a seedling . 37.1.4 The plant flowers and sets fruit - Flowering —the formation of reproductive organs—may be initiated when the plant reaches an appropriate age or size. Some plant species , however, flower at particular times of the year, meaning that the plant must be capable of distinguishing different times of the year. In these plants , the leaves measure the length of the night (shorter in summer, longer in winter) -Once the leaves have determined that it is time for the plant to flower , that information must be transmitted as a signal to the places where flowers will form.
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern