Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
85 Cards in this Set
- Front
- Back
When going over the growth and development of plants there are three terms that should be known, morphology, differentiation and growth. Just briefly describe these terms:
|
Growth is simply the irreversible increase in mass and involves cell expansion and cell division.
Differentiation is the change from a generalized cell type to a specialized cell type with specific functions ---Development = Growth and Differentiation Morphogenesis is the development of form and shape of a cell, organ, or entire plant |
|
What are some unique characteristics for plant growth?
|
A plant has indeterminate growth
Differentiation can be easily reversed There is localized and arithmetic growth There is open growth- can initiate new organs throughout lifespan |
|
What is totipotency?
|
This is when a single differentiated cell can de-differentiate and give rise to a whole new plant
|
|
Describe how totipotency was used in cloning plants?
|
F.C Steward took the carrot phloem cells (differentiated cells), place these cells in a coconut milk(this medium is rich in cytokinins). These cells then became a callus ( a mass of undifferentiated cells) and form a another carrot(plantlet)
|
|
What is a plantlet?
|
This is a small plant that was grown from cells off the original plant.
|
|
What are some plants that make plantlets by themselves?
|
Ferns and kalanchoe plants
|
|
What are some values of plant tissue culture?
|
Propagate individual plants while maintaining desirable traits
Develop new genotypes with desired traits(genetic engineering-cloning) Study genetics of somatic cells Immortality |
|
What is are some of the oldest plants?
|
Bristlecone pines in SC
|
|
Where is the zone of cell elongation and division located on the apical meristem?
|
The bottom is elongation
The top is division |
|
What are the pocket of meristematic cells left behind in a apical meristem?
|
The axillary buds
|
|
In the zone of cell elongation, what else can occur here?
|
Cell differentiation and it is mostly further away from apical meristem
|
|
In the apical meristem, what remains undifferentiated?
|
The axillary buds
|
|
What makes up interphase in cell division?
|
G1, S, G2
|
|
What causes plants to break dormancy” and re-enter cell cycle
|
This is sometimes done by some plant hormones within the G1-Go phase
|
|
What is the driving force for cell expansion/growth?
|
Osmotic pressure (Turgor pressure)
|
|
Describe how the protons play a pivotal part in cell expansion/growth?
|
The protons are pumped into the cell wall via H-ATPase, which in effect lowers the pH. This will then:
-Weaken interactions between wall components (pectins and cellulose, etc) -Stimulate expansins (proteins involved in wall loosening) Also some plant growth hormones stimulate cell enlargement or elongation, such as auxins |
|
When does cell differentiation occur?
|
After cell division (and enlargment and elongation), in order to keep progenitor
|
|
Give an example where cell division itself is involved in differentiation?
|
Trichome initials
|
|
The plant has several responses to the environment, which are coordinated growth and differentiation. One of these is vernalization, explain vernalization?
|
Vernalization is the period for seed germination and needs a pronlonged cold period. Without this will not flower
|
|
In gravitropism which way do the roots grow, negative or positive?
|
Positive, towards gravity
|
|
What is thigmotropism?
|
This is how the plant grows around a substance.
-Will grow faster on one side vs. other -will increase tugor to fold leaves |
|
There are many responses plants have towards lights, name some of these?
|
Photosynthesis
Photomorphogenesis(presence of light)-controls development (Leaves, greening) Phototropism (direction)-grow towards and away from light Photoperiodism (quantity/duration--daylength) -controls flowering in many |
|
What are some miscellaneous environmental factors that can effect plants?
|
Pathogens, herbivores, symbionts and other plants
|
|
Quickly say the four ways plants respond to light, one of them is presence?
|
Duration/quantity (daylength)
Quality (wavelength) Direction Prescence |
|
What are the three system components involved with how the plant responds to light?
|
Photoreceptor-detects light
Signal Transduction system-secondary messengers transmit and amplify signal Response system- gene activation or de-repression |
|
What are the three major photoreceptors?
|
Phototropin
Cryptochrome Phytochrome |
|
What is the proposed role of the anthocyanins?
|
They attract pollinators or are used as seed/fruit dispersers and photoprotection
|
|
What are the three photosynthetic and accessory pigments?
|
Chlorophylls, carotenoids, and xanthophylls
|
|
What color light does phytochrome absorb and what is its main role?
|
It absorbs red light and is involved in the daylength and shading (quality)
|
|
What phenomena are pytochromes involved in:
|
Promote stomatal opening
Promote leaf development Stem elongation in young seedlings Seed germination on surface of soil |
|
What is usually the active phytochrome wavelength and color?
|
Far red(Pfr) and it is 730nm
The inactive is 660nm and is red (Pr) --Red is useable in photosyntheis but the longer wavelength isn't. So if there is a longer wavelength it will pass through leaves, representing shade!!!! |
|
What features of hormones are similar to humans?
|
Act in small quantities/amounts-very potent
Release into plant "circulatory system"-mostly the phloem Target cells/tissues have receptors for the hormones Binding triggers response in target cells |
|
What are the main differnences between plant and animal hormones?
|
Hormones are simple organic molecules
They function alone or in conjunction with other hormones Different tissues may respond very differently to same hormone Some are transported, others have effects where produced |
|
What are the five major plant hormones?
|
Cytokinins
Gibberellins Auxins Abscisic acid Ethylene |
|
What is the coleoptile and what does it bend towards?
|
It is the sheath of cells that cover grass seedlings, it grows mostly be cell elongation and bends towards light, SPECIFICIALLY BLUE LIGHT
|
|
Describe how the coleoptile will bend towards light?
|
The tip of the grass has the phototropin receptor that will receive the blue light.
The auxin, diffusible chemical will travel down and cause the grass to "not show its ass to the light" |
|
What were the two auxin asymetrical distribution hypothesis?
|
Redistribution hypothesis-the light moves auxin to one sides
Auxin destruction-the light kills auxin on side |
|
Which scientist proved the auxin redistribution hypothesis and how?
|
Winslow Briggs-To disprove thee auxin destruction he took an agar block (with tip) and another agar block (tip exposed to light). He then both of the agar blocks, placed in dark but still saw the plant bended the same amount.
The auxin redistribution was proved because with a mica sheet present preventing all flow, the plant bended the same amount. With the mica sheet preventing a reduced flow of auxin, and one side being exposed to light and the other shaded, there was a difference in bending. The side that was shaded bent the most, showing that auxin moved to other side. |
|
If the agar block was placed on leftside of grass, which way would it bend?
|
Bend right
|
|
What is the auxin made of both synthetic and natural?
|
Natural= Indole Ring and Acetic Acide----Indole Acetic Acid (IAA)
Synthetic- Naphthalenacetic acid (NAA) |
|
What amino acid associated with thanksgiving is used in a pathway to make auxin?
|
Tryptophan
|
|
What is the function of auxin?
|
Apical dominance
phototropisms and gravitropism Promotes cell elongation |
|
How is auxin related to expansins?
|
They will overexpress expansins and there is greater plant growth
|
|
In what two forms can auxin be represente?
|
Free form or conjugated to aa/sugars (inactive)
|
|
Not only does Auxin have a different response to certain tissues it has different sensitivities. 10^-5 M is required for_________ and 10^-7-10^-9 is required for ________
|
Stem
Root |
|
Where is auxin produced?
|
Shoot apex, leaf tips
|
|
What is agent orange composed of?
|
2,4-D
2,4,5-T and also has dioxin (teratogen) which causes birth defects |
|
Describe the acid growth hypothesis of Auxin?
|
The auxin will bind to receptors, causing to produce AND activate H-pumps. Pump protons out of cell (K+ brought in to maintain turgor) this will then drop the pH (5.5-4.5), breaks bonds in wall matrix loosens cell wall.
The drop in pH also activates expansins |
|
What are statoliths?
|
Amyloplasts -colorless chloroplasts that store starch
|
|
What does Auxin do to root elongation in horizontal roots?
|
It will inhibit cell elongation on side with most auxin so the root will bend down.
|
|
What is believed to triger the auxin redistribution to the lower side of a horizontal root?
|
The statoliths are believe to contact membrane-bound receptor molecules and the statoliths movement will cause the auxin redistribution
|
|
What is apical dominance?
|
This is how auxin will delay the outgrowth of axillary buds until they are some distance away from the shoot apical meristem.
|
|
If there are more cytokinins than auxins willl there be apical dominance?
|
With more cytokinins there will be an outgrowth of the auxiliary buds
|
|
What is essentially responsible for the effects of Auxin?
|
The tissue that auxin targets, auxin is just the switch
|
|
Summarize the three efffects of auxin?
|
Apical dominance
The gravitopism The plant's morphology in regard to light |
|
Name the two naturally occurring cytokinins and name the synthetically produced one?
|
Zeatin
Isopentyl adenine Synthetic-kinetin |
|
Finish:
Cytokinins are chemical variations on ___________ |
Adenine
|
|
Where are cytokinins primarilly produced?
|
In the root apical meristem, transported to shoot system & axillary buds
|
|
Name this hormone:
Promote cell division in target cells promote axillary bud outgrowth balance root/shoot growth so vigorous root growth can support greater shoot system important in seed development may delay senescence in leaves role in stimulating differentiation & activity of vascular cambium (in conjunction with auxin) |
Cytokinin
|
|
Describe how cytokinin works with auxin?
|
appear to work in conjunction with auxin in many cases
tobacco pith tissue culture: high aux:cyt = stimulates development of roots low aux:cyt = stimulates development of shoots |
|
Where is Gibberellins primarilly produced?
|
In the upperparts of leaves
|
|
What are the functions of gibberellins?
|
Stem elongation and cell division
Growth and differentiation in vascular cambium transition from vegetative to reproductive state in some plants significant roles in seed germination a. stimulate embryo to renew development b. increase α-amylase levels (for starch breakdown) c. activate α-amylase Promote the cell wall extensibility but different than auxin |
|
What hormone works with auxin to cause phloem differentiation in the vascular cambium?
|
Gibberllin
|
|
Describe how gibberellin modulates gene expression, use DELA in this expression?
|
GA once bound to a receptor will degrade the DELA, which is bound to the transcription factor for the alpha amylase.
|
|
What is produced in the leaves and dry roots?
|
ABA
|
|
What hormone(growth inhibitor), promotes dormancy in seed and promotes response to stress, such as closing stomata.
|
ABA
|
|
What hormone is a gas and involved in fruit ripening?
|
Ethylene
|
|
Ethylene cause the following:
kinases neutralize acidity to hydrolases break down chl. amylases “ “ starch pectinases “ “ pectin hydrolases “ “ organics |
Tastier make less acidic
Make colors stand out Make sweeter Make softer Make sweet smelling |
|
What two plant hormones have medical significance?
|
Acetylsalicylic Acid= create aspirin
Paclitaxel = most widely used anti-cancer drug |
|
Describe how auxin and ethylene are correlated?
|
As there is a reduction in auxin concentration, ethylene will then futher decrease auxin and increase ethylene which will create the leaf abscision zone.
Once leaf drops there will be production of corky cells at site of abscission/ |
|
What are the two patterns of gene expression?
|
Spatial-space of regulation
-Cell specific -organ specific -Every cell type Temporal-Time -on all time -rhythmic, repressible |
|
What was gained from molecular cloning of genes?
|
Permitted initial studies of individual gene expression
|
|
Where does developmental regulation of genes occur?
|
Transcription
mRNA stability/degradation Translation Post-Translation Protein stability/degradation |
|
How is gene expression studied?
|
NoRthern blots
Microarrays Nuclease Protection Assay |
|
Describe the pathway of microarray?
|
mRNA---cDNA(incorporate fluorescent-labeled nucleotides)---clone and partially sequence many of them----hyberdize to microarray---then wash away unbound DNA's----identify by sequence homology
|
|
Are most expressed genes developmental?
|
No
|
|
What are strategies to finding key regulatory genes in development?
|
Isolate developmental mutants of a model genetic organism
Map and clone the gene Study gene's structure and function |
|
What do homeotic genes control?
|
They control the overally body plan of an organism
|
|
Why is Arabidopsis thaliana used as a model plant system?
|
small organism
short reproductive cycle n = 5 (chromosomes) smallest known genome of angiosperms (flowering plants) |
|
The shoot apical meristem produces a primordium, giving rise to 4 whorls. What are theses whorls?
|
1-sepal
2-petal 3-stamen 4-carpils |
|
What is the relation with class A and class C homeogenitic?
|
They are anatagonistic
If one not expressed, the other is expressed |
|
What photoreceptor plays a role in the circadian rhythms, is made of FAD, and absorbs blue light
|
Cryptochrome
|
|
What photoreceptor absorbs blue light and has the LOV domain, also in phytochrome and cryptochrome?
|
Phototropin
|
|
What receptor is important for circadian rhythm and floral initiation
|
Cryptochrome
|
|
What receptor is important in daylength and shading, stem elongation, seed germination, promote stomatal opening and promotes leaf development?
|
Phytochrome
|