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bio 205-physiology > lec 26- plant puberty and flowering > Flashcards

lec 26- plant puberty and flowering Flashcards

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Biology 101 flashcards
1
Q

what are the three phases of post embryonic plant development?

A
  1. The juvenile phase
  2. The adult vegetative phase
  3. The adult reproductive phase
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2
Q

what changes occur when going from juvenile to vegetative?

A

changes in leaf shape and rooting ability

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3
Q

what are the lengths of the juvenile phase for annual plants, biannual plants, and perennial plants?

A

annual- days
biannual- occurs in second year, after cold treatment
perennial- 1 month to 30 years

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4
Q

what causes phase changes and induces an increased efficiency to flower?

A

microRNAs

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5
Q

which microRNA inhibits and promotes phase changes and how does it do it?

A

-miR156 inhibits phase changes by inhibiting miR172 causing it to stay in juvenile phase
-miR172 promotes phase changes, occurs when miR156 is reduced over time, letting it to increase competence to flower
-

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6
Q

how long is juvenile phase of arabidopsis?

A

10 days

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7
Q

once juvenile phase changes to vegetative, what triggers the change from vegetative adult to reproductive adult?

A

-environmental triggers like distance from equator, temperature, photoperiod/day length

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8
Q

what is the difference in photoperiod when related to the equator?

A

-days are longer farther from the equator in spring
-days may be shorter near the equator after midsummer

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9
Q

how do jungle plants at the equator do synchronous flowering?

A

by using input like slight seasonal variation to induce flowering

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10
Q

what are the categories of plant species based off of photoperiod?

A

short day plants- flower in short days
long day plants- flower in long days
day neutral plants- flowering is not regulated by day length

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11
Q

do some plants only flower if specific day length is given?

A

yes

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12
Q

do some plants experience accelerated flowering by short and long days?

A

yes

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13
Q

what do red and far red receptors do to plant flowering?

A

mediate day length information for flowering in both short and long day plants

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14
Q

how do the red and far red receptors mediate day length information for plants?

A

long day plants flower, when flashed with a pulse of red light in the night and short day plants are inhibited
short day plants flower, when flashed with a pulse of far red light in the night and long day plants are inhibited

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15
Q

how does phytochrome measure the length of night?

A

by the R/FR ratio, short pulses at night affect flowering

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16
Q

what does grafting of leaves exposed to correct photoperiod do?

A

induces switch from leaf to flower formation at shoot meristem

17
Q

what is the name of the signal sent from the grafted correct photoperiod leaf to the meristems?

A

florigen

18
Q

what is Flowering Locus T (FT) do and what does its mutant do?

A

a component in florigen that causes flowering, its mutant causes delayed flowering

19
Q

what triggers FT protein in leaf phloem companion cells and how does it travel to meristem?

A

a combination of ideal daylength and temperature triggers expression of FT in leaf phloem companion cells, Ft is then transported in the phloem to shoot meristems (sinks), where it induces leaf to flower formation at the flanks of shoot apical meristem

20
Q

what is a floral meristem?

A

a modified shoot meristem that produces flowers

21
Q

what are the 4 organs in a flower and how are the arranged?

A

the four organs are:
-sepals
-petals
-stamens
-carpels
arranged in a pattern of whorls within whorls

22
Q

what are homeostatic mutants?

A

mutants in which one kind of floral organ is replaced by another

23
Q

what are the three classes of arabidopsis and snapdragon mutants?

A
  1. some have only carpels and stamens
  2. some only have sepals and carpels
  3. some only have petals and sepals

each mutant usually lacks 2 of the 4 whorls

24
Q

what are the arrangements of the 3 mutants when 1 is sepal, 2 is petal, 3 is stamen, 4 is carpel?

A

case 1: carpel and stamens
4334
case 2: sepals and carpels
1144
case 3: petals and sepals
1221

25
Q

what type of genes encode for flowering and identity of floral organs?

A

MADS box genes, which are a large family of transcription factors that regulate expression of other genes in plants

26
Q

what are the 4 basic ideas of the ABC model?

A
  1. each of the three genes involved is expressed in two adjacent whorls
  2. A and C genes inhibit each others expressions
  3. A total of four different combinations of gene products can occur
  4. each of the four combinations of gene products triggers the development of a different floral organ
27
Q

what letters and combinations in the 1st to 4th whorl make which type of floral organ?

A

1st whorl: A alone causes cells to form sepals
2nd Whorl: A and B causes cells to form petals
3rd whorl: B and C causes cells to form stamen
4th whorl: C alone causes cells to form carpels

28
Q

what genes inhibit each other in ABC model?

A

C inhibits A gene production and A inhibits C gene production

29
Q

what are the three major regions of a gene needed for gene function and what do they do?

A

-regulatory region: provides binding sites for proteins/transcription factors
-transcription unit: contains the predicted open reading frame of the protein
-terminator: contains the signal motif for ending transcription and motifs for cutting 3’ end and adding poly (A) tail

30
Q

how do the transcription factors initiate transcription?

A

-TFIID binds the promoter creating a pre-initiation complex on the promoter
-TFIIH possesses helicase activity that unwinds the DNA and protein kinase activity that phosphorylates RNA polymerase II
-This releases RNA polymerase II from the transcription factors so it can begin RNA synthesis

31
Q

what binds enhancers to enhance the transcription of the gene in a cell specific manner?

A

regulatory transcription factors

32
Q

do enhancers (and silencers) work in either direction at different distances from transcription starting site?

A

yes

33
Q

does the definition of promoters differ?

A

yes, with or without distant enhancer elements

34
Q

what do MADS box proteins have motifs for?

A
  1. DNA binding
  2. protein-protein interaction
  3. activation
35
Q

what are the 5 steps to dimer formation cause by MADS box protein motifs?

A
  1. dimer formation
  2. one dimer binding one enhancer
  3. one dimer binding another enhancer
  4. form stable complex for support of transcription
  5. the combination of monomers determines what gene is recognized and activated
36
Q

what determines what combination of A, B, and C genes are expressed?

A

cells that express transcription and translation specific MADS box proteins in the meristem

37
Q

what leads to the development of specific floral organs?

A

specific combinations of MADS box proteins that bind to and activate specific genes

38
Q

can the same tetramer combination act as an enhancer or repressor?

A

yes, depending on target gene

bio 205-physiology (29 decks)

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