Transcript new-plants - roisenbiology

PLANTS
CH. 36.3-36.4, 38.1,39.1-39.3
Absorption of Water and Minerals
 Occurs in cells near tips of the roots
 Epidermal cells--permeable to water
 Differentiate into root hairs--modified cells that do most of
absorbing water/soil solution
Epidermal cell
http://www.google.com/search?client=safari&rls=en&q=The+Cohesion-Tension+Hypothesis&oe=UTF-8&um=1&ie=UTF8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=fFyDUfPLHqOhiAKe24GACQ&biw=1330&bih=683&sei=flyDUbqCuaniQKUq4DoDg#um=1&client=safari&rls=en&hl=en&tbm=isch&q=epidermal+cells+of+leaves&revid=1976309581&sa=X&ei=l1yDUYLTAOtiQKG4oH4CQ&ved=0CGcQgxY&bav=on.2,or.r_qf.&bvm=bv.45960087,d.cGE&fp=
Transporting Water and Minerals
 Water and minerals from soil cannot be transported to the
rest of the plant until enters the xylem
 Endodermis--innermost layer of cells in root cortex
 Last checkpoint for selective passage of minerals
 transports needed minerals from soil into the xylem and
keeps unwanted substances out
 Casparian strip--barrier to minerals that reach endodermis
via apoplast (free dif fusional space outside the plasma
membrane)
Bulk Flow Transport in the Xylem
 Xylem Sap- the water and
dissolved minerals in the
xylem
 Gets transported long
distance by bulk flow to the
veins that branch throughout
each leaf
 Transpiration- the loss of
water vapor from leaves
and other aerial parts of
the plant
 If transpired water is not
replaced by water from the
roots, the leaves will wilt,
and the plant will die
http://www.google.com/search?client=safari&rls=en&q=xylem+sap&oe=UTF-8&um=1&ie=UTF8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=yFmDUeDtG4qhiQKIvYDwBw&biw=1330&bih=683&sei=ylmDUeutJIq5iwLooCwCg#imgrc=vY_yafzF4jpQGM%3A%3Bcuvr97dWukOVCM%3Bhttp%253A%252F%252Fwww.bio.miami.edu%252Fdana%252Fpix%252Fxylem_sap_ascent.jpg%3Bhttp%253A%252F%252
Fwww.bio.miami.edu%252Fdana%252F226%252F226F09_10.html%3B500%3B549
Pushing Xylem Sap: Root Pressure
 At night, root cells continue
actively pumping mineral ions
into the xylem and the
Casparian strip prevents the
ions from leaking back into the
soil
 The accumulation of water
lowers the water potential
 Root pressure is generated-- a
push of xylem sap
 Guttation- appearance of
water drops that can be seen
in the morning on the tips of
Guttation
plants
 NOT DEW
http://www.google.com/search?client=safari&rls=en&q=xylem+sap&oe=UTF-8&um=1&ie=UTF8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=yFmDUeDtG4qhiQKIvYDwBw&biw=1330&bih=683&sei=ylmDUeutJIq5iwLooCwCg#um=1&client=safari&rls=en&hl=en&tbm=isch&sa=1&q=guttation+in+plants&oq=guttation+in+plants&gs_l=img.3..
Pulling Xylem Sap
 The Cohesion-Tension Hypothesis
 States that transpiration provides the pull for the ascent of xylem
sap
 The cohesion of water molecules transmits this pull along the entire
length of the xylem
 Negative pressure potential (causes water to move upward
through the xylem) develops on the surface of mesophyll cell
walls
Pulling Xylem Sap
 This transpirational pull relies on:
 Adhesion--attraction between H2O and other polar
substances
 Cohesion--attraction between molecules of the same
substance
 Surface Tension
 Adhesion/cohesion facilitate the transport of water by bulk
flow
http://www.google.com/search?client=safari&rls=en&q=transpirational+pull&oe=UTF-8&um=1&ie=UTF-8&hl=en&tbm=
Rate of Transpiration
 Leaves have high surface-to-volume ratios
 Positive effect: enhances light absorption
 Negative effect: increase water loss by way of stomata
 Stomata
 95% of water lost is through stomata
 Amount of water loss depends on the number of stomata and
the size of their pores
 Under genetic and environmental control
 Ex. Desert plants have a lower stomatal density than marsh
plants
STOMATAL OPENING AND CLOSING
 Guard cells take in water from neighboring cells and become
more turgid
 As a result, increases the size of the pore between the guard cells
 When guard cells lose water, become flaccid and the pore
closes
 This change in turgor pressure relies on the absorption and
loss of K+
XEROPHY TES
 Xerophytes- plants adopted to dry
environments
 Plants in the desert
 Stomata stay open and take in more CO2
 Don’t dry out because complete life cycle
during the rainy season
 Crassulacean acid metabolism (CAM )specialized form of photosynthesis
 Takes in CO2 at night, stomata closed during
the day
http://view.ebookplus.pearsoncmg.com/ebook/launcheText.do?values=bookID::4487::platform::1004:
:invokeType::lms::launchState::goToEBook::platform::1004::globalBookID::CM81419602::userID::4743
886::scenario::3::scenarioid::scenario3::courseid::ROISEN201213::pageid::::sessionID::303594086223
57203292013::smsUserID::40436616::hsid::c62c764303314af28587427e0f7ea24a
Ch. 38.1
Angiosperm
Reproduction
http://0.static.wix.com/media/8d4b4e2fa8ea
1029b0255f379602d8ce.wix_mp_1024
Flower Structure and Function
 Flowers

:
contain four whorls of modified leaves:
 sepals,
petals, stamens, and carpels---which attach to a part of a stem called the
receptacle.
Flower Structure and Function
• Sepals enclose and protect
the unopened floral bud.
• Petals are generally more
brightly colored and may
attract pollinators
http://www.shaneeubanks.com/images/016_flower.jpg
• Stamens consist of a filament
and an anther, which
contains pollen sacs
(microsporangia).
 A carpel consists of a sticky stigma at the top of a slender
style, which leads to an ovary.
 The ovary encloses one or more ovules
 A flower may have a single carpel or multiple fused
carpels; either many be referred to as a pistil.
http://www.esu.edu/~milewski/intro_biol_two/lab_3_seed_plts/images/30_07FlowerStructure-L.jpg
Female Reproductive Organs
oThe pistil is the collective
term for the carpel(s).
oEach carpel includes an
ovary-where the ovules
are produced.
oOvules are the female
reproductive cells- the
eggs.
oA style-a tube on top of
the ovary.
oA stigma-which receives
the pollen during
fertilization.
https://d15mj6e6qmt1na.cloudfront.net/i/2515312/600.jpg
Male Reproductive Organs
o Stamens are the male
reproductive parts of
the flower.
o A stamen consists of an
anther- which produces
pollen- and a filament.
o The pollen consists of
male reproductive cellsthat fertilize ovules.
http://mystudyexpress.com/12%20th%20science%20cbse/biol
ogy/1.%20REproduction/Img%20file/10.png
Development of
Male Gametophyte

Within each microsporangium (pollen sac):






diploid cells called microsporocytes undergo meiosis
to form 4 haploid microspores.
A microspore divides once by mitosis to produce a
tube cell and a generative cell, which moves into
the tube cell.
The spore wall surrounding the cells thickens into the
sculptured coat of the pollen grain.
After the pollen grain lands on the receptive stigma,
the tube cell begins to form the pollen tube.
The generative cell divides to form two sperm cells.
The pollen tube releases the sperm cells near the
female gametophyte.
http://home.sandiego.edu/~gmorse/2009BIOL221/Study_guide2/ang
_male_gam.jpg
Female Fertilization

There are many variations in the development of the
female gametophyte:




also called an embryo sac.
Two integuments surround each megasporangium
except at the micropyle.
The megasporocyte in the megasporangium of an
ovule undergoes meiosis to form four haploid
megaspores, only one of which survives.
This megaspore grows and divides by mitosis three
times, forming the female gametophyte

which typically consists of eight nuclei contained in
seven cells
Female Fertilization continued
 At




the micropylar end of the embryo sac
an egg cell is lodged between two cells
called synergids,
which help attract the pollen tube,
three antipodal cells are at the other end
and two nuclei called polar nuclei are in a
large central cell.
Female
Male
Double Fertilization
 In
double fertilization, one sperms fertilizes
the egg to from the zygote, and the other
combines with the polar nuclei ton from a
triploid nucleus, which will develop into a
food-storing tissue called the endosperm.
 http://www.youtube.com/watch?v=Gq8
NWh98wQs
Double Fertilization
http://25.media.tumblr.com/tumblr_lllb32Jvu41qktyf1o1_r1_500.png
SIGNAL TRANSDUCTION,
SIGNAL RECEPTION, AND
SIGNAL RESPONSE:
CHAPTER 39.1
SIGNAL TRANSDUCTION
• Plants receive and respond to signals dif ferently according to
their environment
• Plants undergo morphological adaptations that allow them to
enhance survival
 The morphological adaptations for growing in the dark are
referred to as etiolation
 The morphological adaptations for growing in the light are
referred to as de-etiolation
 http://www.youtube.com/watch?v=tMMrTRnFdI4
RECEPTION
• Signals are first detected by receptors
• The receptor involved in de-etiolation is a type of phytochrome (a member
of a class of photoreceptors that is located in the cytoplasm rather than
on the membrane)
https://www.google.com/search?sa=N&hl=en&tbm=isch&tbs=simg:CAQSZxplCxCo1NgEGgQICQgLDAsQsIynCBo8CjoIARIU1Ab4BekDoQf2AoQG_1wLkBfAF_1gIaIN49NnbbwBe1oEnziJ5R52nVctxDM14jMkrdmxkiQlmDAsQjq7CBoKCggIARIEQMQO3Aw&ei=kXB_UaX1H4mkigKs0YAg&ved=0CCkQwg4&biw=1024&bih=705#imgrc=_YxOZJBMPCUegM%3A%3BvI8UDMMWvvvUbM%3Bhttp%253A%252F%252Fclassconnecti
on.s3.amazonaws.com%252F590%252Fflashcards%252F699456%252Fjpg%252Funtitled.jpg%3Bhttp%253A%252F%252Fwww.studyblue.com%252Fnotes%252Fnote%252Fn%252Fbio-test3%252Fdeck%252F38238%3B411%3B259
TRANSDUCTION
• Receptors can be sensitive to very weak environmental or
chemical signals
• The transduction of these extremely weak signals involves second messengers (small
molecules and ions in the cell that amplify the signal and transfer it from the receptor to
other proteins that carry out the response)
• Changes in cytosolic Ca 2+ levels plays an important role in
phytochrome signal transduction
• the concentration of Ca2+ is naturally very low at about 10 -7 M, but as a
result of phytochrome activation, Ca 2+ channels open causing a transient
100-fold increase in cytosolic Ca 2+ levels
• In response to light, phytochrome undergoes a change in
shape that leads to the activation of guanylyl cyclase (an
enzyme that produces the second messenger cyclic GMP)
• Both Ca2+ and cGMP must be produced by a complete de-etiolation response
RESPONSE
• Second messengers regulate one or more cellular activities
• In most cases, these responses involve the increased activity of
particular enzymes
• Two main mechanisms by which a signaling pathway can
enhance an enzymatic step in biochemical pathway:
• 1. post-translational modification
 Activates preexisting enzymes
• 2. transcriptional regulation
 Increases or decreases the synthesis of mRNA encoding a
specific enzyme
POST-TRANSLATIONAL MODIFICATION OF
PREEXISTING PROTEINS
• Many second messengers like cGMP and Ca2+ activate protein
kinases directly
• Often, one protein kinase will phosphorylate another protein
kinase, which then phosphorylates another and so on
• These kinase cascades may link initial stimuli to
responses at the level of gene expression
TRANSCRIPTIONAL REGULATION
• In phytochrome-induced de-etiolatin, several
transcription factors are activated by
phosphorylation in response to the appropriate light
conditions.
• The activation of these transcription factors depends
on their phosphorylation by protein kinases activated
by cGMP or Ca2+
De-Etiolation (“Greening”) Proteins
• The types of proteins that are either activated by
phosphorylation or newly transcribed during the de-etiolatin
process are enzymes that function in photosynthesis directly —
others are enzymes involved in supplying the chemical
precursors necessary for chlorophyll production.
PLANTS!!!
Ch. 39.2
Plant hormones help:
• coordinate growth development
• and responses to stimuli
• Plant biologist prefer the broader term plant growth
regulator
• Describe organic compounds (natural or synthetic)
that modify or control one or more specific
physiological processes within plant
Tropisms
The growth of plant towards/away from a stimulus
• Thigmotropisms (touch)
• Gravitropisms/geotropsism (gravity)
• Phototropisms (light)
• A growth towards a stimulus is a postive
tropism
• A growth away from a stimulus is a negative
tropism
Auxin (IAA)
• Function:
• Stimulates stem elongation
• Promotes formation of lateral and
aventitious roots
• Regulates development of fruit
• Enhacces apical dominance
• Functions in photoropism and
gravitropism
• Promotes vascular differentiation
• Retards leaf abscission
http://www.google.com/search?q=auxins&client=safari&rls=en&tbm=isch&tbo=u&sou
rce=univ&sa=X&ei=IfZ9UegBoKQiALDrYGwCQ&ved=0CEIQsAQ&biw=1231&bih=668#imgrc=kcrSXBEbiM_bQM%3
A%3BXBqG6dijiwOIUM%3Bhttp%253A%252F%252Fscienceaid.co.uk%252Fbiology%252
Fplants%252Fimages%252Fphototropism.png%3Bhttp%253A%252F%252Fscienceaid.co
.uk%252Fbiology%252Fplants%252Fplantgrowth.html%3B442%3B293
Cytokinins
• Functions
http://www.google.com/search?q=cytokinins+in+plants&client=safari&rls=en&tbm=isc
h&tbo=u&source=univ&sa=X&ei=kfZ9UZW_Gua2igLxhICACQ&ved=0CEcQsAQ&biw=12
31&bih=668#imgrc=IUSehNUt9ZmedM%3A%3B1six318kh9-7M%3Bhttp%253A%252F%252Fwww.rikenresearch.riken.jp%252Fimages%252Ffigures
%252Fhi_3779.jpg%3Bhttp%253A%252F%252Fwww.rikenresearch.riken.jp%252Feng%
252Ffrontline%252F5836.html%3B449%3B430
• Regulate cell division in shoots
and roots
• Modify apical dominance and
promote lateral bu growth
• Promote movement of
nutrients into sink tissues
• Stimulate seed germination
• Delay leaf senescence (aging)
and apoptosis
Gibberellins
• Functions
• Stimulate stem elongation, pollen development, pollen
tube growth, fruit growth and seed development and
germination
• Regulate sex determination and the transition from juvenile
to adult phases
http://www.google.com/search?client=safari&rls=en&q=gibberellins&bav=on.2,or.r_qf.&bvm=
bv.45645796,d.cGE&biw=1231&bih=668&um=1&ie=UTF8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=A_d9UYP_KsjmigKgh4HQBg#imgrc=4hmgwh
xstHLrxM%3A%3BNCPyQEOkVOvQLM%3Bhttp%253A%252F%252Fwww.biyolojiegitim.yyu.edu.t
r%252Fk%252FGib%252Fimages%252FGibberellin_jpg.jpg%3Bhttp%253A%252F%252Fcatherine
-wwwmyblog.blogspot.com%252F2011%252F04%252Fintroduction.html%3B457%3B262
Brassinosteriods
• Similar to cholesterol and sex
hormones of animals
• Functions
• Promote cell expansion and cell
division in shoots
• Promote root growth at low
concentrations
• Inhibit root growth at high
concentrations
• Promote xylem differentiation
and inhibit pholem
differentiation
• Promote seed germination and
pollen tube elongation
http://www.google.com/search?client=safari&rls=en&q=brassinosteroids&
bav=on.2,or.r_qf.&bvm=bv.45645796,d.cGE&biw=1231&bih=668&um=1&i
e=UTF-8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=iPd9Ua71KS7iwK6oYD4CQ#imgrc=kyIzrjBD9rNnfM%3A%3BiNHRellRjHGNiM%3Bhttp%
253A%252F%252Fwww.ou.edu%252Fcas%252Fbotanymicro%252Ffaculty%252Fpictures%252Fli1.jpg%3Bhttp%253A%252F%252Fwww.ou.edu%252Fcas%252Fbotanymicro%252Ffaculty%252Fli.html%3B827%3B611
Abscisic Acid (ABA)
http://www.google.com/search?client=safari&rls=en&q=abscisic+acid&bav=on.2,or.r_qf.&bvm=bv.4564
5796,d.cGE&biw=1231&bih=668&um=1&ie=UTF8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=Bvh9Uf-eN4S6iwLWiYCgDQ#imgrc=3BvTzSn7BjNaM%3A%3BjuDpDU0mv3KUuM%3Bhttp%253A%252F%252Fusers.rcn.com%252Fjkimball.ma.ultran
et%252FBiologyPages%252FA%252FABA.gif%3Bhttp%253A%252F%252Fusers.rcn.com%252Fjkimball.ma
.ultranet%252FBiologyPages%252FA%252FABA.html%3B197%3B123
• Functions
• Inhibits growth
• Promotes stomatal closure during drought stress
• Promotes seed dormanc and inhibits early germination
• Promotes leaf senescence
• Promotes desiccation tolerance
Strigolactones
• Functions
• Promote seed germination
• Control apical dominance
• The attraction of mycorrihizal fungi to the root
http://www.google.com/search?client=safari&rls=en&q=strigolactones&oe=UTF8&um=1&ie=UTF8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=ivh9UbnFCsSQiALHiICwBA&biw=1231&b
ih=668&sei=jfh9UYapFc3BiwLPloCICQ#imgrc=bDgeL_te5HRsPM%3A%3BWCEY_yT9hl_jfM%
3Bhttp%253A%252F%252Fusers.rcn.com%252Fjkimball.ma.ultranet%252FBiologyPages%25
2FS%252Fstrigolactone.png%3Bhttp%253A%252F%252Fusers.rcn.com%252Fjkimball.ma.ult
ranet%252FBiologyPages%252FS%252FStrigolactones.html%3B265%3B177
Ethylene
• Functions
• Promotes ripening of many
types of fruit, leaf abscission
and the triple in seedlings
(inhibition of stem elongation,
promotion of lateral expansion
and horizontal growth)
• Enhances the rate of aging
• Promotes root and root hair
formation
• Promotes flowering in the
pinapple family
http://www.google.com/search?client=safari&rls=en&q=ethylene&oe=UTF-8&um=1&ie=UTF8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=0fh9UZTXMa_siwKjq4GoAw&biw=1231&bih=668&sei=1Ph9UaLOEaSNigKFkICAAg#um=1&clien
t=safari&rls=en&hl=en&tbm=isch&sa=1&q=ethylene+functions&oq=ethylene+functions&gs_l=img.3..0i24j0i10i24.47240.52837.0.52970.24.18.4.0.
0.1.230.1797.3j9j1.13.0...0.0...1c.1.11.img.g7xboFiHXho&bav=on.2,or.r_qf.&bvm=bv.45645796,d.cGE&fp=2a5ed73fbbf81680&biw=1231&bih=668
&imgrc=BcrDTDJaYI6VUM%3A%3BpO8AiNHuTIg4AM%3Bhttp%253A%252F%252Fwww.qiagen.com%252Fgeneglobe%252Fstatic%252Fimages%25
2FPathways%252FEthylene%252520Signaling%252520in%252520Arabidopsis.jpg%3Bhttp%253A%252F%252Fwww.qiagen.com%252Fproducts%2
52Fgenes%252520and%252520pathways%252FPathway%252520Details.aspx%253Fpwid%253D169%3B780%3B934
Ethylene and the Triple
Respone
• If growing plant encounters and obstacle
in the soil (like a rock) and induces stress
on the tip, the plant will produce ethylene,
which will then control the triple response
• The triple response enables the shoot to
avoid and obstacle
• Ethylene production will decrease when
the plant is clear of the obstacle
(unrestricted growth)
Ethylene and leaf abscission
• Loss of leaves during autum helps prevent
desiccation during seasonal peridos of climateic
stress
• A change in the ratio of ethylene to auxin controls
abscission
• Aging leaf produces less auxin, making the cells of
abscission layer more sensitive to ethylene
• Cause the cells to produce and enzyme that
digest the cellulose and other compents of the
cell wall
Responses to light are critical for
plant success: Chapter 39.3
http://www.google.com/search?client=safari&rls=en&q=photomorphogenesis&oe=UTF-8&um=1&hl=en&biw=1330&bih=683&ie=UTF8&tbm=isch&source=og&sa=N&tab=wi&ei=SVaDUZGaHciUiAK8yYHoBw#um=1&client=safari&rls=en&hl=en&tbm=isch&sa=1&q=
Affect of light on plants
 The effects of light on plant morphology are called
photomorphogenesis
• Plants detect not only the presence of light but also
its direction, intensity, and wavelength (color)
Affect of light on plants
 A graph called an action spectrum depicts the
relative effectiveness of different wavelengths of
radiation in driving a particular process
Image source: Mastering
Biology Textbook
Blue-Light Photoreceptors
• Blue light initiates a variety of responses in plants
including:
• phototropism : the light-induced opening of
stomata
• And the light-induced slowing of hypocotyl
elongation that occurs when a seedling breaks
ground
Blue-Light Photoreceptors
 There are three different types of pigments to
detect blue light:
1. Cryptochromes—molecular relatives of DNA repair
enzymes, are involved in blue-light induced inhibition of stem
elongation (ex. When a seedling first emerges from soil)
 2. Phototropin—a protein kinase involved in mediating
phototropic curvatures
 3. zeaxanthin—the major blue-light photoreceptor involved in
blue-light mediated stomatal opening

Phytochromes as Photoreceptors and
seed germination
• Phytochromes regulate many plant responses to light
• It has two identical subunits, each consisting of a
polypeptide component covalently bonded to a
nonpolypeptide chomophore, the light absorbing part of
the subunit
Image source: Mastering Biology Textbook
Phytochromes and Shade Avoidance
Phytochrome system also provides the plant with
information about the quality of light
 The sensing mechanism enables plants to adapt
to changes in light conditions
Responses to Seasons
 seed germination, flowering, and the onset and
breaking of bud dormancy are all stages that occur at
specific times of the year
 The environmental stimulus that plants use most
often to detect the time of year is the photoperiod,
the relative lengths of night and day
 A physiological response to photoperiod, such as
flowering, is called photoperiodism
Photoperiodism
 Short-day plants require a light period shorter than
a critical length to flower
 Long-day plants generally flower in the late spring
 Day-neutral plants are unaffected by photoperiod
and lower when they reach a certain stage of
maturity, regardless of day length
Night Length
 Researchers learned that flowering and other
responses to photoperiod are actually controlled by
night length, not day length
Sources
 Goldberg, Deborah M.S. Barron's AP Biology. 3rd
ed. New York: Baron's Educational Series, 2013.
Print.
 Reece, Jane B., and Neil A. Campbell. Campbell
Biology. 9th ed. Boston: Benjamin Cummings /
Pearson Education, 2011. Print.