Plant Physiology/ Chapter 1 : Dr. Sherman : BLY 431-101 : University of South Alabama
What regulates the cell cycle?
Cyclin and cyclin-dependent kinases
What are the seven major unifying principles of plants?
1 •Capacity to capture energy via photosynthesis 2• Plants are sessile, they do not move. 3 • "Skeletal" (rigid) structure associated with essentially all of their cells. 4 • Movement of nutrients and other compounds within the plant without pumps 5 • Dependence on continual water loss 6 • Young are provided with "lunch box" of nutrient to take with them 7 • Totipotency of most cells
megaspores develop into _____1_____ gametophytes, and microspores develop in _____2______ gametophytes.
1. Female 2. Male
The haploid gametophytes produce gametes by simple ____1______, whereas haploid gametes in animals are produced by ____2______.
1. mitosis 2. meiosis
Each microfibril is composed of how many estimated parallel chains of (1,4)-linked β-D-glucose?
18
What are three functions for cell walls?
1• protect against adverse conditions 2• regulate cell volume 3• determine cell shape
What at protofilaments?
A column of polymerized tublulin monomers or a chain of polymerized actin subunits
What are pectins?
A heterogeneous group of complex cell wall polysaccharides that form a gel in which the cellulose-hemicellulose network is embedded.
What is the 26S proteasome?
A large proteolytic complex that degrades intracellular proteins marked for destruction by attachment of one or more copies of the small protein ubiquitin
What is a phragmoplast?
An assembly of microtubles, membranes, and vesicles that forms during late anaphase or early telophase and precedes fusion of vesicles to form the cell plate
What are lytic vacuoles?
Analogous to lysosomes in animal cells, plant lytic vacuoles contain hydrolytic enzymes that break down cellular macromolecules during senescence.
What is the rosette-like structures found in the plasma membrane?
CESA complex
What is composed of an array of β(1,4)-linkined glucans?
Cellulose
Cellulose microfibrils are synthesized by large, ordered protein complexes, called _________?
Cellulose synthase (CESA) complexes
What are the three groups of cell wall polysaccharides?
Cellulose, hemicelluloses, and pectin
What is the organelle that is the site of photosynthesis in photosynthetic eukaryotic organisms?
Chloroplast
What happens during prophase?
Chromatin condenses to form distinct chromosomes
__________________ (structural, alive at maturity) • Elongated • No chloroplasts, but well developed Golgi and ER • Locally thickened 1° walls • Plastic support during growth
Collenchyma
What are unstacked thylakoid membranes within the chloroplast called?
Daytona lamellae
What are the two different generations that plant life cycles alternate between?
Diploid and haploid
The storage tissue for gymnosperm seeds in 1N gametophytic tissue because there is no ______________________.
Double fertilization
What is the unique process carried out by all angiosperms which allows two sperm cells to be produced, but only one of which fertilizes the egg. The other sperm fuses with two nuclei in the female gametophyte to produce the 3N endosperm (lunch box).
Double fertilization
What is treadmilling?
During interphase, a process by which microfilaments r microtubules in the cortical cytoplasm appear to migrate around the cell periphery due to addition of G-actin or tubulin heterodimers, respectively, to the plus end at the same rate as their removal from the minus end.
What are prolamellar bodies?
Elaborate semicrystalline lattices of membrane tubules that develop in plastids that have not been exposed to light (etioplast)
________________ cells specialized for • light penetration, • regulating gas exchange (guard cells) • anti‐herbivory physiology (trichomes, hairs) - different in shoots vs. roots
Epidermal
T/F: Primary and secondary cell walls are identical in their components.
False: Primary and secondary cell walls differ in their components.
T/F: a low pectin content of primary cell walls enables them to expand during cell enlargement.
False: high* pectin content
T/F: as cells enlarge, movement tends to decrease
False: increase
T/F: microtubule protofilaments first curl into cylinders then into flat sheets.
False: microtubule protofilaments first assemble into flat sheets before curling into cylinders
T/F: parenchyma cells make up very little of the primary plant body.
False: parenchyma cells make up much of the bulk of the primary plant body.
T/F: Plant cells are surrounded by flexible cell walls.
False: rigid cell walls.
T/F: the symplast cannot transport water, solutes, or macromolecules between cells without crossing the plasma membrane.
False: the symplast can transport water, solutes, and macromolecules between cells without crossing the plasma membrane.
T/F: chloroplast and mitochondrial division are dependent on nuclear division.
False: they are independent of nuclear division
What develop from parenchyma and form elongated support structures with thickened secondary walls both in ground tissue and in vascular tissue?
Fibers (bast fibers)
Figure 1.15 on page 24
Figure 1.15 on page 24
What is interphase?
G1, S, G2
What are the four phases in the cell cycle?
G1, S, G2, M
Where and by what are the matrix polysaccharides synthesized?
Golgi apparatus, by membrane-bound enezymes
At interphase, what two type of chromatin are distinguishable based on their degree of condensation?
Heterochromatin and euchromatin
What are hemicelluloses?
Heterogeneous group of polysaccharides that bind to the surface of cellulose, linking cellulose microfibrils together into a network.
What is cytokinesis?
In plant cells, following nuclear division, the separation of daughter nuclei by the formation of new cell wall
Plant microtubles can be release from the γ-tubulin ring complexes by which ATPase?
Katanin
Where are the three checkpoints located in the cell cycle?
Late G1 phase, late S phase, and at G2/M boundary
What are microstrobili?
Male cones produced by conifers
Together, hemicelluloses and pectins make up the ____________________________.
Matrix polysaccharides
____________________ • Peroxisomes and photorespiration • Glyoxysomes and lipid metabolism
Microbodies
What is the major fibrillar component of the cell wall and is composed of layers of cellulose molecules packed tightly together by hydrogen bonding?
Microfibril
In ___________________, the polarity arises from the polarity if the actin monomers itself: the ATP/ADP nucleotide-binding cleft of the monomer orients toward the slow-growing negative end, while the side opposite the ATP/ADP nucleotide-binding cleft orients toward the fast growing positive end.
Microfilaments
What are the two major types of cytoskeletal elements?
Microtubles and microfilaments
What are the specialized holes in the secondary wall that connect the living fiber cells with each other?
Pits
In ___________________, the polarity arises from the polarity if the α-and β- tubulin heterodimer. The α-tubulin monomer exists only in the GTP form and is exposed on the minus end, and the β-tubulin can bind either GTP or GDP and is exposed on the plus end.
Microtubules
A typical plant fell has two types of energy producing organelles, what are they?
Mitochondria and chloroplast
What does the mitochondria do?
Mitochondria are the cellular sites of respiration, a process in which the energy released from sugar metabolism is used for the synthesis of ATP from ADP and inorganic phosphate.
What is directed organelle movement?
Movement of an organelle in a particular direction, which can be driven by the interaction with molecular motors associated with the cytoskeleton
Plants have two types of motors, what are they?
Myosins and kinesins
What happens during metaphase?
Nuclear envelop breaks down and condensed chromosomes align in the middle of the cell
Oil Bodies • Also known as ____________ • Surrounded by a half-membrane • Storage of trigylcerides
Oleosomes
What is a checkpoint?
One of several key regulatory points in the cell cycle.
What are oil bodies?
Organelles that accumulate and store triacylglycerols.
________________ cells (structural and metabolically active) • Larger volume • Thin wall (primary only) • Vacuole developed • Mature organelles • Isodiametric (in leaves there are specialized types: spongy mesophyll and palisade)
Parenchyma
What are two examples of microbodies?
Peroxisomes and glyoxysomes
What type of cells are living at maturity and have nonlignified cell walls?
Phloem cells
What are etioplasts?
Photosynthetically inactive form of chloroplast found in etiolated seedlings
Why are plant cells frequently tetraploid or polyploid, instead of diploid?
Plant cells can leave the cell division cycle either before or after replicating their DNA. They can go through additional cycles of nuclear DNA replication without mitosis. (Endoreduplication)
What is plant physiology?
Plant physiology is the study of plant processes -how plants grow, develop , and function as they interact with their physical (abiotic) and living (biotic) environments.
what is sclerenchyma?
Plant tissue composed of cells (sclereids and fibers), often dead at maturity, with thick, lignified secondary cell walls.
What are chromoplasts?
Plastids that have carotenoids, which give off orange/yellow/red pigment
Both microtubules and microfilaments ends are different. The ________________ is displayed by the different rates of growth of the two ends, with the more active end being the plus end and the less active being the minus end
Polarity
What are the two types of walls plant cells have?
Primary cell walls and secondary cell walls
What are the protein storage organelles enclosed by a single membrane, found mainly in Ard's tissue?
Protein bodies
What are integral membrane proteins?
Proteins that are embedded in the lipid bilayer of a membrane via at lest one transmembrane domain.
What are microtubules?
Provide structure for cell and scaffolding for movement. Make up flagella and cilia (9+2) Made of polymerized tubulin.
What does it mean if a plant is dioecious?
Refers to plants in which male and female flowers are found on different plants.
What does it mean if a plant is monoecious?
Refers to plants in which male and female flowers are found on the same plant.
In what phase is DNA replicated?
S phase
___________________ (structural, Dead/empty at maturity) • Elongated • Secondary cell walls (lignin-‐containing) • Terminal support after growth • Anti-herbivory role
Schlerenchyma
What are the products of meiosis in diploid plants?
Spores (haploid)
What are diploid plant forms called?
Sporophytes
What is amyloplast?
Starch storing plastid
What is chromatin?
The DNA protein complex found in the interphase nucleus. Condensation of chromatin occurs during cell division to form the rod-shaped mitotic and meiotic chromsomes.
What is "alternation of generations"?
The change in generation between haploid and diploid form.
What happens during telophase?
The chromatin deco senses, nuclear envelope reforms, and the cell plate extends.
What is cytoplasmic streaming?
The coordinated movement of particles and organelles through the cytosol (bulk flow)
What does the cytoskeleton do?
The cytoskeleton helps control the organization and polarity of the organelles and cells during growth.
Which system includes the ER, nuclear envelope, Golgi apparatus, vacuole, endosomes, and plasma membrane?
The endomembrane system
Which system plays a central role in secretory processes, membrane recycling, and the cell cycle?
The endomembrane system
What is the endomembrane system?
The endomembrane system is a series of compartments that work together to package, label, and ship proteins and molecules. In your cells, the endomembrane system is made up of both the endoplasmic reticulum and the Golgi apparatus.
What is the major anatomical innovation of the angiosperms?
The flower
Spores are able to undergo mitosis to form a new haploid multicellular individual that is called ?
The gametophyte
What distinguishes the angiosperms from the gymnosperms?
The presence of a carpel that encloses the seed.
What is the "size exclusion limit"?
The restriction on the size of molecules that can be transported via the symplast.
What is a kinetochore?
The site of spindle fiber attachment to the chromosome in anaphase
What are thylakoids?
The specialized, internal, chlorophyll containing membranes of the chloroplast where light absorption and the chemical reactions of photosynthesis take place
Which generation is dominant in seed plants?
The sporophyte generation
What is the tonoplast?
The vacuolar membrane
What are microfilaments?
They are composed of a monomeric form of the protein actin (globular actin or G-actin)
What is the middle lamella?
Thin layer of pectin-rich material at the junction where the primary walls of neighboring cells come in contact. (glue adjacent cells together)
T/F the ER is a major source of membrane phospholipids and provides membrane proteins and protein cargo for the other compartments in the endomembrane pathway.
True
T/F: Microfibrils are insoluble in water and have a high tensile strength, about half the tensile strength of steel.
True
T/F: Plant morphology is very diverse.
True
T/F: Primary cell walls are thin and are a characteristic of young, growing cells. Secondary walls are thick, strong, and are deposited after most call growth has stopped.
True
T/F: The cellulose-hemicellulose-lignin complex of secondary cell walls forms a rigid matrix that is well suited for strength and compression resistance.
True
T/F: actin, tubulin, and their polymers are in constant flux in the living cell.
True
T/F: ground tissue includes the pith and cortex of primary stems and roots, and the mesophyll in leaves
True
T/F: mitochondria and chloroplast can increase in size without dividing.
True
T/F: if carbons are linked by single bonds the fatty acid chain is saturated, but if the chain includes one or more double bonds, it is unsaturated.
True (double bonds are kinky)
T/F: Plastids and mitochondria can move around plant cells.
True: motorized by plant myosins that move along action microfilaments
How many GTP molecules does each tubulin heterodimer contain?
Two (α&β)
What happens during anaphase?
Two chromatids of each replicated chromosome are separated and move towards opposite poles
What is the endoplasmic reticulum?
a continuous membrane system within the cytoplasm of eukaryotic cells that serves multiple functions, including the synthesis, modification, and intracellular transport of proteins.
What is the nucleolus?
a densely granular region in the nucleus that is the site of ribosome synthesis
What are cisternae?
a network of flattened saccules and tubules that compose the endoplasmic reticulum
What is collenchyma?
a specialized parenchyma with irregularly thickened, pectin-rich, primary cell walls.
What is a nucleosome?
a structure consisting of eight histone proteins around which DNA is coiled
What is rubisco?
an enzyme present in plant chloroplasts, involved in fixing atmospheric carbon dioxide during photosynthesis and in oxygenation of the resulting compound during photorespiration.
What type of meristem is located at the tips of the stem and roots?
apical meristem
Transport though the permeable cell wall space outside the cells is called ?
apoplastic transport
What is the predominant hemicellulose in primary cell walls of most grasses?
arabinoxylan
What are plastids?
cellular organelles found in eukaryotes, bounded by a double membrane, and sometimes containing extensive membrane systems. They preform many different functions: photosythesis, starch storage, pigment storage, and energy transformations.
Unlike ____________, which forms a crystalline microfibril, the matrix polysaccharides are much less ordered and are often described as amorphous.
cellulose
Each CESA complex is made up of six subunits, each of which is believed to contain three to six units of what?
cellulose synthase
The catalytic domain of ______________________ transfers a glucose residue from a sugar nucleotide donor to the growing glucan chain.
cellulose synthase
What is the enzyme that synthesizes the individual glucans that make up the microfibril?
cellulose synthase
What is heterochromatin?
chromatin that is densely packed and transitionally modified or suppressed
the nucleus is the site of storage and replication of what?
chromosomes
Nucleosomes assembly is assisted by large protein complexes called what?
condensins
What are sieve tube elements?
conducting element of the phloem
What are the infoldings of the inner mitochondrial membrane with attached enzymes?
cristae
Plastids divide independently at mitosis and are passed on to __________________
daughter cells
What is the tissue system that covers the outside of the plant body? ; the epidermis or periderm
dermal tissue
What three major tissue systems are present in all plant organs?
dermal tissue, ground tissue, and vascular tissue
What is a telomere?
end of chromosome
In general, stable changes in gene expression that occur without changes in the DNA sequence are referred to as what?
epigenetic regulation
If kept continuously in the dark after germination, proplastids will develop into ___________
etioplasts
What are megastrobili?
female cones produced by conifers
the vast majority of angiosperms both male and female gametophytes occur in a single _______________ flower.
hermaphroditic
What is the family of proteins that interact with DNA and around which DNA is wound to form a nucleosome?
histone
What are the three main types on proteins associated with the lipid bilayer?
intergral, peripheral, and anchored
Protoxylem cells with primary walls begin to differentiate into mature tracheary elements by doing what?
laying down secondary cell walls with spiral bands of cellulose and strengthened with lignin.
Bryophytes are unable to grow more than a few centimeters above the ground because they lack what kind of cell walls?
lignified cell walls
Instead of pectin, secondary cell walls have varying amounts of what?
lignin
what is a highly branched phenolic polymer made up of phenylpropanoid alcohols that is deposited in secondary cell walls?
lignin
what does smooth ER do?
lipid synthesis
What are companion cells?
living parenchyma cells that lie adjacent to each sieve-tube member
What is a localized region of ongoing cell division that enable growth during post-embryonic development?
meristem
Peroxisomes:mitochondria and chloroplasts::glyoxysomes:_____________
mitochondria and oil bodies
What is the double membrane surrounding the nucleus?
nuclear envelope
what forms the selective channels across both membranes, connecting the nucleoplasm with the cytoplasm?
nuclear pores
What is the site in the nucleolus where chromosomal regions that code for ribosomal RNA are clustered and are transcribed?
nucleolar organizer region (NOR)
What is the soluble matrix of nucleus in which the chromosomes and nucleolus are suspended?
nucleoplasm
Ground tissue consist mainly of what three cell types?
parenchyma, collenchyma, and sclerenchyma
Typical primary cell walls of eudicots are rich in ________.
pectins
the branches of roots arise from meristematic cells in the _______________.
pericycle (root branch meristem)
What is the most prominent membrane lipid in plants?
phospholipids
What is the primary function of the leaves?
photosynthesis
Pits of adjoining fibers align with each other forming what?
pit pairs
What allows free movement of molecules between cells?
plasmodesmata
pit pairs in living cells are often grouped together to form fields of what?
plasmodesmata
What are translocons?
pores in the rough ER that enable proteins synthesized on ribosomes to enter the ER lumen
What determines the life span of proteins?
posttranslational regulation
___________ meristems are formed during early embryonic development In these cells... • the walls are thin • the vacuole is largely missing • the plastids are immature
primary
What are the steps of mitosis?
prophase, metaphase, anaphase, telophase
____________ differentiate into various plastid types (e.g. chloroplasts, leucoplasts, chromoplasts, amyloplasts, etc.) based upon needs of the tissue
proplastids
all plastid types start out as ______________
proplastids
What is tubulin?
protein that makes up microtubules
what happens after the adenylated ubiquitin is transferred to a cysteine residue on a second enzyme?
proteins destined for degradation are bound by a third type of protein , a ubiquitin ligase (E3). The E2-ubiquitin complex then transfers its ubiquitin to a lysine residue of the protien bound to E3. The ubiquitinated protein is then targeted to the preteasome for degradation
What are peripheral membrane proteins?
proteins that are bound to the membrane surface by noncovalent bonds, such as ionic or hydrogen bonds.
What are anchored proteins?
proteins that are bound to the membrane surface via lipid molecules, to which they are covalently attached.
What does rough ER do?
rough ER synthesizes proteins that are transported by vesicles either to internal organelles or the plasma membrane
______________ meristems • increase in girth occur here (vascular cambium and cork cambium) • branching also occurs
secondary
What are axillary buds?
secondary meristems that are formed in the axils of leaves. ( become the apical meristem of branches)
What kind of organelle includes plastids and mitochondria?
semiautonomous
Xylem:tracheids and vessel elements::phleom:__________
sieve cell and sieve tube elements/companion cells
What is programmed cell death?
similar to mammalian apoptosis
What are ribosomes?
site of protein synthesis
In lower plants such as ferns and mosses, the sporophyte generation gives rise to _________ that grow into adult gametophytes that then have regions that differentiate into male and female structures.
spores
What are granum?
stacks of thylakoids
What is the fluid surrounding thylakoids?
stroma
What is the continuous system of cell protoplasts interconnected by plasmodesmata?
symplast
What is the transport of small molecules through plasmodesmata called?
symplastic transport
What are two types of transport that are important in vascular systems of plants?
symplastic transport and apoplastic transport
What happens after ubiquitination is initiated?
the adenylated ubiquitin is then transferred to a cysteine residue on a second enzyme, the ubiquitin-conjugating enzyme (E2).
What is euchromatin?
the dispersed, transcriptionally active form of chromatin.
What is an archegonium?
the female sex organ of lower plants such as ferns and mosses
What is ground tissue?
the internal tissues of the plant that aren't vascular tissues.
What is an antheridium?
the male sex organ of lower plants such as ferns and mosses
What is cortical ER?
the network of ER that lies just under the plasma membrane and is associated with the plasma membrane at specific contact points
What is the entire complement of DNA found in the nucleus?
the nuclear genome
What is the membrane bound organelle that contains the genetic information primarily responsible for regulating the metabolism, growth, and differentiation of the cell?
the nucleus
What is a centromere?
the point on a chromosome by which it is attached to a spindle fiber during cell division.
What is transcription?
the process by which the base sequence information in DNA is copied into an RNA molecule
What is translation?
the process whereby a specific protein is synthesized on ribosomes according to the sequence information encoded by mRNA.
What is the mitochondrial matrix?
the space inside the inner membrane of a mitochondrion
Gene expression involves both _________________ and ___________
transcription and translation
What are leucoplasts?
they are colorless and starchless plastids
What is the same basic organization all plant cells have?
they contain cystosol, a nucleus, and other subcellular organelles enclosed by the plasma membrane and cell wall.
xylem, phloem, epidermal, sclerenchyma cells tend to have ________ walls
thick
parenchyma cells will generally have ______ walls
thin
Tracheary elements consist of what?
tracheids and shorter, wider vessel elements
T/F: ribosomes rean mRNA in one direction, from 5' to the 3' end/
true
What is the balance between the rate of synthesis and the rate of degradation? (usually applied to protein or RNA)
turn over
What is a small polypeptide that is covalently attached to proteins, and that serves as a recognition site for a large proteolytic complex, the proteasome?
ubiquitin
When is ubiquitination initiated?
ubiquitination is initiated when the ubiquitin-activating enzyme (E1) catalyzes the ATP-dependent adenylation of the C terminus of ubiquitin.
What are tracheary elements?
water transporting cells of the xylem (nonliving at maturity)
What are the two types of tissues that vascular tissue is composed of?
xylem and phloem
What is the predominant hemicellulose in primary cell walls of most land plants?
xyloglucan
