Plant Phys exam 1

All species in Plantae exhibit…

alteration of generation

How does Miosis in plants occur?

sporic meiosis

directly produces haploid spores and gametes are produced later from haploid structures by mitosis

What are some challenges to living on land?

• avoiding desiccation

• obtaining key minerals

• reproduction in absence of H20

• structural support without buoyancy

—— and ——— are the 2 glucose polymers for plants.

• amylose- 1,4 glucose polymer

• amylopectin- 1,4 glucose polymer + alpha side branches

____ is the primary component of plant cell walls.

cellulose β 1,4 glucose polymer

What does cellulose do?

• provides structural support

• very stable, rigid structure

• most abundant carbon-containing (organic) biological compound on Earth

An angiosperm is…

a plant of a large group that comprises those that have flowers and produce seeds enclosed within a carpel

What are vascular systems used for in plants?

• water & nutrient transport: xylem tissues

• carbohydrate transport: phloem tissues

  **makes up the ‘organs’ of plants- roots, shoots, leaves

What is the benefit of seeds?

• act as physical protection for embryos

• delay germination until favorable environmental conditions occurs

____ and _____ are unique to angiosperms.

flowers (reproductive strategy for dispersal) and fruits (dispersal of offspring)

____ and ____ are types of angiosperms.

monocot and eudicot

Describe cotyledons, veins, and pollen

• embryonic leaves

• vascular tissue organization

• contains male gamete

Why are angiosperms successful?

• 25000+ species

• present in all environments due to seed evolution

• 84% of terrestrial plant species

What is indeterminate growth?

What makes this possible in plants?

producing new organs throughout lifetime of organisms (shots, roots, leaves in plants)

• presence of meristems

What is determinate growth?

growth of organism stops once specific structure is produced (leaves/flowers in plants

What are meristems?

a persistent site for cell division (throughout a plant’s lifetime- key to sessile plant lifestyle)

What are the two types of cells in a meristem?

1- initials: remain undifferentiated… replenish/maintain meristem

2- derivatives: divide several times to produce cells that differentiate into specific ce types/function

how are the two types of meristem cells regulated?

• kept in balance by plant hormones, cell signaling, and genetic pathways

• - plant growth is a result in balance of two cell types

What are the 3 types of meristems in vascular plants?

1- apical: tips of all shoots/roots

2- primary: near apical meristems

3- secondary (lateral): parallel to long axis of plant body

Which type of meristem is not present in all plants?

secondary meristems- produce the woodiness of plants

• occur across length of organisms

Characteristics of lateral/secondary meristem

• produces large increase in circumference of the plant

• vascular cambium- produces the secondary vascular tissues (2 xylem/ 2 phloem)

• cork cambium- produces secondary epidermal tissues

• ** wood inside tree is 2 xylem/bark is 2 phloem

Characteristics of apical meristems

• can exhibit hierarchy/dominance (produce auxin)

• increase overall height/length of plant organs

• key aspect of plant growth/development

• derivative cells **

  2 types= SAM (shoot) & RAM (root)

What type of primary meristems can derivatives cells of apical meristems become?

• protoderm

• procambium

• ground meristem

  • ** can produce one or more cell types- daughter cells that undergo DIFFERENTIATION

Describe the 3 types of primary meristems

• protoderm- produces primary epidermal tissue

• procambium- produces primary vascular tissues (xylem/phloem)

• ground meristem- produces primary ground tissues that ‘fill in’ space between epidermis/vascular tissues

What are xylem and phloem tissues used for?

xylem- water and mineral transport

phloem- carbohydrate transport

Phenotypic plasticity is…

the ability to produce distinct phenotypes in response to environmental variation

Plants alter their phenotype in response to…

their environment

Plants can____ during their natural course of development

de-differentiate= highly specialized to less specialized

• doesn’t usually occur in highly specialized cells

example- callus (undifferentiated mass of cells)… new cells produce suberin in cell walls to protect/cover wound site

Regeneration in tissue culture

1- induction: dedifferentiation of cell

2- proliferation of cells: produces callus

3- morphogenesis of organized structures: shoots/roots

Totipotency is…

when a single cell can dedifferentiate and produce an entirely new individual

differentiated → undifferentiated

Morphogenesis is regulated by…

auxin and cytokinin (hormones- essential to plant viability)

regulate shoot and root formation in callus

What can dedifferentiated cells do?

1- reorganize (self- assemble) to reform meristems

2- differentiate into new cell types/tissues

What are the differences between primary and secondary metabolites?

primary- essential for growth and development

secondary- not critical to plant viability— debated function

What are phytochemicals?

a type of secondary metabolite

Functions of secondary metabolites

• defense & protection against insects/herbivores, microorganisms

• competition with other plants

• attraction/communication with beneficial organisms

How do plants communicate?

using chemicals (with same species AND other species)

Why do humans use secondary metabolites?

medicines, flavorings, pigments, recreational drugs

What characteristics do all eukaryotic cells have?

• bounded by plasma membrane

• nucleus

• mitochondria

• peroxisome

What characteristics are unique to plant cells?

glyoxysomes

plastid (eukaryotic photosynthetic organisms)

plant vacuole

plant cell wall

What is the fluid mosaic model?

• phospholipid bilayer

• fluids are regulated by components of bilayer

• steroids and fatty acid tails

• plants have 1-3 double bonds in a SINGLE tail

Why is it important for plants to have more double bonds?

at lower temperatures it allows plants to be more fluid

Describe passive transport

• movement from high to low (down concentration gradient)

• NO ENERGY REQUIRED

When can substances pass through the bilayer?

if lipid- soluble OR small

• uncharged/polar require transport protein

Describe Active transport

movement against chemical gradient

REQUIRES ENERGY (ATP)

Describe 2nd active transport (co-transport)

movement down concentration gradient is coupled with movement of 2nd substance against concentration gradient

H+ gradients

Describe the difference between symporter and antiporter

Symporter- moving in same direction

antiporter- moving in opposite direction

Plant cells DO NOT HAVE….

a Na+/K+ pump

What is the endomembrane system?

a collection of organelles that work together to synthesize, modify, and transport proteins and membranes amongst themselves (proteins/lipids)

• connected directly (nuclear envelope/ER) or indirectly (transport vesicles)

Where does protein synthesis begin and end?

all begin in cytosol

end in either cytosol OR associated with ER

What is the role of smooth (tubular) ER?

• calcium storage, steroid synthesis, phospholipid synthesis, enzymes to detoxify drugs

What is the role of rough (cisternal) ER?

calcium storage, site for protein synthesis, protein folding, glycosylation of proteins and lipids

Describe the Golgi structure

• enzymes in golgi stacks are unique and different

• only 1 part of golgi receives material from ER

• highly polarized

• function: glycosylation reactions (sequential); produces sugar for cell walls

N-linked vs O-linked oligosaccharides 

N: added in ER, 14 sugar residue(initially), covalently attached to protein througha nitrogen, modified extensively in glogi

O: added in gogli, 1-4 sugar resides, covalently attached, added one at a time to protein, attached to protein through oxygen

How does material move through the PLANT golgi?

• vesicles move forward and backward

• enzymes move backward in same stack

• consistent formation of new stacks (permanent structure)

• vesicles go to vacuole, lysosome, or to plasma membrane (to exocytosis)

What is the equivalent of lysosomes (animals) in plants?

plant vacuoles… small vesicles bud from golgi and fuse to form the vacuole… delivering additional material/proteins to mature vacuole

What is autophagy?

the destruction pf large cellular components including entire organelles

• ER derived membrane encloses organelle

• organelles digested/broken down by enzymes in LYSOSOME

• ** also function in plant vacuole

What is endocytosis?

uptake of large extracellular material into cell

• cell membrane surrounds extracellular material

  ** also function in plant vacuole

What is phagocytosis?

• uptake of VERY large matter… vesicle formed is a phagosome which fuses to lysosome

• a type of endocytosis

• 2 TYPES- nutrition OR defense

Functions of plant vacuoles

• storage: solutes and water

• important role in water balance of plant cells (positive turgor pressure to withstand gravity/upright growth)

• allows for large increase in plant cell size

• can have a lytic function during embryogenesis

• golgi dependent OR independent (different receptors/proteins)

Why are lysosomes and vacuoles considered distinct organelles?

each has different receptors and signals

How do plastids evolve?

From primary endosymbiotic events (proplastids in embryo)

What are proplastids?

undifferentiated plastids-meristems, egg cells, pollen grains, embryo)

absence of light- proplastids→ etioplasts

presence of light → thylakoids form and chlorophyll pigments develop

Light regulates…

transcription of genes required for thylakoid and pigment maturation

What are chloroplasts?

a type of plastid

LEAVES

• primary function= photosynthesis

  • light RXNs- thylakoids

  • light independent RXN: stroma

What are other types pf plastids?

• chromoplasts: pigmented… primary in reproductive functions  (flowers)

• leucoplasts: non pigmented… function in carbon storage

** plastid function depends on position in plant body

What are oleosomes?

oil storing bodies (triglycerides)

• primarily found in embryos… derived from ER

• ** unique to plants

What are glyoxysomes?

unique peroxisomes found primarily in embryos storing lipids/triglycerides for use as energy source during germination (single celled)

function- produces acetyl CoA from beta oxidation of fatty acids

Glyoxoysomes can transition into…

peroxisomes during seedling development

• major site of O2 utilization

• must remove hydrogen peroxide

What can plant cells do with acetyl CoA?

• broken down by mitochondria to produce ATP

• make glucose from lipids in a single cell (gluconeogenesis)

What is gluconeogenesis?

creating lipids to sugars for energy

Define the cytoskeleton.

• a dense network of protein filaments in the cytoplasm of the cell

1- microfilaments

2- intermediate filaments (not in plants)- cellular integrity/support

3- microtubules- determine/maintains cell shape, intracellular transport (kinesins), whole cell motility

Microtubules movement

**unidirectional 

• homologous OR unique

• - end: embedded in spindle pole  + end: growth happens here

Cilia vs flagella

cilia- short, multiple present… fluid moves over stationary object/cells

flagella- longer, few present… push/pull cell through water

** composed of microtubules

Microtubule structure

alpha (-)/beta (+) tubulin dimers

• 13 protofilaments

dimer= alpha + beta

• monomers bound by GTP

• centrosomes and basal bodies (organizing center)

Microtubules and Microfilaments exhibit…

dynamic instability (rapid growth, depolymerization, reformation)

Centrosomes vs basal bodies in microtubules

centrosomes- polymerize cytoplasmic microtubules

basal bodies (responsible for organizing) and polymerize cilia and flagella

**both have structures consisting of 9 triplet microtubules

Centrosome vs centrioles (NOT IN PLANTS)

centrosomes- 2 centrioles perpendicular to each other/ proteins assist in polymerization of microtubules

centrioles- 9 triplet microtubules arranged in a circle (replicated during S-phase)

** replicate semi conservatively

Microfilament function

• determine/maintains cell shape

• generate contraction forces within cell

• responsible for whole cell motility

• intracellular motility/movement

(Actin protein- composed of actin monomers

• most plants use actin for long distance transport

Myosin…

only moves towards + end of microfilaments

requires NRG

can generate tension/contraction when anchored to cell structure

** changes in cell shape

Characteristics of cytoskeleton