A: topic 5 and 6 Flashcards
plant cell specifications
Cell wall – plasmodesmata form a communication between the plant cells
Plastids
Vacuoles
Inclusions
Ploidy
Ploidy level: Number of chromosome sets in a cell
Polyploid: more than two sets (haploid, diploid)
Triploid species: bigger vegetative body, better resistance
Tetraploid species: increased production of reproductive organs Goal of breeding: better attribution
vacoules
- how are they made and of what
- different types
- tonoplast membrane storing solid or fluid compounds and gases
Vesicles of ER and dictyosomes(many together form the gogi apparatus) -> provacuoles
The provacuoles fuse into larger ones -> central vacuole
(In animal cells the vacuoles are of little importance)
- Storage(isolating metabolites), cell lysis, maintaining hydrostatic pressure and pH, dispertion and protection
lysosomes
Thick membrane
Hydrolytic enzymes in the middle – autophagy
vegetative (storage) vacoules
Diluted water solution, mildly acidic pH 5-6 (BUT pl. lemon pH 2)
Ions, by-products, waste products, nutrient storage
inclusions
No constant, but not essential substances
No metabolic activity
no membranes
Protein inclusions; globoid-, crystalloid forms, aleurone layer
Carbohydrate inclusion; mainly stach
oil inclusions: oil droplets
crystals
Accumulation of inorganic compounds: Oxalates, carbonates
silicates Digestion problems, irritation
plastids
1. fuctions and types
1.
Assimilation, synthesising metabolic processes, storage functions
Coloured plastids: chloro- and chromoplastids
Colourless plastids: leukoplastids
- Plastid development
Originates from prokaryotes
Proplastid
No sunlight: Etioplastids(an example of leukoplastids)
Sunlight: chromoplastids
Leucoplastid
Colourless plastids in organs not exposed to sunlight
Storage function!
The plant uses the stored nutrients or plastids can turn into green ones (potato)
Globular or fusiform shape
Examples:
Proteinoplastids – protein
Simple or compound types
storing and modifying proteins
In modified stems, seeds
Chromoplastids
Originated from proplastids or amiloplastids or chloroplastids (ripening, aging leaves)
Less developed inner membranes
Carotenoid pigments
carotene, xanthophylls: the two classes of carotenoid pigments
autumn leaf pigment
Globular, fibrillar or chrystalline forms
In flowers, fruits, leaves, roots Pollination, dispersal
Chloroplast
- Structure and function of thylakoid
- Compounds and functions of stroma
- plastid for C4 plants
1.
Outer membrane similar to cell membrane
Photosystems: intergal proteins and pigments(chlorophyll on membrane)
Electron transport chain: proteins ATP and NADPH production -> photosynthesis (light dependent reactions)
2. RuBisCO enzyme (protein complex)
Photosynthesis (light independent reaction, calvin) – production of glucose and intermediate products
3.
For C4 plants mesophyll cells has a granum structure, but it’s absent from the bundle-sheath cells!
Mesophyll cell and bundle sheath cell are much more closely related: unique step first in mesophyll cell, where CO2 and PEP is the first step to making malate, which will diffuse into the bundle sheath cell where the calvin cycle will happen as normal just with malate as a starting product instead of CO2. glucose is made
the first step in the mesophyll cell is there because PEP can only use CO2 even in low concentrations, while rubisco would have used O2 instead. this way the O2 is also separated form the calvin cycle so that only CO2 is used even in high temp., drought, low CO2
cell wall: major functions - 6
Protection (environmental stress, pathogenes, water loss)
Gives a definite shape
Enables information transport to the exterior
Helps in osmotic-regulation, prevents water loss
Transport processes
ion exchange, mineral uptake (root hairs)
what is the “skeletal structure” of the cell wall
The cellulose:
1,4 linked β–D glucose chain
- primary cell wall
- secondary cell wall
- what can decompose the cell wall?
1.
Primary cell wall:
web of microfibrils + auxin ->loosened structure, formation of new fibrils -> increasing cell wall surface (the “original”, basic cell wall)
- Secondary:
new transverse layers of cellulose fibrils (increased strenght) (layers on top of the primary wall – like padding a brick wall, more secondary wall, decreasing digestibility)
Outer (centrifugal) thickening In case of spores and pollens Spikes, grains, appendages…
Inner thickening: strengthening and protection
3.
Cellulase enzymes ->decomposition of cell wall (secretory ducts, transport vessels)
matrix substances of the cell wall: 3
Pectins (soluble fiber)
- high proportion in fruits and storage organs
Hemicellulose
- cross-link between pectins and cellulose (e.g.: arabinoxylan)
Proteins
- soluble (hydrolitic enzymes, peroxidases)
- insoluble (=extensins) – web-like structure
incrustations of the cell wall: 3
Pigments, Mucilage
- storage of water, gelling effect, Inorganic compounds – in plant hairs -> irritation
Lignin (wood)
- phenolic polymers consists of coumaryl alcohol, coniferyl alcohol, sinapyl alcohol Mainly in the secondary wall (lignification) Increase rigidity Decrease digestibility!
Suberin (cork)
- polymers of aromatic and aliphatic compounds Waterproof layer, decreasing evaporation Decreasing digestibility!
adcrustations
where, what: 2
On cell wall surface
lipid coating: Wax or cutin
Water insulators: decreasing evaporation
plasmodesmata
Channels traverse the cell walls – smooth ER tubes and protein filaments Direct transport between cells
Large number in young cells, later decreasing abundance
Permanent tissues: dermal tissues
External part of the plant
Primary dermal tissue: epidermis
Secondary dermal tissue: epidermal cells + stomata
Stomata types: amaryllis type bean shaped, grass-type dumbbell shape
nutritional value of dermal tissues
Function: absorb water and minerals
Gas exchange for photosynthesis=nutrition
Contains chlorophylls
Subsidiary cell: water and ion reservoirs
the digestibility of dermal tissues
- about the morphology (8)
- functions and chemicals (3)
1.
Often multiple cell layers, but in general one
Outer cell wall can be covered with cutine, wax/cork
Papillae(raised thickeng)
petal cells (epidermal appendages, outbulgings)
for grass and sedge plants are sharp and coarse-> irritation
Trichomes (epidermal appendages, hair-like)
Bristle hairs (stiff hair)
Clinging hair
2.
Function: protection against herbivores
In sec. Dermal tissue: accumulation of tannins, glycosides in bark!
Cause irritation, bezoars, rough texture-> animals reluctant to eat
rhizodermis (root epidermis)
Prim. Dermal tissue of young roots
Major differences from epidermis
Root hairs, no stomata/cuticule/chlorophylls
secondary and tertiary dermal tissues
- secondary, how made
- tertiary, how made
1.
Layer of cork cells are prod. Of the cortex bleow the epidermis, these cells willl later multiply as result of cell division and prod. Sec. Dermal tissues = periderm
(secondary growth incr. thickness)
- If phloem(living tissue) prod. the dermal tissue: tertiary
–>Accumilation of sec. Metabolites in bark aka phloem
ground tissues: parenchyma (4)
Most abundant tissue w/slightly differentiated cells
Cells are isodiametric
Have only primary wall, large vacoules and prominent intercellular cells
Function: basic metbolism, storage, aeration
chloroenchyma
Parenchymal cells that contain chloroplast -> photosynthetic function
Palisade, spongy
storage parenchyma
Lots of leukoplastids – fatty acids, starch, protein-> high nutruitive value
water storage parenchyma
Tissue of succulent plants
Thin cell wall, large vacuoles, water absorption in the form of mucilage
aerenchyma
Parenchyma of waterplants and species living in moist habitats
Large intercellular cavities – important for oxygen supply and gas exhange
Low nutritive value
Secretory tissues
secretion types of parenchyma
- intracellular secretion
- extracellular secretion
- other: 3
1.
Intracellular secretion:
- Metabolites secreted into vacuoles or cell wall
2.
Extracellular secretion:
- A cellgroup that secrete metabollites into intercellular space
- Endogenous: ducts, cavities (Ducts: for protection and to seal wounds from insect and disease entry)
- Exogenous: onto epidermal surface through glands
3.
Hydathodes: water through pores
Salt glands
Nectar glands: sugar rich liquid w/amino acids for pollinators
supporting or mechanical tissues
Mech. Strength to growing organs
Differentiates from parenchymal cells w/ cell wall thickening
(supporting or mechanical tissues): Chollenchyma “glue”
Supportoing tissue of young dicots
Contain living cytoplasms
High tearing resistance, provides flexibility – digestibility
Thickened cells
supporting or mechanical tissues: Sclerenchyma
Dead cells with evenly thickened cell wall
Lignin is deposited into cell wall – low digestibility
xylem
(wood)
Water and minerals from root to leaves – primarely dead cells
Structure
Tracheids – the “pipe”
Vessels : thick lignified wall, elements are shorts and broad
Wood parenchyma: the only living cells: storage and secretion
fibers
phloem
(bark)
Sugars, - primary composed of living cells
Structure
Sieve cells: similar to tracheids, connect to eachother w/ piths
Sieve tubes: mainly in angiosperms
Companion cells: metabolic functions of the sieve tube elements, transport and metabolic processes sugar concentration depends on the location of the cells, ex by the leaves of by the root
Fibers
Phloem parenchyma: mainly food storage
vascular bundles:
- the different types
- bundle sheath
1.
Simple bundles: separate bundles for xylem and phloem
Compounds bundles: both x and p elements
- Concentric bundles: x and p elements form concentric rings in cross section
- Collateral bundles: x and p adjpining each other side by side
2.
parenchymal or sclerenchymal ring around vascular bundles, temporary storage for nutrients, protection of the bundle
Histology of the root
- what are the mature regions
- rhizodermis
- cortex
- endodermis
- casparian strip
- stele
- pith
1.
Mature regions: dermal tissue, cortex and stele
2.
root hairs – generally one cell layer, increase the surface area
3.
mult. Layers of parenhcymal cells or aerenchima cells for water plants
4.
Innermost layer: endodermis
5. Casparian strip (nonpolar) which regulates the water transport
6.
Stele - central part of root - vascular tissue and pericycle around it
- Pith: parenchymal cell layers for storage
- Simple xylem and phloem: alternating bundles
histology of older roots
New root cap bc cell. Div. In pericycle
Prod of vascular cambium: thickening of the root
Decreasing digestibility – thickened walls
histology of storage roots
General lack of mechanical tissues ex carrot
Cambia are arranged is concentric rings
More parenchymal cells, better digestibility
histology of the stem
Shoot apex: initial cells->meristems->permanent tissues
Epidermis: one cell layer in gen., cuticle, wax, appendages
Cortex
Monocots: not sep into cotex and pith->storage parenchyma
Dicots: chloroenchyma, mechanical tissues and less storage parenchyma
Waterplants. Aerenchyma
Stele
Pith, vascualr bundles w/rays and if hollow_: pith cavity
secondary growth
Higher prop. Of lignified cells-> decreased digestibility
Rare in monocots
Four major types in dicots
Differentiation of the dermal tissues
Epidermis-periderm-rhytidome
(outer - middle - inner(dead phloem)
after comes phloem then xylem
histology of the wood: 4 types
Softwood: less fibres and lignification
Hardwood: more fibres and lignification
Heartwood: no watercond. Parenchymal cells block the vessels
Sapwood: conduction of water and nutrients
histology of the leaves
- functions
- histological structures found on the leaf
- kranz leaf anatomy
- leaf primordia
- Protect the stem apex
nervation Transport, mechanical stability
Determined growth, kalanchoe spp. Is unntak
2.
Dermal tissues
- Cuticle, wax, appendages, -1 cell layer
- Kranz leaf anatomy describes the leaf anatomy of a c4 plant specilized for better CO2 fixation
- Young leaves: leaf primordia (its earliest recognizable stage)
histology of flower: sepals, petals and tepals
Similar structure to leaves
Pigments in vacoules, nutrient supply
Poor nutritive value
Papillae and hairs
histology of flower: stamens and pollen
Pollen wall outer layer: sporopollenin
Pollenkitt on pollen for adhesiveness (allergic reactions)
Stamens are modified leaves
histology of flower: pistil
Modified leaf
Sticky surface to catch pollens
Chloroenchyma->storage parenchyma
histology of the seeds:
Taxon specific cells
Parenchymal cells + sclereids
(shelled) Thick seed coat -> digestive problems
Multiple layer storage parenchimal cells
Thin hemicellullose walls: good digestibility, release of nutrients
histology of the fruit
- different types of parenchyma, secretion
- exocarp
- mesocarp
- endocarp
1.
Fleshy fruits: storage parenchyma
Dried fruits: sclerenchyma
In ex drupe the two types are combined
Secretory cavities: secondary metabolites
2.
Exocarp
- 1 cell layer with cuticle, wax, hairs – can be lignified
- Mesocarp
- In fleshy fruits: miltilayered parenchyma for storage
- In dried fruits: consists of sclereids
4. Endocarp - One/miltilayered cells - Meso and endocarp can be fused - Hard, consists of sclereids
