Cells And Tissues Flashcards
How are plant lifeforms separated into groups?
- Bryophytes vs Tracheophytes
- Tracheophytes split into Pteridophytes vs Seeded
- Seeded are separated into Gymnosperms (naked seed) vs. Angiosperms (Ovaries/Flowers)
What are vacuoles?
-constitute bulk of most mature cells. Fluid filled enlargements of space between two layers of endoplasmic reticulum. Consist of... -Membrane (tonoplast) -Anthocyanins (red pigments) Function in... -Storage and disposal of toxins -Storage of sugar nutrients -Regulation of turgor pressure
What functions does the cell wall serve in plant cells?
- Structure/Rigidity
- Absorption
- Transport
- Secretion
- Digestion
- Protection
What are the components of the cell wall in plants?
Cellulose Hemicellulose Pectin Lignin Cutin Suberin
Explain cellulose
- Major structural component
- Equivalent to rebar or steel cables in buildings
- “Tethered” by hemicellulose
Explain Pectin
- Binds cells together
- Regulates water
- Key in primary cell wall and middle lamella formation
- “glues” cells together
Explain hemicellulose
- amorphous and hydrogen bonded to cellulose
- Binds strands of cellulose together
Explain Lignin
- Secondary cell wall in wood cells
- Compressive strength/rigidity
- Waterproofs cells
- Defensive mechanism
Explain cutin and suberin
Cutin is a waxy compound primarily found on leaves for protection and waterproofing.
Suberin is a waxy compound primarily found in cork cells for water proofing.
How is cellulose arranged in wood cells?
Cellulose is arranged at different angles in the primary wall, S1, S2 and S3 to increase strength and rigidity.
What is the lumen?
A straw like hollow in the center of wood cells that transports water
What happens to cells after they specialize?
They die!
but… some adjacent cells remain alive and facilitate the transport water and nutrients
What are the percentages of each cellular component in the Primary Wall?
Cellulose - 20-30% Hemicellulose - 25% Pectin - 30% Lignin - 0% Proteins - 5 to 10%
Explain cytoplasm
All metabolically active protoplasm outside the nucleus
Explain protoplasm
Living part of the cell. Includes non living structures such as vacuoles.
Explain nucleus
Contains chromosomes responsible for genetic and metabolic control
Regulates synthesis and reproductive activities of the cell
Nucleoli?
Also contain nucleic acids and proteins but funtion as intermediates in protein synthesis
Explain lignin
Tough, complex phenolic compounds associated with cellulose. Found In secondary cell walls of xylem (wood cells)
Explain endoplasmic reticulum
Labyrinthine system of membranes that connect cells through plasmodesmata to make plants integrated protoplasmic entities.
Studded with ribosomes in some areas that function in protein synthesis.
What are ribosomes?
Small bundles of nucleic acids and proteins in endoplasmic reticulum that function in protein synthesis.
What are mitochondria?
Sausage shaped organelles responsible for formation of energy rich compounds (ATP)
What are lysosomes?
Cellular scavengers, digesting cytoplasmic particles that are no longer useful.
What is the Golgi bodies role in a cell?
Associated with cell wall formation
Outline cell growth phase
Interphase (replication of DNA and cell contents)
Mitosis (division of chromosomes and formation of daughter cells)
Cytokinesis (formation of new cell walls)
what is the Epidermis and what are its functions?
The epidermis is one cell thick and covers leaves as well as softer portions of stems and roots. It secretes cutin to waterproof its walls.
- Protects against excess evaporation
- assists mineral absorption in roots
- contains pores (stomata) responsible for gas exchange
What are parenchyma cells?
Thin walled large vacuoled cylindrical cells. Frequently contain chloroplasts and manufacture food.
Non green parenchyma are primarily used for storage
What are the percentages of the cellular components of wood?
cellulose - 40%
hemicellulose - 30%
Lignin - 30%
What are the two types of sclerenchyma?
Both are thick walled strength cells
- Elongated tapering fibers (Sieve tubes in phloem and tracheids in Xylem)
- Short stone cells and stone cells (Walnut shells/Bark)
What is Collenchyma? what are its functions?
Cells with reinforced thickenings in corners. Stringy. NOT LIGNIFIED
-provide flexible support
What is sclerenchyma and how does it function?
Thick walled strengthening cells (LIGNIFIED) Contains fibers and sclereids. Thick and tough. Found in secondary cell walls of wood (xylem).
-Non flexible support
What are the elements of Xylem?
- Tracheids (elongated tapering cells) (Dead) (Serve in strength and conduction)
- Vessels (Long continuous tubes formed by the dissolution of ends of vertically elongated cells)
- Parenchyma (storage)
- Fibers (Elongated, pointed strength cells with thick cell walls) Differ from traicheids in thicker cell walls and reduced pits
- No protoplasm
What are the elements of Phloem?
Seive tubes - Cheif conducting cells of phloem. Vertically elongated . Contain cytoplasm
Companion cells - Border seive cells and aid conduction
Fibers - Thick walled, elongated strengthening cells.
Parenchyma - Storage cells
What are some importances of water?
Raw material in food manufacture
Medium for absorption and transportation of nutrients
Turgor pressure and cell rigidity
What are the three types of plant tissues?
Ground tissue
-photosynthesis/food storage/ support and protection/ regeneration
Vascular Tissue
-Transport of water and dissolved nutrients
Dermal Tissue
-Protection against excess evap./ pathogens
Elaborate on vascular tissue
Xylem transports water from roots to leaves and phloem transports products of photosynthesis down from leaves to roots for storage.
Continuous from root to leaf
Elaborate on ground tissue
Simple tissue
Parenchyma, Sclerenchyma and Collenchyma
Define primary growth
Longitudinal growth as a function of the primary meristem.
Takes place in buds.
Define secondary growth
Lateral growth from the secondary meristems
Vascular cambium- produces rings of xylem(wood)to the inside and phloem(outer bark) to the outside.
Cork Cambium - Lies outside phloem and produces cork outward, compressing it against the epidermis to form the outer bark.
What are the primary meristems and the meristematic tissues? where do they arise from.
Protoderm - gives rise to epidermis
Procambium - gives rise to primary xylem and phloem and eventually vascular cambium which is a secondary meristem.
Ground meristem- Gives rise to the cortex and pith and eventually the cork cambium which is a secondary meristem
-Arise from apical meristem
What tissue does cork cambium create?
Phelloderm (Thin layer of cells to the inside of the cork cambium) and Cork to the outside.
What are interfascicular parenchyma?
Parenchyma that specialize to link the vascular bundles of procambium together in a stem, creating a ring of VASCULAR cambium that will serve in secondary growth.
Explain multiplicative division
Production of more initial cells to increase the circumference of the vascular cambium.
explain additive division
When initial cell divides to form a phloem mother cell or xylem mother cell.
What is the function of secondary growth
Enhance conduction
- tracheids
- vessels
Enhance support
- tracheids
- fibers
Outline differences between early and late wood…
Late -high density -thick wall -narrow cell Early -lower density -Thinner cell wall -Wider cell -co-incides with shoot elongation
What is dendrochronology?
Science of tree ring dating
How does bark form?
Epidermis ruptures due to secondary growth
Cork cambium forms within the cortex
Forms new periderms
New cork cambium forms
Significant species variation
What is the difference between xylem cells in gymnosperms and angiosperms?
Gymnosperm xylem conducts through tracheids and angiosperms conduct through vessels.
Where are Ray cells found and what are their functions?
Ray cells are found in the woody tissue of angiosperms.
They conduct gases and water radially, connecting the tree from epidermis to xylem
explain differentiation
meristematic cells differentiate into ground tissues
Explain maturation
When a cell is fully differentiated. Fully differentiated cells are dead and have many important qualities for structure and conduction.
