Module 4 Flashcards
microscopic, consists of protoplast that contain cell wall, organelles & vacuoles
Plant cell
Structures found in plant cells but NOT in animal cells (3)
- Large, centrally located vacuole
- Cellulose cell wall
- Plastids
This structure occupies 90% of the cell’s volume
Central Vacuole
Single membrane surrounding the central vacuole
Tonoplast
Contents of central vacuole (2)
Clear cell sap (water and salts)
Visible crystals, starch, protein bodies, and other fibrous materials
Functions of central vacuole (6)
- Osmotic Regulation
- Tissue rigidity
- Waste storage
- Digestive organelle
- Contain water soluble pigments
- Crystal formation
Organelles characteristic of plant cells
Have no homologues in the animal cell
Vary in form, size, and pigmentation
Plastids
Progenitor Plastid
Proplastid
8 types of plastids
Etioplast
Leucoplast
Proteinoplast
Elaioplast
Amyloplast
Chloroplast
Chromoplast
Gerontoplast
green; chlorophyll
pigments predominate in them
Chloroplasts
lack pigments; if a plant is kept out of light for several days,
its chloroplasts will actually convert
into this.
Etioplasts
forms from
chloroplast during senescence
Gerontoplast
yellow, orange or red;
carotenoid or xanthophyll pigments
predominate in them
Chromoplasts
non-pigmented plastids
found in tissues unexposed to light
Leucoplasts
leucoplasts that store
starch
Amyloplasts
Special amyloplast type found in root cap for gravity perception
Statoliths
Leucoplasts that store proteins
Proteinoplasts
Leucoplasts that store fats and oils
Elaioplasts
Parts of chloroplasts (5)
Outer membrane
Intermembrane space
Inner membrane
Stroma
Thylakoid system
Lipid containing structure that increases in amount in chloroplast stroma. Sign of senescence.
Plastoglobule
All plastids are initially derived from proplastids found in this region
RAMs and SAMs
Plastids are maternally-inherited in the majority of angiosperms, why?
The sperm nuclei already have too many functions therefore no space for plastids
Reserve materials and substances which are produced and stored
in plant cells but DO NOT re-enter the metabolism of the plant
Ergastic Substances or Inclusions
6 Main Ergastic Substances
1) Starch
2)proteins
3) oils, fats, waxes
4) crystals and silica bodies
5) Tannins
6)Pigments
constructed by layered deposition of starch around a nucleation center HILUM
Starch
Types of Starch Grains
Eccentric
Concentric
Semi-compound
Compound
Hilum not centered
Eccentric
Hilum centered
Concentric
Two hilums at center of concentric rings
Semi-compound
No clear center hilum
Compound
Accumulate in Aleurone Grains
Crystalloid and Globoid Proteins
important reserve materials in plants
found in seeds and fruits
produced by
elaioplasts
Fats/Oils/Lipids/Waxes
Types of Crystals (6)
Druse
Raphides
Prism
Styloids
Crystal Sands
Cystolith
Crystal that looks like a diamond
Prism
Crystal that looks like a toothpick
Styloids
Crystal that looks like a bunch of needles
Raphides
Plant cell that differs markedly from neighboring cells
Idioblast
Look like salt grains
Crystal Sand
Looks like flowers or minesweeper bombs
Druse
Stalked crystal formed inside an epidermal cell
Cystolith
Cell containing Cystolith
Lithocyst
are rectangular with undulated margins
deter herbivory and increase the abrasiveness of grass leaf blades
Silica Bodies or Phytoliths
phenol derivatives found in leaves, vascular tissues, periderm, unripe fruits, seed coats
appear as yellow, red, or brown granular masses
deter herbivory (poisonous to insects)
Tannins
Prevents rupture of the cell
Maintains the size and shape of the cell
Only sperm cells of some seed plants lack this
Synthesis controlled by golgi complex
Cell Wall
Give the steps in Formation of CELL WALL
cell wall forms following mitotic telophase
microtubules from the phragmoplast between the two daughter nuclei
phragmoplast serves as the framework for the assembly of the cell plate
cell plate forms within the phragmoplasts from fusion of Golgi-derived vesicles
microtubules of phragmoplasts disappear with the enlargement of the cell plate
T/F: the cell plate is composed of pectic compounds (Ca & Mg pectate)
True
T/F: Middle Lamella is formed immediately
False, the cell plate gradually undergoes changes to form the middle lamella
Cell Wall Layers (4)
Middle Lamella
Primary Wall
Secondary Wall (3 Layers)
Tertiary Wall
T/F: Primary and Secondary walls are permanent, almost never degraded or depolymerized
True
Middle Lamella is characterized by high levels of ______.
Pectin
parallel cellulose molecules crystallize
into ____________ that wound around the cell
Microfibrils
Binds the microfibrils together, produced in Dictyosomes
Hemicellulose
first wall that develops in the new cell;
deposited before and during the growth
of the cell
Made of cellulose, hemicellulose, and pectin
thin and elastic
Primary Wall
Where is cellulose synthesized
In the plasma membrane by Rosette Terminal Complexes
Discuss Cell Wall formation process
Rosette Terminal complexes synthesize cellulose in the plasma membrane. This occurs due to the Cellulose Synthase Complex that binds 1 cellulose polymer at a time to the end of a chain forming the cell wall. Added to inner layer of the wall only
T/F: Plant cells grow in the direction with higher mechanical strength
False, grow towards lower.
What determines microfibril orientation?
cellulose synthase complex (CSC)
deposited between the primary wall and plasma membrane
develops in cells which have ceased to grow much thicker than primary wall and impregnated with lignin
resists chemical, fungal, and bacterial attack
Secondary Cell Wall
T/F: Secondary Cell wall increases in surface and thickness
False, Only thickness
Among the three layers of the Secondary Cell wall (S1, S2, and S3) which one is the thickest due to successive layers of lignin?
S2
T/F: Secondary Cell Wall causes death at maturity
True, secondary wall deposition makes
protoplast small / disappear so the cells become dead at maturity as seen in sclereids
dried residue of degenerated plasma lining that only occurs in some cases
contains xylan (hemicellulose) for integrity and defense
Tertiary Wall
fine holes in the cell walls plasma membrane, small channel of cytosol, and specialized ER of one cell passes through it and is continuous with the plasma membrane of the adjacent cell
act like tunnels through the cell wall which allow communication with other cells
Plasmodesmata
an endomembrane derived structure of the plasmodesmata that connects the
endoplasmic reticulum of two adjacent plant cells
Desmotubule
Main difference between Plasmodesmata and desmotubule
Plasmodesmata is composed of cytoplasm, Desmotubule is a tube of compressed ER connecting to adjacent ERs
thin portions of the primary wall which are traversed by a cluster of plasmodesmata
Primary pit fields or Primordial pits
“unthickened” areas in the secondary cell wall that act as channels for transport between cells with secondary walls
Pits
the hollow area where the secondary cell wall is absent
Pit Cavity
pits of two neighboring cells are found opposite to each other
Pit Pairs
opening at either
end of the pit chamber opening to the inside of the cell
pit aperture
pit cavities of a pit pair are separated by a ___ ________ composed of the middle lamellae and the primary walls of the 2
cells
Pit Membrane
2 Types of Pits
Simple and Bordered
Occur in all vascular plants
Form a channel through secondary wall of neighboring cells
Middle lamella blocks the channel but is perforated by plasmodesmata
Form and size of the opening varies
Simple Pits
The secondary walls arch over the pit cavity
The pith chamber is the part of the pith cavity formed by overarching of
the secondary wall
Middle lamellae and the primary walls are thickened (torus)
Bordered PIts
part of the pit cavity formed by overarching of the secondary wall
Pit Chamber
the pit membrane (primary wall and middle lamella)
is separated into two parts:
a thick impermeable
_____ at the center and the permeable _____
surrounding it
Torus; Margo
Differentiate the functions of torus from margo as bordered pits.
Torus regulates the functions of the bordered pit while margo supports it.
If the torus is the gate, the margo is the hinge that lets it open or close.
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