EXAM 2 Flashcards
3 basic types of cells in plant
Parenchyma
Collenchyma
Sclerenchyma
Parenchyma cells
- Thin & flexible, non-lignified primary walls
- No secondary cells
- Functions: filler, storage, protection, photosynthesis
Collenchyma cells
- Unevenly thick, non-lignified primary walls
- Support in growing tissues
(strings of celery)
Sclerenchyma cells
- Thick, lignified primary & secondary walls
- Function: support in mature tissues
- 2 types : fiber & sclereid
Fiber
Long, slender, pointed on both ends
Sclereid
Multi-shaped or columnar
Cell components
Outer membrane
Cytoplasm
Nucleus
Protoplast
The living plant cell excluding the cell wall
Cytoplasm contains
Organelles
Nucleus contains
chromosomes; DNA
Cell wall
- Cellulose
- Hemicellulose
- Protein
- Pectic substances
- Lignin
Cellulose
Most abundant cell wall component
Cotton = cellulose
Hemicellulose
Filler between the microfibrils
Protein
Mainly structural
Pectic substances
- Cementing agent or filler
- High in middle lamella and fruit
Lignin
- Polymers of phenolic acid
- Harden the cell wall
Where do you find pectin?
Cell walls (middle lamella)
Cell wall function
- Gives cell definite shape and structure
- Structural support
- Protection against pathogens
- Enables transport
- Reduces water loss
- Prevents the cell from rupturing
- Aids in diffusion of gases
Primary cell wall
- All cells
- First to form
- Found where cells are actively growing and dividing
Secondary cell wall
- Occurs when growth stops
- Deposited inside primary cell wall
- Made of cellulose and lignin
- Becomes rigid
Middle Lamella
- Holds together adjacent cell walls
- Pectin rich
- “Glue”
Pectin
Holds plant cells together
Plasma membrane
surrounds the cytoplasm
Regulates absorption into cells and leakage from cells
NOT attached to cell wall
Plasmodesmata
Cell to cell interconnections are produced by cytoplasmic strands
How cells communicate with one anoter
Cytoplasm
- Cytosol plus organelles
- Everything inside of cell (not nucleus)
Cytosol
- Contains proteins and water that fills cells
- Protects nucleus + organelles
- Acts to transport materials in and out
- Important for conferring drought and freezing tolerance
What is in the nucleus and never leaves?
Chromosomes
Chloroplast
- Green plastids that contain chlorophyll
- Site of photosynthesis
- Conversion of light energy stored energy in the form of glucose
- Source of energy
Endoplasmic Reticulum (ER)
- Tubular membranes for communication across cytoplasm
- Site of protein and membrane synthesis
Smooth ER
No ribosomes attached
Synthesis of essential lipids
Rough ER
Ribosomes attached
Produce proteins
Vacuole
- Cavities in cells that contain a liquid (vacuolar sap/ cell sap)
- Maintain cell turgor
- Processing/storage of waste
- Storage of nutriends
DNA
DOUBLE helix chain of sugar-phosphates connected by nucleic acids
RNA
SINGLE stranded chain of sugar-phosphates containing nucleic acids
DNA
Adenine
Guanine
Cytosine
Thymine
RNA
Adenine
Guanine
Cytosine
Uracil
Transcription
DNA sequence in a gene is copied into mRNA
Translation
mRNA is decoded and protein is produced
Why are plants propagated asexually?
- Genetic uniformity
- Hard to propagate by sexual means
Asexual propagation techniques
Cuttings (stem, root, leaf)
Layering
Division
Grafting & budding
Micropropagation
Chimera
Cells from 2 diff sources
What factors affect the success of grafting and budding?
- Plant type (only dicots and gymnosperms)
- Plant relationship (within species)
- Incompatibility
- Season and growth state
- Environment
What does it mean for bark to “slip”?
The vascular cambium is actively growing, and the bark can be peeled easily from the stock piece with little damaged
What types of grafts are used if the bark is slipping?
T-bud, inverted T-bud, I-bud, patch bud, ring bud, flute bud
What types of grafts are used when the bark is NOT slipping?
Chip bud
Scion
Part of the graft nomination to become the shoot system of the plant
Rootstock
Lower part of the graft, the root system
Why would you graft or bud a plant?
- Plants cannot be propagated by other means
- Decrease time to flowering and fruiting
Micropropagation
- Small pieces of plant tissue are grown on sterile media under aseptic (sterile) conditions
- Used to regenerate new plants that are identical to the mother
Advantages of micropropagation
- Allows for rapid production of mature plants
- Sterile production
- Provides way of producing plants that are relatively infertile/difficult to grow from seed
Totipotency
The concept that every cell in a plant has the inherent genetic ability to reproduce the entire plant
Quiescence
State of suspended growth of the embryo/resting condition
Dormancy
State that requires a special event or “trigger” before the embryo can resume growth
Stratification
Requires seeds to be stored in a moist, aerated medium at chilling temperatures for a certain period of time
Scarification
Physical or chemical abrasion of seed coat
Stages of seed germination
1st stage
- Inhibition: Initial absorption of water to hydrate seed
- Activation of metabolism: Increased respiration and protein synthesis
2nd stage
- Digestion of stored food: Starch to sugars in cotyledon
- Translocation to embryo: Sugars move to the embryo for growth
3rd stage
- Cell division and growth: Development of seedling
Microclimate
Environmental conditions within a small area that differs significantly from the climate of the surrounding area
Process of photosynthesis
Light energy is converted to chemical energy
Respiration
Cells break down simple food molecules to release the energy they contain
Photorespiration
A metabolic pathway that consumes oxygen, releases carbon dioxide, generates no ATP, and decreases photosynthetic output
Light reaction
Part of photosynthesis that involves light
Dark reactions
Reactions of photosynthesis that do not require light but use energy produced and stored during light to make glucose
Where in the leaf does most photosynthesis occur?
Mesophyll
Evapotranspiration
Evaporation of water from soil plus transpiration from plants
Translocation
Phloem carry sugar from leaves to rest of plant
Requires energy
C3 plants
- Most common
- Most efficient at photosynthesis in cool, wet climates
C4 plants
Adapted their photosynthetic process to more efficiently handle hot and dry conditions
CAM plants
Clone their stomata during the day, collect CO2 at night, store CO2 in the form of acids until needed
Composition of a mineral soil
45% minerals, 25% water, 5% organic matter, 25% air
org. matter: 75% humus, 10% biomass, 15% residue/by products
Effects of soil texture on soil properties
- As texture becomes more coarse: nutrient retention decreases, susceptibility to erosion decreases, leaching potential increases
Chilling
Injury that occurs ABOVE freezing, 32 - 50
Freeze
Below 32 degrees
Frost
Water vapor in air becomes liquid, condenses on a plant surface, then freezes, can occur when air temp is above freezing
