Midterm 1 Flashcards
What are plant tissues composed of?
Eukaryotic cells (contain a nucleus)
What is the area between cells called and what is it made of
Plasmalemma aka the plasma membrane, composed of pectates (complex set of polysaccharides) – plant glue/cement
What aids in fruit ripening and why
the middle lamella – uses the enzyme pectinases to break down pectins which it is made of to produce a softer fruit
What is the Flavr Savr gene and why is it important
It decreases pectin produced in fruit (started off with a tomato) and allows farmers to harvest fruit later, therefore resulting in something with fuller flavour components and fully developed sugars. Never went to market due to consumer acceptance
How does the plasmalemma aka plasma membrane work
It is semi permeable meaning it is covered in pores that allow smaller things such as water through but not larger things such as organelles (has limitations)
What are the continum of living/non living organisms through the plasmalemma called?
Living: symplast (biotic)
Nonliving: apoplast (abiotic)
What are the 3 components of the plasmalemma called and what are their compositions
lipids: 40%
proteins: 40%
carbs: 20%
What are lipids composed of
They are bilayers with polar heads and nonpolar fatty acid tails (heads out tails in) that are chemically stable - called a unit membrane
What are phospholipids and what do they look like?
They are the most common type of membrane lipid that contain a charged polar head with 2 hydrophobic hydrocarbon tails.
- unsaturated: not all H’s present, creates kinks (crooked)
- saturated: straight tail with all H’s present
What are the 2 most common glycolipids
glucose and galactose
Why are lipid molecules unique
Not covalently linked together so they are able to move around (bob, flex, rotate, flip flop)
What do enzymes do
They act as catalysts and transport metabolites (something made/used when body breaks down stuff) across the cell membrane
What is the optimal temperature for most plants
20 degrees
What occurs during chilling injury and how does it affect the plasma membrane?
When the temperature gets too cold, the inside of the membrane goes from a fluid liquid crystalline state to a solid gel phase. This in turn causes the membranes to leak, causing it to lose its ability to catabolize reactions and creates an imbalance in the organism
- primary mechanism of injuring plant tissues
Why is fluidity important for membranes?
Enzymes no longer work (tertiary and quaternary structures are altered and can’t bind) when its not fluid enough causing the enzymes and proteins not to be able to move in the phospholipid matrix and to function properly (responsible for transport in and out of the cell and hormone binding and primary hormone effects)
Why is semi permeability important for plant tissues
When it becomes too permeable toxic metabolites (such as ethanol and acetaldehyde) are able to enter the plant, giving it an off flavour and it allows the plant to access what it needs and not what it doesn’t
What kind of bonds do low and high temp plants have
low: unsaturated (double bonds - kinks)
high: saturated (straight tails)
What is the definition of critical temperature
the highest temp at which freezing injury to plant tissues can be detected (closest it gets to being damaged)
What is hardening off?
• plants raised in a greenhouse need to be acclimatized to cooler temperatures, lower humidity and increased air movement for about two to three weeks before they are planted outdoors. This ‘toughening up’ process is known as hardening off.
What is the nucleus?
It is surrounded by a porous, double membrane nuclear envelope containing chromosomes (DNA) and one or more nucleoli (dark masses made up of protein and nucleic acids – involved in rRNA synthesis)
What is the endoplasmic reticulum?
a 3D network of membranous tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane. It usually has ribosomes attached and is involved in protein and lipid synthesis.
What are the 2 types of ER?
rough: has ribosomes
smooth: no ribosomes
What are mitochondria?
They are organelles surrounded by a double unit membrane that provide energy for the cell.
- centers of respiration
Dictyosomes or Golgi apparatus
collect, process, and deliver proteins out of the cell
What are vacuoles?
Vacuoles are membrane-enclosed saclike structures that store materials such as water, salts, proteins, and carbohydrates.
- LARGE (take up 30-90% of the cell)
What are the 6 vacuole functions?
- Storage: for water and other materials (sugars, proteins, organic acids and pigments) also can be retrieved and used
- Digestion: contains digestive enzymes such as proteases, nucleases, glycosidases and lipases (work to break down and recycle nearly all cellular components)
- Regulation: pH and ionic homeostasis
pH is normally around 5-5.5 (slightly acidic) = -log[H] - Defense: against microbial pathogens and herbivores by accumulating toxic components such as phenolic compounds, alkaloids, cyanogenic glycosides and protease inhibitors (makes it so they can’t digest it properly so they don’t want to eat it)
- Sequestration: toxic components (such as heavy metals and oxalate) (shed leaves due to an accumulation of toxic components stored in vacuoles
- Pigmentation: Contain anthocyanin pigments to attract pollinators and seed dispersers (in saskatoon fruit, what gives it its dark purple colours)
Pigments can also work to screen out UV and visible light, preventing photooxidative damage to the photosynthetic apparatus (flavonols)
What are plastids?
small organelles such as chloroplasts that contain pigment or food
What are the precursors (forerunner) of all plastids?
Proplastids
What are amyloplasts?
unpigmented organelles responsible for synthesis and storage of starch granules
What are leucoplasts?
colourless plastids involved in the synthesis of monoterpenes (found in essential oils), found in secretory cells associated with leaf and stem prichomes (hairs) and citrus peel
- storage of starch, lipids and protein
What are Chromoplasts?
They synthesize and accumulate carotenoid and xanthophyll pigments making them yellow, red and orange (tomatoes, carrots or red peppers)
What are Etioplasts?
where development from proplastids to chloroplasts has been arrested by absence of light or very low light. Contain no chlorophyll but have colourless chlorophyll precursor (protochlorophyllide)
Light triggers them to develop into chloroplasts (which convert light into chemical energy)
- basically plastids that form in darkness that turn into chloroplasts when exposed to light
What are chloroplasts?
photosynthetic plastids responsible for energy capture that are green due to the presence of chlorophyll
Where are chloroplasts located on plants receiving different sunlight and why?
direct sun: on the sides or else they fry/too much heat
shade: on the top to receive as much light as possible
What are stacked grana thylakoids?
discs that are within a chloroplast used to absorb light (more = will absorb more light)
What are light reactions?
Energy capturing reactions of photosynthesis; convert light energy into chemical energy (sugars make ATP)
What are dark reactions?
energy produced in the light reactions is used to reduce CO2 and synthesize cell constituents (uses E to make sugars)
Gymnosperms
A plant that produces seeds that are exposed - cone bearing plants (primative)
Angiosperms
A flowering plant which forms seeds inside a protective chamber called an ovary (vessel seed)
What are the classes for monocot and dicot?
mono: liliopsida class
di: magnoliopsida class
What are some characteristics of monocots
- One cotyledon
- Usually 3 floral parts (can be multiples)
- Parallel array of leaf veins
- One pore or furrow in the pollen grain
- Vascular bundles are distributed among the ground tissue of the stem
- Fibrous root system
- Very few are woody
What are some characteristics of dicots
2 cotyledons
Usually 4 or 5 floral parts (can be multiples)
Netlike array of leaf veins
3 pores of furrows in the pollen grain
vascular bundles are arrayed in a ring in the stem
Primary taproot
Over 50% are woody
What is a meristem?
a tissue that contains actively dividing cells
vascular cambium
A cylinder of meristematic tissue in woody plants that adds layers of secondary vascular tissue called secondary xylem (wood) and secondary phloem.
- adds to girth of the stem
Protoderm
The outermost primary meristem, which gives rise to the epidermis of roots and shoots
ground meristem
the part of an apical meristem that gives rise to the ground tissue (cortex) in the primary root
- Consists of parenchyma (living), collenchyma (living) and sclerenchyma (dead) cells
procambium
A primary meristem of roots and shoots that forms the vascular tissue consisting of xylem (water and nutrients) and phloem (sugars)
What is the role of the apical meristem
to generate new tissue and lengthen the organ
What is the backup system of axillary buds?
a hormone called auxins when the plant breaks off (get activated/released)
- inhibits axillary bud outgrowth
What is the role of the lateral meristem
they add to the stem/root’s diameter/girth
Where is the intercalary meristem located?
at internodes
What are the 4 root functions?
What are the 4 root functions? Anchor plants into the soil Absorb water and minerals from the soil Conduct water and minerals to and from shoots Provide an area for storage
What does the root cap do?
Protects the root (apical meristem) as it grows through the soil and receives/transmits signals from the environment
What is the cell maturation region?
where primary tissues mature into secondary tissues (where root hairs are formed)
What is the root epidermis?
the outer absorbing layer, has no stomata and cuticle which allows it to absorb nutrients and water and uses root hairs produced from the cell maturation region to increase its SA
What is the cortex?
large thin walled parenchyma cells inside the epidermis
- food storage
What does suberin do?
it slows water and nutrient loss from the root
Apoplastic vs Symplastic
Apo: movement through cell walls and intercellular spaces (less resistance)
Sym: movement through living cells (greater resistance)
What is the endodermis?
the innermost layer of the cortex
- casparian strip acts as a barrier
What is the pericycle?
a thin layer of plant tissue around the vascular tissue
- Where lateral or branch roots arise
- Generates the vascular cambium in secondary growth
What is the pith?
ground tissue located in the center of the root
How does the mycorrhizae fungi help plants?
it shares a mutualistic relationship and absorbs phosphorus and nitrogen for the plant while the plant gives it sugars and amino acids
How does Rhizobium bacteria help plants?
mutually beneficial relationships – bacteria provides usable nitrogen for the plant and plant provides food and lodging in the root nodules for the bacteria
What is leghemoglobin and what is its function?
hemoglobin for legumes, produced in the plants nodules
- allows nitrogenase to function and provides the bacteria with oxygen for respiration
Where are the xylem and phloem produced?
in the procambium
Tracheids vs vessel elements (Xylem)
tracheids: thin and elongated with tapered ends
vessel elements: larger, lack end walls and act like a continuous pipeline for transport
What is the pit membrane and how does it use the torus?
a membrane of the pit with openings to allow water to flow through: uses to torus to seal itself off when the pressure is unequal
cork cambium
Lateral meristematic tissue that produces the outer covering of stems (bark)
What is the torus?
a swollen central area of the pit membrane that can seal off the pit
What is transpiration?
the pulling of water up and it evaporating from stomata in leaves(returns to the air)
- due to the opening of the stomata (loss of water)
- allows CO2 intake
- causes a loss of water
Sieve tube cells
Cylindrical cells lacking nuclei and with perforated sides and end walls that allow the movement of phloem sap (made up of water and sugar) between cells
- alive at maturity
What are companion cells?
Phloem cells that surround sieve tube elements (brains of the operation)
Why is grafting great?
- allows us to produce an exact replica
- no need to wait for the juvenile phase
- pest resistance, propagation ease, etc.
What happened during the great french wine blight?
Mid 19th century, destroyed a bunch of vineyards and the grape industry in France
Brought the aphid phylloxera from north america to europe
Grafted the european varieties onto the north american ones so that they were not susceptible to the aphids
What are the 4 above ground stems?
stolons, tendrils, thorns and crowns
What are the 4 below ground stems?
rhizomes, bulbs, tubers and corms
What are runners?
above ground horizontal stems that function in asexual reproduction (only variation in asexual reproduction is by mutation)
What are tendrils?
above ground and can cling or coil around structures to provide additional support to the plant
- modified leaves
What are rhizomes?
below ground horizontal stems that develops roots and shoots from the nodes and functions in storage of food for renewing shoot growth
What are bulbs?
below ground compressed stems with fleshy leaf like structures called scales
- outer scale (papery) acts as damage protection and keeps the insides from drying out
- inner scale acts as a food reserve storage
- large bud
What are tubers?
underground stems that are ribosomes that branch off into accumulations of starch
- have eyes
- modified stem
What are corms?
underground fleshy stems that form from axillary buds and have food reserves
- stack on top of one another: grow from cormels
What is secondary growth?
growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken
Where does secondary growth NOT occur?
in ferns or monocots
What is the ancestors of all gymnosperms
Progymnosperms
What are the 4 stages of xylem development
Cell division in the cambium
Cell expansion
Secondary cell wall deposition (needs thick/tough cell walls)
Programmed cell death (dead at maturity – hollow tube)
What does the procambium become in secondary growth
Fascicular cambium
What plant part is used for ID
leaves
What are veins composed of?
xylem and phloem cells embedded in parenchyma and surrounded by bundle sheath cells
What does the xylem transport?
transports water and nutrients
What does the phloem transport?
sugars
What becomes the midvein/epdermis and how
expansion and cell division from phloem and xylem in the procambium and protoderm that produce a vascular strand which becomes it
What are the 2 functions of leaves?
- manufacture food by photosynthesis (sunlight)
2. maintain water balance through transpiration
How are leaves formed?
auxin (2 dots across from one another - hormone that triggers cell elongation in cells) trigger cell division at the shoot apical meristem that form the lead primordium (originate as primordia)
What is phyllotaxy and what are the 4 types?
the leaf arrangement on a stem
- opposite (same spot, either side)
- alternate (go back and forth side to side)
- whorled (3 around same spot XYZ)
- basal (whole bunch around one spot – like a little skirt at the bottom of the plant)
For how long does the leaf rely on the rest of the plant?
until it reaches 40% of its final size, then it can sustain itself through photosynthesis
What is the extremity of the leaf composed of
the epidermis (a layer of cells) and the cuticle (a thick waxy layer that prevents excess transpiration)
What are the openings in the epidermis called and what do they do?
stomata: they use guard cells to “protect” the opening to allow photosynthesis in and out and water to move out