Botany Exam 1

protoplast

contents of the cell which push against the cell wall for structure

middle lamella

how cells are glued together, it is a pectin layer

cell wall composition (3 main things, 5 more)

cellulose, hemicellulose, pectin

lignins, callose, cutins, suberins, waxes

cellulose

repeating monomers of glucose that make up the principle component of cell walls. microfibrils that bundle together like cable (high strength)

hemicellulose

determines how stretchy a cell can be. microfibrils linked via H+ bonds that regulate cell enlargement.

pectin

hydrophilic polysaccharides which gives the wall pliability (stretchy). Cross linked with calcium after elongation prevents further stretching.

callose

spirally wound chains of glucose that rapidly accumulate following wounding. seals off plasmodesmata. QUICK

cutins, suberins, and waxes

protective tissues

lignin

complex polymer that makes cell walls stronger, more waterproof, and more resistant to damage from pests. found in later formed cells with supportive functions

pits

where secondary wall is not laid because there is thin primary cell wall for both cells that are connected

plasma membrane

regulates the in and out, located on the inside of the cell wall

symplast

when protoplasts are interconnected so cytoplasm is continuous

apoplast

all intercellular space and cell walls together

nucleus

contains genome and is surrounded by nuclear envelope

mitochondria

double membrane, site of aerobic respiration, creates ATP

vacuole

most plant cells have a large central vacuole. it is surrounded by a membrane called the tonoplast. immature cells have many that then fuse into one with maturity. contains a liquid called the cell sap, stores ions and creates turgor pressure to keep the cell rigid.

plastids

organelles involved with photosynthesis and storage, double membrane, divide by fission, originated by endosymbiosis

primary endosymbiosis

one cell is taken up by another and retained internally so the two cells live together and integrate

endosymbiotic theory

mitochondria and plastid evolved from prokaryotes that took up an endosymbiotic relationship with the host cell

• both of them are double membraned

• both replicate by fission (what bacteria does)

• have their own genome

secondary endosymbiosis

free living organism engulfs product of primary endosymbiosis

• have 4 membranes

types of plastid (5)

proplastid, chloroplast, chromoplast, leucoplast, etioplast

proplastid

undifferentiated, precursor to all other types, found in young and rapidly dividing cells.

chloroplast

have their own DNA, function for photosynthesis, also involved with amino acid and fatty acid synthesis

chromoplasts

pigmented plastid, forms from chloroplasts and internal membranes and chlorophylls disappear, carotenoides accumulate

leucoplasts

colorless plastid, most undifferentiated type, lack pigment and internal structure, storage and synthesis of materials

• starch = amyloplast (synthesis and long term starch storage)

• lipids = elaioplast (form when development of chloroplast is arrested by absence of light, quicky convert back after light exposure)

• proteins = proteinplasts

etioplast

form when there is no light exposure to the plant, converts back to chloroplast after light exposure

when cells are unicellular…

each cell must perform all tasks

when cells are multicellular…

allows for specialization and division of labor among different cell types

2 steps of plant development

growth- irreversible increase in size, cell division and cell expansion

differentiation- cells assume a particular identity and function

meristems

region of specialization where new cells arise. These new cells are totipotent which means they have the potential to differentiate into any cell type

Major types of meristems

apical, axillary, secondary/lateral, intercalary

apical meristem

produce primary tissues at stem and root tips, increase the length of the plant

axillary meristem

produce primary tissues in the axis of leaves, also forms branches

secondary/lateral meristem

produce secondary tissue, vascular cambium and cork cambium, increase the girth of the plant

intercalary meristem

middle of differentiated tissue, increase length of stem from within, found in grasses

root apical meristem

found at the tips of roots

shoot apical meristem

found at the tips of stems and branches

organized in layers and in radial zones

SAM organization

central zone- infrequent cell division, no differentiation

peripheral zone- cell division and differentiation, give rise to cells that will contribute to leaves, inflorescence and flower meristems

rib zone- cell division and differentiation,, gives rise to cells that will contribute to stems

meristematic divisions

anticlinal and periclinal

three types of plant tissue

ground, dermal, and vascular

ground tissue

bulk of plant body, can be specialized for many functions including storage

• parenchyma, collenchyma, and sclerenchyma

dermal tissue

outer protective layer

• epidermis and periderm

vascular tissue

conducting tissues

• xylem and phloem

xylem

transports water, on the inside, cell types are tracheary elements, fibers, and parenchyma

phloem

transports sugar and other solutes, on the outside

simple tissues

composed of only one cell type

• ground tissue

complex tissue

composed of multiple cell types

• vascular and dermal tissues

three tissues location in eudicot stem image

three tissues in eudicot root image

three tissues in eudicot leaf image

what primary meristem did each of the three tissues develop from

ground = ground meristem

dermal = protoderm

vascular = procambium

parenchyma

thin primary cells wall, totipotent (all other cells differentiate from parenchyma), have two functional types

• meristematic parenchyma: totipotent, abundant cytolplasm

• chlorenchyma: chloroplasts containing cells, function in photosynthesis

aerenchyma

intercellular air space in parenchyma, common in aquatic plants because it helps with buoyancy, gas exchange and structure

secretory parenchyma

lines secretory canals, secretes nectar, fragrances, mucilage, resins and oils

collenchyma

living cells at maturity, unevenly thickened primary cell wall with no lignified secondary cell wall, more differentiated than parenchyma, function in flexible support, primarily in cortex of young plants

sclerenchyma

dead cells at maturity, uniformly thick cell walls, rigid support, found in mature plant organs

• two types are sclereids and fibers

tracheary elements

cell type of xylem, dead at maturity, transport water and inorganic nutrients from ground to crown

• tracheids are narrow, tapering end wall, long and in all vascular plants, form a series, water flows through pit pairs

• vessel elements are wide, blunt end wall, shorter, stack to form a vessel, water flows through pit pairs and perforations

sieve elements

principle conducting cells of phloem, living at maturity

• gymnosperms have sieve cells

• flowering plants have sieve tube elements with sieve plates

companion cells

each sieve tube element is associated with one, they deliver information, proteins and ATP to sieve element

epidermis

outer protective layer of plant, compact, typically covered with cuticle (cutin and wax)

stomata

allow gas exchange through the epidermis and cuticle

trichomes

hairlike appendages, for protection, slow transpiration and absorption

5 functions of the stem

support leaves

transport water and solutes

storage

photosynthesis

produce flowers

turgor pressure

cells are so full of water it pushes against cell wall to make them more rigid, how the plants stands up

shoot

above ground part of plant (stem, leaves, flowers)

nodes

where leaves are attached

internodes

regions between nodes

leaf axil

above point of leaf attachment, contains the axillary bud, miniature shoot with dormant apical meristem and several young leaves

terminal bud

at the extreme tip of each stem

typical eudicot stem image

stele

axial cylinder of vascular tissue in stems and roots

typical monocot stem image

no stele, less structure

tendrils

slender threadlike stem of a climbing plant

cladophyll

flattened, leaflike stem

corm

short, fat, underground stem

stolen

horizontal, above ground stem

rhizome

horizontal, underground stem

tuber

storage end of a rhizome (potato)

image of leaf buttresses location

occur further back in development

image of leaf primordia location

phyllotaxis

leaf pattern of movement when they come off (spiral, opposite (decussate), alternate (distichous), whorled)

alternate phyllotaxis

1 leaf per node, distichous is two opposite vertical rows

spiral phyllotaxis

1 leaf per node, organs come off 1 per node but do not form two ranks

opposite phyllotaxis

2 leaves per node, decussate is successive leaf pairs are at a 90-degree angle

whorled phylootaxis

3+ leaves per node, rare

incipient place

place where next primordium will form, then leaf develops from leaf primordium

plastochron

time between development of successive primordia

abaxial surface vs adaxial surface

abaxial is the bottom that faces away from the sky (lower epidermis, where the stomata is) and adaxial faces toward the sky (upper epidermis)

petiole

leaf stalk that connects the lamina to the stem, allows leaves to flutter in the wind

sheathing leaves

leaves that have no petiole, base wraps around the stem

simple leaves

undivided blade, could still be lobed or unlobed

compound leaves

divided blade, prevent tearing, increase heat removal and CO2 uptake, pests or disease spreads less quickly

pinnately compound leaf

leaflets come out of different locations

palmately compound

all leaflets come out of the same location

doubly compound leaf

two leaflets coming out of each location (pinnately x2)

how to determine a simple leaf from a pinnately compound leaf

• leaflets never bear buds in the axils of their petioles

• the tip of the rachis (stem part of the leaflet) never has a terminal bud

• leaflets are always arranged in two rows, never in a spiral, whorled, or decussate phyllotaxy

ovate leaf shape

your basic leaf

• ovate, obviously

cordate leafe shape

heart shape leaf, common in red buds, also called cordiform

• cordate, can I ask you on a date

lanceolate leaf shape

skinny, very veiny

• sir lanceolate is very skinny

needle like leaf shape

obviously just a needle (pine)