BIO 103 JMU McMullen Exam 2 - topic 5

the cell theory

all living organisms are composed of one or more cells

an organism’s chemical reactions take place within its cells

all cells arise from preexisting cells via cell division

eukaryotic cells

all organisms comprised of cells with TRUE NUCLEI are members of Domain Eukarya

eukaryotic cells have a cell membrane, chromosomes comprised of DNA and proteins (surrounded by a double membrane called the nuclear envelope, forms the nucleus), and within their cytoplasm are various membrane-bound organelles, like chloroplasts and mitochondria

the plant cell

have a cell wall to the outside of the cell or plasma membrane, which helps support the cell

nonliving boundary produced by the cell

• chloroplasts, nucleolus, ribosomes, large central vacuole, mitochondrion, cell membrane, cell wall

large central vacuole: liquid filled sac surrounded by a single membrane called the tonoplast, contains a watery substance called cell sap

chloroplasts

contain membranous sacs called thylakoids

grana = stacks of thylakoids

fluid surrounding grana = stroma

embedded on the inner surface of the thylakoid membranes = chlorophyll molecules (the pigment used in photosynthesis

cell or plasma membrane

regulate the movement of materials (such as food molecules and wastes)

lets some things through, but stops others

how do molecules move through membranes

simple diffusion

facilitated diffusion

active transport

simple diffusion

movement of molecules from higher concentration to lower concentration

results in molecules being evenly distributed (equilibrium)

a few substances can do this (water)

osmosis

movement of water molecules across a differentially permeable membrane

occurs from a solution of high water potential (more water) to a solution with lower water potential (less water)

hypertonic solution

more solute (lower water potential)

hypotonic solution

less solute (higher water potential)

plasmolysis

occurs when a plant cell is placed in a hypertonic solution (more solute), a plant will wilt and die when exposed to such conditions for a long time

• when a plant cell is placed in a HYPOTONIC solution, water will diffuse into the cell. this causes the large central vacuole to press up against the cell wall

facilitated diffusion

some molecules (sugars, amino acids, nucleotides) cannot move through plasma membranes by simple diffusion

need help from a transport protein!

active transport

some molecules cannot diffuse through membranes, need help of transport proteins called pumps

these proteins can move molecules against a concentration gradient

plant organs

3 major vegetative organs

roots, stems, leaves

plant tissue systems

ground, vascular, dermal

ground tissue system

carries out photosynthesis, stores photosynthesis products, helps support the plant

vascular tissue system

conducts water and solutes throughout the plant

dermal tissue system

the outer covering of the plant

parts of a leaf

lamina (blade): expanded portion

petiole: stalk-like portion

stipules: small scale-like structures

~ cuticle, epidermis, palisade mesophyll, vein, sponge mesophyll, stomata, lower epidermis

specialized leaves

tendrils, spines, storage leaves, reproductive leaves, floral leaves, insectivorous leaves

tendrils

help some plants hold on to other objects and climb

spines

leaves that have been modified for reduction of water loss and/or protection

storage leaves

retain large amounts of water (succulents) and/or carbohydrates (bulbs)

reproductive leaves

allow some plants to reproduce asexually

floral leaves

these are associated with certain plants that produce flowers with very small or no petals

insectivorous leaves

these allow plants to live in soils that may be poor in nitrogen

phytomere (stem)

node: space where stem branches off

leaf

axillary bud: emerging from node

internode: stem

stem structure

in some stems, the vascular tissue develops into a system of discrete scattered bundles

in other stems, there is a ring of discrete strands of vascular tissue separated from each other by ground tissue

in other stems, there is a continuous ring of vascular tissue

specialized stems

bulbs, thorns, tubers, rhizomes, stolons (runners), succulents, tendrils

bulbs

specialized stems that function in dormancy

thorns

stems that have been modified for protection

tubers

underground stems that have been modified for food storage

rhizomes

underground, horizontal stems that function in vegetative growth

stolons (runners)

above ground, horizontal stems that function in vegetative growth

succulents

stems that have been modified for water storage

tendrils

stems that help some plants hold on to other objects and climb

root morphology

taproot system

fibrous root system

taproot system

primary root (taproot) + lateral or branch roots

fibrous root system

adventitious roots + lateral or branch roots

root structure

root cap

region of cell division

region of elongation

region of maturation

root cap

protects the apical meristem, as the cells grow older they die and slough off, this also forms a slimy lubricant that helps the root move through the soil

region of cell division

the apical meristem, plus the nearby portion of the root where cell division also occurs

region of elongation

responsible for most of the increase in length of the root

region of maturation

where most of the cells mature

as with some stems, some roots become

woody

specialized roots

food storage

water storage

pneumatophores

prop roots

food storage

most roots are storage organs, but in some plants the roots are extra specialized for this function

water storage

roots are extra specialized for this function

pneumatophores

these special roots help plants take in oxygen when the soil itself is oxygen poor

prop roots

these special roots help plants stay upright in unstable soil