OUTLINE!

(1) Microscopy A. Dissecting Microscope

B. Compound Microscope

(2) Preliminary Microscopic Work (3) Magnification and Reduction (4) Two Types of Seed Plant (5) Structure of Plant Cells (6) Cell Types and Tissues (7) Mitotic Cell Division (8) Plant Physiology

A. Osmosis

B. Plasmolysis

C. Cell Turgidity

(9) Kinds of Root System (10) Structure of Root Tip (11) Internal Structure of a Monocot Root (12) Internal Structure of a Dicot Root (13) Specialized Roots

Dissecting microscope

live specimens 3D too large or thick Specimens can be physically manipulated under

magnification, since they do not have to be

mounted onto a slide

low magnification, 10x to 80x magnification, the range depending on the make and model

PARTS OF A DISSECTING MICROSCOPE

1. Stereo Head - moveable top portion with two adjustable eyepieces, similar to binoculars.

2. Ocular Lenses 2 eyepieces, viewer looks through. each set at 10x magnification, though it

is possible to upgrade to higher power

magnification levels.

3. Diopter - Since no two eyes are exactly alike, slight adjustments can be made to the ocular lens

to compensate for the differences, using the

rotating diopter ring found on one or both of the

ocular lenses, allowing both eyes to focus on a

single image clearly.

4. Objective Lens - extends down from the head of the microscope, toward the stage.

magnification is determined by the eyepiece and

objective lenses collectively. Often, stereo

microscopes have two separate objectives, each

one connecting to one of the eyepieces.

5. Rotating Objective Turret - magnification of the objective, zoom control knob

6. Focus Knob - The head of the microscope can be moved up and down with the focus knob,

rack and pinion focusing.

7. Stage Plate - viewing. on base of the microscope, directly under the objective lens.

metal stage clips hold a glass slide in place. The

background color of the stage can be alternated

for optimal contrast with the specimen, usually,

with either white or black stage inserts.

8. Lighting - Many microscopes have both top and bottom lighting. Top lighting shines down on the

stage to light up solid specimens with direct

illumination, and bottom lighting is transmitted

up through the stage to highlight translucent

objects.

9. Light Switch - Usually the light switch or switches can be found on the top or back of the

microscope base. A light source should be

turned on before making any adjustments to the

lenses or observing specimen. Often it is

equipped with a dimmer, which allows the user

to set the desired level of illumination.

PLANT STRUCTURE

The "Typical" Plant Body

1. The Root System

Underground (usually) Anchor the plant in the soil Absorb water and nutrients Conduct water and nutrients Food Storage

2. The Shoot System

Above ground (usually) Elevates the plant above the soil photosynthesis reproduction & dispersal food and water conduction

Note: the shoot system includes the leaves and

the reproductive organs

Two Types of Seed Plants

Monocots Dicots

Roots Fibrous Taproot

Growth Primary only Primary and

Secondary

Examples: Grass, Palm,

Orchid

Oaks, Roses,

Sunflowers

Plant Growth Plant growth is a phenomenon different from

animal growth.

1. Animals pattern determinate growth. After fertilization, the zygote cells are rapidly

dividing, undifferentiated cells

after a certain critical stage, the cells differentiate and form tissues.

From this point onward, their developmental fate is sealed

There are exceptions to this (i.e. stem cells in bone marrow)

Most animals have a pre-programmed body plan (i.e. barring mutation or accident, a heart with

four chambers, etc..)

quit growing after a certain age

2. Plants- indeterminate growth The plant retains areas where rapidly dividing,

undifferentiated cells remain all through the life

of the plant

These areas are called meristems

Meristematic tissue continues to rapidly divide producing undifferentiated cells

which may eventually differentiate to

form the tissue and cell types

Plants do not have a pre-programmed body plan There are constants like leaf shape and

branching patters (opposite, alternate,

etc.) but you can never predict where a

new branch will come about on a tree...

Plants continue to grow throughout their life

CELL TYPES IN THE PLANT BODY

Meristems

The pattern of plant growth depends upon the location of meristems

I. Meristematic Tissues (Meristems) Tissues where cells are constantly dividing, and

produce new cells.

The new cells usually have tiny vacuoles with large nucleus.

The pattern of plant growth depends upon the location of meristems

3 types of Meristems:

1. Apical Meristems - are located at or near the tips of

roots and shoots. The growth increase in length. (grow

up for shoots and down for roots) Located at the tips of

roots and shoots supply cells for the plant to increase in

length .

growth in this direction is primary growth primary growth in monocot &dicot, the vertical

growth of roots and shoots

Example: Growth of tree in height

2. Lateral Meristems - account for secondary growth

in plants. (cambium)

located near the periphery of the plant, usually in a cylinder

supply cells for the plant to increase in girth growth known as as secondary growth found in all woody& some herbaceous plants lateral meristems and secondary growth found only

in dicots

- Secondary growth is the horizontal growth

Example: Growth of tree in girth

3. Intercalary Meristems a region of dividing cells at each internode that allows the stem to grow rapidly. It is

responsible for the regrowth of cut grass

II. Permanent Tissues (Nonmeristematic Tissues) Tissues that do not actively produce new cells. It is made of cells that are produced by the

meristems and are formed to various shapes and

sizes depending on their intended function in the

plant.

2 Types of Permanent Tissues: A. Simple Tissues - one type of cell

A.1 Epidermis

forms a protective covering over herbaceous roots and stems, leaves, and other plant

structures.

functions - prevent entry of pathogenic organisms into the plant ; to prevent excessive

water loss.

Very important in regulating passage of water and gases into and out of the plant.

Cells in the Epidermis:

Trichome a hairlike extension of a dermal cell

Stoma (plural, stomata) a pore in a leaf regulated by two guard

cells; controls the movement of water

vapor, CO2 and O2.

Guard cell one of the two epidermal cells on either

side of a leaf pore

Ground cell at maturity lack chloroplast, and can

produce Cutin, a fatty substance, which

forms a waxy protective layer called the

cuticle. It prevents water loss.

A.2 Parenchyma

Least specialized plant cells Thin and somewhat flexible cell walls Living at maturity Carry on most of the plant's metabolic functions

food and water storage, photosynthesis, gas exchange, maintenance of turgor

pressure, and wound repair.

Generally have a large central vacuole Most parenchyma cells have the ability to

differentiate into other cell types under special

conditions

During repair and replacement of organs after injury

A.3 Sclerenchyma

Thick secondary cell walls Dead at functional maturity More expensive for plants to produce because of

the added cellulose needed to provide the

secondary cell walls

Less common in smaller plants than parenchyma and collenchymas.

Cannot increase in length - occur in parts of the plant which have quit growing in length

Two types - fibers and schlerids Fibers - long, slender cells with a more

or less regular secondary cell wall

reinforced with lignin w/c make them

flexible and strong

Example - hemp fibers for making rope

(stems, trunk of a tree)

Schlerids - shorter cells with an irregular shape (cubical and spherical in shape)

Example - stone cells in pears and hard

nut and seed shells (rough texture/gritty

sand like texture)

*Lignin substance which act as a binder for the cellulose fibers in wood and certain plants and adds

strength and stiffness to the cell walls

A.4 Collenchyma

Thicker primary cells walls (usually with uneven thickness)

These cells have a living protoplasm, like parenchyma cells, and may also stay alive for a

long period of time.

Distinguishing difference from parenchyma cells is the increased thickness of their walls.

Found just beneath the epidermis Living at maturity Role in support of herbaceous plants

Example - the "strings" of celery

B. Complex Tissues - several types of cell / mixed types

of cells; primary functions include the transport of water,

ions and soluble food substances throughout the plant.

XYLEM

Thick secondary cell walls, often deposited unevenly in a coil-like pattern so that they may

stretch

Dead at functionally maturity. Involved in conduct of water and ions in the

plant

Two types - tracheids and vessels Tracheids - long, slender cells connected

to each other by pits. Found in all

vascular plants which are long cells with

tapered ends which are considered water

conducting cells of ferns, conifers and

other non-flowering vascular plants

Vessels - shorter, larger diameter cells with completely perforated cell wall

ends. Found only in Angiosperms

which are water-conducting cells of

most flowering plants and can transport

water and minerals more rapidly than

tracheids. Vessel elements are wider,

shorter and less tapered than tracheids.

PHLOEM

The food-conducting tissue Involved in transport of sucrose, other

organic compounds, and some ions

contains companion cells which has a nucleus and provides proteins to a sieve-tube member

adjacent to it.

Living at functional maturity Protoplast may lack organelles and

nucleus, though

Endwalls connect to each other via sieve-plates Two types of cells in the phloem - sieve-tube

members and companion cells

Sieve-tube members - actual conduit for sucrose transport

Companion cells - has a nucleus that may also control the sieve-tube element

and may aid in sucrose loading

TISSUE ORGANIZATION IN ANGIOSPERM

Dermal Tissue Generally a single layer of cells The "skin" of the plant Primarily parenchyma cells Main role is protection of the plant

Ground Tissue Makes up the bulk of the plant Predominately parenchyma, but collenchyma

and schlerenchyma cells are found

Diverse functions including photosynthesis, storage, and support

Vascular Tissue Involved in the transport of water, ions,

minerals, and food

Also has a secondary role in support Composed of xylem, phloem, parenchyma,

schlerenchyma

MITOTIC CELL DIVISION

Mitosis is nuclear division plus cytokinesis, and

produces two identical daughter cells during prophase,

metaphase, anaphase, and telophase.

Interphase is often included in discussions of mitosis,

but interphase is technically not part of mitosis, but

rather encompasses stages G1, S, and G2 of the cell

cycle.

1. INTERPHASE

The cell is engaged in metabolic activity and performing its prepare for mitosis (the next four

phases that lead up to and include nuclear

division). Chromosomes are not clearly

discerned in the nucleus, although a dark spot

called the nucleolus may be visible. The cell

may contain a pair of centrioles (or microtubule

organizing centers in plants) both of which are

organizational sites for microtubules.

2. PROPHASE Chromatin in the nucleus begins to condense and

becomes visible in the light microscope as

chromosomes. The nucleolus disappears.

Centrioles begin moving to opposite ends of the

cell and fibers extend from the centromeres.

Some fibers cross the cell to form the mitotic

spindle.

3. METAPHASE The nuclear membrane dissolves, marking the

beginning of prometaphase. Proteins attach to

the centromeres creating the kinetochores.

Microtubules attach at the kinetochores and the

chromosomes begin moving. Spindle fibers

align the chromosomes along the middle of the

cell nucleus.

This line is referred to as the metaphase plate. This organization helps to ensure that in the next

phase, when the chromosomes are separated,

each new nucleus will receive one copy of each

chromosome.

4. ANAPHASE The paired chromosomes separate at the

kinetochores and move to opposite sides of the

cell. Motion results from a combination of

kinetochore movement along the spindle

microtubules and through the physical

interaction of polar microtubules.

5. TELOPHASE Chromatids arrive at opposite poles of cell, and

new membranes form around the daughter

nuclei. The chromosomes disperse and are no

longer visible under the light microscope. The

spindle fibers disperse, and cytokinesis or the

partitioning of the cell may also begin during

this stage.

6. CYTOKINESIS Cytokinesis (kytos = hollow vessel = cell, and

kinesis = movement)

the two daughter cells become independent. During cytokinesis (example in Bellevalia) that

follows up the actual mitosis, the cytoplasm of

the daughter cells is divided by a cell membrane

(and in plants also a cell wall) in two single

compartments.

In animal cells the separation of the new cells involves a cleavage furrow that pinches the cell

membrane.

In plants, this process is characterized by the formation and growth of a cell plate (example

in Solanum sp.) that expands from the space

between the two daughter nuclei towards the cell

periphery. Sometimes remants of the spindle

(phragmoplast) are involved in the attachment of

this new wall.

TERMS IN MITOSIS

kinetochore - is the protein structure on chromatids where the spindle fibers attach during cell division to

pull sister chromatids apart.

chromatin - combination of DNA and proteins that make up the contents of the nucleus of a cell.

centromere - part of a chromosome link sister chromatids

chromatid - is one copy of a duplicated chromosome, which generally is joined to the other

copy by a centromere for the process of nuclear

division

Biological importance of mitosis

Growth Asexual reproduction Cell replacement

PLANT PHYSIOLOGY

A. Osmosis

The net movement of water across a partially permeable membrane from a region of high

solvent potential to an area of low solvent

potential, up a solute concentration gradient.

It is a physical process in which a solvent moves without input energy across a semi permeable

membrane separating two solutions of different

concentrations.

Osmosis releases energy and can be made to work as when growing tree root splits a stone.

B. Plasmolysis

A solution that is separated from another solution by a semi-permeable membrane can

have three osmotic states:

In an isotonic solution is the pressure at both sides of the membrane the same.

A hypotonic solution has a lesser number of solute particles than the solution to which it is

compared, while

a hypertonic solution has a higher number of solute particles. At equilibrium is a solution

always isotonic

C. Cell Turgidity

turgor pressure - When a plant cell stores ions, sugars

and other solutes in its vacuole, this causes an influx of

water. The influx of water results in a large turgor

pressure exerted on the plant cell wall. This makes plant

cells to become turgid, thus, helping the plants to stand

upright, and do not wilt.

KINDS OF ROOT SYSTEMS

1. TAP ROOT SYSTEM The taproot is usually relatively large in

diameter and extends more deeply than the

plant's other roots, and often has additional

lateral (secondary) roots

The easiest designation of taproot is the carrot (Daucus carota), where the lateral (secondary)

roots are very thin, so it has a single, thick

central root.

Common in dicots develops from an embryonic root called the

radicle

perennial and undergo secondary growth examples of plants having a tap root system:

carrots, beets, radishes and sunflowers

2. FIBROUS/ADVENTITOUS Fibrous roots are typically thought of as slender,

mass of similarly sized roots and often with few

or no lateral roots.

Fibrous roots do not arise on pre existing roots and they are not radicles thus they are called

adventitious roots.

Common in monocots do not undergo secondary growth examples of plants having a fibrous root system

are wheat, rice, corn, and sweet potatoes;

important in stoloniferous and rhizomatous

plants

DIFFERENCE OF A YOUNG PLANT FROM A

MATURE PLANT A young dicot plant has a few leaves and a small root

system, the narrow trunk with a few vascular bundles

can conduct water and nutrients between them. A mature

dicot has more leaves and a larger root system, the stem

has more wood and bark, which increases the capacity to

conduct water and sugar. Monocots do not undergo

secondary growth so a mature monocot does not have a

stem that is wider than the young monocot.

Consequently, the mature monocot has no more leaves

or roots than the young monocot.

STRUCTURE OF ROOT TIP

Primary Growth in the Root

a. Root Cap

Thimble-like covering which protects the delicate apical meristem

Produced from cells derived from the root apical meristem

Secretes polysaccharide slime lubricates soil Constantly sloughed off and replaced

b. Apical Meristem

Region of rapid cell division of undifferentiated cells

Most cell division is directed away from the root cap

c. Quiescent Center

Populations of cells in apical meristem which reproduce much more slowly than

other meristematic cells

Resistant to radiation and chemical damage Possibly a reserve which can be called into

action if the apical meristem becomes

damaged

d. The Zone of Cell Division - Primary Meristems

Three areas just above the apical meristem that continue to divide for some time

Protoderm - outermost primary meristem - produces cells which will become dermal

tissue

Ground meristem - central primary meristem - produces cells which will

become ground tissue

Procambium - innermost primary meristem - produces cells which will become vascular

tissue

e. The Zone of Elongation

Cells elongate up to ten times their original length

This growth pushes the root further downward into the soil

f. The Zone of Maturation

Region of the root where completely functional cells are found

INTERNAL STRUCTURE OF A MONOCOT

ROOT

Epidermis Dermal tissue Protection of the root

Cortex Ground tissue Storage of photosynthetic products Active in the uptake of water and minerals

Endodermis cylinder once cell thick that forms a

boundary between the cortex and the stele

Even more distinct than dicot counterpart Contains the casparian strip the innermost tissue of the cortex in many

roots and stems.

Stele The cylindrical central vascular portion of the

axis of a plant that is made up of the pericycle,

conducting tissues and the pith.

Pericycle A thin layer of parenchyma or sclerenchyma

cells that surrounds the stele in most vascular

plants.

Vascular Tissue Xylem and Phloem Forms a ring near center of plant

Pith Center most region of root

INTERNAL STRUCTURE OF A DICOT ROOT

Epidermis Dermal tissue Protection of the root

Cortex Ground tissue

Storage of photosynthetic products

Active in the uptake of water and minerals

Endodermis Cylinder once cell thick that forms a boundary

between the cortex and the stele

Contains the casparian strip, which will be explained later when we discuss water uptake

the innermost tissue of the cortex in many roots and stems.

Pericycle found just inside of the endodermis

may become meristematic

responsible for the formation of lateral roots

Vascular Tissue Xylem and Phloem

Forms an X-shaped pattern in very center of root

SPECIALIZED ROOTS

1. NODAL ROOTS 2. AERIAL ROOTS

Orchids are epiphytes. Epiphyte is a plant that derives its moisture and nutrients from the air

and rain and grows usually on another plant.

Roots spread along the surface of the bark and often dangle freely in the air.

The root epidermis of orchids is called the velamen. The velamen acts as a waterproof

barrier, not permitting water to leave the sides of

the root.

3. PROP ROOTS Banyan tree (genus Ficus) produce adventitious

roots which provide increased support and

absorptive capacity.

Palm tree produce adventitious root near the base of the stem and provides extra absorptive capacity and

extra stability.

Screwpine is able to produce extremely long adventitious prop roots that not only stabilize the

large, heavy trunk but laos bring water and minerals

into the stem.

4. BUTTRESS 5. CONTRACTILE

a. The root is firmly fixed to the soil and the stem is pulled downward so that the base of

the shoot is either kept at soil level or, in the

case of bulbs, actually buried deeper.

b. Root contraction is the means by which the shoot becomes anchored in the soil.

c. Common in bulbous plants

6. PNEUMATOPHORES 7. CAUDEX/LIGNOTUBERS 8. HAUSTERIAL

a. A number of angiosperms are parasites because their substrate is the body of

another plant.

b. These roots adhere firmly to their host either by secreting an adhesive or by growing

around a small branch or root.

c. Host-Parasite relationship - Parasitism, they live in another plants body in order to

survive; Mostly attack the xylem but the

parasite carries out its own photosynthesis.

9. STRANGLING ROOTS 10. ROOT TUBERS