Plant Anatomy

Cell

Photosynthetic eukaryotes of the kingdom Plantae.

Cell wall

A structural layer that surrounds some cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with structural support, shape, protection, and functions as a selective barrier.

Protoplast

Cells that have had their cell walls removed by treatment with cellulytic enzymes

Plasma Membrane

Lipid bilayer structure that contains the cellular contents.

Cytoplasm

Inside this there are several types of membrane bound structures (Organelles).

Organelles

Specialized structures within a living cell.

Eukaryote

These kinds of cells contain a nucleus that is separated from the cytoplasm by a membrane.

Prokaryote

A single-cell organism whose cell lacks a nucleus and other membrane-bound organelles.

Nucelus

Contains chromatin/chromosomes

Transcription & RNA splicing

Nucleolus – ribosome subunit assembly

Bounded by nuclear envelope containing nuclear pores

Nuclear envelope

It is made up of two lipid bilayer membranes that in eukaryotic cells surround the nucleus, which encloses the genetic material.

Chromatin

A complex of DNA and protein found in eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures.

Chromosomes

Thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA).

Haploid

The presence of a single set of chromosomes in an organism's cells.

Diploid

A term that refers to the presence of two complete sets of chromosomes in an organism's cells, with each parent contributing a chromosome to each pair.

Nucleolus

A spherical structure found in the cell's nucleus whose primary function is to produce and assemble the cell's ribosomes

Ribosome

An intercellular structure made of both RNA and protein, and it is the site of protein synthesis in the cell.

Chloroplast

Bounded by two membranes (inner & outer)

Internal thylakoid membranes and stroma

Contain their own genome

Import majority of proteins from cytoplasm

Maternally inherited – transgenics contained

Biosynthetically very active

Contains chlorophyll

Plastid

A membrane-bound organelle found in the cells of plants, algae, and some other eukaryotic organisms.

Chromoplast

Plastids that contain pigments other than chlorophyll

Typically contain carotenoids

(yellow, orange, red colors)

Leucoplast

Plastids lacking pigments

No internal membrane structures

One type is amyloplasts which store starch

Etioplasts

Immature plastids

Contain rudimentary internal membrane structures called prolamellar bodies

Outer membrane

Contains porins and is therefore freely permeable to small molecules.

Inner membrane

Impermeable to ions and metabolites, which are therefore able to enter chloroplasts only via specific membrane transporters.

Inner membrane space

The region between the inner membrane and the outer membrane of a mitochondrion or a chloroplast.

Thylakoids

Tiny compartments found inside of chloroplasts. Their role is to help absorb sunlight in order for photosynthesis to occur.

Stroma

The colorless fluid surrounding the grana within the chloroplast.

Grana

Stacks of structures called thylakoids which are little discs of membrane on which the light-dependent reactions of photosynthesis take place.

Chlorophyll

The natural compound present in green plants that gives them their color. It helps plants to absorb energy from the sun as they undergo the process of photosynthesis.

Carotenoids

Essential for photosynthesis and photoprotection. They play critical roles as light harvesting pigments and structural components of photosystems.

Transitory starch

The starch which is synthesized in the leaves directly from photosynthates during the day

Proplastids

Undifferentiated plastids, mainly found in meristematic and reproductive tissues, identified as being small and having clear ultrastructures. “Mother” plastid.

Amyloplast

A colorless plant plastid that forms and stores starch.

Prolamellar body

A periodic bicontinuous membrane structure based on tubular tetrahedral units

Mitochondria

Produce the energy necessary for the cell's survival and functioning. Through a series of chemical reactions, mitochondria break down glucose into an energy molecule known as adenosine triphosphate (ATP), which is used to fuel various other cellular processes.

Respiration

Using the sugars produced during photosynthesis plus oxygen to produce energy for plant growth.

Peroxisomes

Membrane-bound organelle occurring in the cytoplasm of eukaryotic cells. Peroxisomes play a key role in the oxidation of specific biomolecules.

Endoplasmic reticulum (ER)

The endoplasmic reticulum can either be smooth or rough, and in general its function is to produce proteins for the rest of the cell to function

Golgi body

A cell organelle that helps process and package proteins and lipid molecules, especially proteins destined to be exported from the cell.

Vacuole

Membrane-bound organelle that has three main functions which are to provide the plant with support or rigidity, a storage area for nutrients and waste matter and can decompose complex molecules.

Tonoplast

The membrane that surrounds the large vacuole in a mature plant cell.

Cytosol

Major intracellular fluid that acts as the medium for inter-organellar crosstalk and where a plethora of important biological reactions take place.

Transcription

The process with which DNA is copied into RNA.

Translation

The process in living cells in which proteins are produced using RNA molecules as templates.

Rough ER

Has ribosomes on it, which are small, round organelles whose function it is to make those proteins.

Smooth ER

Main function is to make cellular products like hormones and lipids.

Shoot

Consists of any plant stem together with its appendages like leaves, lateral buds, flowering stems, and flower buds.

Phytomere

Functional units of a plant, continually produced by root and shoot meristems throughout a plant's vegetative life-cycle. I

Leaf

A flattened structure of a higher plant, typically green and blade-like, that is attached to a stem directly or via a stalk.

Node

The point on a stem where a leaf or leaves are, or have been attached

Internode

Intervals on the stem between the nodes are called this.

Axillary meristem (bud)

The axillary bud (or lateral bud) is an embryonic or organogenic shoot located in the axil of a leaf.

Branch

A natural subdivision of a plant stem.

Tunica/Corpus

The layers of this normally contribute to the surface layers of the plant (L1, L2), and the correlating part provides the deeper lying tissues (L3)

Anticlinal

Occurring at right angles to the surface or circumference of a plant organ. an anticlinal pattern of cell walls.

Periclinal

Parallel to the surface of an organ or part. The plane of division is parallel to the surface of the plant body.

L1,L2, L3

The single layer of cells making up the epidermis, the single cell sub-epidermal layer and the last layer constitutes the rest of the internal cells.

Central zone

Located at the meristem summit, where a small group of slowly dividing cells can be found.

Peripheral zone

Where new leaf and flower primordia originate and the rib meristem cells are differentiating into cells contributing to the stem and inner parts of the plant.

Ground tissues

All tissues that are neither dermal nor vascular.

Protoderm

A thin outer layer of the meristem in embryos and growing points of roots and stems, which gives rise to the epidermis.

Procambium

The part of the primary meristem of a plant that forms cambium and primary vascular tissues.

Ground meristem

The meristem that develops into all other plant tissues apart from vascular and dermal tissues

Knotted1 (KN1)

Defined by several dominant gain-of-function mutations that alter leaf development. Foci of cells along the lateral veins do not differentiate properly, but continue to divide, forming outpocketings or knots.

Shootmeristemless (STM)

Required for maintenance of undifferentiated cells in shoot and floral meristems and acts at a different regulatory level than the meristem genes.

Wuschel (WUS)

Required for maintenance of stem cell populations in shoot and floral meristems.

Clavata (CLV)

Promote the progression of meristem cells toward organ initiation.

Etiolated

Pale and drawn out due to a lack of light.

Cotyledon

An embryonic leaf in seed-bearing plants, one or more of which are the first leaves to appear from a germinating seed.

Hypocotyl

The part of the stem of an embryo plant beneath the stalks of the seed leaves or cotyledons and directly above the root.

Photomorphogenesis

The process by which plants use light to control their growth and development.

Phytochromes

Red (R)/far-red (FR) light photoreceptors that play fundamental roles in photoperception of the light environment and the subsequent adaptation of plant growth and development.

RNA in situ hybridization

A type of hybridization that uses a labeled complementary DNA, RNA or modified nucleic acid strand to localize a specific DNA or RNA sequence in a portion or section of tissue or if the tissue is small enough, in the entire tissue, in cells, and in circulating tumor cells.

Chemical fixation

Carried out to preserve the morphologies and physical properties at the living states of the specimen as much as possible

Embedding

A process in microscopical preparation in which delicate tissue is impregnated by, and embedded in, a solid supporting medium, such as paraffin wax.

Sectioning

The process of cutting a plant tissue sample into thin slices, typically using a microtome, to allow for detailed microscopic examination of its internal structure under a microscope.

Epidermis

Outermost, protoderm-derived layer of cells covering the stem, root, leaf, flower, fruit, and seed parts of a plant.

Protoderm

The protoderm layer functions like the skin of the plant and forms the outer layer, protecting the plant from the environment.

Stomata

Regulate gas exchange between the plant and environment and control of water loss by changing the size of the stomatal pore.

Trichomes

Fine outgrowths or appendages on plants, algae, lichens, and certain protists.

Cuticles

The outermost layer interacting with the environment.

Epicuticular wax

A waxy coating which covers the outer surface of the plant cuticle in land plants.

Guard Cells

Specialized plant cells that control gas exchange in plants by regulating the opening and closing of stomatal pores

Pore

Microscopic openings in the epidermis of leaves and stems.

Transpiration

Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers.

Asymmetric cell division

A fundamental process whereby the asymmetric inheritance of cellular components (e.g. proteins, RNAs) during mitosis defines distinct fates for each daughter cell.

Primary meristemoid

Shoot and root meristems that are initiated at opposite poles of the plant embryo.

Pavement cell

A cell type found in the outmost epidermal layer of plants. The main purpose of these cells is to form a protective layer for the more specialized cells below.

Guard mother cell

The immediate precursor cell to the stomatal guard cells. GMCs divide once, symmetrically, to produce the pair of guard cells that make up a single stoma.

Subsidiary cell

Two specialized epidermal cells that surround the guard cells. It provides the better functioning of guard cells as well as protection from external forces.

Root hair cell

Specialised (to perform a specific function). Their structure allows the plant to absorb more water. They also allow a plant to take in the minerals it needs to survive.

Glabrous1 (GL1)

An R2R3 MYB homolog that is essential for the initiation of trichome development.

Transparent testa glabra (TTG)

Regulates several developmental and biochemical pathways in Arabidopsis, including the formation of hairs on leaves, stems, and roots, and the production of seed mucilage and anthocyanin pigments.

Initiation

Plant organs initiate from meristems and grow into diverse forms.

Morphogenesis

The shaping of an organism by embryological processes of differentiation of cells, tissues, and organs and the development of organ systems according to the genetic “blueprint” of the potential organism and environmental conditions.

Parenchyma

Even thickness of cell wall (primarily thin)

Living at maturity

Capable of cell division

Function in photosynthesis, storage & secretion

Wound regeneration

Mesophyll

“middle of leaf”

composed of parenchyma cells

typically chloroplast containing cells called chlorenchyma cells

palisade and spongy cell types - different locations, cell shapes and

functions

Collenchyma

Uneven thickened cell wall

Living cell at maturity

Often found in leaves and supporting stem

Non-lignified cell walls

Function in supportive tissues

Chlorenchyma

A specialized type of Parenchyma cells found in plants. It is responsible for storing chlorophyll.

Sclerenchyma

Have thick lignified secondary walls and often die when mature. Provides the main structural support to the plant.

Sclerid

Reduced form of sclerenchyma cells with highly thickened, lignified cellular walls that form small bundles of durable layers of tissue