Farjana Islam Aovi

Lecturer

Daffodil International University

Farjana Islam Aovi

Lecturer

Daffodil International University

Structure of cell

Structure of cellPlant cells are eukaryotic cells.

Organelles:

Cell membraneCell wallNuclear membranePlasmodesmaVacuolePlastidsChloroplastLeucoplast

ChromoplastGolgi BodiesCytoplasmNucleusDNAChromatinRNACytoskeletonNucleolusMitochondrion

Plant cell wall A cell wall is composed

of cellulose and hemicellulose, pectin and in many cases lignin, is secreted by the protoplast on the outside of the cell membrane.

Cellulose is a structural carbohydrate and is considered a complex sugar because it is used in both protection and structure.

The plant cell wall consists of three layers.

It can be tough, flexible and sometimes rigid .

Function- to provides cells with structural support and protection and to act as a filtering mechanism.

PlastidsIt is a major double-membrane organelle.

PlastidsPlastids are the site of manufacture and storage of important chemicalcompounds used by the cell.

They often contain pigments used in photosynthesis, and the types ofpigments present can change or determine the cell's color.

They have a common origin and possess a double-stranded DNA moleculethat is circular, like that of prokaryotes.

Those plastids that contain pigments can carry out photosynthesis.

Plastids can also store products like starch and can synthesise fattyacids and terpenes, which can be used for producing energy and as rawmaterial for the synthesis of other molecules.

For example, the components of the plant cuticle and its epicuticularwax are synthesized by the epidermal cells from palmitic acid, which issynthesized in the chloroplasts of the mesophyll tissue.

Plastids

In plants, plastids may differentiate into several forms, depending upon which function they play in the cell. Undifferentiated plastids (Proplastids) may develop into any of the following variants:Chloroplasts (green plastids): for photosynthesis;Chromoplasts (colored plastids): for pigment synthesis and storageGerontoplasts: control the dismantling of the photosynthetic apparatus during senescenceLeucoplasts colorless plastids: for monoterpene synthesis;leucoplasts sometimes differentiate into more specialized plastids:

Amyloplasts: for starch storage and detecting gravityElaioplasts: for storing fatProteinoplasts: for storing and modifying proteinTannosomes: for synthesizing and producing tannins and polyphenols

Plastids

Plant morphology Plant morphology or phytomorphology is the study of

the physical form and external structure of plants. Plant morphology treats both the vegetative structures of plants, as

well as the reproductive structures. The vegetative (somatic) structures of vascular plants include two

major organ systems: (1) a shoot system, composed of stems and leaves, and (2) a root system.

-These two systems are common to nearly all vascular plants, and provide a unifying theme for the study of plant morphology.

By contrast, the reproductive structures are varied, and are usually specific to a particular group of plants. Structures such as flowers and fruits are only found in the angiosperms; sori are only found in ferns; and seed cones are only found in conifers and other gymnosperms.

-Reproductive characters are therefore regarded as more useful for the classification of plants than vegetative characters.

Plant morphology