Plant Tissues & Basic Cell Types

Plant Tissues & Basic Cell Types Mr. Chapman Biology 20

Recall the Difference Between Plants Cells and Animal Cells... • Remember that in addition to all of the cell structures that animal cells have, plant cells have a few additional structures. • These structures are: • Chloroplasts • Cell walls • Plastids • Large Central Vacuole

Plants are Simple... Plants have three main organs, which are made of three types of tissues, which are made of three types of cells...

Plant Cells • Similar to animals, plants are made up of many types of cells that are organized into tissues. • There are 3 basic types of plant cells: Parenchyma cells, collenchyma cells, and sclerenchyma cells. 3 Types of Plant Cells

Parenchyma Cells Least specialized, most adaptable!

Parenchyma Cells • The most abundant and least structurally specialized of plant cells. • They occur throughout plants and have many functions, including photosynthesis, food storage, and general metabolism. • An important characteristic of parenchyma cells is that they can divide and become specialized for various functions.

A Parenchyma Cell: Nothing too special about this guy...

Collenchyma Cells Flexible plant cells that can change size and stretch. Where do you think these cells would be found the most, and in what kinds of plants?

Collenchyma cells • Specialized for support while still allowing the plant to grow. Most common in younger tissues of leaves and shoots. • Collenchyma cells have thick stretchable cell walls that provide flexible support. • The tough strings of celery stalk are made of collenchyma cells.

Collenchyma Cells: Thicker outer cell walls allow for some stretching in these cells while still allowing the cells to grow...

Sclerenchyma Cells: Strong, tough, durable cells with TWO cells walls!

Sclerenchyma Cells: • The strongest of the three types of cells, they have the thickets cell walls out of any of them. This makes them very tough and durable. • Lignin makes the cells very tough and durable. These cells are so tough and inflexible that they cannot grow with the rest of the plant. As a result, they are typically found in the parts of the plant that are no longer lengthening. • Many sclerenchyma cells die after they reach maturity, and their rigid cell walls are left behind in the plant as skeletal support.

Sclerenchyma Cells Continued... • Dead sclerenchyma cells form support structures for the water conducting tissues of the plant. • Sclerenchyma cells form a major part of fruit pits and the hard outer shells of nuts. • Responsible for the gritty texture of pears. • Used by humans to make linen and rope.

Sclerenchyma Cell:

Comprehension Questions • What are the three types of cells in a typical plant? • Which of the cells is found in areas of the plant that are growing, and why is this the case? • What type of cell typically dies at maturity, and in what portion of the plant is it typically found? • Which type of plant cell is the least differentiated, but can differentiate into different types of plant cells?

Plant Tissue Types: Three Different Kinds: Dermal, Ground, and Vascular

Dermal Tissue... • Your body is covered with skin. Plants don’t have skin, but they do have what is called dermal tissue. • Dermal tissue covers the outside of the plant and protects it in a variety of ways. • Epidermis is made of live parenchyma cells that in the non-woody parts of plants. • Dermal tissue formed from dead parenchyma cells makes up the outer bark of woody plants.

Dermal Tissue

Ground Tissue System • Ground tissue is surrounded by the dermal tissue, and makes up a great deal of the plant’s structure. • The function of ground tissue is to provide support for the plant, as well as to provide storage for materials inside the stem and the roots. • Ground tissue in the leaves is where chloroplasts are and photosynthesis takes place, allowing plants to make their own food. • Parenchyma cells are the most common cells found in ground tissue, but all three types are generally present.

Ground Tissue

Vascular Tissue System • We have been learning previously in class about how critical the vascular tissue is to plants. • Vascular tissue transports water, mineral nutrients, and organic compounds to the rest of the plant. • Vascular tissue of a plant is made of hollow tubes that are somewhat like the veins and arteries of humans. There are two main types of vascular tissue in the body of a plant:

Xylem • Xylem is the vascular network in a plant that is responsible for transporting water and dissolved mineral nutrients up from the roots to the rest of the plant. • Xylem, as we will learn, is mostly formed of dead sclerenchyma cells that form a solid structure in the center of the plant’s stem.

Phloem • Phloem is the vascular network that is responsible for carrying the products of photosynthesis down from the leaves to the remainder of the plant. • Recall that the products of photosynthesis are sugar and oxygen. Phloem carries sugar down from the leaves to the remainder of the plant. • Xylem and phloem transport material through the plant in different ways, as we will learn in the next section.

Xylem and Phloem

Comprehension Questions • What are the three basic types of tissue that are found in a plant? • What are the main functions of ground tissue in the plant? • Where are sclrenchyma cells typically found in a plant? What do dead sclerenchyma cells form inside the plant? • What are the two types of vascular tissue, and what is the function of each one?

Plant Tissues & Basic Cell Types