4.1 Structure of a plant cell

Natural sciences

Grade 9

Plants: structure, including genetics

Module 26

Structure of a plant cell

Activity:

To understand the structure of a plant cell

[lo 2.1, 2.2, 2.3, 2.4]

Ask your educator for a leaf from a moss plant, or some other example, to study through a microscope.

You could study the structure of a typical leaf. The following illustration is a simple line drawing providing a two-dimensional image of what you might see:

The cell consists of a framework filled with a special liquid – PROTOPLASM – with a variety of structures floating in it. Some of these are too small to be seen through an ordinary microscope. We need to use an electron microscope to examine these small structures. Remember that you see the cell from one side only. It is actually shaped like a brick and we say that it is three-dimensional. Ask your educator to explain this concept to you.

Find out about microscopes and electron microscopes.

Assignment 1:

1. Provide a caption for the sketch.

2. Add labels in the numbered boxes.

3. What are the functions of each?

Assignment 2 : The nucleus contains fine details that you need to get to know before working through the rest of the module:

Discuss each of the labels of the nucleus in class and summarise their functions.

Can you remember the main function of the nucleus?

Although the nucleus is the control centre of the cell, there are two other organelles that require closer investigation because of the important functions that they perform.

Plants engage in PHOTOSYNTHESIS and RESPIRATION. The organelles that are involved in this are the CHLOROPLAST (photosynthesis) and the MITOCHONDRION (respiration). You will be learning more about these organelles in future.

Your educator will show detailed sketches of these organelles to introduce them in greater detail.

Assessment: The identification of cellular structure

Were you able to distinguish the basic structures?

[ LO 2.1; LO 2.3]

Assignment 3:

Make simple line drawings of the organelles,

Which of the structures and aspects that form part of the plant cell would you not expect to come across in an animal cell? Supply reasons:

(Suggestion: Look at yourself and at a plant, and feel what you are like and what a plant is like.)

Assessment: Line drawings and deductions

Were you able to do the sketches and make deductions? [LO 2.3; LO 2.4]

By now, you probably understand that plant cells have particular characteristics but that they do not all look the same, because they are adapted to fulfil specific functions. These adaptations in their structure are referred to as DIFFERENTIATION and the accompanying change of function is known as SPECIALISATION . Both terms are important in cellular studies.

A group of cells that are adapted to perform a particular function is called a particular kind of TISSUE . Some conduct water through the plant. Other groups of cells are responsible for strengthening the plant. More, still, are adapted for photosynthesis.