UNIT VIII. PLANT CELL

In this unit:

• talking about the structure of a plant cell

• speaking about the functions of organelles

• using the Modal Verbs

1. Read the text and be ready to answer the following questions:

1. What is a cell?

2. What do we call eukaryotes?

3. Why do plants need to use sunlight?

4. Where are the constituents of the cell suspended?

5. Which structure of a cell contains the DNA?

Plant cell

All living organisms on Earth are divided into cells. The main concept of cell theory is that cells are the basic structural unit for all organisms. Cells are small compartments that hold the biological equipment necessary to keep an organism alive and successful.

Plants are unique among the eukaryotes, organisms whose cells have membrane-enclosed nuclei and organelles, because they can manufacture their own food. Chlorophyll, which gives plants their green color, enables them to use sunlight to convert water and carbon dioxide into sugars and carbohydrates, chemicals the cell uses for energy.

Plants usually require significant amounts of water, which is needed for the photosynthetic process, to maintain cell structure and facilitate growth, and as a means of bringing nutrients to plant cells. The amount of nutrients needed by plant species varies significantly, but nine elements are generally necessary in relatively large amounts. Termed macroelements, these nutrients include calcium, carbon, hydrogen, magnesium, nitrogen, oxygen, phosphorus, potassium, and sulfur. Seven microelements, which are required by plants in smaller quantities, have also been identified: boron, chlorine, copper, iron, manganese, molybdenum, and zinc.

Plant cell contains membrane that bounds nucleus and many cellular structures. These structures, organelles, carry out functions that are necessary for the proper functioning and survival of the cell. The cell organelles of the plant are enclosed by a cell wall and cell membrane. The constituents of the cell are suspended in the cytoplasm. 

The parts of the plant cell are as follows: 

• Cell wall is the outermost rigid covering of the plant cell. It is a characteristic feature of plant cell. 

• Cell membrane is the outer lining of the cell inside the cell wall. 

• Cytoplasm is the gel-like matrix inside the cell membrane which constitutes all other cell organelles.

• Nucleus is the control center of the cell. It is a membrane bound structure which contains the hereditary material of the cell – the DNA 

• Chloroplast traps light energy and converts it to chemical energy by the process of photosynthesis.

• Mitochondria carry out cellular respiration and provide energy to the cells.

• Vacuoles are the temporary storage center of the cell.

• Golgi body is the unit where proteins are sorted and packed.

• Ribosomes are structures that assemble proteins.

• Endoplasmic reticulum is a membrane covering organelles that transport materials.

Vocabulary practice

1. Match the words and their definitions:

1. eukaryote	a. a chemical element required in relatively large quantities for the normal physiologic processes of the body
2. facilitate	b. the substance between cells or in which structures are embedded
3. macroelement	c. to make an action or process easy or easier
4. photosynthesis	d. any of the properties that are characteristic of smth.
5. matrix	e. the material or protoplasm within a living cell, excluding the nucleus
6. feature	f. an organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus.
7. nucleus	g. a space or vesicle within the cytoplasm of a cell, enclosed by a membrane and typically containing fluid
8. cytoplasm	h. a small spherical body in the cytoplasm of most cells responsible for energy production
9. vacuole	i. the process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water
10. mitochondrion	j. a dense organelle present in most eukaryotic cells, typically a single rounded structure bounded by a double membrane, containing the genetic material