Download Plant Structure and Function

UNIVERSITY OF NAIROBI
FACULTY OF EXTERNAL DEGREE STUDIES AND FACULTY OF SCIENCE
Plant Structure and Function
(SBT 204)
Written By
Dr. Norman C. Njoroge and Dr. Nelson O. Amugune
Lecturers: Department of Botany
University of Nairobi
Reviewed By
Dr. Elijah M.W. Akunda
Senior lecturer: Department of Botany
Lecture 1
Lecture outline
Plant Cell Structure
Page
1.0 Introduction
1.1 Plant cell components
1.2 Cell Size
1.3.0 Cell Compartmentation
1.3.1 The significance of compartmentation of a plant cell
1.3.2 Integration and coordination of cell metabolism
1.4.0 Structure of the cell wall
1.4.1 Middle lamellae
1.4.2 Primary cell wall
1.4.3 Secondary cell wall
1.4.4 Further modifications of the secondary cell wall
1.4.5 Simple and bordered pits
1.4.6 Plasmodesmata
1.4.7 Functions of the cell
1.5.0 Protoplast
1.5.1 Organelles
1.5.2 Nucleus
1.5.3 Nuclear membrane
1.5.4 Nucleoplasm
1.5.5 Chromatin
1.5.6 Nucleolus
1.6.0 Cytoplasm
1.6.1 Ground substance
1.6.2 Organelles bounded by two membranes
1.6.2.1 Plastids
1.6.2.1.1 Chromoplasts
1.6.2.1.2 Leucoplasts
1.6.2.1.3 Chloroplasts
1.6.2.2 Mitochondria
1.7.0 Organelles bounded by one membrane
1.7.1 Microbodies
1.7.1.1 Peroxisomes
1.7.1.2 Glyoxysomes
1.7.2 Vacuoles
1.8.0 Endomembrane system
1.8.1 Endoplasmic reticulum
1.8.2 Golgi bodies
1.8.2.1 Relationship between Golgi apparatus and endoplasmic reticulum
1.8.3 Plasma membrane
1.9.0 Cytoskeleton
1.9.1 Microtubules
1.9.2 Microfilaments
2.0 Ribosomes
2
3
5
6
6
7
7
7
8
10
10
10
12
13
13
14
14
14
15
15
15
15
16
16
16
16
16
16
18
19
19
19
20
20
20
20
21
22
22
22
22
23
23
Introduction
We shall begin the study of this unit by reviewing the structure of the different
parts of a plant cell and how the structures of those parts are suited to the function they
perform. As we have already learned, the cell is the basic unit of structure and function.
A good understanding of cell structure and function is essential because it will help us
understand how a particular tissue is able to carry out its functions. For example, when
we study the structure of a pallisade cell in a leaf, we are then able to understand how its
structure enables it carry out photosynthesis. In our study of cell structure and function in
the unit on “Introductory biochemistry and genetics” we simply stated the function of
various organelles, but throughout this unit we are going to relate the structure of what
we study to its function.
Let us consider the example of glucose and fructose mentioned in the introduction
of the unit. Both sugars contain exactly the same kinds and number of atoms (C6H12O6),
but the atoms are arranged differently (figure 1). The two monosaccharides differ in the
position of the C=O group. This small difference in position of the C=O group,
distinguishes glucose that a cell can use directly in production of energy during
respiration, from fructose that cannot be used directly as a source of energy.
Glucose
Fructose
Figure 1 The structure of glucose and fructose. Both glucose and fructose contain the
same kind and number of atoms, but the C=O group is on carbon 1 in glucose and on
carbon 2 in fructose.
So in this unit our main focus is to describe the structure of a plant part and explain how
that structure enables that part carry out the task or tasks it is supposed to perform.
In this lecture, we begin by identifying the plant cell components. We shall then
discuss the size and shape of a plant cell and how the components of the cell are
organized inside into organelles or compartments. We shall then review the advantages of
having such an organizational set up with respect to some different chemical reactions
that take place in the cell. Once we finish looking at the organization of a plant cell, we
shall look at the cell wall, the outermost part of a plant cell, and then move into the
interior of the cell for study of the relationship between structure and function of the cell
organelles.