Parenchyma Cell. Magnification 2375X

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1 Parenchyma Cell The large size of parenchyma cells is due in part to their relatively large vacuole (V) and in part also to the large number of chloroplasts (Cp) they contain. From a crimson clover, Trifolium incarnatum, leaf. Magnification 2375X

Phloem Cell Cross section of three relatively thick-walled sieve elements (SE). The cytoplasm of these elements is characteristically free of cell organelles.

2 Phloem Cell Cross section of three relatively thick-walled sieve elements (SE). The cytoplasm of these elements is characteristically free of cell organelles. Sieve elements generally show multiple invaginations of the plasma membrane (arrows) as the cell ages. From a crimson clover, Trifolium incarnatum, leaf. Magnification 5 100X

3 Tracheid Cell Transverse section through a differentiating tracheid cell. In this section primary (CW1) and secondary wall, (CW2) thickenings are visible. The cytoplasmic contents at this stage are still intact. From a crimson clover, Trifolium incarnatum, leaf. Magnification 8 100X

Typical Plant Cell The protoplast of the cell is set off from the cell wall (CW) by a thin dark line, which represents the plasmalemma or plasma membrane (PM).

4 Typical Plant Cell The protoplast of the cell is set off from the cell wall (CW) by a thin dark line, which represents the plasmalemma or plasma membrane (PM). The nucleus (N) is surrounded by the cytoplasm, which contains mitochondria (M), proplastids (Pp), a golgi apparatus (GA), vacuoles, and endoplasmic reticulum. From a crimson clover, Trifolium incarnatum, stem. Magnification 8 400X

5 Chloroplasts A single plastid from a mesophyll cell of crimson clover, Trifolium incarnatum. The relatively large chloroplast is located between the cell wall (CW) and vacuole (V) and is held in this position with its longest axis parallel to the cell surface. The chloroplast contains several grana (G) and starch (S) granules. From a crimson clover, Trifolium incarnatum, leaf. Magnification 8 400X

6 Ultrastructure of Chloroplast Plastids, like mitochondria are bounded by a double membrane (arrows). The grana (G) are composed of tight stacks of thylakoid membranes. The plastid stroma contains starch (S) granules and ribosomes (R). From a crimson clover, Trifolium incarnatum, leaf. Magnification X

7 Proplastid Proplastids (Pp) generally have a stroma denser than the surrounding cytoplasm and are bound by a double membrane. Note that only a few lamellae (L) are present in these organelles. From Acacia georginae tissue culture. Magnification 9 000X

8 Golgi Apparatus The golgi apparatus (GA) appears in vertical section as a stack of thin flat vesicles. There are usually 5 to 7 of these vesicular units in each complex. Toward the margins of these flat cisternae, golgi vesicles (GV) are commonly observed. From a crimson clover, Trifolium incarnatum, leaf. Magnification X

9 Nucleus The nucleus is bounded by a double membrane envelope (NE) and contains a rather large nucleolus (Nu). The nucleolus is characteristically composed of a finely granular substance. From Acacia georginae tissue culture. Magnification 9 000X

10 Nuclear Envelope A nucleus (N) cut in tangential section often permits the visualization of nuclear pores (arrows). These pores are about nanometers in diameter. From tobacco, Nicotiana tabacum, tissue culture. Magnification 8 400X

11 Spherosomes Spherosomes (Sp) are irregularly shaped, dense bodies which are surrounded by a unit membrane. These organelles have a granulated structure which is believed to be proteineic in nature. From a wheat, Triticum aestivum, leaf. Magnification 8 100X

12 Guard Cells of Stomata The four cells which comprise the stomatal complex in wheat (Triticum aestivum) are shown in cross section. The central two are the guard cells (GC) and the pair lateral to them the subsidiaries (Sc). A thin, dense layer of cuticle (Cu) covers the side exposed to the environment. From a wheat, Triticum aestivum, leaf. Magnification 8 800X

13 Microbodies Microbodies (MH) are small organelles with a finely granular matrix which frequently contains crystalline (arrows) inclusions. The organelle is surrounded by a unit membrane. From tobacco, Nicotiana tabacum, tissue culture. Magnification X

Cell Wall and Plasmodesmata Longitudinal section of two plasmodesmata (Pd) clearly illustrating the connection between the cells on either side of the cell wall (CW).

14 Cell Wall and Plasmodesmata Longitudinal section of two plasmodesmata (Pd) clearly illustrating the connection between the cells on either side of the cell wall (CW). The plasmodesmata which are approximately 50 nanometers in diameter are shown in cross section in the insert. From a Jerusalem cherry, Solanum pseudo-capsicum, leaf. Magnification X

15 Tonoplast and Vacuoles The electron microscope reveals the vacuolar envelope, called the "tonoplast" (T), to be a unit membrane having the same appearance as the plasma membrane. Portions of 2 vacuoles (V) are seen in this cell. From a corn, Zea mays, leaf. Magnification X

16 Mitochondrion Two mitochondria (M) in a crimson clover, Trifolium incarnatum, leaf. These organelles are surrounded by a double envelope. The inner membrane invaginates into the mitochondrion to form the cristae (C). Magnification X

Microtubules Individual microtubules (Mt) are about 25 nanometers in diameter and several micrometers in length. The insert shows the microtubules in cross section.

17 Microtubules Individual microtubules (Mt) are about 25 nanometers in diameter and several micrometers in length. The insert shows the microtubules in cross section. These structures are frequently found in close association with the cortical zone (ectoplasm) of plant cells. From a Jerusalem cherry, Solanum pseudo-capsicum, leaf. Magnification X

18 Sieve Plate A sieve plate with at least two pores transected by the section. They are approximately 100 nanometers in diameter. The pore space is lined with callose (C) and occupied by many 10 nanometer thick filaments of P-protein (Pp). From a Canada thistle, Cirsicum arvense, leaf. Magnification 9 00OX

Endoplasmic Reticulum The endoplasmic reticulum is a system of cisternae and channels which are apparently continuous with one another and with the nuclear envelope.

19 Endoplasmic Reticulum The endoplasmic reticulum is a system of cisternae and channels which are apparently continuous with one another and with the nuclear envelope. Flattened cisternae covered on their cytoplasmic surfaces by ribosomes are known as rough-surfaced cytoplasmic reticulum (RER). From a Jerusalem cherry, Solanum pseudocapsicum, leaf. Magnification X

20 THE END

Introduction to Botany. Lecture 10

Introduction to Botany. Lecture 10 Alexey Shipunov Minot State University September 21, 2015 Shipunov (MSU) Introduction to Botany. Lecture 10 September 21, 2015 1 / 33 Outline 1 Questions and answers