Important roles of the vacuoles are:
Energetically efficient means to increase surface to volume ratio in the dendritic
growth from since 90 % of the cell volume is vacuole, therefore 90% of the cell is
water which is relatively cheap in metabolic terms.
Water storage: - Probably a minor role: mostly in succulent plants.
Waste disposal: The vacuole can be considered the cell cesspool. It contains many
secondary metabolites.
Organelle Function
Cell Wall Supports and protects the cell
Nucleus Stores heredity information in DNA; Synthesis RNA & Ribosomes
Mitochondrion Transfers energy from organic compounds to ATP
Vacuole Stores enzymes & waste products
Plastids Stores food or pigments; one type (Chloroplast) transfers energy form
light to organic compounds
Ribosome Organizes the synthesis of proteins
Endoplasmic Prepares proteins for export(Rough ER); synthesis steroids, regulates
reticulum (ER) Calcium level, breaks down toxic substances (Smooth ER)
Golgi Apparatus Process & Packages substances produced by the cell
Microfilaments& Contribute to the support. Movement, and division of cell
Microtubules
Cilia & Flagella Propel cells through the environment; move materials over the cell surface
11
,Lecture 4
Plant Tissue
A group of similar or dissimilar cells having a common origin and performing a similar
function.
A. Meristematic tissue
The term meristem has been derived from a Greek word meristos- which means
divisible or having cell division activity, so meristem is a group of cell which
has power of continuous division.
Meristems are the site of formation of new cells within the plant. eg.: meristem
at apex of stem, root and vascular cambium, etc. .
The term meristem was given by C. Nageli (1858) for group of continuously
dividing cells.
12
, Characteristics of meristematic cell:
1- Living cells found in vegetative regions of the plant
2- They have thin walls of cellulose.
3- Cells are normally isodiametric, oval, polygonal or rectangular
4- Abundant cytoplasm is present, vacuoles are either absent or very small, large nucleus is
present and their plastids are in proplastid stage.
5- Cells are compactly arranged and lack intercellular spaces.
6- Cells have the capacity to divide.
Classification of merestimatic tissue
Meristematic tissues may be classified on the basis of:
(a) Origin and development
(b) Position in the plant body
(c) Plane of division
(d) Functions
13
Energetically efficient means to increase surface to volume ratio in the dendritic
growth from since 90 % of the cell volume is vacuole, therefore 90% of the cell is
water which is relatively cheap in metabolic terms.
Water storage: - Probably a minor role: mostly in succulent plants.
Waste disposal: The vacuole can be considered the cell cesspool. It contains many
secondary metabolites.
Organelle Function
Cell Wall Supports and protects the cell
Nucleus Stores heredity information in DNA; Synthesis RNA & Ribosomes
Mitochondrion Transfers energy from organic compounds to ATP
Vacuole Stores enzymes & waste products
Plastids Stores food or pigments; one type (Chloroplast) transfers energy form
light to organic compounds
Ribosome Organizes the synthesis of proteins
Endoplasmic Prepares proteins for export(Rough ER); synthesis steroids, regulates
reticulum (ER) Calcium level, breaks down toxic substances (Smooth ER)
Golgi Apparatus Process & Packages substances produced by the cell
Microfilaments& Contribute to the support. Movement, and division of cell
Microtubules
Cilia & Flagella Propel cells through the environment; move materials over the cell surface
11
,Lecture 4
Plant Tissue
A group of similar or dissimilar cells having a common origin and performing a similar
function.
A. Meristematic tissue
The term meristem has been derived from a Greek word meristos- which means
divisible or having cell division activity, so meristem is a group of cell which
has power of continuous division.
Meristems are the site of formation of new cells within the plant. eg.: meristem
at apex of stem, root and vascular cambium, etc. .
The term meristem was given by C. Nageli (1858) for group of continuously
dividing cells.
12
, Characteristics of meristematic cell:
1- Living cells found in vegetative regions of the plant
2- They have thin walls of cellulose.
3- Cells are normally isodiametric, oval, polygonal or rectangular
4- Abundant cytoplasm is present, vacuoles are either absent or very small, large nucleus is
present and their plastids are in proplastid stage.
5- Cells are compactly arranged and lack intercellular spaces.
6- Cells have the capacity to divide.
Classification of merestimatic tissue
Meristematic tissues may be classified on the basis of:
(a) Origin and development
(b) Position in the plant body
(c) Plane of division
(d) Functions
13
