Lecture 2: Review of Cell Structure – Their Role in Physiological Processes Flashcards
(37 cards)
Derived from Latin word “cella”, meaning ‘storeroom’ or ‘chamber’
First uses in biology in 1665 by English botanist Robert Hooke to describe the individual units of the honeycomb-like structure he observed in cork under a compound microscope (Taiz & Zeiger, 2002)
The size of individual cells varies from ____ in diameter to macroscopic units up to ____
0.5 um, 10 um
(0.5 um = micrometer; 1 um = 1/26,000 in)
In higher plants, the general range in diameter is ________
10 um - 100 um
(0.5 um = micrometer; 1 um = 1/26,000 in)
A single leaf on a tree may have more than ________
40,000,000 cells
- Eukaryotic cells that differ in several key respects from the cells of other eukaryotic organisms
- They are eukaryotic cells, which have a true nucleus along with specialized structures called organelles that carry out different functions.
Plant Cells
- The basic unit of life in organisms of the kingdom Plantae.
- They also have a cell wall that provides structural support.
Plant Cells
Plant cells have ________ , constructed outside the cell membrane and composed of cellulose, hemicellulose and pectin.
Cell Walls
Plant cells contain ________, a water-filled volume enclosed by a membrane known as the tonoplast.
Large Central Vacuole
Plant cells contain a specialized cell-to-cell communication pathways known as ________.
Plasmodesmata
Plant cells contain plastids, e.g:
Chloroplasts, amyloplasts, chromoplasts, mitochondria
Types of Plant Cells (Ground Tissues)
- Parenchyma cells
- Collenchyma cells
- Sclerenchyma cells
Living cells that functions for storage and support to photosynthesis and phloem loading. Have thin, permeable primary walls enabling the transport of small molecules; involved in metabolic reactions; mainly present in the soft areas of the stems, leaves,root, flowers, fruits, etc.
Parenchyma
- Alive at maturity and have thickened cellulosic cell walls; elongate; rich in pectins
- Derives from the Greek word “kól-la”, meaning “glue”, which refers to the thick, glistening appearance of the walls in fresh tissues.
- Provide structural support, particularly in growing shoots and leaves (e.g. resilient strands in stalks of celery).
Collenchyma
Types of Collenchyma cells
- Angular collenchyma - Thickened at intercellular contact points
- Tangential collenchyma - Cells arranged into ordered rows and thickened at the tangential face of the cell wall
- Lacunar collenchyma - Have intercellular space and thickening proximal to the intercellular space
- Cells dead at maturity
- Thick, secondary, lignified cell walls
- Functions in structural support
- Their walls consist of cellulose, hemicellulose and lignin.
- Principal supporting cells in plant tissues that have ceased elongation.
- “Sclerenchyma” is derived from the Greek word “sklē-rós” meaning “hard”.
- Include fibers and sclereids
Sclerenchyma cells
Types of Sclerenchyma cells
- Fibers
- Sclereids
Roots, stems, leaves
(3 Plant Major Tissues)
- Ground tissue - For photosynthesis, food storage, regeneration, support and protection (parenchyma, collenchyma,sclerenchyma
- Vascular tissue - For transport of water and minerals; for transport of food (xylem and vessel tissues)
- Dermal tissue - For protection and prevention of water loss (epidermis, peridermis)
It gives shape and structure to the cell and to the whole plant as well
(Plant Cell Parts and their Functions)
Cell wall
The living part of the cell where
organelles are embedded
(Plant Cell Parts and their Functions)
Cytoplasm
A plastid containing the green pigment
called the chlorophyll
(Plant Cell Parts and their Functions)
Chloroplast
Controls the activities of the cell; the presence of the DNA in the nucleus explains why it is this part of the cell that controls cellular activities
(Plant Cell Parts and their Functions)
Nucleus
The site of respiration
(Plant Cell Parts and their Functions)
Mitochondrion
The site of protein synthesis
(Plant Cell Parts and their Functions)
Ribosomes
