Lecture 2: Review of Cell Structure – Their Role in Physiological Processes Flashcards
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
Involved in cell transport
(Plant Cell Parts and their Functions)
Endoplasmic reticulum
The cytoplasmic membrane separating the cytoplasm from the cell wall; controls the entry or exit of materials into the cell; sensory transduction, i.e., the sensing and initiation of the cellular response to changing environmental conditions
(Plant Cell Parts and their Functions)
Plasma membrane
Involved in the synthesis of new cell walls
(Plant Cell Parts and their Functions)
Golgi bodies
Fluid-filled organelles bound by a single membrane called the tonoplast and contain a wide range of inorganic ions and molecules.
(Plant Cell Parts and their Functions)
Vacuole
Site of other activities, e.g. peroxisomes and glyoxysomes
(Plant Cell Parts and their Functions)
Other microbodies
- Non-protoplasm materials found in cells
- The living protoplasm of a cell is sometimes called the bioplasm
- Usually organic or inorganic substances that are products of metabolism, and include crystals, oil drops, gums, tannins, resins and other compounds that can aid the organism in defense, maintenance of cellular structure, or just substance storage
- May appear in the protoplasm, in vacuoles, or in the cell wall
Ergastic substance
- Cellulose and starch are the main ergastic substances of plant cells
- Cellulose is the chief component of the cell wall, and starch occurs as a reserve material in the protoplasm
- Starch, as starch grains, arise almost exclusively in plastids, especially leucoplasts and amyloplasts
Carbohydrates
Although ________ are the main component of living protoplasm, ________ can occur as inactive, ergastic bodies—in an amorphous or crystalline (or crystalloid) form. A well-known amorphous ergastic ________ is gluten.
(One Answer)
Proteins
A protein composite that appears in foods processed from wheat and related species, including barley and rye.
Gluten
- Waste/metabolic products or protective (deter herbivory);
- Plants mostly deposit such material in their tissues. Such mineral matter is mostly salts of calcium (e.g., raphides, druses) and anhydrides of silica
Crystals
- Tri-/di-glyerides (storage, secretion)
- _____ (lipids) and _____ are widely distributed in plant tissues
- Substances related to ____—____, suberin, and cutin—occur as protective layers in or on the cell wall
(3 Answers)
Fats, Oils, Waxes
Protein (storage)
(Type of Ergastic substance)
Aleurone grains
Phenol derivatives (deter herbivory, infection, etc.)
Tannins
