bio 374

What pigments are found in plant cells? Where are they located within a cell?

1. Flavonoids (mainly anthocyanins, anthoxanthin, etc.): range in color from red to blue to purple; water soluble so usually in vacuole; ex: tomato with red color but water soluble so in vacuole 2. Carotenoids (carotenes, xanthophylls): usually yellowish/orange; water insoluble so usually in plastids and membranes 3. Chlorophyll: green and in thylakoids membranes; major key for photosynthesis; so many in cells that it usually masks the colors of other pigments until seasons change 4. Betalains (betacyanin): water soluble; ex: red in beats 5. Tannins: brownish; mainly water insoluble and so in vacuole but can also be in cytoplasm and cell wall too 6. Phytochrome: blue pigment but not very intense; light sensing pigment that gets environmental signals

Define a meristem

A meristem is a developing plant tissue composed of undifferentiated cells with the capability of dividing indefinitely. This division will give rise to similar undifferentiated cells or to newly differentiated cells that will form the plant's tissues and organs.You can think of 'meristem' as any kind of plant tissue that is made of cells that don't know what they want to be when they grow up, like happy, 'merry' children Meristems are classified by their location in the plant as apical (located at root and shoot tips), lateral (in the vascular and cork cambia), and intercalary (at internodes, or stem regions between the places at which leaves attach, and leaf bases

How big is a "typical" isodiametric parenchyma cell?

A typical isodiametric parenchyma cell is ~10um (micrometers) but can range from 10-100um depending on the function of the cell.

Distinguish between apical meristems and primary tissue meristems.

Apical meristem is found at the tips of the plant, both the tip of the shoot and the root, and is a region of actively dividing cells.Apical meristem causes the plant to grow up and down to get longer. The cells produced by divisions in the apical meristem region are soon identifiable as three zones of distinct tissues that differentiate below the apical meristems. These are the primary meristems, : theprotoderm, the procambium, and the ground meristem. They give rise to the tissue systems of the primary plant body.

What are the general functions of all the cellular components?

CELL STRUCTURE Plasma membrane (plasmalemma): the fluid-mosaic model

Compare and contrast the organization, size, shape, and components found in a meristematic cell and in a mature parenchyma cell.

Meristematic cell: cell shape:isodiametric diameter:15-25 um cell wall: primary,thinner vacoules: many,small position of cytoplasm:throughout organelle differentiation:undifferentiated organelle density: higher Mature Cell: cell shape: isodiametric or elongated diameter:100-300 vacuoles: one or more,large position of cytoplasm:peripheral and in transvacuolar strands organelle differentation:differentiated organelle density:lower

Distinguish between primary walls, secondary walls, and the middle lamella.

Middle Lamella-is a pectin layer which cements the cell walls of 2 adjoining cells together Primary wall- cellulose containing layer laid down by cell that are dividing and growing. to allow for cell wall expansion during growth the primary walls are thinner and less rigid than those of cells that have stopped growing secondary wall- responsible for most of the plants mechanical support as well as having a permanent stiffness and load bearing capacity. it is thick

Why can't the ground tissue in monocot stems be assigned to cortex and pith?

Monocots usually do not have a defined cortex and pith like that found in the Dicots. Monocots have their vascular bundles randomly scattered throughout the stem. Ground tissue helps support the stem and is called pith when it is located towards the middle of the stem and called the cortex when it is between the vascular tissue and the epidermis

protoplasts

Most of the metabolic activities of the cell—the chemical reactions of living systems—occur within protoplasts in plants, the unit of protoplasm inside the cell wall, including the nucleus

What types of adaptations do external secretory structures possess?

Nectary glands: secrete nectar; floral/extrafloral nectaries; attract pollinators b. Hydathodes: secrete water (guttation); usually on leaves; relieve pressure c. "Digestive" glands: secrete digestive enzymes; common in insectivorous plants d. Salt glands: secrete excess salt; common in salty/marsh/coastal plants

pholem

Phloem is the food conducting tissue. It is composed of sieve elements, parenchyma cells, fibers and sclereids. Phloem differentiated from procambium is called primary phloem; secondary phloem is initiated from vascular cambium. Primary Phloem: This is classified into Protophloem and Metaphloem. In protophloem, sieve tube members are without companion cells. Sieve tubes function for a brief period and soon they get crushed by the surrounding pressure. The crushed cells may disappear. Metaphloem tissue survives for a longer period. Its elements are longer and wider. Usually fibers are absent in dicotyledons, where as in monocotyledons and herbaceous dicots, parenchyma cells are absent. Secondary phloem: Similar to secondary xylem, there are two systems of arrangements in secondary phloem - 1) Axial system producing sieve elements, phloem parenchyma and phloem fibers. 2) Transverse system producing ray parenchyma cells.

What is the relationship between the pit membrane and the primary pit field?

Pits are defined as regions where the primary wall is not covered by secondary wall.Pit membranes are the specific area where there are two primary walls of adjacent pits (pit pair) with the middle lamella between them. pits of primary and secondary cell wall show considerable differences. well organized pits can be seen on the secondary wall. pits of primary wall look like depressions on the cell wall.these depression like pits on the primary wall are called primary pit fields. the cells with only primary cell wall, parenchyma, have only primary pit fields. the primary cell cell wall of primary pit fields is relatively thin than other portions

plasmodesmata

Plasmodesmata (singular, plasmodesma) are small channels that directly connect the cytoplasm of neighboring plant cells to each other, establishing living bridges between cells.

Compare and contrast primary and secondary growth

Primary growth results in a lengthening of the plant at the shoots and roots. This growth, or cell division, occurs at the apical meristems. Alternatively, secondary growth is the increase in girth or width of the plant, which occurs at the vascular cambium and cork cambium. This growth primarily occurs in woody or piney plants and can be seen in the rings of a tree trunk.cork cambium give rise to protective cells in the outer region of the stems and roots, usually wood/bark Both types of growth produce tissues of the xylem and phloem.

Compare and contrast plant and animal cells.

Similarities - Both plant and animal cells contain the following cellular features - cytoplasm, ribosomes, mitochondria, Endoplasmic Reticulum, Golgi Apparatus, Plasma Membrane, Microtubules and most importantly a nucleus because they are both eukaryotic cells. Differences - Plants contain a cell wall made of cellulose, large central vacuole that maintains the turgor pressure (as opposed to potential smaller vacuoles in animal cells), plastids such as amyloplasts and chloroplasts. Animal cells also contain centrioles, cilia and lysosomes whereas most plant forms do not.

Distinguish between simple and complex tissues, and between tissues and tissue systems.

Simple tissues are the plant tissues that are made up of only one type of cells.There are three types of simple tissues; parenchyma, collenchyma and sclerenchyma. Parenchyma has thin-walled living cells and makes the softer parts of plants. The functions of parenchyma include storage of foods and photosynthesis. The living cells of collenchyma have thickenings at the corners. Collenchyma is found in growing stems and leaves and provides mechanical support. Sclerenchyma has thick-walled dead cells (fibers) and makes the hard parts of the plant body. Hence, it provides strength to the plant parts. Complex tissues are the plant tissues that contain more than one type of cells. There are two types of complex tissues; dermal and vascular. Dermal complex tissues are further divided into epidermis and periderm. Epidermis is composed of epidermal cells and their outgrowths. It secretes cuticle and control gas exchange and water loss. The periderm is composed of cork cells, cork cambium, and parenchyma cells. It protects the older stems and roots by forming a protective cover. Vascular tissues are xylem and phloem. Xylem is composed of tracheids, vessel members, parenchyma cells, and sclerenchyma cells. The main functions of xylem are to distribute water and water soluble nutrients and also to provide structural support. Phloem is made up of sieve-tube members, parenchyma cells, and sclerenchyma cells. This tissue helps to transport sugars and provides support to the plant.

stomata

Stomata are Pores, each guarded by two guard cells, which control the size of the pore. Cells surrounding guard cells, but differing from other epidermal cells, are called subsidiary cells. Guard cells are kidney shaped; their cell walls are thick on the inner surfaces. Guard cells contain many chloroplasts.

Which cell components can only be seen in the electron microscope?

The cell wall, nucleus, vacuoles, mitochondria, endoplasmic reticulum, Golgi apparatus, and ribosomes. Cell wall texture (cellulose microfibrils) Plasmodesmata, Phospholipid bilayers of membranes, Cistae and matrices of mitochondira

What is the outer limit of a cell?

The outer most limit of a cell is its plasma membrane, which is composed of a lipid bilayer that is responsible for many functions that include regulation in/out of the cell. In a plant cell the outermost limit would be the cell wall, which is composed of secondary cell wall (sometimes several layers), primary cell wall, and middle lamella, in that order going from in to out of the cell respectively. Secondary cell wall-->primary cell wall-->middle lamella

What are the components of the plant cytoskeleton? What do they do?

The three components of the plant cytoskeleton are actin filaments, intermediate filaments, and microtubules. The components contribute to the mechanical structure/integrity of the plant cell and provide a means of movement for organelles and cytoplasm within the cell.

What feature helps you identify the tunica layers?

The tunica layer is identified by the outermost layer of the shoot apical meristem. about 1-5 cell layers thick and consists of a uniform arrangement of cells derived from only anticlinal division.

What is unusual about laticifer cell growth

They irregularly distributed in the mass of parenchymatous cells. Laticiferous ducts, in which latex are found are again two types- Latex cell or non-articulate latex ducts Latex vessels or articulate latex Also called as "non-articulate latex ducts", these ducts are independent units which extend as branched structures for long distances in the plant body. They originates as minute structures, elongate quickly and by repeated branching ramify in all directions but do not fuse together. Thus a network is not formed as in latex vessels.

secondar meristem

Vascular cambium and cork cambium: These are referred to as secondary meristems because they produce secondary tissues, and increase the thickness of the plant body. This process is called secondary growth, seen in dicotyledons and gymnosperms.

What are the differences between: an initial and a derivative?

When a meristematic cell divides in two, the new cell that remains in the meristem is called an initial, the other the derivative. As new cells are added by repeated mitotic divisions of the initial cells, the derivatives are pushed farther away from the zone of active division. initial --> 1 initial + 1 derivative -derivatives can further divide to produce derivatives and/or later differentiate -derivatives can become initials in certain circumstances, dependent on location and action by developmental controls

xylem

Xylem is the water conducting tissue. It consists of living cells like parenchyma and dead cells like tracheary elements. Fibers are also present. Xylem elements differentiating from an apical meristem constitute primary xylem where as secondary xylem is differentiated from vascular cambium. Xylem is the most preserved tissue in fossils, due to the development of lignified secondary walls. Primary Xylem: This is differentiated into Protoxylem and Metaxylem, denoting the xylem that appears first. In stems, protoxylem is found nearest to central axis (endarch xylem) and in roots away from centre (exarch xylem). The protoxylem elements have annular, spiral and sometimes reticulate secondary thickenings. Fibers are absent in protoxylem. Metaxylem appears after protoxylem. Metaxylem has only pitted secondary walls. Metaxylem is more complex than protoxylem and its elements are wider. Secondary Xylem: The vascular cambium (intrafascicular cambium interfascicular cambium) producing secondary xylem consists of fusiform and ray initials. Here also the secondary xylem is also of two-system-1) Axial or vertical system with living and nonliving cells and 2) ray or horizontal system with living cells. When compared with primary xylem, secondary xylem is more complex and shows orderly development. Pitted and scalariform secondary thickenings are developed.

Protoplasm

a general term for the living substance of all cells (usu. excluding cell wall, sometimes excluding organelles)

What are the main types of internal secretory cells/tissues? How are their cells modified?

a. Secretory cells: storage and/or production and secretion of oils, other biochemicals, etc.) b. Canals, resin ducts, and cavities: resins and oils, etc. c. Laticifers: secrete latex; seals wounds and protection

Collenchyma

a. structure: cells in collenchyma tissue have unevenly thickened primary cell walls that are rich in pectins & hydrated, not lignified; alive at functional maturity b. function: provides support in growing/elongating regions; the walls are extensible & plastic c. distribution: mainly under the epidermis at ridges, corners, and midribs in elongating regions d. types: angular, lamellar, lacunar collenchyma

Parenchyma

a. structure: living cells often indistinct morphologically; often grouped together as parenchyma tissue b. function: basic metabolism, storage, secretion, transport, photosynthesis c. distribution: common in ground tissue; cells also present in vascular and dermal tissue systems d. types: chlorenchyma, aerenchyma, transfer cells

Meristematic tissues:

active sites of undifferentiated cell division

Cytoplasm

all living components excluding nucleus, vacuoles, cell wall

APOPLAST

dead" parts

SYMPLAST

living components/protoplas

Does the mature sclerenchyma cell possess a protoplast? Explain In what parts of the stem are mature fibers found? Where would one find sclereids?

no they are dead cells that have heavily thickened walls containing lignin.Such cells occur in many different shapes and sizes, but two main types occur: fibres and sclereids. Fibres are greatly elongated cells whose long, tapering ends interlock, thus providing maximum support to a plant. They can be found almost anywhere in the plant body, including the stem, the roots, and the vascular bundles in leaves. Sclereids are extremely variable in shape and are present in various tissues of the plant such as the periderm, cortex, pith, xylem, and phloem.

Apical meristems:

produce new cells and establish patterns (SAM, RAM)

plasodesmata

provide cytoplasmic connectivity between adjacent cell. through the plasmodesmata the protoplasm of living cell are interconnected

What is a bordered pit pair?

the pit cavity is enclosed by overarching borders called it chambers. the pit aperture can be circular,linear,oval or irregular. when the border of the pit os thick a pit canal appears which forms a passage between the pit chamber and the cell lumen.

What are the differences between tunica and corpus

tunica organization:1-5 layers of initals plane of division:anticlinal only location:outermost layers primary tissue meristems produced: procambium, ground meristem, protoderm corpus organization:mass of intials not really layered plane of division:anticlinal and periclinal primary tissue meristems produced: procambium and ground