Download - Post-Laboratory Discussion Bio21
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Post-laboratory Discussion
First Departmental Exam
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Microscopy
• Review- Parts and function of the microscope- Computation of the CF- Magnification of the drawing- Principles of Microscopy
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Some points to remember:
• Plane side- sufficient amount of light• Concave side – artificial light is used
• Cedar oil – oil used in oil immersion objective• Xylol or xylene – to remove the cedar oil
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Plant CellCell wall • Composed of cellulose
and hemicellulose, suberin, lignin and proteins
• Functions1.provides shape to the cell2.Contains and protects the
protoplasm Allium cepa
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• Layers1. Primary wall2. Secondary wall
• Middle lamella - composed of pectic substances- binds cells; found between 2 adjacent cell- Hydrolyzed by the enzyme pectinase when the
fruit ripens softening
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Nucleus• Functions 1.control center of the cell2.cellular reproduction3.Controls and directs protein synthesis
nucleus
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Protoplasm cytoplasm & nucleoplasm
Cytoplasmic streaming / CYCLOSIS- Distributes nutrients, gases and wastes all over
the cell- counterclockwise and clockwise direction- Directs chloroplast to the direction of sunlight
Hydrilla verticellata
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Plastids- are round, oval and disk-shaped bodies found
in the cells of green plants1.Proplastids - In young cells, from which other plastids may
develop.2. Chloroplasts- with green pigment called chlorophyll- functions in photosynthesis
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3. Chromoplasts- plastids responsible for the red, yellow,
brown or orange color of many fruits and veggies
- pigments are called carotenoid such as xanthophyll and carotene lipid-soluble
Capsicum frutescens
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4. Leucoplast- colorless plastid that is responsible for food
storage.• Amyloplast – stores starch; stains bluish-
black in iodine in potassium iodide solution (IKI)
• Elaioplast- fats & oils• Aleuroneplast- proteins
Solanum tuberosum
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Vacuole- watery compartment surrounded by a
membrane called the TONOPLAST- houses or contains metabolic wastes- stores water, salts, starch, protein bodies and
granules
• Pigmentsanthocyanin - Trandescantia spathacea
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- other pigments are betacyanin, anthoxanthin- function :1. coloration/ aesthetic purpose2. defense mechanism of plants against herbivory
• Crystals – metabolic waste product- Functions:1. taxonomic identification2. Anti-herbivory3. Calcium balance
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• Types1.Raphide – Sansiviera sp., Diffenbachia sp.2.Styloid - Sansiviera sp., Diffenbachia sp.3.Prismatic – Begonia sp.4.Druse/rosette - Sansiviera sp., Diffenbachia sp. calcium oxalate1.Sandy crystal – Sansiviera sp. silica1.Cystolith – Ficus elastica calcium carbonate
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Circle = sandyArrow- styloid
Circle = prismaticArrow- druse
druse raphide cystolith
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Plant cells vs Animal cellsParts Plant cell Animal cell
Cell wall present absent
Centrioles absent present
Cleavage furrow absent present
Phragmoplast present absent
lysosomes absent present
Central vacuole present absent
plastids present absent
cilia absent present
*Animals have vacuoles but they are smaller than the central vacuole and has a different function.
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Cell Cycle
• Phases1.Karyokinesis – nuclear division
1.Cytokinesis – cytoplasmic division
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Mitosis• Interphase - not a resting phase; metabolically active cells- nucleolus very visible- presence of nuclear envelope- uncoiled chromosome = chromatin
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• Events1.G1 – presynthesis phase; growth and normal
metabolic process occur2.S – synthesis phase; DNA replication happens3.G2 – premitotic phase; preparing for cell
division
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• Prophase- disintegration of nuclear
envelope - Disappearance nucleolus- densely thick chromosomes (2
sister chromatids)- formation of spindle fiber- Centromere (point of attachment of
the 2 sister chromatids
• Metaphase- presence of metaphase
plate- chromosomes (2 sister
chromatids) are aligned in the center
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• Anaphase- chromosomes (1 chromatid)
have migrated to the opposite poles
- # of chromosomes have doubled
Metaphase- presence of metaphase plate (imaginary plane)- chromosomes are aligned in the center
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• Telophase- opposite of prophase- formation of cell plate phragmoplast,
vesicles, cell wall
- The cell divides into two- The chromosomes
uncoil.- The nucleus reforms.- The spindle apparataus
disassembles.
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Plant tissues
• Meristematic tissue• Fundamental tissue
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Meristematic Tissue
• Region where there is new cell formation and growth initiation
A.Apical Meristem- for the shoot and root elongation or increase in length
1.Root apical meristem – Allium cepa l.s.2.Shoot apical meristem – Coleus blumei l.s.
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The Root cap is composed of irregular, nondividing cells. The purpose of the root cap is to protect the apical meristem.The apical meristem is composed of dividing cells.
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B. Lateral Meristem – for increase in girth
1.Vascular cambium – produce xylem and phloem
2.Cork cambium – produce cork cells and phelloderm
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Vascular cambium
cork cambium
Tilia sp. stem
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Simple/Fundamental tissue
1. Parenchyma• thin walled; for storage2. Collenchyma• unevenly thickened walls; for plastic support3. Sclerenchyma• for elastic support, rigidity and strengthening1. Fibers- thickened walls2. Sclereids- isodiametric in shape
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C P
Apium graviolens stem
Collenchyma
Parenchyma
Coleus blumei
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Sclereid (Stone cells) in Pyrus malus
Bundle cap(Fibers)
Helianthus sp.
Bundle sheath(Fibers)
Zea mays
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Complex Tissue• Xylem – conduction of water1. Trachieds – narrow with tapered ends2. Vessels – thick and wide with perforations*both have secondary thickenings composed of
LIGNIN
• Phloem – conduction of food and nutrients1. Companion cells- nucleate, regulates metabolism
of sieve tubes2. Sieve tube element – enucleate, conduction of
food* Only have 1° wall unlike xylem.
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2°XYLEM
vessel tracheid
•Pinus sp. only have trachieds because they are non-flowering•Helianthus sp. both have vessels and tracheids since they are flowering plants
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Monocot• Zea mays stem – scatterd type of vascular
bundle distribution
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(Bundle sheath)
Zea mays vascular bundle
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Dicot
• Helianthus sp. – concentric type of vascular bundle distribution
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Bundle cap
xylem
Vascular Cambium
Phloem
Collateral Vascular Bundle of Helianthus sp.
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Cucubita sp. stem
P
P
X
VC
VC
Bicollateral vascular bundle of Cucurbita sp.
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Trichomes
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Function
• Anti-herbivory• Defense of plants• Creates a layer of immobile air next to the leaf
which allows water that diffused to bounce back in
• Shades leaves
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Epidermis
• Cuticle protects the epidermis from desiccation or water loss
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Stomatal Apparatus
The guard cells are the only epidermal cells that have chloroplasts. The other cells in the epidermis do not possess chloroplast.
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• The Guard cells control the stomatal openings in the epidermis of the leaf. It regulates the exchange of CO2, oxygen and water vapor.
• Three environmental factors regulate these cells. These factors are light, CO2 concentration and water availability.
• When the guard cells are activated, K+ pumps actively transport K+ into the guard cells, resulting in a high [K+] in the cells.
• As a result, water enters the cells by osmosis. This causes the guard cells to swell. The one side of the guard cells is thicker than the other and does not stretch. As the guard cells swell up they bend.
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Some tips for the exam
• Be sure to know your manual by heart.• Know everything that you’ve answered in the manual• Know the structures, functions and specimens
(including scientific names) where they can be found.• Read the pre-lab part• Bring a calculator :D
Good luck in your exam. Study hard … - jedayao