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Flashcards in cytology Deck (87)
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1

fundamental unit of living material showing a variety of functional specializations which perform all the activities necessary for the survival, growth and reproduction of the organism.

Cells

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2 cell types

prokaryotic
eukaryotic

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2 cell types
– presence of true nucleus surrounded by a nuclear envelope


1. Eucaryotic cell

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2 cell types
– absence of nuclear envelope; nuclear substance is mixed with the rest of the cytoplasm

2. Procaryotic cell

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part of a cell
the outer limiting membrane that serves as a selective barrier

Plasmalemma –

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part of a cell
the protoplasm outside of the nucleus which contains the different organelles and inclusions of the cells

Cytoplasm –

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part of a cell
contains the genetic material of the cell

Nucleus –

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Pertains to the outer trilaminar-appearing membrane surrounding the cell.

A selective barrier that regulates the entrance and exit of substances into the cell.

cell membrane

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2 Models of cell membrane

1. The Classical Model of Davson and Danielli
2. The “ Fluid Mosaic Model” of Singer and Nicholson

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Cell Membrane model
The membrane proteins are globular and float like iceberg in a sea of lipid

The more acceptable model

In a dynamic state

The “ Fluid Mosaic Model” of Singer and Nicholson

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This model postulates a lipid center sandwiched by a coat of protein on each surface.

1. The Classical Model of Davson and Danielli

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type of model
1. The plasmalemma is composed of a bilayer of ionic and polar head groups and the membrane protein complexes are embedded in a “mosaic configuration.”

2. Other protein molecules on the external and protoplasmic surfaces of the plasmalemma give an asymmetrical appearance of the molecular structure


The “ Fluid Mosaic Model” of Singer and Nicholson

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type of model


3. Oligosaccharide chain from the surface of the plasmalemma amplify the inherent asymmetry.

The “ Fluid Mosaic Model” of Singer and Nicholson

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Consist of a bilayer of phospholipid molecules which are amphipathic i.e. polar hydrophilic head and non- polar hydrophobic tail

cell membrane

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Glycoprotein & polysaccharide covering of the external surface of the cell membrane

Imparts a special identity to each cell type, therefore, plays an important role in histocompatibility

glycocalyx

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functions of cell surface

1. Filtration barrier

2. Allows sudden changes in ion permeability in response to changes in electrical potential

3. Receptor site for hormones & enzymes

4. Cell recognition
(GLYCOCALYX)

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ground substance

hyaloplasm

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part of cytoplasm
usually in sol phase and manifest active streaming
cellular components are carried along by directed movements

endoplasm

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part of cytoplasm
usually in gel state
relatively free of cellular components
occupies the periphery of the plasmalemma

2. Exoplasm

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cytoplasmic organelles (9)

1. Endoplasmic reticulum: RER & SER
2. Golgi Complex
3. Mitochondria
4. Lysosomes
5. Centriole / centrosome
6. Peroxisomes (microbodies)
7. Filaments
- Myofilaments
- Tonofilaments
8. Microtubules
9. Annulate lamellae

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Consist of an anastomosing network of intercommunicating channels and sacs formed by a continuous membrane

ER

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2 Forms of ER

A. Granular / Rough Endoplasmic Reticulum
B. Smooth Endoplasmic Reticulum

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Most typical er

Interconnecting network of membranous tubules, vesicles & flattened sacs

Presence of ribosomes on its membrane surface

ROUGH ENDOPLASMIC RETICULUM

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FUNCTIONS OF THE RER:

Synthesis of secretory protein and its storage within the intracisternal space

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Non- granular

Membranes are also arranged in an anastomosing network of tubules

Cisternae are more tubular

May also connect with the RER, the plasmalemma, and the Golgi complex.

SER

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Function of SER in striated muscle:

as sarcoplasmic reticulum

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Function of SER In endocrine cells:

biosynthesis of steroid hormone

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Function of SER In intestinal villi:

synthesis of neutral fats

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Function of SER In parietal cells of the stomach:

formation of HCl acid

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System of stacked saucer shaped cisternae with concave (maturing / trans face) facing the nucleus and a forming / cis face adjacent to rough ER

golgi apparatus

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