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Transcript of slides 3rd lec
8/3/2019 slides 3rd lec
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Third Micro Slides
Done by : Rmz Rabadi
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Introduction (continued)
Viruses
Composed of only a few genes
protected by a protein coat .
Depend on the energy and
metabolic machinery of a host cell in
order to reproduce.
They are acellular , that is , they are
not composed of cells .
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Eucaryotic cell structure
Sorry if the picture is not clear enough but this is the best I could do «
you can search the net for a better one
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TEM of Yeast cell
Sorry if the picture is not clear enough but this is the best I could do
« you can search the net for a better one
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Eucaryotic Cell Structures
Cell membrane
Mosaic of large molecules of proteins and
phospholipidsRegulates passage of nutrients , waste
products and secretions in and out of the cell
Has selective permeability
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THE Nucleus
The command center of the cell
3 components : nucleoplasm , chromosomes ,andnuclear membrane .
Chromosomes are embedded in the nucleoplasm . Eucaryotic chromosomes consist of linear DNA
molecules and proteins .
-genes are located along the DNA
molecules.- each gene contains the information to produce a geneproduct .
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The Nucleus ( continued)
Most genes code for proteins but some code for 2types of ribonucleic acid ( RNA)- Ribosomal ribonucleic acid (rRNA)
- Transfer ribonucleic acid (tRNA) The organisms complete collection of genes is the
organisms genotype or genome .
The number and composition of chromosomes and the
number of genes on each chromosome arecharacteristic of the particular species of organism .
Human diploid cells have 46 chromosomes or 23 pairs
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Eukaryotic cell structure
(continued) Cytoplasm :
A semi fluid gelatinous nutrient matrix.
Contains storage granules and a variety of organelles
Each organelle has a specific function .
The cytoplasm is where most metabolicreactions occur
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Eukaryotic cell structure
(continued) Endoplasmic reticulum :
A highly compressed system of membranes
arranged to form a transport networkIn the
cytoplasm
Ribosomes :
Mainly ribosomal RNA and protein
Important in the synthesis of proteins
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Eukaryotic cell structure
(continued) Golgi complex :
Also Golgi apparatus or Golgi body .
Connects or communicates with ERCompletes the transformation of newly
synthesized proteins and packages them for
storage or export .
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Eukaryotic cell structure
(continued) Lysosomes and Peroxisomes :
Originate in the Golgi complex
Lysosomes contain lysosyme and otherdigestive enzymes
Peroxisomes are membrane bound vesicles
where H2O
2 is generated and broken down
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Eukaryotic cell structure
(continued) Mitochondria :
power plants
powerhouses or energy factors of theeukaryotic cells
ATP molecules are formed by cellular
respiration .Number of mitochondria varies depending on
activities of cell
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Eukaryotic cell structure
(continued) Palastids
Membrane bound structres containing
photosynthetic pigmentsThey are sites of photosynthesis
Chloroplasts are type of plastid
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Eukaryotic cell structure
(continued) Cytoskeleton
A system of fibers throughout the cytoplasm
3 types of fibers :1. Microtubules
2. Microfilaments
3. Intermediate filaments
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Eukaryotic cell structure
(continued) Cell wall :
Some eukaryotic cells contain cell wall : an
external structure to provide shape ,protection and rigidity .
Simpler than prokaryotic cell wall
Chitin found in cell wall of fungi , cellulose incell wall of algae and plants