slides 3rd lec

8/3/2019 slides 3rd lec

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Third Micro Slides

Done by : Rmz Rabadi



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 .



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



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



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



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 .



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



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




(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




(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 .




(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




(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




(continued) Palastids

Membrane bound structres containing

photosynthetic pigmentsThey are sites of photosynthesis

Chloroplasts are type of plastid




(continued) Cytoskeleton

A system of fibers throughout the cytoplasm

3 types of fibers :1. Microtubules

2. Microfilaments

3. Intermediate filaments




(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

slides 3rd lec

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