1. T HE C ELL (P ROKARYOTES – E UKARYOTES )

2. T YPES OF C ELL : Prokaryotes Eukaryotes

3. P ROKARYOTES : They are Micro-organisms where the DNA is concentrated as Neocloid body and the DNA is a single strand or a double strand.

4. Prokaryotes Bacteria (exists in most environments) Archaea (exists in hot and salty environments)

5. T YPES OF PROKARYOTIC : ProkaryoticBacteriaArchaea

6. SimilaritiesDifferences All cells are surrounded by a plasma membrane. The semi-fluid substance within the cell is called “cytosol”, containing the cell organelles. All cells contain chromosomes which have genes in the form of DNA. All cells have tiny organelles called “Ribosomes” that make proteins. A major difference between prokaryotic and eukaryotic cells is the location of chromosomes. In an eukaryotic cell, chromosomes are contained in a true nucleus. In a prokaryotic cell, the DNA is concentrated in the nucleoid without a membrane separating it from the rest of the cell. In prokaryotic cell, DNA is a single strand or double strand DNA. But in eukaryotic cell, DNA is double strand. P ROKARYOTIC & E UKARYOTIC

7. 1-B ACTERIA Its consisted of : 1. The Bacterial capsule: its a protective layer that surrounds the bacteria and helps it stick to the host cell and increases its own resistance to the hosts defenses. 2. The Bacterial cell wall: it maintains the shape’s cell and prevents it from bursting in a hypotonic environment as well as protection.

8. B ACTERIA Functions :  maintains the shape of the cell.  affords physical protection  prevents the cell from bursting in a hypotonic environment. NOTE: The walls of Archaea lack peptidoglycan Functions :  maintains the shape of the cell.  affords physical protection  prevents the cell from bursting in a hypotonic environment. NOTE: The walls of Archaea lack peptidoglycan Functions :  Adhere bacteria cells to their substratum.  Increase bacteria resistance to host defenses.  Stick bacterial cells together when live as colonies.  Protect bacterial cell. Functions :  Adhere bacteria cells to their substratum.  Increase bacteria resistance to host defenses.  Stick bacterial cells together when live as colonies.  Protect bacterial cell.

9. 1-B ACTERIA Its consisted of : 1. The Bacterial capsule: its a protective layer that surrounds the bacteria and helps it stick to the host cell and increases its own resistance to the hosts defenses. 2. The Bacterial cell wall: it maintains the shape’s cell and prevents it from bursting in a hypotonic environment as well as protection.

10. T HE G RAM ’ S S TAIN It is a tool for identifying specific bacteria, based on differences in their cell walls. ( Types based on Gram’s Stain ) Their cell walls have large amounts of peptidoglycans that react with Gram’s stain (appear violet- stained ). their cell walls have no or small amount of peptidoglycan. So, do not react or very weakly react with Gram’s stain ( do not appear stained )

11. T HE G RAM ’ S S TAIN  Gram- negative species are pathogenic more threatening) than gram-positive species.  Gram-negative bacteria are commonly more resistant than gram-positive species to antibiotics.

12. P RODUCTION OF B ACTERIA  Prokaryotes reproduce only asexually by binary fission A single cell produce a colony of offspring

13. Nutrition refers to how an organism obtains energy and a carbon source from the environment to build the organic molecules of its cells. CO2 as Carbon source Organic compounds as Carbon Source Photo- Autotrophs Photo- Heterotrophs Chemo- Autotrophs Chemo- Heterotrophs Light as energy source CO 2 as C source Light as energy source CO 2 as C source Chemicals as energy source CO2 as C source Chemicals as energy source CO2 as C source Light as energy source Organic compounds as C source Light as energy source Organic compounds as C source organic substances organic substances as a source for both energy and carbon

14. V IRUSES

15. V IRUSES ARE MUCH SMALLER THAN BACTERIA

16. V IRUS IS ABOUT 20 NM IN DIAMETER A CTUALLY V IRUSES ARE NOT CELLS

17. A VIRUS IS A GENOME ENCLOSED IN A PROTECTIVE COAT

18. V IRAL C APSID A protein shell that encloses the viral genome. It is rode-shaped, helical, polyhedral or more complex.

19. Capsomeres: Are the protein units that form capsid.

20. E NVELOPE E NVELOPE viral envelopes Some viruses have viral envelopes, membranes cloaking their capsids. These envelopes are derived from the membrane of the host cell.

21. V IRAL G ENOME : (H EREDITARY MATERIAL ) Viral genomes may consist of: double-stranded DNA (dsDNA), single-stranded DNA (ssDNA), double-stranded RNA (dsRNA), single-stranded RNA (ssRNA). depending on the specific type of virus. The viral genome is usually organized as a single linear or circular molecule of nucleic acid. fourgenes severalhundred The smallest viruses have only four genes, while the largest have several hundred.

22. V IRAL G ENOME (H EREDITARY MATERIAL ) double-stranded DNA dsDNA Single-stranded DNA ssDNA Double-stranded RNS dsRNA Single-stranded RNA ssRNA The viral genome is usually organized as a single linear or circular molecule of nucleic acid. The smallest viruses have only four genes, while the largest have several hundred.

23. V IRUSES WITH AN OUTER ENVELOPE USE THE ENVELOPE TO ENTER THE HOST CELL. Glycoproteins on the envelope bind to specific receptors on the host’s membrane. The envelope fuses with the host’s membrane, transporting the capsid and viral genome inside. The viral genome duplicates and directs the host’s protein synthesis machinery to synthesize capsomeres with free ribosomes and glycoproteins with bound ribosomes. After the capsid and viral genome self- assemble, they bud from the host cell covered with an envelope derived from the host’s plasma membrane, including viral glycoproteins. NOTE: These enveloped viruses do not necessarily kill the host cell. NOTE: These enveloped viruses do not necessarily kill the host cell.

24. It is retrovirus and it includes:  an envelope with glycol- proteins,  a capsid containing two identical RNA strands as its genome  two copies of reverse transcriptase. HIV V IRUS THE VIRUS THAT CAUSES AIDS

25. It has a 20-sided capsid- head that encloses their DNA and protein tail piece that attaches the phage to the host and injects the phage DNA inside. B ACTERIA INFECTING V IRUSES BACTERIOPHAGES OR PHAGES

26. T YPES B Y C YCLE The phage reproductive cycle results in the death of the host. In the last stage, the bacterium lyses (breaks open) and releases the phages produced within the cell to infect others. Virulent phages reproduce only by a lytic cycle. The phage reproductive cycle results in the death of the host. In the last stage, the bacterium lyses (breaks open) and releases the phages produced within the cell to infect others. Virulent phages reproduce only by a lytic cycle. The phage genome replicates without destroying the host cell. Temperate phages, like phage lambda. May use both lytic and lysogenic cycles. During a lytic cycle, the viral gene immediately turn the host cell into a virus-producing factory, and the cell soon lyses and releases its viral products. The phage genome replicates without destroying the host cell. Temperate phages, like phage lambda. May use both lytic and lysogenic cycles. During a lytic cycle, the viral gene immediately turn the host cell into a virus-producing factory, and the cell soon lyses and releases its viral products.

27. P HAGE T4 Reproduced by a lytic cycle only It’s a “Virulent virus” that causes the death of the host

29. P HAGE L AMBDA It may use both Lytic and Lysogenic cycles It’s a “Temperate virus”

30. phage lambda Phage T4

31. LyticLysogenic \ Lytic Phage T4 Many tail fiber Phage Lambda Only 1 tail fiber E XAMPLES

32. Bacteriophages Phage lambdaLysogenic cycleLytic cyclePhage T4Lytic cycle

33. K EY C HARACTERS V IRUSES

34. DNA enclosed in a protein coat ( sometimes, membranous envelop also ) DNA enclosed in a protein coat ( sometimes, membranous envelop also )

35. Can be crystallised Can be crystallised

36. Each type of virus infects a limited range of host cells ( host range ) Each type of virus infects a limited range of host cells ( host range )

37. They lack enzymes for metabolism They lack enzymes for metabolism

38. Have no ribosomes for making their own proteins Have no ribosomes for making their own proteins

39. Reproduced only within a living host cell Reproduced only within a living host cell ( obligate parasitism ).

40. Human cold AIDS Most viruses of eukaryotes attack specific tissues. eg. Human cold viruses infect only the cells lining the upper respiratory tract, and AIDS virus binds only to certain white blood cells (Immune system).

42. Q1: W RITE WHETHER EACH OF THE FOLLOWING STATEMENTS IS T RUE (T) OR F ALSE (F): 2- G RAM STAINING OF BACTERIA DEPENDS ON THE AMOUNT OF PEPTIDOGLYCAN WHICH EXISTS IN THE CELL WALL. 3- L YSOGENIC CYCLE OF VIRUSES RESULTS IN DEATH OF THE HOST CELL. 4- B ACTERIA AND VIRUSES ARE CLASSIFIED AS EUKARYOTES. 5- A LL PROKARYOTES ARE AUTOTROPHS. 6- T HE GENOME IN INFLUENZA VIRUS AND HUMAN IMMUNODEFICIENCY VIRUS ( HIV) IS DNA WHILE IN T4 BACTERIOPHAGE IS RNA. 7- C HEMOHETEROTROPHS, USE ORGANIC MOLECULES FOR BOTH ENERGY AND CARBON SOURCE. Q1: Write whether each of the following statements is True (T) or False (F): 1- Gram staining of bacteria depends on the amount of peptidoglycan which exists in the cell wall. 2- Lysogenic cycle of viruses results in death of the host cell. 3- Bacteria and viruses are classified as eukaryotes. 4- All prokaryotes are autotrophs. 5- The genome in influenza virus and human immunodeficiency virus( HIV)is DNA while inT4 bacteriophage is RNA. 6- Chemoheterotrophs, use organic molecules for both energy and carbon source.

43. Q 2: Choose the correct answer (one answer only): 1- Viral capsid is made up of: a- protein. c- lipid. b- carbohydrates. d- both a and b. 2- Which of the following would be found in animal cells but not in bacteria cells? a-DNA. b-plasma membrane. c-endoplasmic reticulum. d-ribosomes. 3- Organisms that use light as energy source&organic substances as carbon source are :- a-photoheterotrophs. b-chemoautotrophs. c-photoautotrophs. d-chemoheterotrophs. 4- The nucleic acids of viruses may be: a- RNA. b- DNA. c- a and b. d- a or b. 5- Gram staining of bacteria depends on the amount of peptidoglycan which exists in: a)- capsule b)- cell wall c)- plasma membrane d)- nucleoid 6-Which of the following characteristics or processes is common to both bacteria and viruses? a- binary fission. b- ribosomes in cytoplasm. c-nucleic acid as the genetic material. 7- Phage-λ reproduce in the bacterial cell by: a)- lytic cycle b)- lysogenic cycle c)- mitotic division d)- binary fission 8- Bacterial capsule is important for: a)- adherence of bacteria to each other b)- adherence of bacteria to substratum c)- protection d)- all of the above -