1. By: Zahraa Aljibory Brie Mason Aman Yhesmein Alhassan
3.4 The Cell Cycle
By: Zahraa Aljibory
Brie Mason
Aman
Yhesmein Alhassan

2. The cell cycle: is a series of changes a cell endures from the time of its formation until it divides.
A newly formed cell grows then divides to form 2 new cells
The new cells then my grow and divide
Brie

3. The phases of the cell cycle
Interphase
Mitosis
Cytoplasmic division (cytokinesis)
Differentiation
Brie

4. The cell cycle
Brie

5. Check points
Checkpoints: a group of special proteins that interact with the cell cycle at certain times.
Restriction check points: determines a cell’s fate weather it will finish the cell cycle and divide or it will move onto a non dividing stage and die .
Brie

7. The cell cycle is strictly regulated
Any type of hormone or growth factor has the capability of triggering cell division.
Example: breasts develop into milk producing glands during pregnancy. If the cell cycle is too infrequent then the wound can't heal. If cell division is too frequent than cancer grows.
Yhsmeen

8. Some cells may divide in large various amounts
Cells don't normally continuously divide. Continuous cell division causes cancer. Cells usually divide 40/60 times only.
Some cells may divide in large various amounts
Example: cells that line the small intestine
Some cells don't divide.
Example: nerve cells
Yhsmeen

9. A cell knows to stop dividing because of a built in clock in form of chromosome tip.
These chromosome regions are called telomeres; which shorten cell division.
Telomeres shorten length of the division process through which a cell no longer contains the ability to divide.
Yhsmeen

10. Interphase
Period of preparedness that allows a cell to grow and duplicate the majority of its content.
2 daughter cell join together to form 1.
Aman

11. Time of large synthetic activities. During interphase
the cell gets its nutrients.
uses it to make new living material .
Maintains routine.
Aman

12. The most important task is the replication of genetic material.
The cell duplicates
Membranes
Ribosomes
Lysosomes
Mitochondria
The most important task is the replication of genetic material.
In Order for 2 new cells to have genetic instruction.
Aman

13. S phase (synthesis): DNA is replicated G1 phase: growth phase
Phases of interphase
S phase (synthesis): DNA is replicated
G1 phase: growth phase
G2 phase: check for errors in replication
Zahraa

14. Zahraa

15. The cell
Zahraa

16. Cell division A cell is able to divide in 2 ways.
One type of cell division is meiosis.
Meiosis:
part of gametogenesis
Formation Of eggs (in females)
Formation of sperm( in males)
Aman

17. 23 chromosomes from sperm.
An egg fertilized by a sperm must have a normal complement of 46 chromosomes.
23 chromosomes from egg.
23 chromosomes from sperm.
Both the egg and the sperm must ½ their normal chromosomes through a reduction process called meiosis.
Aman

18. Mitosis: division of the nucleus
Other types of cell division that increase cell number are essential for growth, development,and wound healing.
Mitosis: division of the nucleus
Cytokinesis: division of the cytoplasm
Sperm, egg, and blood cells can't go through the process of mitosis.
Zahraa

19. Division of the nucleus must be precise because it contains the DNA.
Each new cell resulting mitosis must have a complete accurate DNA to survive.
The process of mitosis is continuous without changes in steps.
The steps of mitosis
Prophase
Metaphase
Anaphase
Telophase
Zahraa

20. Zahraa

21. Prophase
A sign that a cell is going to divide is when the chromosomes become visible in the nucleus
Because the cell went through S phase each prophase chromosome is made up of 2 identical portions (chromatids) which are temporarily attached to a region called the centromere.
Centrioles of centrosome replicate before mitosis starts
Zahraa

22. 2 newly formed centrioles move to the opposite side of the cell.
The nucleus and the nuclear envelope than break up and dissolve “they are no longer their”
Microtubes are put together from proteins in the cytoplasm and they are involved with the centrioles and chromosomes.
Spindle shaped microtubes form between centrioles as they move apart.
Zahraa

23. Zahraa

24. Metaphase
As a result to microtubule activity chromosomes line up midway because of the centrioles.
Spindle fibers attach to the centromeres of each chromosome.
This happens so that a fiber from one pair of centrioles contacts one centromere
Also for another pair of centrioles to attach to another centromere.
Zahraa

25. Zahraa

26. Anaphase Centromeres are pulled apart.
While the chromatids separate they become singular chromosomes.
Because of microtubule activity the separated chromosomes move in opposite direction.
Spindle fibers become short and pull the chromosomes attached to them toward the centrioles at the opposite end of the cell.
Zahraa

27. Zahraa

28. Telophase
This phase starts after the cells complete their migration towards the centrioles.
The process is the opposite of prophase.
When the chromosomes get near the centrioles they begin to elongate (become larger) and unwind.
They go from a rod like appearance to a thread of chromatin.
Zahraa

29. Around each chromosome set a nuclear envelope forms.
Nucleoli appear with the new nuclei.
Microtubules break apart into free tubulin molecules.
Zahraa

30. Telophase
Zahraa

31. Mitosis Recap
Zahraa

32. Zahraa

33. Cytoplasmic Division Begins during anaphase.
Cleavage furrow: type of construction that begins in anaphase and continues through telophase.
The cell membrane becomes narrower in the middle of the cell
A ring of microfilaments which were put together in the cytoplasm become narrower (constrict) and attache to the inner surface of the cell membrane and then divides the cytoplasm.
Zahraa

34. The contractile rings lie at right angles to the microtubules that pulled the chromosomes to the opposite side of the cell.
The ring pinches inward and separates the newly formed nuclei and it distributes ½ of the organelles into the new cell.
The new cells may be different in size, shape, and organelle content but they all have the same genetic information.
Zahraa

35. Zahraa

36. Zahraa

37. Zahraa

38. Cell Differentiation
The cell division has a cell cycle and there are several steps which are in the m-phase there called interphase,prophase, metaphase,anaphase,telophase, cytokinesis. They all play a big role in the cell cycle. (ex: if you have cancer it's probably from the genes of your family like your mother had it and then past it on to you.)
Aman

39. Aman

40. Stem cells
The growth and repair of tissues are called stem cells. Stem cells divide into two daughter cells or one daughter cell. There are two different daughter cells one is by mitosis and the other is by meiosis. Mitosis produces genetically identical to the mothers cells which is diploid. Meiosis produces half the mothers cell which is a haploid.
Aman

41. Aman

42. Aman

43. Aman

44. progenitor cell
PROGENITOR CELL IS LIKE a stem cell but it cannot divide it's also more specific than a stem cell but there both found in a bone marrow.
A bone marrow is a soft fatty tissue inside your bones that you can take out for a healthy one. (ex: treats people that have leukemia or other immune systems)
Aman

45. Genome
Genome is a set of long dna molecules containing tens of thousands of genes.
Aman

46. Cell Death How do cells die?
•Cells either die from an unplanned or planned death.
• Unplanned death: cells die in an unplanned matter when they're exposed to many different environmental agents. These occur both in chemical and physical events Especially if a cell is injured (and or lack of oxygen, suffer from trauma) it then swells up and burst out its contents and causes surrounding cells to react defensively.
Yhsmeen

47. • Planned death is also known as "Apoptosis".
•Apoptosis is basically the opposite of an unplanned death. When apoptosis occurs it executes a certain cell sometimes known as a "programmed cell death" or in others words cell suicide.
Yhsmeen

48. Cell Remains
Once the cell does, its genes controlling the breakdown process are activated. It condenses and breaks down its nucleus, DNA and cytoplasm. Immune cells called phagocytes, whose job it is to remove unwanted material from the organism, envelop the remaining cell material and it is then broken down.
Yhsmeen

49. Clinical Connection
In certain highly specialized cell types, endocytosis and exocytosis become structurally and functionally linked in the process of transcytosis.
In transcytosis a particle enters by endocytosis.
Brie

50. I.E.: transcytosis occur in the genital tract and in the rectum.
Transcytosis through the M cell protects proteins against some forms of food poisoning infectious poison proteins can enter the body by evading the M cell barrier in the small intestine.
I.E.: transcytosis occur in the genital tract and in the rectum.
HIV(the virus that causes AIDS) uses this mechanism to cross the epithelium and reach the bloodstream.
Brie