1. Unit 7 Mitosis and Asexual Reproduction

2. Something to Think About !!!!
How does the size of your cells now compare to the size of your cells when you were a baby?

3. Answers to Think About It:
The cells of an adult organism are no larger than those of a young organism –there are just more of them.

4. One More Thing To Think About ……
Why do cells make so many new cells instead of just having their cells get larger and larger?

5. Reason # 1
DNA Overload
1.The information that controls a cell’s function is stored in DNA
2.DNA is able to meet the cell’s need when cells are small
3.If a cell were to grow too large, there is not enough information in the DNA molecule to control the larger cell and it is called DNA overload.

6. Reason # 2 Exchanging Materials
If cells were larger, the surface area to volume ratio would become too small and the cell wouldn’t be able to move materials fast enough across the cell membrane.
There would be traffic jams similar to the Thruway toll booths on a holiday weekend!

7. When do new cells need to be produced?
Replacement
Cells get damaged and need to be replaced.
Not all cells can be reproduced.
Growth
The addition of more cells to make the organism larger.

8. Life Span of Various Human Cells
Cell Type
Lining of esophagus
Lining of small intestine
Lining of large intestine
Red blood cells
White blood cells
Smooth muscle
Cardiac muscle
Skeletal muscle
Nerve cells
Life Span
Cell Division
2-3 days
Can divide
1-2 days
Can divide
6 days
Can divide
Less than 120 days
Cannot divide
10 hours to decades
Cannot divide
Long-lived
Can divide
Long - lived
Cannot divide
Long-lived
Cannot divide
Long-lived
Most do not divide

9. The cell cycle is a series of events that cells go through as they grow. It consists of four phases.

10. Cells spend 90 % of their time in Interphase.
G1 Phase
M Phase
S Phase
G 2 Phase
Cells spend 90 % of their time in Interphase.

11. Mitosis (M Phase)
The M phase is brief and consists of a division of the cell’s nucleus and cytoplasm that results in two identical daughter cells.
The identical daughter cells have the same number of chromosomes and the same genetic composition as the starting parent cell.
In human cells, which have 23 pairs of chromosomes, the number of chromosomes (2n = 46) remains unchanged from the beginning till the end of mitosis.

12. Mitosis has Four Phases
Prophase
Metaphase
Anaphase
Telophase (Cytokinesis)
Memory helper:
PMAT

13. Prophase 1st and longest phase of mitosis
Nuclear membrane (envelope) disappears
Chromosomes condense and you can see sister chromatids and centromeres
Spindle fibers form. They are a microtubule structure that helps separate the chromosomes.
Sister Chromatids
Centromere
Nuclear membrane
Spindle

14. The four C’s Vocabulary
Chromatin – The relaxed state that the DNA is in during
interphase. It can look like a tangled up mess of spaghetti
or string.
Centromere - the part of a chromosome that links sister
chromatids. During mitosis, spindle fibers attach to the
centromere and help to split the sister chromatids apart.
Sister Chromatids - They are created when a single
chromosome is replicated into two copies of itself. They are
connected by a centromere.
Centrioles– They assist in mitosis by allowing the spindle fibers
to attach to them. They are not visible when the cell is not dividing

16. Metaphase Chromosomes move to the middle of the cell
Each sister chromatid is attached to spindle with a centromere
Spindle
centromere

17. Metaphase

18. Sister chromatids are pulled apart to opposite sides of the cell
Anaphase
Centromeres split
Sister chromatids are pulled apart to opposite sides of the cell
Each chromatid is now a separate chromosome
Sister Chromatids

19. Anaphase

20. Telophase Two nuclear membranes (envelopes) reform
Chromosomes begin to uncoil and relax reverting back to the chromatin state.

21. Telophase

22. Cytokinesis Cytoplasm divides Two new daughter cells are now separate
Cytokinesis occurs at the end of telophase.
Pinching in of
cell membrane

23. Okay, Now it’s your turn!

24. 1 2 3 4 5 6 7 Interphase? Prophase? Metaphase? Anaphase? Telophase?
Prophase
Anaphase
Interphase

25. Think of it as mitosis gone bad! There are 2 types of tumors:
What is a Tumor ?
A tumor is a mass of cells that results from uncontrolled cell division.
Think of it as mitosis gone bad!
There are 2 types of tumors:
1. Benign
2.Malignant

26. Benign Tumors
A benign tumor is a mass of cells that lacks the ability to invade neighboring tissue or metastasize.
Metastasize is the spread of a cancer from one organ or part to another organ or part.
They are considered to be non-cancerous.
Moles are benign tumors
Lymphatic system tumor

27. Joseph Merrick August 5,1862 – April 11,1890 ‘The Elephant Man’
In 2001 it was proposed that Merrick had suffered from a combination of neurofibromatosis type I and Proteus syndrome. DNA tests conducted on his hair and bones have proven inconclusive.

28. James O’Neal ( )
Benign Facial Tumors
(neurofibromatosis)

29. Melanoma Mouth Cancer Malignant Tumors
They invade surrounding tissues, and can spread to distant tissues and organs, which means that they can metastasize.
They are considered to be cancerous.
Cancer is uncontrolled cell division (mitosis) that can’t be stopped.
Melanoma
Mouth Cancer

30. Cancerous Cells Affects Homeostasis
Interferes with nervous system tissue and blocks important nerve connections.
Cancer cells absorb nutrients needed by the healthy cells.
Prevent organs from functioning properly.
Lung Cancer

31. Asexual Reproduction
It Only Takes One !

32. Characteristics of Asexual Reproduction
Only one parent is involved.
Offspring are genetically identical to their parents.
There are different types of asexual reproduction.

33. Type # 1 Binary Fission
Binary fission is when an organism divides by mitosis to form two daughter cells of equal size.
The nucleus and cytoplasm divide equally.
All cells that come from a single cell are genetically identical to each other
It occurs in single-celled organisms like Amoebas, paramecia, and bacteria

34. Binary Fission in Paramecium
Binary Fission in Bacteria

35. Type # 2 Budding
Budding is when a new organism arises as an growth of an older organism.
The new organism is called the bud.
The bud is a duplicate of the parent. It may separate or remain attached to form a colony.
In budding there is an equal division of the nucleus, but unequal division of cytoplasm. So, one of the daughter cells is larger than the other.
It occurs in multicellular organisms such as yeast, hydra and some cacti.

36. Yeast Budding
Desert Cactus
Hydra Budding

37. Type # 3 Sporulation
Spores are specialized sex cells that contain a nucleus and small amount of cytoplasm.
Spores are produced in large numbers by mitosis.
They are surrounded by a tough protective coat that enables them to survive extreme conditions such as heat or cold.
When conditions are favorable, the spores develop into a new organism.
Bread mold, mushrooms, mosses, and ferns reproduce this way

38. Spores on a
Fern leaf
Spore Pods

39. Moss Sporulation

40. Type # 4 Regeneration
Regeneration is the development of a new organism from a part of a parent organism
It occurs in starfish, planaria,hydra,crayfish, salamanders,newts
Regeneration can also replace lost body parts like tails, claws, legs,and arms.

42. P L A N R I R E G N A T I O

43. Type # 5 Vegetative Propagation
It is the process by which new plants develop from the roots, stems, or leaves of the parent plant.
There are many different ways for this type of reproduction to occur:
1. runners
2. bulbs
3. tubers
4. cuttings

44. Examples: strawberries, blackberries, spider plants, mint , ivy
Runners
Stems that grow over the surface of the soil and at certain points the runner puts down roots and new plants grow from there.
Examples: strawberries, blackberries, spider plants, mint , ivy
Strawberry Plant
Ivy Plant

45. Bulbs
A bulb is a short underground stem surrounded by thick leaves and contains stored food. As the plant grows it produces new bulbs which will grow into new plants.
Examples:
Onions
tulips
lilies

46. Tubers
A tuber is an enlarged part of an underground stem that contains stored food.
Potatoes are tubers. The have eyes, or tiny buds that can form a new potato plant.
Carrots and radishes
are also examples.

47. Cutting Rooting Planting Cuttings
A cutting is when a piece of roots, stems, or leaves develop into new plants.
Cutting
Rooting
Planting