1. Warmup 4/26/16: Complete the Mitosis vs. Meiosis Inquiry Activity
Warmup 4/26/16: Complete the Mitosis vs. Meiosis Inquiry Activity. There are two sides to this activity.
If you were absent, please check your folder for work.

2. What if mitosis runs rampant?
CANCER- uncontrolled cell division
What do you already know about cancer?
Cancer cells do not respond to the signals that regulate cell growth.
Video 1
Cancer is a disease of uncontrolled cell division. It starts with a single cell that loses its control mechanisms due to a genetic mutation. That cell starts dividing without limit, and eventually kills the host.
Normal cells are controlled by several factors.
Normal cells stay in the G1 stage of the cell cycle until they are given a specific signal to enter the S phase, in which the DNA replicates and the cell prepares for division. Cancer cells enter the S phase without waiting for a signal.
Normal cells are mortal. This means that they can divide about 50 times and then they lose the ability to divide, and eventually die. This “clock” gets re-set during the formation of the gametes. Cancer cells escape this process of mortality: they are immortal and can divide endlessly.
Normal cells that suffer significant chromosome damage destroy themselves due to the action of a gene called “p53”. Cancer cells either lose the p53 gene or ignore its message and fail to kill themselves.

3. What are Mutations?
A Mutations is when there is a MISTAKE in the DNA sequence.
Mutations can be BAD, GOOD or NEUTRAL!

4. What happens in a BODY cell?
The mutations will ONLY affect that PERSON
What happens in a SEX cell?
The mutation can be passed onto the offspring!

5. Who is Henrietta Lacks?

6. It all started in February of 1951
Dr. George Gey of Johns Hopkins was given a sample of cervical cancer cells that had been taken from young Henrietta Lacks, who was dying of cervical cancer.
Lacks Video

7. Uses of HeLa
Henrietta Lacks was found to have cervical cancer in January of 1951 – died October 4, 1951.
HeLa cells were used to develop the first polio vaccine in 1954 by Jonas Salk. At the time millions were suffering from polio.
They were sent into space for experimentation regarding zero gravity in 1960.
HeLa cells helped to produce numerous drugs for diseases including leukemia, influenza, and Parkinson's.
They were also used to develop the cancer drugs and chemotherapy.
Her cells were also later used for advancements like in vitro fertilization, gene mapping, and cloning.

8. Why Stem Cells?
Stem cells allow us to study how organisms grow and develop over time.
Stem cells can replace diseased or damaged cells that can not heal or renew themselves.
We can test different substances (drugs and chemicals) on stem cells.
We can get a better understanding of our “genetic machinery.”

9. What are two types of stem cells?
Embryonic Stem Cells
Adult Stem Cells

10. What are EMBRYONIC stem cells?
Embryonic cells which have not yet differentiated (changed) into different cell types
Form soon after the egg and sperm meet!
Embryo = a fertilized egg that is in the beginning stages of a pregnancy

11. What are ADULT stem cells?
Adult Stem Cells: stem cells found in organisms, such as in bone marrow
The adult stem cells can only become the type of cells in the part of the body where they are found
Ex.: stem cells found in the bone marrow can only become bone marrow cells

12. Stem Cells

13. How can different cells perform different functions if all cells have the same genes and DNA?
All cells have the SAME DNA
BUT, cells have different JOBS
This is because of the expressionof the genes in their DNA (what is ‘turned on’)

14. What is GENE EXPRESSION?
An expressed gene is a gene that is ‘turned on’ to create proteins.
Those cells that are not expressed remain “silent”
Cells have different jobs based upon which genes are turned ON and which are turned OFF
Not all the genes are being used at all times
Also called GENE REGULATION

15. How is GENE EXPRESSION like a PIANO?
Every piano has the same set of keys
Just like every cell has the same DNA
The piano keys can play different songs depending on which keys are played
Just like different cells are able to perform different functions (jobs) depending on the genes that are “chosen” to be expressed or “played”

16. How does an organism know when to turn a gene on or off?
Environmental influences
Different genes are expressed depending on the environment of the cell.
Ex. E. coli bacteria in the human stomach
E. coli feed on lactose (a sugar found in milk)
When the sugar is present in your stomach, certain genes are turned on, or expressed, so the bacteria can digest lactose
When nosugar is present, those genes remain silent (OFF) and no proteins are created (because the proteins are not needed)

17. What is CELL SPECIALIZATION?
Different genes are expressed depending on the specific job of the cell
This creates different types of cells (muscle cells, nerve cells, sperm cells, etc.)
Ex. Keratin
Keratin is a protein that produces hair.
The genes that produce keratin are expressed (ON) in skin cells but remain silent (turned OFF) in blood cells

18. What can happen if the genes are turned ON or OFF at the wrong time?
Making the wrong proteins can ruin your body, and even your life.
Cancer: proteins are created at the wrong time, which causes uncontrolled cell reproduction leading to tumors that may cause cancer (genes are always turned ON)

19. Rejection? Is rejection a possibility? Embryonic vs. Somatic/Adult
Adult stem cells hold a distinct advantage in that a patient's own cells are identified, isolated, grown and transplanted back into the patient. The recipient's immune system does not reject the cells because they are compatible with that person's body.
With embryonic stem cells, the potential for immune rejection would require strong immune suppressing drugs.
Risk of microscopic diseases that may be present in the transplanted cells, as well as other diseases that could be present in the hospital environment.
Research
Studies have injected them into the legs of mice with compromised immune systems, the cells thrived and multiplied.
In mice with functioning immune systems, however, the cells began to die within a week and were completely gone after 10 days.
When the researchers tried to inject more stem cells into the mice, their immune systems remembered the foreign invaders, and the cells fared worse—dying in two to four days.

20. Clear your desk, we will now take your quiz on Mitosis and asexual Reproduction.
When you finish, place your quiz in the basket.
Get a Chromebook from the cart.
Complete the meiosis web quest.

21. Meiosis

22. Important Vocabulary
Chromosomes: DNA tightly coiled around protein in nucleus; the structure on which genetic material is stored
Genes: Sections of chromosomes (DNA) that code for a specific protein which determines a specific trait in an organism.

23. Homologous Chomosomes
Homologous: same
Homologous chromosomes: Chromosomes of the same length with the same gene types, but 1 is from the mother and 1 is from the father
Humans have 23 homologous chromosome pairs

24. Sister Chromatids
two exact copies of a chromosome attached together by a centromere
created during DNA replication during interphase

26. Think about it…
What would happen if your Mom and Dad gave you a full set of 46 chromosomes?
Are you made from sexual or asexual reproduction?
How many chromosomes are you getting from your Mom? Dad?

27. So how do sex cells become haploid?

28. Meiosis A.K.A Reduction Division
-Production of sex cells with half the number of chromosomes as a body cell.
-Cell division of 1 diploid (2n) cell resulting in 4 haploid (1n) cells
-Gametes are produced in the ovaries (female) and the testes (male)

29. 1 diploid (2n)
Parent cell
4 haploid (1n)
daughter cells

30. Haploid Haploid: 1 set of chromosomes from one parent
Represented by the letter “n”
“n” for humans = 23 chromosomes
We have 46 total and half come from each parent
We have a haploid number of chromosomes in egg and sperm cells
MEMORY TRICK: Haploid = HALF
Example: If an alligator has 50 total chromosomes, what is the HAPLOID number?

31. Gamete Cells: “SEX CELLS”
Cells specifically for reproduction
Made by MEIOSIS cell division (sexual reproduction)
Are HAPLOID (1 set of chromosomes)
Also known as “n”
Examples:
Animals: sperm (male) and egg (female)
Plants: pollen (male) and ovule (female)

32. Checkpoint Question Which of the following is a gamete? nerve cell
sperm cell
body cell
skin cell

33. Diploid Diploid: 2 set of chromosomes, one set from each parent
Represented by the letter “2n”
“2n” for humans = 46 chromosomes
We have 46 total chromosomes in our SOMATIC (body cells)
MEMORY TRICK: Diploid = DOUBLE
Example: If a rat has 20 chromosomes in its sperm cell, how many chromosomes are in the body cell?

34. Types of Cells Somatic Cells: “BODY CELLS” Cells NOT for reproduction
Made by MITOSIS cell division (asexual reproduction)
Are DIPLOID (2 set of chromosomes)
Also known as “2n”
Examples:
Animals: all tissues form non-sex organs (skin cells, liver cells, tongue cells, etc.)
Plants: leaves, roots, stems, Tissues from non-sex organs!

35. Checkpoint Questions
What is the difference between a haploid cell and a diploid cell?
haploid cells have 2n number of chromosomes
diploid cells have n number of chromosomes
haploid cells have n number of chromosomes
diploid cells have 3n number of chromosomes

36. Checkpoint Question
If a tongue cell in an alligator has 18 chromosomes, how many chromosomes will be found in its sperm cells?
a. 72 b c d. 9

37. Meiosis Produces GAMETE CELLS (sex cells)
The whole reason for meiosis is for SEXUAL REPRODUCTION to take place.
Gametes have a HAPLOID number of chromosomes
so they can come together to form a new offspring.
Meiosis occurs in all organisms with many cells:
Humans
Animals
Plants

38. During meiosis, the chromosome pairs separate and are distributed to two different cells. The resulting sex cells have only half as many chromosomes as the other cells in the organism.

40. Key Facts about Meiosis
DNA REPLICATES before division
# of divisions: 2
# of daughter cells: 4
Daughter cells are NOT IDENTICAL (genetic variation!)

42. Synapsis and Crossing Over
During Prophase I of meiosis, homologous chromosomes pair up (synapsis) and exchange genetic information. This is known as crossing over. Crossing over allows gametes to receive a unique set of genetic information and produces variation of a species. Crossing Over Video

43. Mitosis vs. Meiosis

44. Mitosis and Meiosis Relationship

45. diploid zygote with 46 chromosomes
Now the zygote will undergo mitosis to grow into a multicellular organism XY XX
diploid zygote with 46 chromosomes
Multicellular
Organism
= 46 chromosomes
union of gametes
Egg
23 haploid chromosomes
Sperm
23 haploid chromosomes

46. Fertilization: When an egg and sperm come together
46 homologous chromosomes in this diploid zygote
Zygote = fertilized egg
100% Unique combination of genes!!!!
23 single chromosomes 1n XY 1n
X or X
23 single chromosomes

47. Guided Practice: Mitosis vs. Meiosis
Cell Type
Gametes Cells
Somatic Cells
Body or Sex Cells?
Made by what type of cell division (mitosis or meiosis)?
Haploid or Diploid?
Number of chromosomes (2n or n)?
# of chromosomes in humans?
Animal Examples
Plant Examples
Number of cell divisions?
Genetic stability or variation?
Type of reproduction (asexual or sexual)?

48. Guided Practice: Mitosis and Meiosis – Summary: In the margin of your notes, copy the summary. We will fill in the blanks together.
One cell division, exact copies, half, gametes, two cell divisions,
diploid cell, two diploid cells, same, chromosomes, original cell,
gametes.
Mitosis begins with a _______________ and produces _____________ using ___________________. This forms _____________________ that have the _______________ number of _________________ as the ____________________.
Meiosis begins with a _______________ and produces _____________ using __________________. This forms ____________________ that have _____________ the number of _________________ as the ___________________.

49. Steps to Sexual Reproduction
Male Human Female Human (testes) (ovaries) Gamete Gamete (sperm) (egg) Fertilization Zygote Death
MEIOSIS
MEIOSIS
MITOSIS
MITOSIS

50. Think-Write-Pair-Share
1) Describe a pollen cell from a flower. For this particular flower, a pollen cell has 10 chromosomes. In your Response, use the following terms. For some terms, you may not use them because they do not apply to a pollen cell: 2n/n, haploid/diploid, gametes/somatic cell, mitosis or meiosis, sexual/asexual.

51. Think-Write-Pair-Share
2) Describe a skin cell from a human. In your response, use the following terms: 2n/n, haploid/diploid, 23 or 46 chromosomes, gametes/somatic cell, homologous chromosomes, mitosis/meiosis, sexual/asexual.

52. Let’s try it…
A diploid cell of a mouse contains 12 chromosomes. How many chromosomes will be found in a haploid cell of a mouse?
The diploid cell of a bird contains 16 chromosomes. How many chromosomes will be found in the sperm cell?