1. The Cellular Basis of Inheritance

2. All Cells come from cells…
All organisms reproduce their own kind
This is an important characteristic of all living things.

3. Video Intro
Mcgraw hill:

4. Repair and Growth Living cells reproduce
Like “your skin” they replace dead cells (or damaged)
This goes on your whole life
They also (cells) grow in size
Because of reproduction, by the addition of new cells you grow
All of this occurs from a single fertilized egg

5. Reproduction Asexual Reproduction
Reproduction by duplicating its genetic material and then splitting into two genetically identical cells.
Produces offspring (and all genetic material) from one parent
Offspring are genetically identical to parent and one another
Single – celled organisms reproduce this way

6. Asexual Reproduction
There are multi-cellular organisms that can reproduce asexually at times
Seastars – can be cut in two pieces and grow into two whole new individuals

7. Sexual Reproduction
Genetic material from each of two parents combine producing offspring that differ genetically from both parents
Involves the union of sex cells
Egg and Sperm

8. Chromosomes and Cell Division
The Cell Cycle
Chromosomes and Cell Division
Genes found in the nucleus
Chromatin – a combination of DNA and protein
This is how genetic material exist most of the time
As/or in this state they are long and thin – can’t be seen under a microscope

9. Chromosomes and Cell Division
Chromosomes – when the fibers of chromatin
condense;
happens just before cell division
Each species has their own number of chromosomes
For example humans have 46 chromosomes.
Each chromosomes may contain hundreds of genes.

10. Chromosomes and Cell Division
Sister Chromatids
Happens before cell division
A cell duplicates all its chromosomes
The chromosomes are identical and joined
Centromere – the region where the two
chromatids are joined together
After splitting; the result is two offspring nuclei, each with 46 chromosomes.

11. Chromosomes and Cell Division

12. Chromosomes and Cell Division
Cell Cycles – starts at birth of cell till it
reproduces
Some once a day (some more / some less)
Some cells once mature DO NOT divide.
Muscle cells – reason why once torn muscles tissue is not quite the same.
Normal Muscle Tissue
Torn Muscle Tissue

13. Prokaryotic Cell Cycle
Prokaryotic cells divide and reproduce rapidly
Type of asexual reproduction called Binary Fission
Binary fission is a form of asexual reproduction during which two genetically identical cells are produced.

14. Eukaryotic Cell Cycle Consists of 4 phases: Interphase: G1, S, G2 G1
S phase G2
M phase
Interphase: G1, S, G2
Phases where cell prepares to divide in M phase

15. Eukaryotic Cell Cycle: G1, S, G2
Interphase
S phase (DNA synthesis
G2 (cell prepares for division)
G1 (cell growth)
M Phase (Cell Division)

16. Interphase Cells spend 90% of time in interphase
This is the stage when the cell carries out its metabolic functions
During this time a cell: increases proteins, increases number of organelles and grow in size.

17. 3 parts of Interphase G1: Cell grows and matures
Cell increases in size, makes new proteins
S Phase: DNA synthesis
DNA duplicates to prepare for division
End with 2x the DNA
G2: Cell prepares for division during M-phase

18. How do cells regulate the cell cycle?
Cancer is a disorder in which some of the body’s cells lose the ability to control growth.
Checkpoints are biological stoplights telling the cell if it can safely go or when to stop and fix a problem.
G1 checkpoint makes sure the cell is large enough to enter the S phase.
G2 checkpoint makes sure the DNA is completely replicated, that replication errors have been repaired, and the cell is large enough to replicate.
M checkpoint make sure the chromosomes are aligned on the spindle ready for nuclear division.
Cells have several systems for interrupting the cell cycle if there is a problem.

19. Day 2- M-phase
Cell Division

20. Bellringer
Draw and fill out the missing information on the cell cycle diagram
3. What happens in this phase?
2. Name for these 3 phases
S-Phase
1. Name this phase G2
G2 Checkpoint
4. What does this check for?
5. What happens in this phase?

21. M- Phase
M-phase: After cell clears G2 checkpoint, ready to begin division process
Begins with Mitosis-Division of the cell’s nucleus
After nucleus divides, the cytoplasm divides in the final division stage called cytokinesis

22. The Two Processes of Mitotic Phase
Mitosis
duplicated chromosomes (2n) in nucleus divide
Divided materials are split evenly
Form two daughter nuclei
Cytokinesis
Cytoplasm divides in two
Happens when mitosis is complete
Both mitosis/cytokinesis produce two genetically identical daughter cells

23. Chromosome Number
Body Cells undergo mitosis and have a chromosome number of 2n
N represents chromosome #
“2” means two sets
2n is the diploid number
At the end of mitosis, two identical diploid cells are produced
Starts with 2nends with 2n

24. Mitotic Phase
Spindle – A football shaped microtubule framework that guides chromosome movement. Centrosomes – area where spindle grow from
Centrosome
Spindle
Nucleus

25. Mitosis- 4 steps
Prophase
Metaphase
Anaphase
Telophase

26. Steps of Mitosis Prophase (First step of Mitosis) Nucleus disappears
Chromatin fibers thicken
You can see them under a microscope
Nucleus disappears
Nuclear envelope breaks down
Spindle forms
Chromatids attach to microtubules

27. Steps of Mitosis Metaphase
Chromosomes line-up down the middle of the cell
Spindle fibers are full formed.

28. Steps of Mitosis Anaphase Chromosomes separate
Spindle microtubules shorten
Pull chromosomes closer to poles

29. Steps of Mitosis Telophase
Begins when chromosomes reach the poles of the spindle
Process of prophase are reversed
Spindle disappears
Two nuclear envelopes reform
Chromosomes uncoil and lengthen
Nucleoli reappear

30. Mitosis

31. Cytokinesis in Animals and Plants
Cytokinesis- division of the cytoplasm
Completes cell division
Happens along with telophase
Cytokinesis in Animals and Plants
Animal cells: pinching inward of membrane
Plant Cells: division via cell plate

32. Animal Cell Cytokinesis
Pinching inward of membrane creates a cleavage furrow
Results in two identical daughter cells
Cleavage Furrow

33. Plant Cell Cytokinesis
Cell Plate - A disk containing cell wall
Forms inside the cell and grows outward
This “wall” divides the cell in two
Results = two new identical cell + a cell
wall

34. Cancer

35. Cancer Tumors – a mass of cells; reproducing out of control
Benign Tumor – an abnormal mass of “normal
cells”
Can be a health problem because of location but can be completely removed by surgery
They do not migrate around the body

36. Cancer Malignant Tumor – the reproduction of cancer
cells that form a mass.
Cancer – a disease caused by the severe
disruption of the mechanisms that
normally control the cell cycle.
Leads to uncontrolled cell division

37. Cancer – Dangerous Characteristics
Ability to spread
Displaces normal tissue
Metastasis – the spread of cancer cells
beyond their original site

38. Cancer - Treatment Removal when possible
Radiation Therapy – high energy radiation to
cancerous parts of the body
This disrupts cell division
Affects cancer cells more than normal cells because cancer cells divide more rapidly

39. Cancer - Treatment Chemotherapy – the treatment with drugs that
disrupt cell division.
Antimitotic Drugs – prevent cell division by
interfering with mitotic
spindle.
Some freeze spindle after it forms
Some prevent the formation of spindle all together

40. Cancer – Treatment Side Effects: (radiation & chemotherapy)
Radiation can damage cells of the ovaries and testes
Causing sterility
Chemotherapy can lead to hair loss
Many other side effects as well but each individual is different

41. Meiosis- Sex Cell Division
In Mitosis, we asexually reproduced BODY cells (aka- SOMATIC cells)
Meiosis is the formation of SEX cells (GAMETES)
Essential Question-
How does sexual reproduction result in genetic variation based on the process of meiosis?

42. Meiosis Karyotype – a display of chromosomes
Used to examine / study chromosomes
Note each chromosome has a twin; 1 for each parent

43. Meiosis
Each offspring in a sexually reproducing species inherits a unique combination of genes from both parents

44. Meiosis Homologous Chromosomes - the inherited chromosomes
from each parent.
Meiosis – a type of cell division that produces
four cells
Remember that all cells from any individual organism has the same number and types of chromosomes.
“Humans” normally have 46 chromosomes

45. Meiosis
Each Homologous Chromosome represent genes that are responsible for the same inherited characteristic.
The gene for eye color is located at the same place, even if they are different

46. Meiosis Humans have 23 homologous chromosomes Sex Chromosomes
Females have 46 identical “looking” chromosomes
Males have two chromosomes where one of the pair do not look the same
Sex Chromosomes

47. Meiosis Sex Chromosomes – the 23rd chromosome, determines sex
Two Forms:
X – Females have XX
Y – Males have XY

48. Diploid and Haploid Cells
Having two sets of inherited chromosomes:
One from each parent is key to life in sexual reproducing organisms.
Diploid – means containing two homologous
sets of chromosomes
Almost all human cells are diploid
Gametes – sex cells; egg and sperm cells
Each gamete has a single set of chromosomes
One from each homologous pair

49. Gametes

50. Diploid and Haploid Cells
Fertilization – the fusion of the nuclei along
with the cytoplasm from gametes
This is how the Diploid number is restored

51. Diploid and Haploid Cells
Zygote – a fertilized egg (Now a Diploid Cell)

52. Meiosis vs. Mitosis Differences:
Meiosis produces four new offspring cells
Each with one set of chromosomes
½ the number of chromosomes as the parent cells
Mitosis produces two identical offspring cells, each with the same number chromosomes as the parent cell
Meiosis involves the exchange of genetic material

53. The Two Meiotic Divisions
Meiosis I (2n): Homologous chromosomes;
each composed of two sister
chromatids
Separated from one another
Meiosis II (n): sister chromatids are separated
like they are in mitosis
The result are haploid rather than diploid

54. Meiosis I
Prophase I
Protein cause homologous chromosomes to stick together along with their length
Tetrads – the paired chromosomes
Now 4 chromatids
Chromosome #: 2n
1 set from mom
1 set from dad
1(mom)+1(dad)= 2n

55. Meiosis I – Prophase I
Crossing Over – 2nd “new” step; tetrads exchange genetic material

56. Meiosis I
Metaphase I
Tetrads move to the middle of the cell and line up across the spindle.

57. Meiosis I
Anaphase I
Homologous chromosomes separate and migrate to opposite poles
Sister chromatids migrate together
Each chromosome is made up of two copies

58. Meiosis I Telophase I The chromosomes arrive at poles
Each pole has a haploid daughter nucleus because it only has one set of chromosomes

59. Meiosis I Cytokinesis Form two daughter cells
Chromosomes in each daughter cell are still duplicated (double in number)
CHROMOSOME NUMBER: n
Because mom’s set and dads set were separated, now you have haploid number

60. Meiosis II Prophase II In each haploid daughter cell, spindle forms
Attach to centromeres
Chromosomes are moved to the middle

61. Meiosis II
Metaphase II
Chromosomes line-up in the middle of cell

62. Meiosis II
Anaphase II
Sister chromtids separate and move to opposite poles

63. Meiosis II Telophase II & Cytokinesis Chromatids arrive at poles
Now individual chromosomes
Cytokinesis splits cells

64. Produced four haploid daughter cells
Meiosis Finished
Produced four haploid daughter cells

65. Genetic Variation
How chromosomes line-up and separate at Metaphase I is a matter of chance
So the chromosomes that end up in the resulting cells occur randomly
Four combinations possible
If you know the number of haploid for an organism you can calculate the number of possible combinations

66. The possible combinations are equal to 2
Genetic Variation
The possible combinations are equal to 2
Where n is the haploid
If n = 2 the number of chromosome combinations is 2² = 4
For humans n = 23
So 2²³ = 8 million possible combinations n

67. Genetic Variation Crossing Over – The exchange of genetic
material between
homologous chromosomes
Happens during Prophase I
When crossing over begins homologous chromosomes are closely paired all along their length
Segments of the two chromatids can be exchanged at one or more sites.

68. Genetic Variation Genetic Recombination
the crossing over produce a single chromosome that contains a new combination of genetic information from different parents
Because many hundred of genes a single cross over event can affect many genes
More than one cross over can occur in each tetrad