1. 10.1 Cell Growth Limits to Cell Growth
Key Concept - What problems does growth cause for cells and how does cell division solve the problem?
Limits to Cell Growth
Larger cell= more demands the cell’s DNA
Larger cell = more trouble moving nutrients in across cell membrane
Larger cell= more trouble moving wastes out across cell membrane

2. 10.1 Cell Growth Limits to Cell Growth Larger cell: more demands cell’s DNA
DNA, “overload”
Library metaphor: as the town gets larger, too many people are trying to check out the same books. Better to build another library!

3. 10.1 Cell Growth Limits to Cell Growth Problems Exchanging Materials
•Food, Oxygen, and Water need to get in through cell membrane (surface area)
•Wastes need to leave the cell through the membrane (surface area)
•Amount of nutrients needed and waste produced depends on volume.

4. 10.1 Cell Growth Limits to Cell Growth Problems Exchanging Materials Food, Oxygen, and Water get in through cell membrane (surface area) Wastes need to leave the cell through the membrane (surface area) Amount of nutrients needed and waste produced depends on volume.
Problem: as volume increases, surface area increases
But not as quickly as volume increases

5. 10.1 Cell Growth Limits to Cell Growth Problems Exchanging Materials

6. 10.1 Cell Growth Limits to Cell Growth Ratio of Surface Area to Volume
Problem: as volume increases, surface area increases
But not as quickly as volume increases

7. 10.2 CellDivision
Prokaryotes: just separate into two
Eukaryotes: Two stages
mitosis division of nucleus
cytokinesis dividing cytoplasm in two
Chromosomes:
Only visible during cell division
At other times chromatin
At cell division, chromosomes have been duplicated, and so are seen as two sister chromatids

8. Chromosomes • Only visible during cell division
•At cell division, chromosomes have been duplicated and are seen as two sister chromatids
•joined at centromere

9. Chromosomes:
DNA twisted together with proteins histones Then twisted again and again into chromatids

10. Cell Cycle Interphase: time between divisions cell growth
duplication of genetic material
Mitosis: nucleus and chromosomes divide
Cytokinesis: cytoplasm divides

11. Cell Cycle

12. Cell Cycle
Interphase: time between divisions

13. Cell Cycle Prophase: Chromatin organizes into chromosomes.
Nuclear membrane breaks up

14. Cell Cycle
Metaphase: Chromosomes line up along cell equator

15. Cell Cycle
Anaphase: Chromosomes separate toward opposite poles

16. Cell Cycle
Telophase: Nuclear membrane reformes. Cytokinesis begins.

17. Cell Division: Mitosis

18. Cell Division: Mitosis

19. Work of Gregor Mendel Genes and Dominance
Trait a specific characteristic (color, height)
that varies from individual to individual
Mendel crossed plants with different colors
Hybrids are offspring of parents with different traits
F1 first generation of that cross
Mendel expected F1 offspring to be a blend of parent traits
Instead, all the offspring had characteristics of one parent

20. Work of Gregor Mendel Genes and Dominance
Trait a specific characteristic (color, height)
that varies from individual to individual
Mendel crossed plants with different colors
Hybrids are offspring of parents with different traits
F1 first generation of that cross
Mendel expected F1 offspring to be a blend of parent traits
Instead, all the offspring had characteristics of one parent
Genes chemical factors that determine one trait
Alleles different forms of that gene
Dominance some alleles are dominant, some are recessive.

21. Work of Gregor Mendel Round Yellow Gray Smooth Green Axial Tall
Seed Shape
Seed Color
Seed Coat
Color
Pod
Shape
Pod Color
Flower Position
Plant Height
Round
Yellow
Gray
Smooth
Green
Axial
Tall
Wrinkled
Green
White
Constricted
Yellow
Terminal
Short
Round
Yellow
Gray
Smooth
Green
Axial
Tall

22. Work of Gregor Mendel P Generation Tall Short F1 Generation

23. Work of Gregor Mendel Segregation
What happened to the recessive alleles?
P Generation
F1 Generation
F2 Generation
Tall
Short
Tall
Tall
Tall
Tall
Tall
Short

24. Work of Gregor Mendel Segregation
What happened to the recessive alleles?
P Generation
F1 Generation
F2 Generation
Tall
Short
Tall
Tall
Tall
Tall
Tall
Short

25. Work of Gregor Mendel Segregation The F1 Cross
What happened to the recessive alleles?
The F1 Cross
How did the recessive traits disappear and then reappear?
SEGREGATION in formation of sex cells or gametes, alleles are separated. Each gamete carries only one copy of each gene.
F1 plant produces two types of gametes one with the allele for tallness and one for the allele for shortness.

26. 11.2 Probability and Punnett Squares
•EXPLAIN how geneticicsts use the principles of probability
•DESCRIBE how geneticists use Punnett squares

27. Probaility and Punnett Squares
Genetics and Probability
Probability can be used to predict the outcome of genetic crosses
The ratio of probability that an allele will be expressed
Is proportional to the number of offspring expressing that allele.

28. Probaility and Punnett Squares
are used to determine the possible gene combinations from a genetic cross
The Punnett square can be used to predict the ratio of offspring
Punnett Square vocabulary:
•Homozygous has two identical alleles for a given trait (ie tt or TT)
•Heterozygous has two different alleles for the trait (ie Tt)
•phenotype physical characteristic (Tall Tt or TT)
•genotype genetic make up (TT is different than Tt)

29. Probaility and Punnett Squares

30. Probaility and Punnett Squares

31. Probaility and Punnett Squares

32. Probaility and Punnett Squares

33. Probaility and Punnett Squares

34. Probaility and Punnett Squares
Phenotype: tall
Phenotype: tall
Phenotype:
short
Phenotype: tall

35. Probaility and Punnett Squares
Probability and Segregation
Did segregation occur?
The recessive gene that had been hidden in the F1 generation reappeared in the F2 generation.
The ratio was 3 tall plants to 1 short plant

36. Probaility and Punnett Squares
Probabilities Predict Averages
Just as in a coin flip
The larger the sample, the more likely the result will match the prediction

37. 11.3 Exploring Mendelian Genetics
Independent Assortment
Alleles segregate during gamete formation
Do they segregate independently?
Does the gene for seed color (Yellow, Y or Green, y)
have anything to do with the gene for seed shape (round, R or Wrinkled, r)?

38. 11.3 Exploring Mendelian Genetics
Independent Assortment
Two Factor Cross: F1
First Mendel crossed an rryy plant with an RRYY plant
That cross produced all RrYy offspring
What would happen in the next generation (F2)?
Would there be any Ry or rY plants?
Or would the dominant and recessive alleles stick together?

39. 11.3 Exploring Mendelian GeneticsRY Ry rY ry
RRYY
RRRy
RrYY
RrYy
RRYy
RRyy
Rryy
rrYY
rrYy
rryy
11.3 Exploring Mendelian Genetics
Independent Assortment
Two-Factor
Cross: F2
Independent
Assortment
Genes for different
Traits segregate
independently

40. 11.3 Exploring Mendelian Genetics
Summary of Mendelian Principles
Inheritance determined by genes passed from parents to offspring
Genes may be dominant or recessive
Adult has two copies of each gene, one from each parent
Alleles for different genes usually segregate independently

41. 11.3 Exploring Mendelian Genetics
Beyond Dominant and Recessive
Some alleles are neither dominant nor recessive
Incomplete Dominance Heterozygous offspring show a phenotype somewhere in between the two homozygous phenotypes (pink four o’clocks)
Codominance both alleles contribute to the phenogype of the organism (roan cattle have both red and white hairs)

42. 11.3 Exploring Mendelian Genetics
Beyond Dominant and Recessive
Some alleles are neither dominant nor recessive
Multiple Alleles More than two alleles possible (coat color in rabbits)
PolygenicTraits controlled by more than one
gene (human eye color, human skin color)

43. 11.3 Exploring Mendelian Genetics
Applying Mendel’s Principals
Drosophila:
Often used in genetic research
Fruit fly produce a new generation of hundreds of offspring every 14 days
Human applications
Albinism controled by one gene
Skin pigment is dominant, Albinism is recessive
Pigmented parents have an albino child.
What is the chance that the next child will be albino?

44. Focus Week 11.4 Meiosis and 11.5 Linkage and Gene Mapping
Skip to Tuesday
Focus Week 11.4 Meiosis and Linkage and Gene Mapping
Due Thursday (in class work - not homework)
11.4 p 278 q 1 - 5
11.5 p 280 q 1 - 4
Homework
Study for final
80% of questions will come from study guide and standardized test prep (end of each chapter)

45. Normal human body cells each contain 46 chromosomes
Normal human body cells each contain 46 chromosomes. The cell division process that body cells undergo is called mitosis and produces daughter cells that are virtually identical to the parent cell.
1. How many chromosomes would a sperm or an egg contain if either one resulted from the process of mitosis?
2. If a sperm containing 46 chromosomes fused with an egg containing 46 chromosomes, how many chromosomes would the resulting fertilized egg contain? Do you think this would create any problems in the developing embryo?
3. In order to produce a fertilized egg with the appropriate number of chromosomes (46), how many chromosomes should each sperm and egg have?

46. 11.4 Meiosis
GOALS
Contrast the chromosome number of body cells and gametes
Summarize the events of meiosis
Contrast meiosis and mitosis
HOW TO EXPLAIN MENDEL’S OBSERVATIONS
Organisms inheirit a single copy of each gene from each parent
Offspring’s gametes contain only one set of each gene

47. 11.4 Meiosis Chromosome Number
Homologous: two genes that belong to the same pair
i.e. Fruit flies have 8 chromosomes, four homologous pairs, 4 chromosomes from each parent
Diploid: containing both sets of homologous chromosomes 2N

48. 11.4 Meiosis Chromosome Number
Homologous: two genes that belong to the same pair
i.e. Fruit flies have 8 chromosomes, four homologous pairs, 4 chromosomes from each parent
Diploid: containing both sets of homologous chromosomes
2N (i.e. 2N = 8)
Gametes: contain only a single set of chromosomes (therefore genes)
And so are called
Haploid: containing only one set of chromosomes N (i.e. N=4)

49. 11.4 Meiosis Phases of Meiosis
Meiosis: reduction division. Chromosome number cut in half by separating homologous chromosomes of diploid cell
Meiosis I
Each chromosome is replicated
Homologous chromosomes pair up
forming tetrad joined at centromere
homologous chromosomes separate
Meiosis II

50. 11.4 Meiosis Phases of Meiosis Meiosis II
Meiosis: reduction division. Chromosome number cut in half by separating homologous chromosomes of diploid cell
Meiosis I
Each chromosome is replicated
Homologous chromosomes pair up
forming tetrad joined at centromere
homologous chromosomes separate
Meiosis II
No duplication of genetic material
Chromosomes (only half of the diploid number) line up and chromatids separate

51. 11.4 Meiosis Phases of Meiosis - Meiosis I Interphase I
DNA replication, forming duplicate Chromosomes.

52. 11.4 Meiosis Phases of Meiosis - Meiosis I Interphase I Prophase I
DNA replication, forming duplicate Chromosomes.
Prophase I
Each chromosome pairs with corresponding homologous chromosome to form a tetrad.
Metaphase I
Spindle fibers attach to the chromosomes.
Anaphase I
The fibers pull the homologous chromosomes toward the opposite ends of the cell.

53. 11.4 Meiosis Phases of Meiosis - Meiosis I Interphase I Prophase I
DNA replication, forming duplicate Chromosomes.
Prophase I
Each chromosome pairs with corresponding homologous chromosome to form a tetrad.
Metaphase I
Spindle fibers attach to the chromosomes.
Anaphase I
The fibers pull the homologous chromosomes toward the opposite ends of the cell.

54. 11.4 Meiosis Phases of Meiosis - Meiosis I Interphase I Prophase I
DNA replication, forming duplicate Chromosomes.
Prophase I
Each chromosome pairs with corresponding homologous chromosome to form a tetrad.
Metaphase I
Spindle fibers attach to the chromosomes.
Anaphase I
The fibers pull the homologous chromosomes toward the opposite ends of the cell.

55. 11.4 Meiosis Phases of Meiosis - Meiosis II Prophase II Anaphase II
Meiosis I results in two haploid (N) cells, each with half the number of chromosomes of parent cell
Anaphase II
The sister chromatids separate and move toward opposite ends of the cell.
Metaphase II
The chromosomes line up in a similar way to the metaphase in mitosis.
Telophase II
Meiosis II results in four haploid (N) daughter cells.

56. 11.4 Meiosis Phases of Meiosis - Meiosis II Prophase II Anaphase II
Meiosis I results in two haploid (N) cells, each with half the number of chromosomes of parent cell
Anaphase II
The sister chromatids separate and move toward opposite ends of the cell.
Metaphase II
The chromosomes line up in a similar way to the metaphase in mitosis.
Telophase II
Meiosis II results in four haploid (N) daughter cells.

57. 11.4 Meiosis Phases of Meiosis - Meiosis II Prophase II Anaphase II
Meiosis I results in two haploid (N) cells, each with half the number of chromosomes of parent cell
Anaphase II
The sister chromatids separate and move toward opposite ends of the cell.
Metaphase II
The chromosomes line up in a similar way to the metaphase in mitosis.
Telophase II
Meiosis II results in four haploid (N) daughter cells.

58. 11.4 Meiosis Phases of Meiosis - Meiosis II Prophase II Anaphase II
Meiosis I results in two haploid (N) cells, each with half the number of chromosomes of parent cell
Anaphase II
The sister chromatids separate and move toward opposite ends of the cell.
Metaphase II
The chromosomes line up in a similar way to the metaphase in mitosis.
Telophase II
Meiosis II results in four haploid (N) daughter cells.

59. 11.4 Meiosis
Crossing-over
During Meiosis I,

60. 11.4 Meiosis Crossing-over
During Meiosis I, homologous chromosomes may, “cross-over,”

61. 11.4 Meiosis Crossing-over
During Meiosis I, homologous chromosomes may, “cross-over,” and exchange portions of their chromatids.

62. 11.4 Meiosis Gamete Formation
•In male animals, meiosis produces four haploid (1N) sperm cells
•In female animals one of the haploid egg cell receives most of the cytoplasm
the remaining, “polar bodies,” do not participate in reproduction

63. •Mitosis two genetically identical diploid cells
11.4 Meiosis
Comparing Mitosis and Meiosis
•Mitosis two genetically identical diploid cells
•Meiosis four genetically different haploid cells

64. 11.5 Gene Linkage and Mapping
Some genes appear to be inherited together, or “linked.”
If two genes are found on the same chromosome, does it mean they are linked forever?

65. 11.5 Gene Linkage and Mapping
1. In how many places can crossing over result in genes A and b being on the same chromosome?
2. In how many places can crossing over result in genes A and c being on the same chromosome?
Genes A and e?
3. How does the distance between two genes on a chromosome affect the chances that crossing over will recombine those genes?

66. 11.5 Gene Linkage and Mapping
Identify the structures that actually assort independently
Explain how gene maps are produced
Independent assortment:
Genes are assorted independently
But what about genes on the same chromosome

67. 11.5 Gene Linkage and Mapping
Mendel worked with 7 characteristics
Six of them happened to be on different chromosomes
The one pair on the same chromosome were so far apart on the chromosome that they appeared to assort independently.

68. 11.5 Gene Linkage and Mapping

69. 11.5 Gene Linkage and Mapping
1910 Morgan’s research on fruit flies
Studied 50 traits
Many (red-eyed, short winged) appeared to be, “linked.”
Grouped into four linkage groups
Four chromosomes
Conclusion: It is chromosomes, not individual genes, that assort independently.

70. 11.5 Gene Linkage and Mapping
Gene Maps
Are those linked genes linked forever?
No, crossing over may separate linked genes.
1911 Sturtevant (student of Morgan) hypothesis:
The farther genes are from eachother
The more likely they will be separated by cross-over
Produced gene map using recombination rates