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Genetic Disorders. . . Achromatopsia Down Syndrome Neural Tube Defects Aicardi Syndrome Epidermolysis Bullosa Noonan Syndrome AlbinismFamilial Dysautonomia Optic Atrophy Alexander Disease Fibrodysplasia Osteogenesis Imperfecta Alpers' Disease Fragile X Syndrome Peutz-Jeghers Syndrome
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1. Genetic Continuity Pg. 78-195
2. Genetic Disorders
3. Achromatopsia
Down Syndrome
Neural Tube Defects
Aicardi Syndrome
Epidermolysis Bullosa
Noonan Syndrome
Albinism
Familial Dysautonomia
Optic Atrophy
Alexander Disease
Fibrodysplasia
Osteogenesis Imperfecta
Alpers’ Disease
Fragile X Syndrome
Peutz-Jeghers Syndrome
Alzheimer’s Disease
Deficiency Anemia
Phenylketonuria (PKU)
Angelman Syndrome
Galactosemia
Pseudoxanthoma Elasticum
Autism
Gaucher Disease
Progeria
4. Genetic Research The scientist who grew a human ear on the back of a mouse has suggested it may one day be possible to "grow" a liver.
5. Human Skin Equivalent
6. Beck Weathers The biggest loss of life on Everest occurred in May 1996 when eight climbers died in a fierce storm.
One American climber, Beck Weathers, was left for dead on the mountain during the storm but he regained consciousness and staggered, snowblind, to safety.
He lost both of his hands and his nose to frostbite but survived.
Nose regeneration.
7. Regenerated Finger http://www.youtube.com/watch?v=GwcT1ViM-hw&feature=related
10. Reproduction Review Types of Reproduction
Asexual reproduction
Does not involve sexual intercourse
Offspring identical to parent – why?
Sexual reproduction
Produces offspring by uniting two sex cells (fertilization), one from each parent
Produces offspring with a variety of traits – why?
11. Questions? Under what circumstances do cells divide?
How does the rate of cell division change?
Why do some cells divide quickly while others do not?
Why do some cells specialize and others do not?
Why do some cells divide while others do not?
What makes each cell do such unique functions?
13. Cell Theory Review All living things are made up of one or more cells
Approx. 100 trillion cells in your body
All cells are made from pre-existing cells by cell division
A single cell can create 2 cells through mitosis, cytokinesis
Parent cell divides to create 2 daughter cells
The cell is the basic unit of life
A one celled organism is a living thing
One cell can do all of life functions
14. Cells and Genetic Information Genetic info is in DNA
DNA is packaged as chromosomes
Chromosomes are in the nucleus
A human body cell has 46 chromosomes
(23 pairs)
15. The Cell Cycle The sequence of events from one cell division to another
Is a continuous process that doesn’t pause after each phase
Phases help scientists explain mitosis and cytokinesis
Mitosis is a short but very important part of the cell cycle
16. Mitosis Cell replicates each DNA molecule (chromosomes doubled)
Each chromosome is separated from its copy
Daughter cells genetically identical to each other and the parent cell
Replication of genetic info ensures future cell divisions
Each daughter cell is potential parent cell for next generation
# of chromosomes before division = # after
All body cells have same genetic info
Can still have different shapes and functions
18. The Cell Cycle Interphase
Time between nuclear divisions
Cells grow, make structural proteins, move nutrients, eliminate wastes, prepare for mitosis – cell lives!
Genetic material is called chromatin at this point
All the DNA molecules and associated proteins in the nucleus in long, thin strands scattered in the nucleus in a tangled, fibrous mass
Each chromosome duplicates itself
Original and duplicate attached by a centromere = sister chromatids
The pair is considered one chromosome
19. Mitosis Prophase
First phase
Chromosomes in nucleus become visible under microscope as they shorten and thicken
In animal cells:
Centriole separates and moves to poles to form spindle
In plant cells:
No centrioles, but spindle fibres still form
nuclear membrane dissolves to allow the separation of chromosomes and cell organelles
20. Mitosis Metaphase
Second phase
Chromosomes (sister chromatids) move toward equatorial plate
Chromosomes are dark, wiry structures attached to spindle fibres
most visible at this stage, hard to count because they’re entangled
21. Mitosis Anaphase
Third phase
Centromeres divide, sister chromatids go to opposite poles of the cell
the same # and type of chromosomes should be found at each pole
Segments of the chromatids may break apart and may reattach
22. Mitosis Telophase
Last phase
Chromosomes reach opposite poles of the cell and begin to lengthen
Spindle fibres dissolve
Nuclear membrane forms
23. The Cell Cycle Cytokinesis
Cytoplasm starts to divide
In animal cells:
A fold develops, pinching the cell into 2 parts
In plant cells:
A cell plate forms between the 2 chromatin masses and separates them - eventually develops into a new cell wall
24. Cloning The process of forming identical offspring from one cell or tissue
Sketch the process on pg. 96/97
25. Cancer Broad group of diseases associated with the uncontrolled and unregulated growth of cells
Dangerous because a cell can break off and move to another tissue (mestasis)
26. Meiosis Forms gametes (sex cells)
Two stages of cell division
# of chromosomes in daughter cell is half the # in parent cell
Haploid refers to the # of chromosomes in a gamete (n)
Diploid refers to 2 times the # of chromosomes in a gamete (2n)
Human offspring have 23 chromosomes from each parent that are paired
Paired chromosomes called homologous chromosomes
Similar in size, shape, gene arrangement, and gene information
Deal with the same traits
Each body cell, except sex cells, has 23 homologous chromosome pairs
Interact during meiosis
During fertilization, haploid sperm cell + haploid egg = diploid zygote
Restores the diploid chromosome number in the zygote
Zygote begins to divide by mitosis and a multicellular human baby is made
29. Meiosis I Prophase I:
Nuclear membrane starts to dissolve, the centriole splits and its parts move to opposite poles within the cell and spindle fibres are made
Synapsis
Chromosomes come together in homologous pairs
Each pair made of 4 chromatids and called a tetrad
Crossing over can occur
Metaphase I:
Homologous chromosomes attach to spindle fibres and line up along equator
30. Meiosis I Anaphase I:
Homologous chromosomes segregate
Reduction division
One member of each homologous pair will be found in each of the new cells consisting of 2 sister chromatids
Telophase I:
A membrane begins to form around each nucleus
Each daughter nuclei has 1 member of the chromosome pair
These “daughters” are NOT identical!
Cells are now ready for Meiosis II
31. Meiosis II Happens at approx. the same time in each haploid daughter cell
Pairs of chromatids will separate and move to opposite poles
No replication of chromosomes prior to meiosis II
Prophase II:
Signals beginning of second division
Nuclear membrane dissolves and spindle fibres form
Metaphase II:
Equatorial lineup
Anaphase II:
Chromatids separate and move to opposite poles
Nuclear membrane forms around chromatids, now called chromosomes
Telophase II:
Second nuclear division is completed and the second division of cytoplasm occurs
4 haploid daughter cells are produced from each meiotic division
32. Create a comparison organizer for Mitosis vs. Meiosis Venn diagram
Sims diffs chart
???
34. Gregor Mendel Scientists originally thought crossbreeding would create a blend of traits
Mendel proved that isn’t true
When he crossbred round seeds with wrinkled seeds the offspring always had round seeds
The round trait dominated whether it was from the male or female parent
1 trait always dominated over the other
Tall plants dominated over short, yellow seeds dominated over green
Factors control plant traits (genes) and different forms of a gene (alleles)
Ex. Green and yellow are different alleles for seed colour
Traits expressed most often are dominant, the less frequent are recessive
Mendel crossbred 2 hybrid plants with round seeds, but some of the offspring expressed the gene for wrinkled seeds (Figure 5, Pg. 132)
35. Creating a personal Profile Try this pg. 133
36. Single-Trait Inheritance Terms:
Genotype:
refers to the alleles that an organism contains for a particular trait, ex. TT/Tt for a tall plant, tt for a short plant
Phenotype:
the observable traits of an individual, ex. Tall or short
Homozygous:
describes genotypes with 2 of the same alleles, ex. TT or tt
Heterozygous:
describes genotypes with two different alleles, ex. Tt
Monohybrid Cross:
cross involving 1 allele pair, ex. tt x TT
Punnett Square:
chart used to show possible combinations of alleles in offspring
37. Steps for Solving Punnett Squares 1. Figure out the genotypes (ex. Heterozygous = Yy, homozygous dominant = BB, homozygous recessive = yy)
2. Break the genotypes down into gametes (ex. Yy = Y and y)
3. Use the gametes in a Punnett square by writing them across the top and left side
38. A plant that is heterozygous tall is crossed with a short plant. Determine the genotypes and phenotypes of the F1 generation.
39. Do Monohybrid Cross Practice Problems
40. Multiple Alleles Possible to have more than 2 different alleles for 1 gene
Ex. Fruit flies have many possible eye colours (wild type is dominant over apricot, which dominates over honey, which dominates over white)
Ex. Blood types
Capital letters and superscripts are used to express the different alleles and their combinations
See Table 1, Pg. 143
41. Incomplete Dominance and Codominance Capital letters and superscripts are used to express the different alleles and their combinations
Incomplete dominance
When two alleles are equally dominant, they interact to create a new phenotype
Ex. Red snapdragons + white snapdragons = pink snapdragons
CRCR + CWCW = CRCW
Codominance
Both alleles are expressed at the same time
Ex. Red bull + white cow = roan calf (red and white hair)
HRHR + HWHW = HRHW
42. Try This! An extra finger is a rare human trait, but is due to a dominant gene. When one parent is normal and the other parent has an extra finger, but is heterozygous for the condition, what is the probability that their children will be normal?
43. Answer to Try This
44. Test Cross Often performed to determine the genotype of a dominant phenotype
Always performed between the unknown genotype and a homozygous recessive type
If any offspring show the recessive trait, the dominant individual must be heterozygous
If all offspring show the dominant trait, the dominant individual must be homozygous
Must have numerous repeats of the cross to ensure valid results
45. Sex-linked Traits Traits located on the sex chromosomes
We will focus on recessive traits that are carried on the x-chromosome but “missing” on the y-chromosome
Observed more often in males (no other allele to mask one recessive allele)
Use X and Y with superscripts to solve these problems (see pg. 166 for example)
46. Dihybrid Crosses Express parental genotypes and use foil rule to determine gamete genotypes (4 per parent)
Punnett square will have to be a 4x4 grid instead of a 2x2 grid
Offspring will have 4 letters, 2 of each type
List the alleles for one gene first (dominant alleles first) and then the alleles for the other gene
47. Pedigree Charts Presentation of a family tree that allows patterns of inheritance to be followed for a gene
Use symbols that identify gender, relationships between individuals, and if an individual expresses a trait or carries the allele as part of a heterozygous genotype
48. Genetic Screening Before insulin could be taken from animals many people who had the recessive homozygous alleles for the condition died before passing their genes on to offspring
Genetic screening works to detect these conditions before conception
Prenatal testing can be used to determine the sex of the offspring and to identify the presence of genetic conditions
Amniocentesis and CVS are commonly used
49. Virtual Fly Simulation
50. The Source of Heredity A gene can effect how nerve cells receive information
All genes interact with the environment
How much is a phenotype affected by genes and how much is it affected by the environment?
Ex. The same species of fish develop differently depending on water temp.
Ex. Himalayan rabbits are partially black if raised at low temperatures, and white if raised at high temperatures
51. Early Developments in Genetics We know genes are responsible for heredity
1831- nucleus discovered
Many misconceptions were cleared up by 1865, after Mendel’s work
Known that egg and sperm unite to produce a zygote
Better microscopes being developed around the time of Mendel’s work
This created cytology, the study of cell formation, structure, and function
1882- Walter Fleming described the separation of threads in the nucleus during cell division
1882- Edouard van Benden noticed that roundworm sperm and egg cells have 2 chromosomes, but fertilized eggs have 4
1887- August Weisman theorized that a special division takes place in sex cells
1900- Mendel’s experiments rediscovered and their significance realized
52. Development of the Chromosomal Theory 1902- Walter S. Sutton & Theodor Boveri
separately observed that chromosomes are in pairs that separated during meiosis
Chromosomes formed new pairs when the egg and sperm united
Supported Mendel’s theory of inheritance based on paired factors
These paired factors are now called alleles -- 1 allele from each sex cell
Cellular evidence proved the formation of new allele combinations in further generations
Chromosome behaviour during gamete formation helped explain Mendel’s laws of segregation and independent assortment
Sutton and Boveri knew phenotypes weren’t dependent on 1 parent
Cells in the egg and sperm determine heredity
Determined that Mendel’s factors were carried on chromosomes
Sutton hypothesized that chromosomes carry genes and genes on the same chromosome are considered linked
53. Chromosomal Theory Improvement of the microscope led to advances in cytology and the union of cell biology and genetics
Summary of the Chromosomal Theory of Genetics:
Chromosomes carry genes, the units of heredity
Paired chromosomes segregate during meiosis. Each sex cell has half the # of chromosomes found in the somatic cells (not sex cells). This is why a gamete has only 1 of each paired allele
Chromosomes arrange independently during meiosis
Each gamete gets 1 member of each chromosome pair
The pairs don’t influence the movement of each other
54. Morgan’s Experiments and Sex Linkage Used fruit flies to study the principles of inheritance
Reproduce quickly and offspring can mate shortly after leaving the egg (possible to study many generations at one time)
Observed mutations linked to other traits (Table 1, Pg. 164)
Saw a white-eyed male in with the red-eyed offspring and determined that white eyes are a mutation
Mated a white-eyed male with a red-eyed female, all the offspring had red eyes
Continued to breed different generations and discovered that only males had white eyes
Realized Y chromosome doesn’t carry the gene for eye colour
Sex-linked trait because gene is located on sex chromosomes
Male offspring always inherit sex-linked traits from the mother
Sex-linked genes are also found in humans
Ex. Red-green colourblindness
55. Barr Bodies Dr. Murray Barr discovered a small,dark spot of chromatin in the nucleus of a female mammal cell, now called a Barr body
Caused by 1 of the X chromosomes becoming inactive in each cell
Showed that not all female cells are identical
Some cells express a certain trait while others show a different form
Has been estimated that the X chromosome carries 100 to 200 different genes
This means there are many sex-linked traits, like hemophilia, nearsightedness etc. that affect males more than females
The Y chromosome carries the information determining gender
56. Looking Inside the Chromosome Nucleus of every bodily cell contains DNA
DNA is the only molecule known to be capable of replicating and allowing cellular reproduction
DNA is the way hereditary information passes from generation to generation and contains instructions to ensure life continues
As organisms grow, cells specialize according to the instructions given by DNA
In older organisms, DNA instructs how to repair and replace worn cell parts
This info is carried by chemical messages between the nucleus and cytoplasm
DNA has all the instructions to make you unique
Proteins, made up of nucleic acids, are the major structural and functional components of all cells
Nucleotides are the basic units of nucleic acids
57. Video: DNA Structure
58. Discovering the Structure of DNA Rosalind Franklin developed a technique that photographed the DNA molecule and produced photos showing its helical structure and where the phosphate sugars are located
Scientists knew DNA was made up of sugars, phosphate, and 4 different nitrogenous bases (A, T, G, C), but they didn’t know the arrangement
New research showed there are equal amounts of G and C, and equal amounts of A and T
Suggested that the bases were arranged in pairs
James Watson understood the chemical data, while Francis Crick could understand the X-ray diffraction results
Together they developed a 3D model of DNA they presented in 1953
59. The Structure of DNA Double helix, like a spiral ladder
Sugars and phosphates make the backbone of the staircase, and the nitrogenous bases make the rungs
Purines pair with pyramidines
60. Genetic Research and Technologies
61. Genetic Research and Technologies Cystic Fibrosis:
Inherited disorder associated with 1 gene that produces a protein called CFTR
One allele must be inherited from each parent
A team at the Hospital for Sick Children identified the gene in 1989
Possible to correct the basic defect by delivering a normal version of the CFTR protein in mice
Muscular Dystrophy:
Group of genetic disorders causing muscle deterioration
Some forms are linked to non-sex cells and can occur in males and females
Other forms are sex-linked and affect males, but females may show mild symptoms (Table 2, Pg. 182)
62. DNA Fingerprinting Long stretches of the DNA molecule are similar from person to person
Less than 1% of DNA is unique to an individual
DNA samples can be taken from skin samples, hair, semen, or blood
They are cut with restriction enzymes at specific sites and reproducible DNA fragments are created
Location and # of cuts are distinct for each person, so DNA profiles are unique to each person
Fragments are transferred to a nylon sheet and a radioactive marker identifies the unique sequence of the DNA chain
The sheet is placed against an X-ray film and black bands appear where markers have attached to the segments
A print is made from the film and used to compare samples
63. Gene Therapy Replaces defective genes with normal genes to cure genetic conditions
Three possible strategies:
Insert a normal gene into position on the chromosome of the affected cell
Chemically modify the defective gene to hopefully recode the genetic message
Use surgery to replace the defective gene with a normal gene
1990- 1st clinical use on 4 year old girl who had insufficient amounts of ADA, an enzyme
A genetically modified virus was used to carry a normal ADA gene into her immune cells so the right enzyme would be produced
The trick to using a virus to insert new genetic information is to ensure it will be placed in the right location
Many projects are currently underway to hopefully help those suffering from a variety of genetic disorders
64. What is the phenotypic ratio of the offspring of the following Drosophilia?