13. Remember what homologous chromosomes are? THEY ARE: A pair of chromosomes containing the same gene sequences , each derived from one parent . The chromosomes tend to pair during meiosis.
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17. The homologous chromosomes below have the same traits on them, but they are for two different alleles . Both chromosomes in the homologous pair contain the trait for hair texture, but one carries the allele for curly hair & the other one carries the allele for straight hair .
22. When figuring out what the PHENOTYPE will be when a certain GENOTYPE is present, you need to find out the _____________ of each allele. INTERACTION
37. In each of your body cells, how many genes do you have for 1 specific trait? 2 Why? There is one gene on each of the homologous pairs. You got one gene from your mom and one gene from your dad .
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39. Remember: Meiosis only occurs in __________________. SEX CELLS SEX JUST KIDDING! NO SEX FOR SALE!
40. The homologous pairs were separated during meiosis. How and when are homologous pairs separated in meiosis in order to make a sperm or an egg?
41. Metaphase I: How are the homologous chromosomes lined up? In metaphase I of meiosis, homologous pairs are lined up so the homologous pairs are next to one another.
42. Anaphase I: How are homologous chromosomes separated? Homologous pairs are separated in Anaphase I of meiosis.
43. At the end of meiosis I, the homologous chromosomes have been separated, the cells are now haploid.
44. The homologous pairs are split up randomly, so we don’t know which particular chromosome of each pair will be found in each cell. Law of Independent Assortment http://www.frogstar.com/wav/displaywav.asp?fil=bb-alive.wav The alleles for a trait separate when gametes are formed. These allele pairs are then randomly united at fertilization.
55. What are 5 traits he was looking at and what were the 2 possible alleles for each? TEXTURE Seed Color Pod Color Flower color
56. When the gene interaction is dominant vs. recessive, you need to know the genotypes of the parents in order to accurately figure out what the possibilities are for their children.
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58. Example: A species of bird has 2 possible alleles for wing color, red and green . The alleles have a dominant vs. recessive interaction with one another. The red allele is dominant over the green allele. We will be representing the red allele as “ R ” and the green allele as “ r ”.
64. Punnet square problem #1 A man who is heterozygous for brown eyes has a baby with a woman who is heterozygous for brown eyes. What are the possible phenotypes and genotypes their children could have? Do a Punnet square The brown eye allele is dominant over blue. 1. Brown is dominant over blue 2. Both parent’s phenotypes are brown. 3. Both parents are heterozygous - Bb
65. Punnet Square Mother’s and father’s genotypes are both Bb Possible egg genes are B or b Possible sperm genes are B or b B b B b Possible genotypes for offspring are: BB Bb Bb bb BB, Bb, bb Possible phenotypes are: Brown and blue What are the chances of Getting a brown eyed child? A blue eyed child? The ratio is 3:1 brown to blue. 75% chance of brown and 25% chance of blue
66. Punnet Square Mother’s and father’s genotypes are both Bb Possible egg genes are B or b Possible sperm genes are B or b B b B b Possible genotypes for offspring are: BB Bb Bb bb BB, Bb, bb Possible phenotypes are: Brown and blue What are the genotypic ratios? The ratio is 1:2:1 1 BB 2 Bb 1 bb
67. Punnet Square Question #2 brown and yellow 2:2 --> 1:1 A female duck with yellow feet mates with a male duck who is heterozygous for brown feet. What are the possible feet colors for the chicks? Brown is dominant over yellow. Mother duck’s genotype is: bb Father duck’s genotype is: Bb b b B b Bb bb Bb bb Possible phenotypes are: Possible genotypes are: Bb and bb 2:2 --> 1:1 Going further….
69. Punnet Squares With 2 Traits Mother’s genotype : Bbll Father’s genotype : bbLl A woman who is heterozygous for brown eyes and has small toes marries a man who has blue eyes and heterozygous for large toes. What are the possible genotypes and phenotypes of their children? Brown eyes are dominant over blue Large toes are dominant over small toes
70. To form the possible egg and sperm… Think: First with third, first with fourth Second with third, second with fourth Bbll Bl Bl bl bl
71. Punnet Squares With 2 Traits Mother’s genotype: B b l l Father’s genotype: b b L l Possible eggs: Bl, Bl, bl, bl Possible sperm: bL, bl, bL, bl Bl Bl bl bl bL bl bL bl BbLl BbLl Bbll Bbll BbLl BbLl Bbll Bbll bbLl bbLl bbll bbll bbLl bbLl bbll bbll
72. Punnet Squares With 2 Traits Mother’s genotype: B b l l Father’s genotype: b b L l Bl Bl bl bl bL bl bL bl BbLl BbLl Bbll Bbll BbLl BbLl Bbll Bbll bbLl bbLl bbll bbll bbLl bbLl bbll bbll Possible genotypes: BbLl Bbll bbLl bbll 1:1:1:1 Ratio Possible phenotypes: Brown eyes/large toes Brown eyes/small toes blue eyes/large toes blue eyes/small toes 1:1:1:1 Ratio
73. Punnet Squares 2 Traits - Difficult A female wavy fur spaniel with heterozygous brown paws is mated with a male wavy fur spaniel with heterozygous brown paws. • What are the possible genotypes and ratios? • What are the possible phenotypes and ratios? Straight and curly fur show incomplete dominance . Brown paws are dominant over white paws. Female’s genotype is: Male’s genotype is: csBb csBb
74. Punnet Squares 2 Traits - Difficult Female’s genotype is: csBb Male’s genotype is: csBb Possible genes in eggs: cB, cb, sB, sb Possible genes in sperm: cB, cb, sB, sb cB cb sB sb cB cb sB sb ccBB ccBb csBB csBb ccBb ccbb csBb csbb csBB csBb ssBB ssBb csBb csbb ssBb ssbb
97. In the dentist’s office, why do they place a lead apron over a person’s lap? They want to protect the reproductive organs. If a mutation occurs in the reproductive organs, it may end up disfiguring a future child, or worse.
105. Cancer is a disease where cells begin to divide by mitosis uncontrollably. A mutation(s) can occur in one single cell, and by the process of mitosis it can grow into tens of thousands or more cells in a relatively short period of time.
106. What forms when a cell has undergone mitosis uncontrollably for a while in one central spot? A Tumor
108. 2. Chemotherapy- Treatment with drugs that kill cancer cells or make them less active. 3. Radiation- uses high-energy waves, such as X-rays (invisible waves that can pass through most parts of the body), to damage and destroy cancer cells.
109. 4. Another option is a STEM CELL TRANPLANT Radiation and anti-cancer drugs are very good at destroying cancer cells, but unfortunately they also destroy healthy cells. http://www.leapingmedia.com/Media/TransplantAnimation.mov
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116. Sex Linked Genes When we refer to a “sex linked gene”, it means that the gene is located on a sex chromosome . Very few traits are found on the Y chromosome, so when we talk about sex linked genes, you can assume the gene is located on the X chromosome .
117. Sex Linked Punnet Squares When doing Punnet squares with sex linked genes, you have to include the sex chromosome as well as the gene it carries. To show that an X chromosome carries a gene, you put the letter as a superscript of the X. X B X b would indicate a female who is heterozygous for the trait “B”
118. Color blindness is an X linked gene A woman who is a carrier (heterozygous) of the color blind gene has children with a man who is not colorblind. Colorblind (c) is a recessive gene to the dominant color seeing gene (C). What are the chances that they could have a son who is colorblind? A daughter who is color blind? Genotype of the mother is: Genotype of the father is: X C X c X C Y
119. Color blindness is an X linked gene Possible genotype for the egg: Possible genotype for sperm: Genotype of the mother is: Genotype of the father is: X C X c X C Y X C or Y X C X C X c Y X C or X c
120. Color blindness is an X linked gene Possible genotype for the egg: Possible genotype for sperm: X C or Y X C X C X c Y X C or X c X C X C X C Y Y X c X C X c The chance that they will have a colorblind SON is 50% The chance that they will have a colorblind DAUGHTER is 0% (but 50% for a carrier)
121. Color blindness is an X linked gene A woman who is homozygous for color seeing has a child with a man who is colorblind. What are the chances that his daughter will be colorblind? What are the chances that his son will be colorblind? Colorblind (c) is a recessive gene to the dominant color seeing gene (C). Woman’s genotype: Man’s genotype: X C X C X c Y
122. Color blindness is an X linked gene There is 0% chance that they will have a color blind boy or girl. But 100% chance That their daughters would all be carriers. Woman’s genotype: Man’s genotype: X C X C X c Y X C X c X C Y X C X c X C Y Y X c X C X C
123. Color Blindness Test What number do you see? Okay, so this is the one that everyone is supposed to be able to see!
126. Male patterned baldness is X linked One of the science teachers above has 2 children, a boy and a girl. His wife is heterozygous for the male patterned baldness gene. What are the possibilities that his son or daughter will have male patterned baldness? (Male patterned baldness is a recessive allele)
127. Results X H X h X h Y H = Hair h = bald X H X H X h X h X h X h Y Y 50% chance son will bald 50% chance daughter could bald Testosterone is needed to “ turn on” this balding gene, so it is very unlikely that a girl will go bald even if she is homozygous for this balding gene.
128. If a young man wants to get some idea if he may have male patterned baldness, who should he look at, his father or his mother’s father? Why?
129. Because the male patterned baldness is sex linked, he did not receive the gene from his father, he got it from his mother. Looking at the father’s side of the family is useless because he got his Y chromosome from his dad, not an X.
130. Pedigree Pedigrees are symbolic representations of a family and the alleles they have. When creating a pedigree, this symbol means the person is male. When creating a pedigree, this symbol means the person is female. When creating a pedigree, this symbol means the person is of unknown gender. This is often used if in the history of family, a child died at birth and the gender of the child is not known.
131. Pedigree The horizontal line connecting this man and woman means that they are married. The same symbol as above but having a diagonal line through the marriage line means that the couple is divorced. This collection of symbols means that the man is divorced and remarried. A symbol with a diagonal line through it means that The person is no longer living.
132. Pedigree What collection of symbols could show a couple who is married and has son and a daughter.
133. Pedigree A couple is married, they have A son and a daughter. Their son is married and he and his wife have a son. Get the idea?
134. Pedigree Representing genetic traits within a pedigree. The symbol colored in means that the person is homozygous for the allele. The symbol half colored in means that the person is heterozygous for the allele. The symbol not colored in means that the person does not have the allele.
135. Pedigree for the blue eye allele A pedigree for a brown eye allele The brown eye allele is dominant In this family,who has brown eyes? Everyone except This woman.
