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Monday3/19/12 AIM: What is heredity? Homework: Handout Section 11.2 Read pages 288-291. Reading check on page 288. 2- Use figure 11.7 and in your own words,

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Presentation on theme: "Monday3/19/12 AIM: What is heredity? Homework: Handout Section 11.2 Read pages 288-291. Reading check on page 288. 2- Use figure 11.7 and in your own words,"— Presentation transcript:

1 Monday3/19/12 AIM: What is heredity? Homework: Handout Section 11.2 Read pages 288-291. Reading check on page 288. 2- Use figure 11.7 and in your own words, summarize steps A-C 3- Answer question 1 page 295 of the handout

2 Transcribe and translate DNA: TACGTTTGCGACACCACT

3 What do genes do? Units of heredity that are passed down from generation to generation Hold the code to build physical traits

4 Where are genes located? On DNA which builds chromosomes which are in the nucleus

5 How many codons are there in total? 64 How many amino acids are there in total? 20

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7 Why is it a good thing to have multiple codons specify the same amino acid? Because if the gene is mutated there is still a chance the protein therefore physical trait will be unaffected!

8 If a person with brown eyes has a baby with a person with green eyes? What color eyes do you think their baby will have and why do you think that?

9 Light blue0 dominant alleles Blue1 dominant allele Blue-green2 dominant alleles hazel3 dominant alleles Light brown4 dominant alleles Brown5 dominant alleles Dark brown / black6 dominant alleles

10 What is Heredity? The transfer of characteristics from one generation to the next

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12 Human heredity Chromosomes are built from DNA wrapped around proteins Genes are parts of DNA –Specific nucleotide sequences Therefore genes are found on chromosomes One chromosome might have 1000 genes on it Your cells have more genes than chromosomes

13 Thursday 3/22/12 AIM: Why is Gregor Mendel the “father of Genetics”? DO NOW: If a person with brown eyes has a baby with a person with green eyes? What color eyes do you think their baby wil have and why do you think that? HOMEWORK: Text page 265 Inquiry Lab. Page 266 using words question 2

14 What are Traits? A characteristic that is determined by your genes A pair of genes will determine the trait –Examples: Tongue rolling Earlobes Widow’s Peak Hair Whorl Dimples

15 What is genetics? The science of how traits are inherited

16 Who is Gregor Mendel? “Father of Genetics” Studied pea plants He crossed pea plants with different characteristics and studied their offspring He was able to determine how traits get passed on from generation to generation

17 Gregor Mendel Father of genetics Looked at the pea plant Specifically 7 visible traits Followed their inheritance over many generations

18 The pea plant displayed one of 2 possible characteristics for each trait

19 How did Mendel experiment with the pea plant?

20 Mendel’s pea plant Key feature: reproduction can be controlled and manipulated Self- fertilization and cross-fertilization were easily obtained

21 Fertilization Self-fertilization: egg in the flower is fertilized by the sperm of the same flower Cross-fertilization: sperm from a foreign plant fertilizes an egg

22 Friday 3/23/12 AIM: How did Gregor Mendel develop his 3 laws of heredity? DO NOW: Explain the difference between self and cross fertilization. Homework: Complete any assignment you missed this week Last nights hw. 1- Page 265 Inquiry Lab 2- page 266 Understanding words # 2

23 Mendel’s work At first Mendel self fertilized plants in order to create true breeds True breed or pure breed has only one trait to pass on –Ex: Seed color –Yellow seed yellow seed True breeds are homozygotes

24 Monday 3/26/12 AIM: How did Gregor Mendel develop his first two laws of heredity? DO NOW: Explain why Mendel choose to work with pea plants HOMEWORK: textbook read pages 267- 269. questions 1 and 3 on page 270

25 Mendel’s work Mendel did not know anything about dominant or recessive behavior He did know how to make pea plants reproduce

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27 Definitions Genes: instructions to build physical characteristics Chromosome: large unit of DNA and protein that carry genes on them Human cells: –Somatic cells: body cells: diploid(2n) –Gametes: sex cells: haploid(n)

28 Somatic Cells ALL somatic (body cells) have the same 46 chromosomes Each cell is different due to the genes that get turned on or off

29 How is a cell’s DNA like a library?

30 Wednesday 3/28/12 AIM: How did Gregor Mendel develop his law of dominance? DO NOW: Explain the difference between diploid and haploid and give an example of each HOMEWORK: Textbook page 270 questions 2 and 4 I AM CHECKING 1-4 TOMORROW

31 Diploid (2n) vs haploid (n)

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33 Mendel’s work He self fertilized plants for several generations to ensure that all were pure breeds True breed or pure breed: plants with a trait such as purple flowers that is always inherited by all offspring –Only have 1 type of allele for a specific gene (homozygous)

34 Mendel’s work Cross fertilized plants that were true breeding for 7 specific traits Hybrid: The offspring of a cross fertilization –2 parents similar to sexual reproduction –Has genetic information from both parents

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37 Mendel’s work Crossed two true breed parents that displayed opposite traits.(P or Parental generation) All First filial or F1 offspring were purple

38 Genetics vocabulary Gene: part of DNa which holds the instructions to build a protein Allele: copy of a gene –Specific directions Genotype: genetic makeup of an organism Phenotype; resulting physical characteristics

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41 What happened to the white color?

42 Self-fertilized F1 Second filial or F2 generation yielded about ¼ white and ¾ purple

43 Mendel’s conclusion When the white flowered plants showed up in the F2 generation, Mendel concluded that the white characteristics must have been hidden in the F1

44 Self-fertilized F2 Saw that all white flowered F2 yielded all white F3 but the purple still yielded 3:1 ratio of purple to white Therefore the white allele was not lost but rather hidden or masked by the purple allele

45 From these experiments, Mendel concluded: Traits are determined by physical unit that come in pairs Pairs are separated during gamete formation Gametes only 1 allele each The particular allele that ends up in a gamete is caused by chance One allele is dominant and one recessive From Mendel’s Monohybrid cross he developed the law of dominance and the law of segregation

46 3/29/12 Thursday AIM: how did Mendel develop his law of Independent assortment? DO NOW: Explain why ALL of the F1 generation had purple flowered plants. Homework: Textbook

47 Mendel’s Law of segregation Pairs of alleles on homologous chromosomes separate from each other during gamete formation Gametes receive only one allele from a homologous pair. Fertilization produces offspring with a copy of one allele from mom and one from dad

48 Mendel’s Law of dominance When two different alleles are present, the dominant alleles gives the resulting trait and masks the trait of the recessive allele However the recessive allele is still present

49 Friday 3/30/12 AIM: how did Gregor Mendel develop his law of independent assortment? DO NOW: Explain the difference between genotype and phenotype

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54 Which two laws did Mendel Develop from his Monohybrid crosses?

55 Answer Law of segregation: alleles separate during gamete formation Law of Dominance: when two different alleles for a trait are present, one is expressed (dominant) the other is masked

56 According to Mendel why do homozygote dominant and heterozygote genotypes show the same phenotype? Both have a copy of the dominant allele

57 Monohybrid cross ONLY tracks one physical trait at a time. From Mendel’s monohybrid crosses, he developed: –Law of segregation –Law of dominance

58 Mendel was not satisfied He wanted to see if alleles could be inherited together He looked at two traits at the same time Ex: seed shape and seed color His results were inconclusive

59 R-round r-wrinkled Y-Yellow y-green

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61 Mendel’s dihybrid cross P: true breed RRYY x rryy All F1: RrYy Allowed F1 to self-fertilize which yielded the following phenotypic ratio F2: 9:3:3:1 ratio of Round Yellow: Round green: wr Yellow: wr,green

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71 Law of independent assortment Multiple traits are inherited independently of each other because alleles of genes are distributed independently during gamete formation Genes for different traits are inherited independently

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73 Mendel’s laws Law of segregation Law of Dominance Law of independent assortment Still used today they paved the foundation for genetics Although his observations and laws explain the simplest form of genetics

74 Monday 4/3/12 AIM: What are some exceptions to Mendel’s laws? DO NOW: Why did Mendel perform his di hybrid cross and what were his results? Homework: Textbook read page 282-284. questions 1-3 page 284. Write out the question followed by the answer

75 Mendel gave us a foundation to build on genetics Without his experiments and discoveries, we may not have known anything about heredity

76 According to Mendel, phenotypically how does a homozygote dominant and a heterozygote react? Answer: Law of dominance: if the dominant allele is present it will be expressed They will both display the same phenotpye

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78 Incomplete Dominance Incomplete dominance is basically just a blending of traits The heterozygous form is a blend of the dominant and the recessive traits dominant recessive

79 Wednesday AIM: how can more than one allele code for the same trait? DO NOW:Explain how the pink snap dragon defies Mendel’s law of dominance

80 How does this happen? Usually the law of dominance: if the dominant allele is present it is expressed. So the Rr snapdragon would be Red BUT instead it is pink due to incomplete dominance. The heterozygote Rr is a combination of the dominant R and recessive r phenotypes

81 Usually alleles code for enzymes which in turn code for chemical reactions to occur. In the case of the snap dragon, R allele codes for an enzyme which catalyzes a reaction which makes the red pigment r- white pigment Both are made and mix just like mixing red and white paint Homozygous Dom Homozygous recessive Heterozygous

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84 Tuesday 4/3/12 AIM: How are two alleles expressed at the same time? DO NOW: Explain HOW the snap dragons of a red and white cross yielded all pink snap dragons HOMEWORK: Textbook page 284 questions 4-6

85 Wednesday 4/4/12 AIM: How does human blood type defy Mendel’s laws? DO NOW: Explain how human blood type is determined. HOMEWORK: Read page 284. reading Check on 284

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87 Question 1- A woman with blood type A and a man with blood type B have a child with blood type O. How did this happen? 2- Baby daddy DRAMA! A woman claims her son is Mr. Clide’s. The woman has blood type O Mr. Clyde has blood type AB and the child also has blood type O. Is Mr. Clyde the boy’s father Explain why or why not

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89 Codominance There is more than one dominant allele Ex: Human blood Type There are 3 alleles that code for the antigen protein found on the surface of the Red Blood Cell

90 Blood type is an example of codominance A person with blood type AB is showing the results of having both the I A and I B codominant genes 3 alleles code for blood type Specifically blood typing alleles code for antigens Antigen: specific recognition protein found on the surface of red blood cells

91 Antibody A protein that defends the body against foreign antigens In relationship to blood type, each antigen has the opposite antibody floating in the plasma

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93 Rh factor Determines if blood is + or – It is a completely different protein and has NO connection to antigens

94 List and explain the 2 exceptions to Mendel’s laws we have discussed so far Incomplete Dominance COdominance

95 Monday 4/16/12 AIM: How does one gene control several characteristics? DO NOW: Explain the difference between codominance and incomplete dominace HOMEWORK: textbook page 280 sex linked traits. Answer the Reading check on page 280

96 Incomplete dominance; The heterozygote is a combination of the dominant and recessive allele Codominance: There is more than one dominant allele and both are fully expressed when present at the same time

97 SO FAR EXCEPTIONS to Mendel’s 3 laws of Inheritance –Incomplete dominance (pink snap dragons) –Codominance (Blood type AB) –Multiple allele inheritance: more than one allele determines a trait. (human blood type)

98 Polygenic Inheritance More than one gene coding for the same trait Eye color is known to have a polygenic inheritance pattern, possibly governed by 6 or more genes. There are also 6 different described eye colors. Basically, dark is dominant at each of the 6 genes. The more dominant alleles that you have the darker your eyes are.

99 Light blue0 dominant alleles Blue1 dominant allele Blue-green2 dominant alleles hazel3 dominant alleles Light brown4 dominant alleles Brown5 dominant alleles Dark brown / black6 dominant alleles

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101 Pleiotropy Single gene influences several traits Ex: SRY gene on the Y chromosome Sex determining region SRY gene: initiates sequence of events that affects many different body structures Specifically during development it turns the gonads into testis and is responsible for all male charatceristics

102 Chromosomes are inherited Mendel did not know the difference between a gene and chromosome Thomas Hunt Morgan: worked with Drosophila fruit flies –He figured out that genes are the inherited unit

103 Remember Chromosomes are the inherited unit –Humans have 22 pairs of Autosomes –1 sex pair –Totaling 23 pairs = 46 Genes are carried on chromosomes and contain the directions to build a protein One gene codes for one protein

104 The chromosomal basis of inheritance Genes are located on chromosomes Inheritance pertains to the behavior of chromosomes during meiosis and fertilization Gene locus: the actual position of an allele on a chromosome

105 Some gene loci are very close together

106 Tuesday 4/17/12 AIM: How are some traits inherited together? DO NOW: Explain the difference between polygenic inheritance and pleiotropy. Homework: textbook Read page 335.Explain how DNA helped to identify unknown individuals whose coffins floated out of burial sites

107 What did Mendel’s Law of independent assortment say According to Mendel, genes or alleles found on different chromosomes cannot be inherited together

108 Remember Mendel’s Law of Independent assortment Independent Assortment of Alleles

109 Wednesday 4/18/12 AIM: How can genes be inherited together? DO NOW: List ALL of the exceptions to Mendel’s laws that we discussed. HOMEWORK: Reading check page 283 and Monday’s Reading check page 280 will be collected tomorrow

110 Gene linkage Some alleles are so close to each other on a chromosome that they are inherited together This defies Mendel’s law of independent assortment Gene linkage only occurs when loci is close

111 Genetic linkage When two genes are very close on the same chromosome they do not segregate independently, they are said to be linked. Linkage is a powerful tool in modern genetic counseling. Autosomes (chromosomes 1-22) do display linkage however it is most understood in the sex chromosomes(X and Y) Since most X-linked traits are seen in males

112 Sex-linked genes Found on the X chromosome Are easy to track because traits are often seen in males due to males having only one X chromosome

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114 Thursday 4/19/12 AIM: What are some of the human genetic disorders? DO NOW: Explain why sex linked disorders are easier to trace in males over females Homework: textbook page 339-340 questions: 1,2,3,4,5,6,9,14,17. write out the question followed by the answer except for # 14.

115 Sex-linked genes Found only on X chromosome Specifically Y chromosome holds only about 20 genes Where as the X chromosome has about 1500 genes

116 How do our chromosomes determine sex?

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118 Formation of a zygote

119 Genetic makeup of your cells Whatever chromosomes and genes the zygote receives, EVERY cell is genetically identical to it Cell differentiation: when cells become specialized

120 Friday 4/20/12

121 If all of our cells are genetically identical, then why does a neuron transmit electrical impulses while a muscle cell provides movement? Cells become specialized by turning on specific genes while turning other genes off

122 Apoptosis Programmed cell death

123 Mutation Any change in the coding sequence that causes a change in the physical characteristic. Chromosomal mutations: loss or gain of a complete chromosome –Usually chromosomal mutations lead to miscarriage The baby does not develop to be born –There are only a few chromosomal mutations that will lead to full term development but the child will have severe abnormalities

124 Mutations continued Genetic mutations: occur at a single gene –Change in the “reading frame” or nucleotide sequence that causes a change in the physical characteristic –Much more common than chromosomal mutations

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127 Human Genetic disorders Sex-linked genetic disorders –Only on the X chromosome –Seen more in males than females Examples: –Red-green colorblindness –Hemophilia

128 Red Green Colorblindness

129 Hemophilia: Inability for blood to clot People do not produce one of the proteins necessary for proper blood clotting

130 Females exhibit normal dominant or recessive expression As long as the dominant allele is present, it will be expressed

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132 Sex Linked traits Females must be homozygote recessive in order to display the sex linked disorder

133 Sex-linked dominant disorder Vitamin D resistant Rickett’s Ingestion of Vitamin D is ineffective Causes bone deformity and bow leggedness

134 Human Recessive Genetic disorders Homozygote Recessive is the only way to display Heterozygotes are carriers Sickle Cell Anemia Albinism Cystic fibrosis

135 Sickle cell anemia Homozygote recessive disorder Causes the hemoglobin protein to sickle in shape Hemoglobin can not carry oxygen

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137 Cystic Fibrosis European descent 1:2500 Lack of a membrane protein that transports Cl- Accumulation in the extracellular matrix leads to cells producing a thick sticky mucous

138 Renal cystic fibrosis

139 Albinism Albinism: homozygous recessive allele for the enzyme tyrosine which builds melanin

140 Human Dominant Disorders Both Homozygote Dominant and Heterozygote display trait

141 Huntington Disease People usually have symptoms for up to 10 years before they find out they have Huntington's disease. Most people are diagnosed between the ages of 30 and 50, although this can happen much earlier or later. Symptoms are often overlooked, as they are mild and commonly experienced by well people mild tremor clumsiness lack of concentration difficulty remembering things mood changes, including depression sometimes, aggressive antisocial behavior

142 Huntington’s disease: dominant allele causes slow deterioration of brain and nervous system

143 Achondroplasia Dwarfism “without cartilage formation”cartilage the defect is not in forming cartilage but in converting it to bone

144 Hypertrichosis Excessive hair growth over and above the normal for the age, sex and race of an individual Exact cause is unknown but has been linked to a spontaneous mutation

145 Nondisjunction and Down’s syndrome In Down syndrome, 95% of all cases are caused by this event: one cell has two 21st chromosomes instead of one, so the resulting fertilized egg has three 21st chromosomes. Recent research has shown that in these cases, approximately 90% of the abnormal cells are the eggs. The cause of the nondisjunction error isn't known, but there is definitely connection with maternal age

146 Trisomy Trisomy 13Trisomy 18

147 Nondisjunction

148 Nondisjunction leads to abnormal numbers of chromosomes Turner’s syndrome: XO: no hormones lead to no menstruation and no secondary sex characteristics Infertility Short stature, folds on neck, more X linked recessive disorders, color blindness, hemophilia etc.

149 Trisomy X 1 in every 1000 woman have 3 X chromosomes Very tall Below normal intelligence

150 Klinefelter syndrome 1 in every 1000 males have XXY Most never even know they have it At puberty may experience mixed secondary sex characteristics such as partial breast development, widening of the hips and small testis These men are usually infertile

151 XYY males High levels of testosterone Severe acne More than 6 feet tall Lower IQ

152 Genetic testing and counseling Punnett squares, testcrosses and genetic screening helps to determine the genotype of parents You can then predict the probability of zygote receiving traits Medical tests that identify changes in chromosomes, genes and proteins

153 Fetal Testing Ultrasound Amniocentesis Chorionic Villus Sampling Fetoscopy Newborn Screening

154 Ultrasound Sounds waves are used to produce an image

155 Fetoscopy Viewing scope is placed into the uterus creating an image Enables blood samples to be taken Detects Spina bifida Only done if there is a history of birth defects

156 Amniocentesis 14 th -16 th week 10 mL of amniotic fluid Looks at chemicals and molecules present chromosomal disorders, including Down’s syndrome, trisomy 13,18,Turner’s syndrome, Kleinfelter’s syndrome Sickle Cell, Tay Sachs spina bifida and anencephaly

157 Chorionic Villus Sampling 8 th -10 th week Insert through the cervix into the uterus Take a tissue sample from the placenta Contain fetal cells which divide more rapidly than amniotic cells

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159 New born Screening Examines newborn blood to detect genetic disorders PKU: phenylketonoria Treated with diet regulation

160 Hemophilia: the inability to clot blood Sex-linked disorder found on the X chromosome It is a recessive trait therefor a female can have one copy of the allele and not display the trait however a male will always display the trait

161 Females exhibit normal dominant or recessive expression As long as the dominant allele is present, it will be expressed

162 Because males have only 1 X chromosome, if they receive the recessive allele from mom they show the recessive trait


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