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Presentation on theme: "Genetics."— Presentation transcript:

1 Genetics

2 Heredity Lesson 1

3 Do Now Video: What are genes?

4 Heredity The passage of these coded instructions from one generation to the next Some traits are readily observable – ex: hair color, leaf shape, shape of wing.. Etc. ** others are less obvious ex: defective heart, sickle cell anemia, color blindness

5 Inheritance of chromosomes
Egg + sperm  zygote egg meiosis zygote mitosis & development fertilization sperm

6 Inheritance of genes On the chromosomes passed from Mom & Dad to offspring are genes may be same information may be different information eye color (blue or brown?) eye color (blue or brown?)

7 Effect of genes Genes come in different versions brown vs. blue eyes
brown vs. blonde hair alleles

8 Where did the blue eyes go??
Genes affect what you look like X bb BB Bb Bb Bb Bb Where did the blue eyes go??

9 Why did the blue eyes stay??
Genes affect what you look like… X bb Bb Bb Bb bb bb Why did the blue eyes stay??

10 Where did the blue eyes come from??
Genes affect what you look like… X Bb Bb BB or Bb BB or Bb BB or Bb bb Where did the blue eyes come from??

11 What did we show here? Genes come in “versions”
brown vs. blue eye color alleles Alleles are inherited separately from each parent brown & blue eye colors are separate & do not blend either have brown or blue eyes, not a blend Some alleles mask others brown eye color masked blue

12 How does this work? Paired chromosomes have same kind of genes
but may be different alleles eye color (blue?) eye color (brown?) hair color

13 In Class Assignment Hereditary Simulation Worksheet
Determining your genes worksheet

14 Homework History and Terminology worksheet

15 Punnett Crosses Lesson 2

16 Do Now Take out Homework from last night & begin looking over the questions for the video Where do your genes come from?

17 Traits are inherited as separate units
For each trait, an organism inherits 2 copies of a gene, 1 from each parent a diploid organism inherits 1 set of chromosomes from each parent diploid = 2 sets of chromosomes 1 from Mom homologous chromosomes 1 from Dad

18 Making gametes Remember meiosis! B BB BB = brown eyes bb = blues eyes
 brown is dominant over blue  blue is recessive to brown B b Bb Remember meiosis!

19 How do we say it? B BB 2 of the same Homozygous BB = brown eyes b
bb = blues eyes bb b homozygous dominant homozygous recessive Bb B b 2 different Heterozygous Bb = brown eyes

20 Punnett squares B b BB Bb B b Bb bb Bb x Bb X male / sperm
female / eggs Bb bb

21 Genetics vs. appearance
There can be a difference between how an organism looks & its genetics appearance or trait = phenotype brown eyes vs. blue eyes genetic makeup = genotype BB, Bb, bb 2 people can have the same appearance but have different genetics: BB vs Bb

22 Genetics vs. appearance
How were these brown eyes made? eye color (brown) eye color (brown) eye color (brown) eye color (blue) vs. BB B Bb B b

23 In class assignment Genetics Practice 1: Basic genetics

24 Homework Basics Punnett Squares

25 Penny Genetics Lesson 3 Lab Activity

26 Genetics & The Work of Mendel Lesson 4

27 Do Now BrainPop: heredity

28 Gregor Mendel The Founder of Genetics
An Austrian monk who lived over 100 years ago and studied how traits were passed from 1 generation to the next He did hundreds of experiments on thousands of pea plants in the monastery and used mathematical analysis to explain who heredity worked

29 Gregor Mendel Modern genetics began in the mid-1800s in an abbey garden, where a monk named Gregor Mendel documented inheritance in peas used good experimental design used mathematical analysis collected data & counted them excellent example of scientific method He studied at the University of Vienna from 1851 to 1853 where he was influenced by a physicist who encouraged experimentation and the application of mathematics to science and a botanist who aroused Mendel’s interest in the causes of variation in plants. After the university, Mendel taught at the Brunn Modern School and lived in the local monastery. The monks at this monastery had a long tradition of interest in the breeding of plants, including peas. Around 1857, Mendel began breeding garden peas to study inheritance. 29

30 Mendel’s work Bred pea plants ? cross-pollinate true breeding parents
Pollen transferred from white flower to stigma of purple flower Bred pea plants cross-pollinate true breeding parents raised seed & then observed traits allowed offspring to self-pollinate & observed next generation all purple flowers result P = parents F = filial generation self-pollinate ? 30

31 Mendel collected data for 7 pea traits

32 Looking closer at Mendel’s work
true-breeding purple-flower peas true-breeding white-flower peas X Parents 100% 1st generation (hybrids) purple-flower peas In a typical breeding experiment, Mendel would cross-pollinate (hybridize) two contrasting, true-breeding pea varieties. The true-breeding parents are the P generation and their hybrid offspring are the F1 generation. Mendel would then allow the F1 hybrids to self-pollinate to produce an F2 generation. self-pollinate 2nd generation 3:1 75% purple-flower peas 25% white-flower peas 32

33 What did Mendel’s findings mean?
Some traits mask others purple & white flower colors are separate traits that do not blend purple x white ≠ light purple purple masked white dominant allele functional protein affects characteristic masks other alleles recessive allele no noticeable effect allele makes a non-functioning protein I’ll speak for both of us! allele producing functional protein mutant allele malfunctioning protein homologous chromosomes 33

34 Genotype vs. phenotype Difference between how an organism “looks” & its genetics phenotype description of an organism’s trait genotype description of an organism’s genetic makeup F1 P X purple white all purple Explain Mendel’s results using …dominant & recessive …phenotype & genotype 34

35 PP pp Pp Making crosses x Can represent alleles as letters
flower color alleles  P or p true-breeding purple-flower peas  PP true-breeding white-flower peas  pp F1 P X purple white all purple PP x pp Pp 35

36 phenotype & genotype can have different ratios
Punnett squares Aaaaah, phenotype & genotype can have different ratios Pp x Pp 1st generation (hybrids) % genotype % phenotype P p male / sperm PP 25% 75% Pp 50% P p female / eggs PP Pp Pp Pp pp 25% 25% pp 1:2:1 3:1 36

37 Law of Segregation Two alleles in an individual will separate during gamete formation and act independently.

38 Law of Independent Assortment
Describes the relation between different genes. Ex. Plant Height and Color, if on different chromosomes can act independently during test crosses

39 Law of Independent Assortment

40 Linkage Alleles fail to assort independently because they are on the
same chromosome Recombination affects Linkage - The further apart the genes the more recombination

41 Linked Genes On the same chromosome = inherited together
ex: red hair/freckles (crossing over can “unlink” genes) Karyotype = photograph of chromosomes with camera attached to a microscope  paired up and # from largest to smallest Human karyotype = 22 pairs of perfectly matched chromosomes (autosomes) 1 pair of sex chromosomes XY (male) or XX (female)

42 Egg cells always have 22 autosomes + X
Sperm cells always have 22 autosomes + X or Y  sperm cells determines the sex of the organism Probability of having a boy or girl in pregnancy: 50% chance boy 50% chance girl

43 Inheritance Patterns Pedigrees – family tree depicting inheritance of a particular trait over several generations Males are indicated by squares, females by circles Individuals affected by trait are shaded while those unaffected are unshaded Carriers of the trait are half shaded

44 Pedigree

45 In class assignment Simple Genetics Practice Problems

46 Homework Complete simple genetics practice for homework

47 Gene Expression Lesson 5

48 Do Now Directed Reading Activity: Gene Expression

49 Environment effect on genes
Phenotype is controlled by both environment & genes Human skin color is influenced by both genetics & environmental conditions Coat color in arctic fox influenced by heat sensitive alleles The relative importance of genes & the environment in influencing human characteristics is a very old & hotly contested debate a single tree has leaves that vary in size, shape & color, depending on exposure to wind & sun for humans, nutrition influences height, exercise alters build, sun-tanning darkens the skin, and experience improves performance on intelligence tests even identical twins — genetic equals — accumulate phenotypic differences as a result of their unique experiences Color of Hydrangea flowers is influenced by soil pH 49

50 In class assignment Gene Expression

51 Homework Regents Practice Questions

52 Beyond Mendel’s Laws of Inheritance
Lesson 6 52

53 Do Now Gregor Mendel Video: Heredity

54 Extending Mendelian genetics
Mendel worked with a simple system peas are genetically simple most traits are controlled by single gene each gene has only 2 version 1 completely dominant (A) 1 recessive (a) But its usually not that simple! 54

55 Incomplete Dominance Both alleles contribute to produce a trait unlike either parent Ex: Japanese Morning Glory Red flowers White flowers RR X WW = RW (pink flowers) OR co-dominance – 2 dominant alleles expressed at the same time

56 Incomplete dominance Hybrids have “in-between” appearance RR WW RW
RR = red flowers rr = white flowers Rr = pink flowers make 50% less color RR WW RW RR Rr rr 56

57 Incomplete dominance P 1st 100% 1:2:1 2nd X true-breeding red flowers
white flowers 100% 100% pink flowers 1st generation (hybrids) self-pollinate 25% white 2nd generation 25% red 1:2:1 50% pink 57

58 Incomplete dominance RW x RW RR R W RW RR RW R W RW WW RW WW 25% 25%
genotype % phenotype RR 25% 25% R W male / sperm 50% 50% RW RR RW R W female / eggs RW WW 25% 25% RW WW 1:2:1 1:2:1 58

59 Incomplete Dominance Ex: Cattle color Reddish coat White Coat RR X WW
=RW (Roan – both colors expressed together)

60 Codominance Equal dominance human ABO blood groups 3 version
A, B, i A & B alleles are codominant both A & B alleles are dominant over i allele the genes code for different sugars on the surface of red blood cells “name tag” of red blood cell 60

61 Multiple Alleles ** More than 2 alleles for each gene Ex: Blood types:
A = IA B = IB O = i Type Genotype A IA IA or IA i B IB IB or IB i AB IA IB O ii

62 Genetics of Blood type A A A or A i B BB or B i AB O i i pheno-type
genotype antigen on RBC antibodies in blood donation status A A A or A i type A antigens on surface of RBC anti-B antibodies __ B BB or B i type B antigens on surface of RBC anti-A antibodies AB both type A & type B antigens on surface of RBC no antibodies universal recipient O i i no antigens on surface of RBC anti-A & anti-B antibodies universal donor 62

63 One gene: many effects The genes that we have covered so far affect only one trait But most genes are affect many traits 1 gene affects more than 1 trait dwarfism (achondroplasia) gigantism (acromegaly) The genes that we have covered so far affect only one phenotypic character, but most genes are pleiotropic 63

64 A trait may be determined by multiple genes
Combination of genes from both parents  Polygenic Inheritance ex: height, birth weight, IQ, skin color Unlike peas, that are either tall or short, human height has a variety of expression Bell curve of gene expression

65 Many genes: one trait Polygenic inheritance
additive effects of many genes humans skin color height weight eye color intelligence behaviors 65

66 Human skin color AaBbCc x AaBbCc can produce a wide range of shades
most children = intermediate skin color some can be very light & very dark 66

67 In class assignment Genetics Practice 3: Blood Types Genetics

68 Homework Co-dominance and incomplete dominance OR Genetics Practice 3
Mutliple Alleles

69 Sex-Linked Genetics Lesson 7

70 Do Now Review Genetics Practice 3 OR practice co dominance and incomplete dominance

71 Thomas Morgan Studied genetics by using the fruit fly (small, easily identified traits, breed quickly, large # of offspring) He found that some genes were carried on the X chromosomes (in humans also) They are sex-linked traits  Male only needs 1 of the alleles to have this trait

72 Human Disorders that are Sex-Linked
Hemophilia – (Queen Victoria line) defect in blood clotting so the person bleeds too much - usually found in males - must get the factor from X Muscular Dystrophy – destruction of muscle cells  gradual loss of function - usually found in males, die young

73 Human Disorders that are Sex-Linked
3. Color Blindness – can’t tell between red/green - more common in males Ex: Male (normal vision) Female carrier (has color blind gene) Passes from mother to son  Females are the carriers

74 In couples who have any genetic disorders – genetic counselors can make a chart from which they can predict the “odds” of having a child with a disorder

75 Genetics of sex Women & men are very different, but just a few genes create that difference In mammals = 2 sex chromosomes X & Y 2 X chromosomes = female: XX X & Y chromosome = male: XY X X X Y 75

76 Sex chromosomes 76

77 Sex-linked traits Sex chromosomes have other genes on them, too X X X
especially the X chromosome hemophilia in humans blood doesn’t clot Duchenne muscular dystrophy in humans loss of muscle control red-green color blindness see green & red as shades of grey X X Duchenne muscular dystrophy affects one in 3,500 males born in the United States. Affected individuals rarely live past their early 20s. This disorder is due to the absence of an X-linked gene for a key muscle protein, called dystrophin. The disease is characterized by a progressive weakening of the muscles and loss of coordination. X Y 77

78 Sex-linked traits XHY HH XHXh Hh x XHY Y XH XH Y XHXH XHXH XHY XHY XH
sex-linked recessive XHY HH XHXh Hh 2 normal parents, but mother is carrier x XHY Y XH XH Y male / sperm XHXH XHXH XHY XHY XH Xh female / eggs XHXh XH Xh XHXh XHXh XhY XhY 78

79 Dominant ≠ most common allele
Because an allele is dominant does not mean… it is better, or it is more common Polydactyly dominant allele 79

80 Polydactyly recessive allele far more common than dominant
individuals are born with extra fingers or toes the allele for >5 fingers/toes is DOMINANT & the allele for 5 digits is recessive recessive allele far more common than dominant  only 1 individual out of 500 has more than 5 fingers/toes  so 499 out of 500 people are homozygous recessive (aa) 80

81 In class assignment genetics_xlinked

82 Homework X-Linked Worksheet

83 Variations on a Human Face
Variations Lab

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