EXAM IS POSTPONED. ttpp. TtPp TTPP EXAM TWO WILL TAKE PLACE. Monday Feb 26th. (TTPP) (TTPp) (TTpp) (TtPp) (TtPP) (TtPp) (Ttpp) (ttpp) (ttpp) (ttpp)

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1 EXM IS OSONED RUE BREEDIN F1 (all all-urple) F2 (9:3:3:1 ratio) (9 all-urple) EXM WO WILL KE LE Short white flower Monday Feb 26th (3 all-white) (3 Short-urple) all urple Flowers (1 Short-White) generation ametes F1 generation F1 (all all-urple) MEES tp () p t (¼*¼) (¼*¼)+ (¼*¼) (¼*¼) () (p) (pp) () p t F2 (¼*¼)+ (¼*¼) (¼*¼)+(¼*¼)+(¼*¼) (¼*¼)+ (¼*¼) (¼*¼) (¼*¼)+ (¼*¼) (¼*¼) (t) () (p) (tt) (t) (tp) 1

2 p t erminology p t enotype the genes possesed by an indiviual (i.e. pp or t) p t p t pp tall-white p tall-white tt short-purple t short-purple p tall-white t short-purple tp short-white 9 : 3 tall-white: 3 short-purple: 1short-white henotype he appearance or form of the individual (i.e. all and white flowered or short and purple flowered) Monohybrid cross where only one trait is being studies or observed ( a tall plant crossed with a short plant) Dihybrid cross where two traits are being studied or observed ( a tall purple flowered plant crossed with a short white flowered plant) erminology ene alocation on a chromosome that codes for one trait llele alternate forms of a gene Homozygous both alleles are of the same type (i.e. tt or or pp) Heterozygous the two alleles are of different types (i.e. t or Dominant an allele that is expressed when only one copy is present Recessive an allele that is masked when present in the prsence of the dominant allele Independent ssortment all eas rossed With Short eas x tt t (all tall) txt ¾tall, ¼Short urple eas rossed White eas x pp ll purple p x p ¾ purple, ¼ white all, urple peas crossed with Short, White peas x tp (ll tall & purple) x 9/16 tall purple, 3/16 tall white, 3/16 short purple, 1/16 short white MEES -, p, t, robablities 0.5 x 0.5 =

3 Meiosis and Mendel s Laws Each cell contains chromosomes. here are two types of chromosomes: Homologous and nalogous here are pairs of homologous chromosomes Homologous hromosomes Segregate during metaphase I nalogous chromosomes Independently ssort during metaphase II Mendel s heory Law of Independent ssortment Each pair of alleles segregate independently of other alleles ll possible combination of factors are possible OS MENDEL ENEIS hromosome segregate and assort like alleles. hromosomes contain DN Sequence of base pairs in DN creates alleles Definition of Some erms ene a locus (site) on a chromosomes that codes for a given trait. llele lternate forms of a gene amete a reproductive cell that contains ½ the normal number chromosmes (egg or sperm) Zygote the cell formed by the fusion of two gametes 3

4 Examples and redictions x tt t tx t ¼, ½t, ¼tt= ¾tall ¼short x t? ttx t? Mendel s heory Law of Independent ssortment Each pair of alleles (gene) segregate independently of other alleles ll possible combination of factors are possible Natural Selection and Inheritance ssumed parental traits passed to offspring. How? ssumed near infinite amount of variations. What was the source of variation? Meiosis and Mendel s Laws Each cell contains chromosomes. here are two types of chromosomes: Homologous and nalogous here are pairs of homologous chromosomes Homologous hromosomes Segregate during metaphase I nalogous chromosomes Independently ssort during metaphase II 4

5 DN as enetic Material enes are composed of sequences of DN Each genes located at a specific location of a chromosome. Different sequence of base pairs results in different alleles Mutation can change the sequence enes code for proteins DN DN hosphate + sugar forms chain Nitrogenous bases onnect chains Four Forms denine, hymine, uanine, ytosine always binds always bind 5

6 Semiconservative Replication Replication of DN such that each new strand consists of ½ an old strand he old strand is used to as a template to derive a new strand he new strand will be complimentary to the old. 6

7 enes are sequences of DN DN coils in at several levels form chromosomes enes are a sequences of DN located at specific locations on chromosomes DN as enetic Material enes are composed of sequences of DN Each genes located at a specific location of a chromosome. Different sequence of base pairs results in different alleles Mutation can change the sequence enes code for proteins Dominance omplete (Full) the dominant allele is always expressed if present Incomplete dominance all x Short may result in intermediate height 7

8 olygenic Inheritance For many traits more than one gene contributes to the phenotype. Multiple genes may result in many possible phenotypes. onsider three genes,b, each of which can have two alleles. Height - nalogy hree gene example aabbcc, abbcc, abbcc, abbc, BBc, BB 1/64 =aabbcc = Very Short 7/64 = abbcc = Short 14/64 = abbcc = Short - Medium 20/64 = abbc = Medium 14/64 = Bbc = Medium-all 7/64 = BBc = all 1/64= BB = Very all 8