LESSON-1_MENDELIAN-GENETICS.pdhshsjsksjjdjd

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1. MENDELIAN GENETICS
L A W S OF INHERITANCE
BIO 170: FUNDAMENTALS OF GENETICS| JAZZLYN T. IMPERIAL, MSc

2. 3
5
TOPIC
OUTLINE
1 ALL ABOUT MENDEL
6 TRIHYBRID CROSS
2 MENDEL’S EXPERIMENTS
MONOHYBRID CROSS
4 MODERN GENETICS TERMINOLOGIES
DIHYBRID CROSS
FUNDAMENTALS OF GENETICS| BIO 170 3

3. WHO IS MENDEL?
(1822-1884)
FATHEROFGENETICS

4. Gregor
THE FATHER OF GENETICS
1Austrian monk
scientist, Augustinian friar and abbot
2Studied the inheritance of traits in pea plants
cultivated and tested some 28,000 pea plants
3Developed the laws of inheritance
Law of Dominance Segregation and Independent Assortment
4Stated that physical traits are inherited as “particles”
Chromosomes and DNA
FUNDAMENTALS OF GENETICS| BIO 170
https://commons.wikimedia.org/wiki/File:Gregor_Mendel_Monk.jpg

5. MENDEL’S EXPERIMENT
HYBRIDIZATION EXPERIMENT
Pisumsativum

6. FUNDAMENTALS OF GENETICS| BIO 170 7
PATTERNS OF INHERITANCE
EASY TO GROW AND HYBRIDIZE
ARTIFICIALLY
SELF-FERTILIZING IN NATURE
EASY TO CROSS-BREED
EXPERIMENTALLY
SEVEN VISIBLE FEATURES
GARDEN PEA
Why Pisum sativum?
https://www.amazon.com/Sativum-Vegetable-Organic-Planting-Delicious/dp/B076T3TH2V

7. WHAT
DO THE
PEAS
LOOK
LIKE?

8. HOW MENDEL BEGAN
FUNDAMENTALS OF GENETICS| BIO 170
Mendel produced
pure strains by
allowing the plants
to self-pollinate
for several
generations

9. Self Pollination vs
Cross Pollination
FUNDAMENTALS OF GENETICS| BIO 170
http://www.differencebetween.net/science/difference-between-self-and-cross-pollination/

10. Seven Pairs of Contrasting
FUNDAMENTALS OF GENETICS| BIO 170
Mendel’s Experimental Results

11. F
1 generation • first-generation offspring in a breeding
experiment. (1
st
filial generation)
• From breeding individuals from the P1
generation
Generation
FUNDAMENTALS OF GENETICS| BIO 170
SOME TERMS
Parental P
Generation the parental generation in a
breeding experiment
F
2 generation
• second-generation offspring in a
breeding experiment.
(2nd filial generation)
•From breeding individuals from
the F1 generation

12. Following the Generations
Cross 2 Pure
Plants
TT x tt
Results in all
Hybrids
Tt
Cross 2 Hybrids
get
3 Tall & 1 Short
TT, Tt, tt
FUNDAMENTALS OF GENETICS| BIO 170

13. 1
2
3
4
5
FUNDAMENTALS OF GENETICS| BIO 170
PHENOTYPE
ALLELES
physical expression of a trait of
the individual
alternative forms of a single gene
that determines the phenotype
GENOTYPE
designates the genetic makeup
of an individual for the trait or
traits it describes, whether the
individual is haploid or diploid
HOMOZYGOUS
When both alleles are the same
(DD or dd)
HETEROZYGOUS
when the alleles are
different (Dd)
Modern

14. GENE-sectionsofDNAthatcodefora
specifictrait
-Geneinteraction
ALLELES–Differentformsofthesame
gene
•DominantAllele
•RecessiveAllele
Gene specifies the trait, alleles specify the gene that takes

15. GENOTYPE
•The gene pair
an individual
carries for a
particular
trait
symbolized
with a pair of
letters. (TT ,
Tt, tt)
PHENOTYPE
•The
observable
trait of an
individual
based on its
genotype.
(Tall , short)

16. 01
02
03
RulesinwritingALLELES
FUNDAMENTALSOF GENETICS|BIO170
ACCORDINGTOCONVENTION…
✓thefirstletteroftherecessive
traitsymbolizesthe characterin
question
✓inlowercaseitalic, itdesignatesthe
allelefortherecessivetrait
✓inuppercaseitalic,itdesignates
thealleleforthedominanttrait
PlantHeight
Tall
dwarf

17. MONOHYBRIDCROSS
Revealshowonetraitistransmittedfromgeneration
togeneration

18. PunnettSquare
Used tohelp
solvegenetics
problems
Reginald
Punnett
Vertical
column
represent
female
Horizontal
rowsrepresent
males

19. PunnettSquare

20. MONOHYBRIDCROSS
FUNDAMENTALSOF GENETICS|BIO170
Madebymating true-
breedingindividuals
fromtwoparent
strains,each
exhibitingoneofthe
twocontrastingforms
ofthecharacterunder
study

21. P
1MONOHYBRIDCROSS
ww
WWwWw
WWwWw
:Ww
:Round
:100% Ww or4:0Ww
:100%Roundor4:0Round
Trait: SeedShape
Alleles:W–Roundw–Wrinkled
Cross: RoundseedsxWrinkledseeds
WW x ww
Genotype
Phenotype
GenotypicRatio
PhenotypicRatio

22. P
1MONOHYBRIDCROSSREVIEW
HomozygousdominantxHomozygousrecessive
OffspringallHeterozygous(hybrids)
OffspringcalledF
1generation
Genotypic&PhenotypicratioisALLALIKE

23. F
1MONOHYBRIDCROSS
SeedShape
W–Roundw–Wrinkled
Trait:
Alleles:
Cross:Roundseeds
Ww x
xRoundseeds
Ww
W w
WWWWw
wWwww
WW, Ww, ww
Round&wrinkled
1WW:2Ww:1ww
3round:1wrinkled
Genotype:
Phenotype:
GenotypicRatio:
PhenotypicRatio:

24. F
1MONOHYBRIDCROSSREVIEW
Heterozygousxheterozygous
Offspring:
•25%HomozygousdominantRR
•50%HeterozygousRr
•25%HomozygousRecessiverr
OffspringcalledF
2generation
Genotypicratiois1:2:1
PhenotypicRatiois3:1
https://www.thoughtco.com/homozygous-a-genetics-definition-373470

25. F
2MONOHYBRIDCROSS(1
ST)
SeedShape
W–Round w–Wrinkled
Trait:
Alleles:
Cross:Roundseeds x Roundseeds
WW x Ww
W w
WWWWw
WWWWw
WW,Ww
Round
1WW:1Wwor1:1
AllRound(100%or4:0)
Genotype:
Phenotype:
GenotypicRatio:
PhenotypicRatio:

26. F
2MONOHYBRIDCROSS(2
ND)
SeedShape
W–Round w–Wrinkled
Trait:
Alleles:
Cross: Wrinkledseedsx
wwx
Roundseeds
Ww
Ww, ww
Round&Wrinkled
1Ww:1wwor1:1
1round:1wrinkled or1:1
Genotype:
Phenotype:
GenotypicRatio:
PhenotypicRatio:
W w
wWwww
wWwww

27. F
2MONOHYBRIDCROSSREVIEW
Offspring:
•50%HomozygousWWorww
•50%HeterozygousWw
Homozygousxheterozygous(hybrid)
PhenotypicRatiois1:1
CalledTestCrossbecausetheoffspringhaveSAMEgenotypeas
parents

29. MENDEL’S
FUNDAMENTALSOF GENETICS|BIO170
RESULTSOFMONOHYBRID CROSSES
1.UNIT FACTORSINPAIRS
Geneticcharactersarecontrolledbyunitfactorsexistinginpairs
inindividualorganisms.
2.DOMINANCE/RECESSIVENESS
Whentwounlikeunitfactorsresponsiblefor asinglecharacterare
presentinasingleindividual,oneunitfactorisdominanttotheother,
whichissaidto berecessive.
3.SEGREGATION
Duringtheformationofgametes,thepairedunit factorsseparate,or
segregate,randomlysothateachgametereceivesoneortheother
withequallikelihood.

30. LAWOFDOMINANCE
https://gfycat.com/ringedaccurateamericanratsnake-hortensia-jimenez-diaz-tededucation

31. APPLYINGTHELAWOFSEGREGATION
18

32. DIHYBRIDCROSS
Crossinvolvingtwopairsofcontrastingtraits
TWO-FACTORCROSS
FUNDAMENTALSOF GENETICS|BIO170

33. INDEPENDENTASSORTMENT
FUNDAMENTALSOF GENETICS|BIO170 32
MENDEL’SFOURTHPOSTULATE
Duringgameteformation,segregating pairsofunitfactors
assortindependentlyofeachother
Foronepair whicheverunitfactorisreceiveddoesnot
influence theoutcomeofsegregationof any otherpair
Allpossiblecombinationsof gametesshould be
formed

34. DIHYBRIDCROSS
Abreedingexperimentthattracksthe
inheritanceoftwotraits.
Mendel’s“LawofIndependent
Assortment”
•a.Eachpairofallelessegregatesindependently
duringgameteformation
•b.Formula:2
n
(n=#ofheterozygotes)
FUNDAMENTALSOF GENETICS|BIO170

35. •Howmanygameteswillbeproducedforthe
followingallelearrangements?Question:
(n =#ofheterozygotes)Remember:2
n
1.RrYy
2.AaBbCCDd
3.MmNnOoPPQQRrssTtQq
FUNDAMENTALSOF GENETICS|BIO170

36. ANSWER:(n=#ofheterozygotes)
1.RrYy:2
n=2
2=4gametes
RY RyrYry
ABCDABCdAbCDAbCd
aBCDaBCdabCDabCD
3.MmNnOoPPQQRrssTtQq: 2
n=2
6=64gametes
FUNDAMENTALSOF GENETICS|BIO170
2. AaBbCCDd: 2
n=2
3=8gametes

37. Traits:
DIHYBRIDCROSS
Seedshape&Seedcolor
Alleles: Wround Gyellow
wwrinkled ggreen
WwGgxWwGg
Allpossiblegametecombinations
WGWgwGwg WG Wg wGwg

38. DIHYBRIDCROSS
WG Wg wG wg
WG
Wg
wG
wg
WWGG WWGg WwGG WwGg
WWGg WWgg WwGg Wwgg
WwGG WwGg wwGG wwGg
WwGg Wwgg wwGg wwgg
Round/Yellow:9
Round/green:3
wrinkled/Yellow:3
wrinkled/green:1
Phenotypicratio:
9:3:3:1

39. DIHYBRIDCROSS
Klug,W illiamS.,Cummings,MichaelR.ConceptsofGenetics.11
thEdition.
PearsonEducation,Li m i ted.2016.

40. COMPUTATIONOF
COMBINEDPROBABILITIES
G g
GGGGg
gGggg
W w
WWwWw
wWwww
PR:¾yellow:¼green
PR:¾round:¼wrinkled

41. DIHYBRIDCROSS
Klug,W illiamS.,Cummings,MichaelR.ConceptsofGenetics.11
thEdition.
PearsonEducation,Li m i ted.2016.

42. TESTCROSS:TWOCHARACTERS
Ifindependentassortment
occurs,theF1individual
(RrYy)produces4different
gametesinequalfrequencies
Thiscanbe testedwitha
dihybridtestcross:
RrYyxrryy
FUNDAMENTALSOF GENETICS|BIO170

43. Exercise:
In rabbits, gray hair is dominant to white hair.
Also, black eyes are dominant to red. Identify the
phenotypic ratio and genotypic ratio of the
cross WWrrx wwRr.
½ WwRrgray hair, black eyes
½ Wwrrgray hair, red eyes

44. TRIHYBRIDCROSS
Threepairsofcontrastingtraits
THREE-FACTORCROSS
FUNDAMENTALSOF GENETICS|BIO170

45. TRIHYBRIDGAMETEFORMATION
Klug,W illiamS.,Cummings,MichaelR.ConceptsofGenetics.11
thEdition.
PearsonEducation,Li m i ted.2016.
Remember:
n=#ofheterozygotes
FUNDAMENTALSOF GENETICS|BIO170
P1gametes:n=0
2
0=1
F1gametes:n=3
2
3=8

46. FORKED-LINEMETHOD
Klug,W illiamS.,Cummings,MichaelR.ConceptsofGenetics.11
thEdition.
PearsonEducation,Li m i ted.2016.
FUNDAMENTALSOF GENETICS|BIO170

47. FORKED-LINEMETHOD
46https://courses.lumenlearning.com/bccc-bio101/chapter/laws-of-inheritance/

48. FORKED-LINEMETHOD:
WwGgDdxWwGGDD
Where:
W–Roundw–wrinkled
G–Yellowg–green
D–Talld-dwarf
¼WW
½GG
½Gg
½Ww
½GG
½Gg
¼ww
½GG
½Gg
1/16WWGGDd
1/16WWGgDD
½DD1/16WWGGDD
½Dd
½DD
½Dd1/16WWGgDd
½DD1/8WwGGDD
½Dd1/8WwGGDd
½DD1/8WwGgDD
½Dd1/8WwGgDd
½DD1/16wwGGDD
½Dd
½DD
½Dd
1/16wwGGDd
1/16wwGgDD
1/16wwGgDd
12/16
or3/4
Round,
Yellow,
Tall
4/16or
1/4
Wrinkled,
Yellow,
Tall

49. ANOTHERWAYOFGETTINGPHENOTYPICRATIO
W w
WWWWw
wWw ww
WwGgDdxWwGgDd Where:W–Roundw–wrinkled;G–Yellowg–green;D–Tallt-dwarf
PR:¾Round:¼wrinkled
G g
G GG Gg
g Gg gg
D d
D DDDd
d Dddd
PR:¾Tall:¼dwarf
PROBABILITYOFGETTING:
•Round,YellowandTall?
•Round,green anddwarf?
PR:¾Yellow:¼green
=3/64Round,greern&dwarf
¾X¼X¼
=27/64Round,Yellow&Tall
¾X¾X¾

50. PRACTICE:CROSSRrYyxRrYy
Amongoffspring:
•pr(R_)
•pr(rr)
•pr(Y_)
•pr(yy)
=3/4
=1/4
=3/4
=1/4
Ifthegenesassortindependentlythenwecanaskwhat
proportionoftheoffspringareexpectedtobeR_Y_?
FUNDAMENTALSOF GENETICS|BIO170
pr(R_Y_) =pr(R_)Xpr(Y_)=3/4X3/4=9/16R_Y_

51. PRACTICE:CROSSRrYyx RrYy
Foralltheothertypesseenfromthiscross:
•pr(R_yy)=pr(R_)xpr(yy)=3/4x1/4=3/16
•pr(rrY_)=pr(rr)xpr(Y_)=1/4x 3/4=3/16
•pr(rryy)=pr(rr)x pr(yy) =1/4x1/4=1/16
Theindependentbehaviorofgenesisthebasisfor
the9:3:3:1ratio
FUNDAMENTALSOF GENETICS|BIO170

52. Independentassortmentofgenescanbeextendedtomorethantwogenes:
FUNDAMENTALSOF GENETICS|BIO170
foreachgene:
✓pr(A_)=3/4,pr(aa)=1/4,pr(AA)=1/4,pr(Aa)=1/2
✓pr(B_)=3/4,pr(bb)=1/4,pr(BB)=1/4,pr(Bb)=1/2
✓pr(C_)=3/4,pr(cc)=1/4,pr(CC)=1/4,pr(Cc)=1/2
✓pr(D_)=1/2,pr(dd)=1/2,pr(Dd)=1/2,pr(DD)=0
MORE PRACTICE:
Cross AaBbCcDdx AaBbCcDd

53. Independentassortmentofgenescanbeextendedtomorethantwogenes:
FUNDAMENTALSOF GENETICS|BIO170
foreachgene:
✓pr(A_)=3/4,pr(aa)=1/4,pr(AA)=1/4,pr(Aa)=1/2
✓pr(B_)=3/4,pr(bb)=1/4,pr(BB)=1/4,pr(Bb)=1/2
✓pr(C_)=3/4,pr(cc)=1/4,pr(CC)=1/4,pr(Cc)=1/2
✓pr(D_)=1/2,pr(dd)=1/2,pr(Dd)=1/2,pr(DD)=0
MORE PRACTICE:
Cross AaBbCcDdx AaBbCcdd

54. Ifthegenesassortindependently,whatproportionshouldbe:
FUNDAMENTALSOF GENETICS|BIO170
•pr(A_)Xpr(B_)Xpr(C_)=¾X¾X¾=27/64
•pr(A_)Xpr(B_)Xpr(cc)=¾X¾X¼=9/64
•pr(A_)Xpr(B_)Xpr(C_)Xpr(dd)=¾X¾X¾X½
= 27/128
A_B_C_?
A_B_cc?
A_B_C_dd?
MORE PRACTICE:
Cross AaBbCcDdx AaBbCcdd

55. 60
https://www.pinterest.ph/pin/313774299026309088/