16 biology 1-30-08 mendelian genetics-dom-reces-exceptions-punnett squares

8/9/2019 16 Biology 1-30-08 Mendelian Genetics-Dom-Reces-Exceptions-Punnett Squares

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Mendel’s Principle of

Dominance or Recessiveness

Traits found in humans



Engage Map of X and Y Chromosomes



Explore 1 undamentall! "enetics

You and !our groups #ill $e loo%ing at each

other to determine #hether !ou are dominant

or recessive for the follo#ing traits&



Tongue Rolling



Earlo$es



Ear$ump 'ften called Dar#in’s Ear (ump

Dominant ) *aving a small $ump on theear

Recessive ) +ot having the $ump



*itchhi%er’s Thum$



Pol!dact!l!



-!ndact!l! eet



-!ndact!l! *ands



-evere -!ndact!l!



-!ndact!l! -urger!



Cleft Chin



Cloc%#ise *air ,horl



.utosomal Dominant and Recessive *untington Disease / Dominant Disease

C!stic i$rosis / Recessive Disease

-ic%le Cell .nemia

Ta!)-ach’s

P0



Explore 2 (ugs3 (ugs3 (ugs

"enes for traits are encoded and arranged linearl! on

structures called chromosomes found in the nuclei ofmost cells& ,hen organisms reproduce3 the resulting

offspring should receive an e4ual num$er of

chromosomes from the mother and the father&

5n this activit! !ou use the chromosomes and (ugTraits 0e! to determine the genot!pe and phenot!pe

of the offspring&



Exploration 6 Wisconsin Fast Plant Genetics Lab



Explore 7 Punnett -4uares

You #ill $e a$le to predict the outcomes of

crosses $! completing this next activit!&



Mendel &

The Gene Idea

Explain



Mendel and "enetics .ns#er the follo#ing 4uestions as #e

explain the concepts surrounding $asic

genetic



5t .ll (egan #ith Mendel 8Y59 "regor Mendel #as $orn in 1:22& Called the ;ather of "enetics<

=ate 1:>> chromosomes and the process of

meiosis #ere un%no#n& Mendel’s #or% #as considered o$scure and

unimportant until 1?>>

,alter -utton proposed the Chromosome Theor!

and people $egan to listen to his ideas& Chromosome Theor! / specific genes are

located on specific chromosomes



Three Conclusions to *is Research1& Principle of Dominance and

Recessiveness'ne allele in a pair ma! mas% the effect of

the other

2& Principle of -egregation

The t#o alleles for a characteristic separateduring the formation of eggs and sperm

6& Principle of 5ndependent

.ssortmentThe alleles for different characteristics are

distri$uted to reproductive cellsindependentl!&



Mendelian genetics Character

8herita$le feature3 i&e&3 fur color9

Trait

8variant for a character3 i&e&3 $ro#n9 True-bred

8all offspring of same variet!9

Hybridization

8crossing of 2 different true)$reds9

P generation 8parents9

F1 generation 8first filial generation9



"enetic voca$ular!@@& Punnett square: Gene: point on a chromosome

that controls the trait AlleleA an alternate form of a gene

A or a Hoozygous: identical alleles

for a character Heterozygous: different alleles

for a gene Phenoty!e: ph!sical traits

Genoty!e: genetic ma%eup Testcross: $reeding of a

recessive homoB!gote X dominate phenot!pe 8$ut un%no#ngenot!pe9



($ X ($Phenot!pic Ratio

6A1"enot!pic Ratio

1A2A1 B b

B

b

B B B b

b B b b



($Tt x ($Tt(T (t $T $t

(T ((TT ((Tt ($TT ($Tt

(t ((Tt ((tt ($Tt ($tt

$T ($TT ($Tt $ $TT $$Tt

$t ($Tt ($tt $$Tt $$tt



Exceptions to Mendel’s Rule



5ncomplete Dominance The phenot!pe of the

heteroB!gote is

intermediate $et#eenthose of the t#o

homoB!gotes&

Ex9 -nap DragonColor

Red3 Pin%3 ,hite



Multiple .lleles Ex 9(lood t!pe

(lood t!pe . and ( are co-doinant3#hile ' is recessi+e&

orms possi$le $lood t!pes of .3 (3 .(3and '&



(lood .lso -ho#s Codominance



-ex)Determination Chromosome pairs 1)22 are autosoes

Chromosome pair 26 are se chroosoes

The! determine the sex of an individual

XX female XY male



E=.('R.T5'+ 1

Exceptions to the Rule

Punnet -4uaresA Dih!$rid3 -ex)=in%ed3Multiple .lleles3 Co)Dominance35ncomplete Dominance



Ela$oration 2 ,ho’s the Parents

pon completion of this la$3 !ou #illA determine the .(' $lood t!pes of t#o sets of

parents and t#o ne#$orn children

examine the genetic relationships possi$le

$et#een the parents and children

match the ;mixed up< children #ith their proper

parents&

16 biology 1-30-08 mendelian genetics-dom-reces-exceptions-punnett squares

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