Exploring Mendelian Genetics

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Amanda Barker
6 years ago
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1 Exploring Mendelian Genetics

2 GENES are more complicated than Mendel thought ENVIRONMENT influences the. expression of genes = Nature vs Nurture Genes provide the plan for development, but how plan unfolds also depends on conditions. environmental

3 GENES are more complicated than Mendel thought Some traits have allele choices MORE than 2 = MULTIPLE ALLELE TRAIT EX: blood type A B O Allele choices

4 GENES are more complicated than MENDEL thought Some traits are determined by MORE THAN ONE GENE POLYGENIC TRAIT = EX: human height. intelligence, skin & eye color

5 GENES are more complicated than MENDEL thought Traits determined by have ONE gene MORE than phenotypes in-between many

6 GENES are more complicated than MENDEL thought KINDS OF DOMINANCE COMPLETE DOMINANCE INCOMPLETE DOMINANCE CO-DOMINANCE

7 COMPLETE DOMINANCE Dominant allele recessive the one masks PATTERN? Recessive allele returns in a ratio in the F 2 3:1 generation

8 INCOMPLETE DOMINANCE DON T SEE expected 3:1 ratio in F 2 generation Heterozygous organisms with one dominant and one recessive allele show a in-between trait BLENDED Image modified from:

9 CO-DOMINANCE BOTH traits are expressed at SAME TIME ( ) NO BLENDING in heterozygote A HORSE ROAN has BOTH RED hair and WHITE hair side by side

10 Chickens (Erminette expresses black and white feathers)

11 CO-DOMINANCE Both traits are expressed together (NO BLENDING) in heterozygote Persons with an A allele AND a B allele have blood type AB

12 REMEMBER Membrane proteins with attached that sugars help cells recognize self = GLYCOPROTEINS

13 BLOOD TYPES have more than 2 allele choices = MULTIPLE ALLELE TRAIT The pattern of sugars that is attached is determined by genes Allele choices are: A B O

14 BLOOD TYPES An A allele tells the cell to put A glycoproteins on its surface

15 BLOOD TYPES A B allele tells the cell to put a different B glycoprotein on its surface

16 BLOOD TYPES An O allele tells the cell NOT to put anything on the surface

17 A and B are CO-DOMINANT A cell with BOTH an A and a B allele has BOTH A and B glycoproteins on its surface

18 BLOOD TYPES & ALLELES GENOTYPE I A I A I A i I B I B I B i ii I A I B PHENOTYPE (BLOOD TYPE) A A B B O AB

19 DONOR BLOOD A and AB see A as like me Body images modified from: B and O see A as Different! IMMUNE SYSTEM ATTACKS!

20 DONOR BLOOD B and AB see B as like me Body images modified from: A and O see B as Different! IMMUNE SYSTEM ATTACKS!

21 DONOR BLOOD O can donate to EVERY BLOOD TYPE = UNIVERSAL DONOR Nothing on surface to recognize as NOT SELF YOU DON T HAVE ANYTHING I DON T HAVE! Body images modified from:

22 DONOR BLOOD Only AB sees AB as like me Body images modified from: A, B, and O see AB as Different! IMMUNE SYSTEM ATTACKS!

23 AB can only GIVE to AB BUT... Body image modified from: AB can RECEIVE FROM EVERY BLOOD TYPE = UNIVERSAL RECIPIENT

24 BLOOD TYPE FREQUENCY IN USA A 40% B 10% AB 4% O 46%

25 ABO SYSTEM is NOT THE ONLY ONE Rh + Rh -

26 OTHER BLOOD TYPES NO PROBLEMS IF: MOM is & BABY is Image modified from: Rh + MOM is Rh + Rh + & BABY is Rh -

27 Can be a PROBLEM IF: Mom is Rh - Baby is Rh+ 1 st baby OK but few baby cells entering mom s bloodstream put mom s immune system on alert for + cells. Next + baby, mom s immune system can attack baby as it is growing Image modified from: Mom given shot after 1 st birth prevents this

28 Sex-Linked Traits Characteristics that are inherited from genes found on the sex chromosomes. Sex Determination Females XX Males XY Almost all sex-linked traits are found on the X chromosome Y chromosome contains very few genes and is mainly involved in sex determination

29 Sex-linked It is possible for a female to be a carrier of an X-linked trait, but not express it Men will express all X-linked traits they inherit

30 Example: Color Blindness Various tests for color blindness.

31 Example- Hemophilia

32 A high incidence of hemophilia has plagued the royal families of Europe Was the down fall to the Royal families -Queen Victoria) Russia s last Czar

33 The Last Czar

34 Sex-influenced traits characteristic may appear in both sexes but expression of the phenotype differs. Example: Early balding (pattern baldness) in humans. Heterozygous men (b+/b) lose their hair; heteroyzgous women do not have significant hair loss. Homozygous men or women (b/b) become bald. The trait is therefore dominant in men, recessive in women. (We used b to designate the mutant baldness allele even though the allele is dominant in males.)

35 Sex-influenced

36 Variations on Mendel s Principles Codominance, multiple alleles Pleiotropy (control of more than one phenotypic characterisitic by a single gene) Polygenic traits (trait controlled by 2 or more genes) Sex-linked genes Environmental effects (Epigenetics)

Exploring Mendelian Genetics 11-3

Exploring Mendelian Genetics 11- GENES are more complicated than Mendel thought Some traits have MORE than 2 allele choices = MULTIPLE ALLELE TRAIT http://www.eslkidstuff.com/images/tallshort.gif EX: blood