biology-class-12-unit-05-chapter-05-genetics-evolution-principles-of-inheritancevariation-l-5-7-kvzunjrvlg0

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritancevariation L-5 </Success>
### <primary style="font-size:24px"> XX/XY sex-determination system </primary>
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- Female & Male

- X Chromosome

- Y Chromosome

- Sex Chromosome

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<footer style = "font-size: 18px">Genetic evolution $\rightarrow$ Sex determination in humans $\rightarrow$ <span style = "color:blue"> XX/XY sex-determination system </span> $\rightarrow$ Gamete formation $\rightarrow$ Fusion of gametes </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritancevariation L-5 </Success>
### <primary style="font-size:24px"> Gamete formation & fertilisation </primary>
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* Male produces A+X & A+0 gametes    
 
* Male heterogamy    
 
* Female produces A+X gametes only    
 
* Female is homogametic     
 
* A+X sperm fuses with A+X ovum,the progeny is-AA+XX Female   
 
* A+0 sperm fuses with A+X ovum the progeny is -- Male

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![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-05-genetics-evolution-principles-of-inheritancevariation-l-5_7-kvzunjrvlg0-07.jpg)

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<footer style = "font-size: 18px">XX-XO mechanism $\rightarrow$ XO system of sex-determination $\rightarrow$ <span style = "color:blue"> Gamete formation & fertilisation </span> $\rightarrow$ ZZ-ZW mechanism $\rightarrow$ Gamete formation & fertilisation </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritancevariation L-5 </Success>
### <primary style="font-size:24px"> ZZ-ZO mechanism </primary>
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- Seen in certain butterflies
 
- Female is heterogametic- produces two types of gametes-A+z & A+0

- Male is homogametic - produces A+Z type sperms only    
 
- A+Z sperm fuses with A+Z ovum, the progeny is AA+ZZ- Male    
 
- A+Z sperm fuses with A+0 ovum, progeny is Female

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![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-05-genetics-evolution-principles-of-inheritancevariation-l-5_7-kvzunjrvlg0-11.jpg)

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<footer style = "font-size: 18px">Gamete formation & fertilisation $\rightarrow$ Sex determination in chickens $\rightarrow$ <span style = "color:blue"> ZZ-ZO mechanism </span> $\rightarrow$ Haplodiploidy mechanism $\rightarrow$ Sex determination in honey bees </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritancevariation L-5 </Success>
### <primary style="font-size:24px"> Haplodiploidy mechanism </primary>
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- Seen in bees, wasps,saw flies,ants   
 
- Unfertilised egg developes into - male  
 
- Fertilised egg developes into female   
 
- Female is diploid (2n)   
 
- Male is haploid (n)   
 
- Sperms are produced by mitosis   
 
- Ovum is produced by meiosis    
 
- Here sex is determined by number of set of chromosomes

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![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-05-genetics-evolution-principles-of-inheritancevariation-l-5_7-kvzunjrvlg0-12.jpg)

![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-05-genetics-evolution-principles-of-inheritancevariation-l-5_7-kvzunjrvlg0-13.jpg)

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<footer style = "font-size: 18px">Sex determination in chickens $\rightarrow$ ZZ-ZO mechanism $\rightarrow$ <span style = "color:blue"> Haplodiploidy mechanism </span> $\rightarrow$ Sex determination in honey bees $\rightarrow$ Haplodiploidy mechanism </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritancevariation L-5 </Success>
### <primary style="font-size:24px"> Haplodiploidy mechanism </primary>
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- diploid female bee(meiosis)$\rightarrow$ eggs $\rightarrow$ no fertilisation $\rightarrow$haplodid female bee

- diploid female bee(meiosis)$\rightarrow$ eggs $\rightarrow$fertilisation $\rightarrow$diploid male bees

- haplodid male bees(no meiosis)$\rightarrow$ sperms $\rightarrow$ fertilisation $\rightarrow$daplodid female bee

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<footer style = "font-size: 18px">Haplodiploidy mechanism $\rightarrow$ Sex determination in honey bees $\rightarrow$ <span style = "color:blue"> Haplodiploidy mechanism </span> $\rightarrow$ Haplodiploidy mechanism $\rightarrow$ Haplodiploidy mechanism </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritancevariation L-5 </Success>
### <primary style="font-size:24px"> Polygenic inheritance </primary>
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- It is also known as quantitative inheritance or multiple genic inheritance or cumulative gene effect   
 
- A character is controlled by many genes

- **Eg:**Skin colour in human, height in individual, hair colour, weight, intelligence, milk production in cattle, egg laying in chicken, etc

- A character controlled by many genes is known as polygenic character    
 
- Each dominant gene shows additive effect or cumulative effect in the production of the phenotype

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![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-05-genetics-evolution-principles-of-inheritancevariation-l-5_7-kvzunjrvlg0-21.jpg)
![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-05-genetics-evolution-principles-of-inheritancevariation-l-5_7-kvzunjrvlg0-22.jpg)

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<footer style = "font-size: 18px">Pleiotropy $\rightarrow$ Pleiotropy $\rightarrow$ <span style = "color:blue"> Polygenic inheritance </span> $\rightarrow$ Human skin colour $\rightarrow$ Human skin colour </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritancevariation L-5 </Success>
### <primary style="font-size:24px"> Human skin colour </primary>
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- The skin colour ranges from pure black (negro) to pure white with so many gradations.

- Pure black or negro :  1/64
- Very dark brown :      6/64
- Dark brown :           15/64
- Mulatto :              20/64
- Light brown :          15/64
- Very light brown :     6/64
- Pure white :           1/64

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![image](/subject-images/iitpal/image/biology-class-12-unit-05-chapter-05-genetics-evolution-principles-of-inheritancevariation-l-5_7-kvzunjrvlg0-27.jpg)

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<footer style = "font-size: 18px">Human skin colour $\rightarrow$ Human skin colour $\rightarrow$ <span style = "color:blue"> Human skin colour </span> $\rightarrow$ Human skin colour $\rightarrow$ Human skin colour </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritancevariation L-5 </Success>
### <primary style="font-size:24px"> Human skin colour </primary>
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<footer style = "font-size: 18px">Human skin colour $\rightarrow$ Human skin colour $\rightarrow$ <span style = "color:blue"> Human skin colour </span> $\rightarrow$ Pedigree analysis $\rightarrow$ Pedigree analysis </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritancevariation L-5 </Success>
### <primary style="font-size:24px"> Pedigree analysis </primary>
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- Both sexes are involved

- Generation not skipped

- "Vertical" transmission

- Spontaneous mutation

- 50% risk for affected child, if parent affected

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<footer style = "font-size: 18px">Pedigree analysis $\rightarrow$ Pedigree analysis $\rightarrow$ <span style = "color:blue"> Pedigree analysis </span> $\rightarrow$ Pedigree analysis $\rightarrow$ Pedigree analysis </footer>

### <Success style="font-size:25px"> Genetics Evolution Principles Of Inheritancevariation L-5 </Success>
### <primary style="font-size:24px"> Haemophilia </primary>
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<footer style = "font-size: 18px">Haemophilia $\rightarrow$ Haemophilia $\rightarrow$ <span style = "color:blue"> Haemophilia </span> $\rightarrow$ Thank you $\rightarrow$  </footer>