General Genetic Bio 221 Lab 7 Exceptions to

General Genetic Bio 221 Lab 7

Exceptions to Simple Inheritance (Non-Mendelian inheritance) Non – Mendelian inheritance : is trait do not segregate in accordance to Mendel Laws. Some traits are carried on sex chromosomes X and Y. Most traits carried are present on only the X chromosome while the Y Chromosome is smaller and very few genes are located on this chromosome. There are 3 Categories of genes that may have different effects depending on an individuals gender : 1 - Sex – Limited genes. 1 -Beard and Breast. 2 - Milk Production. 3 -White and yellow color of special specie of butterfly. 4 -Feathering in birds. 2 - Sex – Influenced genes. 1 - Bald ness. 2 - Scurs show by heterozygous polled cattle can have scurs. 3 - X– Linked inheritance. 1 - Dominant sex – linked trait Example : Hemophilia (hh). 2 - X- linked recessive 1 -Whit eye (rr) in Drosphilia. 2 - Red / Green color blind ness.

Definition : That are inherited by both men and women but are normally only expressed in the phenotype of one of them. Example : 1 - Beard and Breast are secondary sexual characters that depend on sex hormones. In female lacks in beard and male lacks in developed breasts. 2 - Milk Production. Is trait expressed by cows and affected by gene on Somatic chromosome 14. Both Bulls and Cows carry this gene and both contribute an allele to their daughters which affects the quantity of milk that daughter produces. 3 - White and yellow color of special specie of butterfly. That male always have yellow color while (WW) the female have in two color white and yellow (ww). Male WW X ww Female WW Ww Ww ww Male Yellow Female White Yellow

Example : 4 - Feathering in birds. Males have long , pointed curved fringed feathers on tail and neck , but feathers of female are shorter , rounded , straighter.

The sex hormones of the animal affect the expression of a trait by the heterozygous and provide different cellular environments in males and females. The genes behave differently in two sexes. Ex : amount of body hair and muscle mass. Example : 1 - Baldness (BB). In male physiological factors helps in the expression of hair ( Recessive allele ) in males than females. The gene for baldness behaves as a dominant in males but as a recessive in females. Heterozygous males are bald and will pass the gene to about 50% of their offspring of either sex. The amount of thinning of the hair or balding that is observed depends both on genotype and the amount of testosterone exposure. male BB x bb Female BB Bb Bb bb Male Baled Hair Female Baled Hair

Example : 2 - Scurs show by heterozygous polled cattle can have scurs. In females 2 copies of the scur allele are needed , for the cow or heifer to have scurs. In males a single copy of the scur allele is produce scurs.

3 - X– Linked inheritance. Information : That inheritance is different males than females , and That inheritance controlled by Genes on X – Chromosomes. - Mother 1 - pass X-linked alleles to only sons. 2 - Females ( homozygous) have 2 allele for each gene 3 -Female can be : Normal , Affected , Carrier. 4 -Females have 2 X- Chromosomes that good chance of having the normal gene on one of the two. - Fathers 1 -pass X-linked alleles to only daughters. 2 -Male can be : Normal , Affected. 3 - males ( hemizygous) have one X – Chromosomes and have recessive condition much more commonly than females. 4 -Males have 1 X- Chromosome does not carry of the same genes , so there is no normal gene to counter the defective X. Kinds of : 1 - Dominant sex – linked trait 2 - X- linked recessive.

Kinds of : 1 - Dominant sex – linked trait Most male lethal Example : Hemophilia (hh) 1 -Male can be : Normal (HH) , Affected (hh). 2 -Female can be : Normal (HH) , Carrier (Hh) , Affected (hh). When a female with hemophilia has children , she will pass the gene to each of her sons. .

Kinds of : 2 - X- linked recessive The genes on X – Chromosome which behave more or less as recessives. 1 -Females have 2 X- Chromosomes that good chance of having the normal gene on one of the two. 2 -Males have 1 X- Chromosome does not carry of the same genes , so there is no normal gene to counter the defective X. Examples: 1 -Whit eye (rr) in Drosphilia. *Consider the red /white eye allele of Drosphilia. Red eyes are dominant (Normal) and codes (RR) , (Carrier ) (Rr) and White eyes are codes ( rr). *The recessive phenotype is more common in males , because the R/r locus is on X – Chromosome that means the males are haploid , the only genotype have R or r for that R male has red eyes and r males have white eyes.

Examples: 2 - Red / Green color blindness. * Is condition of color vision. It appears to normal state of animals that active at night. Because , the vision is mediated not by cone receptors but by rods which respond to low intensity of light. (Normal) code (CC) , (Carrier ) (Cc) and Affected ( cc).

1 - CC Cc c XX XY Female Normal Male Affected C Cc C XX XY Female Carrier Male Normal 2 - cc Cc C XX XY Female Affected Male Normal c Cc c XX XY Female Carrier Male Affected Female Carrier Male affected 3 - Cc c XX XY Female Carrier Male Affected Cc XX C XY XX XY Female Carrier Male Normal Female Affected Male Affected cc c

Experimental 1 - Separate the drosophelia (F 2 ) From first Low and record the changes for chi –square ++ vg Male 1 -++ Female Total Obs. 2 - vg /D. S 2 - Separate between F 1 & F 2 ( Larva ) From Second low , and survive to F 2 to grow. After that , Breeding F 2 (Male and female Wild type phenotype) 3 - The whit eye Experiment (X- linked recessive)- ( Breeding between Female wild type(RR) with male white eye (rr).