1 / 17

Genetics After Mendel

Genetics After Mendel. Types of Dominance. 1. Complete -1 gene masks the other (Tt…see Mendel) 2. Incomplete -Neither gene is dominant, neither is recessive. -The gene effect is mixed -We use 2 different letters for the homologous pair since neither is

daquan-conley
Download Presentation

Genetics After Mendel

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Genetics After Mendel

  2. Types of Dominance 1. Complete -1 gene masks the other (Tt…see Mendel) 2. Incomplete -Neither gene is dominant, neither is recessive. -The gene effect is mixed -We use 2 different letters for the homologous pair since neither is dominant.

  3. Use a Punnet square to predict offspring! Red Flower – RRWhite Flower - WW R R W 100% PINK!!! W

  4. Try this one: • Bird feathers show incomplete dominance. For example, the gene for black feathers, B, may be incompletely dominant to the gene for white feathers, b. The heterozygous condition produces a bird with blue feathers. Determine the genotypic and phenotypic ratios that will result from each of the following crosses: A) blue x white B) black x blue C) blue x blue

  5. Answers: A) 50% Bb (Blue); 50% bb (White) • 50% BB (Black); 50% Bb (Blue) • 25% BB (Black); 50% Bb (Blue); 25% bb (White)

  6. Types of Dominance 3. Co-Dominance -Neither gene is dominant or recessive -Gene effects are not mixed -Both genes are expressed at the same time! -Eg. Roan Cattle – Red hairs and white hairs THERE’S NO NEED TO MOAN ABOUT BEIN’ ROAN!

  7. Co-DominanceCont. -Write C (for co-dominance) and a super script (R=Red, W=white) -Red haired = CRCR -White haired = CWCW -Red and White (Roan) =CRCW Use a Punnett square to predict offspring: • Cross a white cow with a red bull X

  8. CR CR CW 100% Roan!! CW 2) Cross a white cow with a roan bull

  9. A Special Case – Blood Type • There are three alleles! A B O • A and B are co-dominant • O is recessive • FYI: +/- is the Rh factor (If the major Rh antigen is present, the person is Rh+; if not, they are Rh-) Predict offspring bloodtypes for: • Heterozygous type A mother, type O father

  10. Blood Type… Cont. A O 50% AO 50% OO O O b) Mother: AB; Father: Hetero type B

  11. Try these ones: • Mother: AB; Father: Hetero type B • Match the children and parents:

  12. What’s your type? • AB universal plasma donors • AB+ universal recipients • O+ blood most needed • O- universal RBC donor

  13. X-Linked Traits • All genes found on the ‘X’ chromosome are “linked”. • Many of the genes on the ‘X’ are not on the ‘Y’. • The ‘X’ is larger and has many genes that are not related to gender… (i.e. colour vision, blood clotting etc.)

  14. Are you colour blind? WHAT DO YOU SEE?

  15. X-Linked Traits • If a recessive gene is on the ‘X’: - always expressed in males - no homologous pair on the ‘Y’. - recessive, X-linked diseases are much more common in males!

  16. Hemophilia – I can’t stop bleeding!! Since gender and the gene are important, both must be noted. • Dominant allele – H • Recessive allele – h • XH – dominant gene on ‘X’ • Xh – recessive gene on ‘X’ • Y – no gene on the ‘Y’

  17. Hemophilia • Female genotypes XHXH – Normal XHXh – Normal but a ‘Carrier’ XhXh – Hemophiliac (very rare) • Male genotypes XHY – Normal XhY - Hemophiliac Predict the offspring for: -Mother carrier and a normal father!

More Related