recap
Download
Skip this Video
Download Presentation
RECAP

Loading in 2 Seconds...

play fullscreen
1 / 15

RECAP - PowerPoint PPT Presentation


  • 93 Views
  • Uploaded on

RECAP. Manx cat. Manx Death Normal. PLEIOTROPY. Is multiple effects of a single gene on the phenotype Occurs for several reasons suppression of single gene can affect cell function in more than one way A gene may be expressed in different cell types in a multicellular organism

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' RECAP' - muhammad-jasmi


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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
recap
RECAP
  • Manx cat

Manx

Death

Normal

pleiotropy
PLEIOTROPY
  • Is multiple effects of a single gene on the phenotype
  • Occurs for several reasons
    • suppression of single gene can affect cell function in more than one way
    • A gene may be expressed in different cell types in a multicellular organism
    • A gene may be expressed at different stages of development
    • Eg cystic fibrosis, inability to recycle salt causing extra salty sweat
5 gene interactions

5- GENE INTERACTIONS

Compiled by

Siti Sarah Jumali

Level 3 Room 14

Ext 2123

polygene interactions
Polygene interactions
  • Mendel studied one gene for height but he did not realize that there are other genes that also affect height
  • i.e.
    • Tall strain KK LL MM NN OO PP QQ RR SS TT
    • Dwarf strain KK LL MM NN OO PP QQ RR SS tt
epistasis
EPISTASIS
  • An inheritance pattern in which the alleles of one gene mask the phenotypic effects of the alleles of a different gene
epistasis1
EPISTASIS
  • Occurs when: gene at one locus affects the expression of an allele at a different locus b.
  • eg: fur color in mice
  • 1) B is allele for black fur

2) b is allele for brown fur

3) BUT, must have allele C at a different locus to have colored fur

4) if different locus has cc, then fur is colorless even if B or b is present

5) see what happens when BbCc mouse is crossed with BbCc mouse

(a) expect a (9:3:3:1 ratio) (b) get a 9:3:4

chicken comb recessive epistasis
Chicken comb (recessive epistasis)

Rose R_pp

Pea rrP_

Walnut R_P_

Single rrpp

WT

R is dominant to r

P is dominant to p

RP is codominant (walnut)

rrpp single comb

epistasis on chicken comb
Epistasis on Chicken Comb
  • Alleles of one gene mask the phenotype of alleles on another gene. In this case, rrpp masks a walnut comb
epistasis on flower
Epistasis on Flower
  • 9:7 ratio is a modification of phenotypic but not genotypic Mendelian ratios.
  • TheC and P genes independently assort, the presence of a recessive genotype at one locus (i.e., cc or pp) masks the effects of the alleles at the other locus.
  • There are 9 combinations of alleles in the F1 generation that feature at least 1 dominant C and 1 dominant P allele, which would yield a purple flower phenotype
  • Conversely, there are seven combinations that result in either a cc or a pp, which would yield the white flower phenotype-hence, the 9:7 ratio of purple to white flowers.
9 7 phenotypic ratio
9:7 phenotypic ratio
  • In this case, white masks purple petal
9 3 4 ratio
9:3:4 ratio
  • Agouti x Agouti
    • BbCc x BbCc
    • Brown agouti & albino mask agouti
    • c epistatic to B;

b epistatic to C

question
Question
  • Manx cats are heterozygous for a dominant mutation that results in no tails (or very short tails), large hind legs, and a distinctive gait. The mating of two Manx cats yields two Manx kittens for each normal, long-tailed kitten, rather than three-to-one as would be predicted from Mendelian genetics. Therefore, the mutation causing the Manx cat phenotype is likely a(n) __________ allele.
  • A. pleiotropic
  • B. codominant
  • C. epistatic
  • D. lethal
  • E. sex-linked
ad