Class Notes (839,147)
Canada (511,218)
Biology (6,826)
Biology 1001A (1,727)
Lecture 12

Biology 1001A Lecture 12.pdf

3 Pages
37 Views

Department
Biology
Course Code
Biology 1001A
Professor
Beth Mac Dougall- Shackleton

This preview shows page 1. Sign up to view the full 3 pages of the document.
Description
Biology 1001A | 2012 LECTURE NOTES Lecture 12 Inheritance in Populations –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– - Which of the following is a true characteristic of dominant alleles? a. They are the most evolutionarily fit alleles. b. They are the most common alleles in a population c. They inhibit the expression of recessive alleles d. They determine the phenotype of heterozygotes - Answer: Only d - If you mated a pure-breeding black pig with a pure-breeding brown pig, what do you think the piglets will look like? - Answer: all black piglets - the allele for black colour must be dominant to the allele for brown colour - if two F1s were crossed, what would the resulting piglets look like? - Answer: Some would be black and some would be brown in Mendel’s 3:1 ratio Why is it dominant? - why is the black allele dominant over brown? - skin and hair pigments are created in specialized cells called melanocytes - two kinds of melanin can be made, one in each colour - to melanin is shipped in melanosomes to the skin cells, resulting in the pigmentation of the skin and hair - when MC1R is “on”, cyclic AMP (cAMP) levels in the cell are high and the melanocyte produces - The as both kinds of melanosomes - the black allele is insensitive to hormone control and cAMP is always high - when both of these alleles are together, - two alleles (black and brown) in the nucleus get transcribed, spliced, exported out of the nucleus, find ribosomes, taken t o the ER and those proteins get packaged into vesicles and put into the Golgi and get sent to the cell membrane for export - pig cell has both receptors functioning at the same time - it doesn’t matter what the brow allele is doing because the black allele keeps the black melanin level high at all times - the black allele never interferes with the brown allele in any way - this is one mechanism that will be dominant because it is always on, as opposed to the other allele which is only on for part of the time - dominance arises from expression of the allele, not competition between the two alleles - what will be the phenotype of B R heterozygotes? - Answer: brown piglets - the brown allele is recessive to black but is dominant to red Biology 1001A | 2012 - dominance and reces
More Less
Unlock Document

Only page 1 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit