I am sorry for the delay, but, after a whole weekend with no internet at home, my connection has finnaly returned, so I can post last week summary.

Tuesday 16th of February.

At the beginning of the class, Fernando, as usual, asked if there was any problem with the homework. After that, he spoke about non-mendelian genetics, focusing on co-dominance and incomplete dominance. Thanks to the help of the whiteboard, the teacher explained co-dominance ( by Wikipedia: “Co-dominance occurs when both alleles contribute to the phenotype.”) and incomplete dominance (inheritance in which one allele is not completely dominant over the other one) in flowers, with the example of roses. As incomplete dominance shows, an offspring of red (homozygous) and white (homozygous) parents will be heterozygous and its phenotype will be pink and as we can learn from co-dominance, this offspring will be red with white spots or white with red spots :

Traits Red White
Alleles R W
Co-dominance Red

RR

Red and white with spots

RW

White

WW

Incomplete dominance Red

RR

Pink

RW

White

WW

After this little bit of theory, we corrected some homework from previous days and continued with the photocopy with genetics exercises.

Thursday 18th of February.

In this lesson, Fernando talked about human blood types explaining that human blood is determined by co-dominant alleles, and that there are three different alleles for our blood types( IA, IB, i) with this possible genotypes:

Genotype Blood Type
AA  (IA IA )

AO  (IA i )

A
BB  (IB IB)

BO  (IB i)

B
AB  (IA IB) AB
OO  ( i i) O

Alleles ‘IA and ‘IBare co-dominant between them, but ‘i’ is recessive to both of them.

When we had learned this previous information, Fernando made us guess (in an exercise) his parents genotypes just by giving us his and his brother’s phenotype.

Friday 19th of February.

After correcting some exercises from previous activites about human blood types, Fernando explained us how human sex inheritance works (or a part of it).

Women’s haploid cells contain 23 chromosomes (22 plus the chromose X) and men’s contain 22 plus the X or Y chromosome. When an X sperm cell enters in a X egg cell, the possible result is going to be always a girl (XX). When an Y sperm cells enters a X egg cell, the results are shown in this table below.

X X
X XX XX
Y XY XY

After learning this information, we spent the rest of the class doing exercises with the help of the teacher about human diseases (such as colorblindness or hemophilia) passed through sexual inheritance.

As Fernando wanted us to post web pages that we usually visit, here I let you this link where you can find a web page about science.

Thank you for worrying so much, i’m glad (^^). I think the problems may have ocurred when copying the text from the text processor (just 1 out of 3 tables copied correctly, and I think some sentences were missed in between). Sorry about the spelling problems, and, by the way, I checked in this page that the pronunciation of homozygous and heterozygous is different depending on the way you speak (English or American).

Advertisements