LEARNING GENETICS MORE!

January 20, 2015. Tuesday.

 I came to school late at the second time around. Last meeting Ma’am Ruby Lorenzana gave an assignment to us and here are the questions:

                                   

                               

 As expected, since I don't have enough knowledge in test crossing and identifying the phenotype and genotype of an offspring ,I and my partner in this assignment decided not to answer it. The moment I enter our room, Ma'am Ruby started discussing about our assignment. At first I don't really understand what my teacher discussing but as time goes by, i decided to listen carefully for me to gain more knowledge about the topic and understand it. Let me share some example of problem involving Incomplete Dominance.

 We use again the punnet square for us to identify the phenotypic ratio and genotypic ratio of an offspring. Ma'am Ruby Lorenzana discuss and explain to us the first question. After learning and knowing how to answer the following questions, our teacher gave number two and three as a seatwork but this time in indivual work.Time flies so fast, we answer the seatwork in about 30mins. Ma'am Ruby ask two of my classmates to answer the two questions in the black board. After that, she gave us a quiz about it and the question is all about a husband and wife that have a thalassemia minor.

At this moment, we are given a chance to become a Genetic councilor. Our teacher ask us "If you are a genetic councilor would you require a male and female who has a thalassemia minor to produce an offspring?" and my answer goes this way, " As a genetic councilor I would ruther say unto them not to produce an offspring because there's a big chance that their offspring will be aa thalassemia major which will no longer reach the adulthood."

"THE LAWS OF GENETICS APPLY EVEN IF YOU REFUSE TO LEARN THEM"

NON MENDELIAN MODE OF INHERITANCE

January 15, 2015

The moment I enter our classroom I’m quite nervous for some un-explainable reasons. I wake up late, I arrived with a very slow run of a tricycle and there you are I enter the classroom late. I’m in a bad mood when my sit mate Jessica told me that they already have our quiz that is all about our past lesson (technique in test cross), for me it’s like a big “WHAT??” “I enter the room 10 minutes late, in that short period of time they already have our quiz?” This is the question that lingers in my mind. I asked my other classmate if that’s true, and they answer me “oo,late kana kase pumasok e ang lapit ng bahay niyo”. I gave them a poker face and said to myself “special quiz nalang. Madame naman kameng late.”

After a few minutes, as my teacher present a power point that is all about the Non-Mendellian Modes of Inheritance Jessica whisper a word saying, “joke lang di kame nagquiz. Hahaha.” That sentence gives a relief to me. After that, I therefore have the chance to focus in our topic. As the discussion goes by, I learn again a lot of things.Non Mendelian Mode of Inheritance is a general term that refers to any pattern of inheritance in which traits do not segregate in accordance with Mendel’s laws. These laws describe the inheritance of traits linked to single genes on chromosome in the nucleus. In Mendelian Inheritance, each parent contributes one of two possible alleles for a trait. If the genotype of both parents in a genetic cross are known, Mendel’s laws can be used to determine the distribution of phenotype expected for the population of offspring. There are several situations in which the proportions of phenotypes observed in the progeny do not match the predicted values.Let me share and gave some example in what Ma'am Ruby presented to us.

• Incomplete dominance (also called partial dominance) occurs when the phenotype of the heterozygous genotype is distinct from and often intermediate to the phenotypes of the homozygous genotypes.

                     This Punnett square illustrates incomplete dominance. In this example, the red petal trait associated with the R allele blends with the white petal trait of the r allele so that plants with the Rr genotype have pink flowers.

• Codominance is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked. The heterozygote condition manifests BOTH extreme phenotypes.

                          A good example of co dominance is that of the roan coat as seen in some cattle.

Anothe r slide that makes me realize that i'm so lucky.In terms of out come appearance and some other reasons.

This is a pleiotropy in individual. Pleiotropy in which one gene pair has many effects and the affected individuals may express different subsets of symptoms that may superficially appear as if they are caused by different disorders. One example of disorder is the Phenylketonuria (PKU)-a genetic disorder in which the body can't process part of a protein called phenylalanine (Phe). Phe is in almost all foods. If the Phe level gets too high, it can damage the brain and cause severe intellectual disability.

• MULTIPLE ALLELES where there are at least three types of alleles for a particular trait, with two alleles occupying a single locus at any given time. A very good example of this is the fur color of the rabbit with a phenotype Agouti, Chinchilla, Himalayan, and Albino. Here, dominance hierarchy may be exhibited.

                               

                                                   ABO blood typing in humans

We also discuss: SEX INFLUENCED TRAITS,SEX LINKED TRAITS, & HYPERTRICHOSIS PINRAE AURIS.

 At the end of the discussion I again say that my knowledge about Genetics extended.

In the course of individual development, inherited characters appear, in general, earlier than adaptive ones, and the earlier a certain character appears in ontogeny, the further back must lie in time when it was acquired by its ancestors. 

— Ernst Haeckel

Gregor Mendel (Father of modern genetics)

“Studying Genetics is such an interesting one.”

Gregor Mendel the father of genetics discovered the fundamental principles of genetics by breeding garden peas.He is an Augustinian friar who presented his paper Versuche uber Pflanzenhybriden (experiments on plant hybridization) at two meetings of the Natural History Society of Brunn in Moravia in 1865.

In this information I gain more knowledge about him. As the discussion goes by, I realize that this topic is quite connected to our last topic about human traits (e.g Law of Dominance).After this realization we do the test cross which means a way to explore the genotype of an organism. Early use of the test cross was as an experimental mating test used to determine what alleles are present in the genotype.

Punnet square with 2 traits (Dihybrid)

At the end of the discussion Ma’am Ruby Lorenzana show some picture of genetic dis-order.

• ACHONDROPLASIA - have short stature, with an average adult height of 4 feet, 3.8 inches for males and 4 feet, 0.6 inches for females.

                                                  

• XERODERMA PIGMENTOSUM - genetic disorder of DNA repair due to UV exposure. It has  multiple basal cell carcinomas (basaliomas) and other skin malignancies occur at younger age.

                                                        

• POLYDACTYL - a congenital physical anomaly in humans , dogs, cats and having supermerary finger or toes.

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