Unit 3 - Genetics

Definitions for Vocabulary:
Gene - one set of instructions for an inherited trait
Heredity - the passing of genetic traits from parent to offspring
Dominant Trait - the trait observed in the first generation when parents have different traits and are bred
Recessive Trait - a trait that reappears in the second generation after disappearing in the first generation when parents with different traits are bred
Pedigree Chart - a diagram that shows the occurrence of a genetic trait in several generations of a family
Sex Chromosomes - one of the pair of chromosomes that determine the sex/gender of an individual
Alleles - one of the alternative forms of a gene that governs a characteristic; such as hair color
Phenotype - an organism's appearance or other detectable characteristic
Genotype - the entire make up of an organism; also the combination of genes or one or more specific traits
Probability - the likelihood that a possible future event will occur in any given instance of the event
Homologous Chromosomes - chromosomes that are the exact same sequence (pure-bred)
Heterozygous Chromosomes - opposite of homologous (hybrid)
Meiosis - a process in cell division during which the number of chromosomes decrease to half of the original number by two divisions of the nucleus, which result in the production of sex cells
(definitions from Georgia Holt science and Technology Life Science Textbook)

Genes and Traits

Your genes make up the different DNA strands that end up making your separate chromosomes. You have 23 sets (of 2) chromosomes, or 46 chromosomes. You get half of your mother's chromosomes and half of you father's. You could get your father's nose and your mother's eyes, or the other way. It is "randomly selected". You will also sometimes got the recessive trait within your family, like you get your grandfather's blond hair.

Genes are sets of instructions for an inherited trait. These mini-microscopic instructions are what give us our on special traits. Traits are the special features of your body.

You have dominant traits (refer back to last post) and recessive traits (refer back to last post), your genes decide which trait you actually get, whether its the recessive trait or the dominant trait. If depends on whether you get dominant and dominant, dominant and recessive, or recessive and recessive traits. If you get any dominant trait, that trait will overshadow the recessive trait and will make you have that dominant trait as your physical look. If you get recessive and recessive, you will then have the recessive trait as your physical appearance.

Your genes make up the different double helix (type of DNA strand) DNA strands that end up making up your separate chromosomes. You have 23 sets (of 2) chromosome, or 46 separate chromosomes. You get half of your mother's chromosomes, and half of your father's chromosomes, but the traits that you receive from each parent is randomly "selected" by the chromosomes. You can get your mother's eyes but have your father's nose. You will also sometimes you will get the recessive trait within your family, so maybe only your grandmother will have blue eyes, while everyone else has some shade of brown (refer to recessive and dominant traits in earlier paragraph).


Gregor Mendel:

He is the "Father of Genetics." He was a monk that loved math and science. Gregor's special "love" though was for heredity, he wanted to see if there was a predictable pattern to it. Since he was the monastery's gardener, he decided to do an experiment with pea plants.
First he chose a pure-bred green and a pure-bred yellow pea plant. His first try, none of the pea plants were yellow, they were all green (this is the second generation of pea plants). He was very confused about this so he took two plants from the second generation and bred them. This time he saw that only 1/4 or 25% of the pea plants were yellow. With this information and a few more experiments to make sure his theory was right, he concluded that there are two alleles making/controlling a trait. Some alleles are dominant over others though. It was 30 years later that the scientific community finally saw Mendel's theory as some use.

1st Generation

2nd Generation

Go to these websites for more information:

 http://www.google.com/url?q=http%3A%2F%2Fglowing-genetics.blogspot.com%2F&sa=D&sntz=1&usg=AFQjCNGHCcfKNr1CziyQZNVOuyilKVD--g   

 http://learn.genetics.utah.edu/