Each cell in a human’s body contains 46 chromosomes:
The 46 chromosomes in each human cell contains more than 3.2 billion base pairs in their DNA and have more than 30,000 genes. "If our strands of DNA were stretched out in a line, the 46 chromosomes making up the human genome would extend more than six feet [close to two metres]. If the... length of the 100 trillion cells could be stretched out, it would be... over 113 billion miles [182 billion kilometres]. That is enough material to reach to the sun and back 610 times." [Source: Centre for Integrated Genomics]
Heredity- The passing of traits from parent to offspring. Trait- A characteristic of organism. Traits may be visible, such as eye color, or not visible, such as blood type.
Alleles- Different forms a gene may have for a trait.
Genetics Genetics- the study of how traits are inherited. Heredity- the passing of traits from parent to offspring. Trait- a characteristic of an organism. Traits may be visible, such as eye color, or not visible, such as blood type. Alleles- the different ways a trait can look. For example- eye color alleles would be blue, brown, green, hazel. Hair color alleles would be blonde, brown, black, red.
The Father of Genetics Gregor Johann Mendel was an Austrian monk, who in 1856 begin experimenting with pea plants.
Why peas you may ask? They have distinctive traits They grow fast He could control pollination and fertilization.
What was Mendel's first experiment? Mendel crossed (pollinated) two tall pea plants. All of the offspring were tall pea plants.
Next, Mendel crossed two of the newly produced pea plants. For every three tall pea plants produced, there was on short pea plant. WOW!!!
What did all this mean to Mendel? genes are always in pairs (each one passed on from a parent) some forms of a gene (allele) are stronger than others.
More notes: Gregor Mendel was an Austrian monk, who in 1856 began experimenting with pea plants. He found that genes are always in pairs (each one passed on from a parent) and that some forms of a gene (alleles) are stronger than others.
In peas, the tall gene is stronger over the short gene. If a pea plant receives a tall gene from one parent and a short gene from the other parent the offspring will be Tall
In genetics, the stronger gene is called dominant. It prevents the other gene from being seen. Dominant alleles are written as a capital letter (T). While the weaker gene is known as recessive. The recessive allele will not be seen is a dominant allele is present. It is written as a lower case letter (t).
Even more notes: Dominant- the stronger allele. It prevents the other from being seen. Dominant alleles are written as a capital letter. For example- Tall pea plants (T), Tongue roller (R) Recessive- the weaker allele. The recessive allele will not be seen if there is a dominant allele present. It is written as a lower case letter. For example- Short pea plants (t), Non-tongue roller (r)
Reginald Punnett Reginald Punnett developed a tool used to predict all the possible gene combination of offspring. It is know as a Punnett Square.
By knowing the combinations of alleles in the parents, we use the Punnett square to predict the possible offspring. If a parent has two of the same alleles, either 2 dominant (TT) or 2 recessive (tt), it is known as homozygous. If a parent has two different alleles, one dominant and one recessive (Tt), it is know heterozygous. From a Punnett Square we can tell what the genes the offspring will have (genotype) and how the trait will appear. (phenotype)
Yes, even more notes: Punnett Squares- A tool used to predict all the possible gene combination of offspring. Homozygous- two of the same alleles. Having two dominant alleles (TT) or two recessive alleles (tt) Heterozygous- two different alleles, one dominant and one recessive allele (Tt). Genotype- the genes the organism has. For example- TT, Tt, tt Phenotype- the physical appearance of the organism. How the trait appears. For example- Tall or short