Understanding Traits
A trait is a feature or quality that you notice about a person. We all have a different combination of traits that make us unique. Traits are passed on from generation to generation, inherited by our parents and passed on to our children.
Physical traits are characteristics of our physical make-up. These include hair color, eye color, and height.
Behavioral traits are characteristics of the way we act. A sheepdog's herding instinct and a retriever's desire to fetch are examples of behavioral traits.
Predisposition to a Medical Condition is an increased risk of contracting a certain type of disease, which is a type of trait that can be passed on from parent to child. Some examples of diseases include cancer, heart disease, and some types of mental illnesses.
The instructions encoded in our genes play a big part in which traits we acquire, but non-genetic or environmental influences also play a role. Sometimes they can even change a trait.
For example, with respect to physical traits, such as hair color, you could have brown hair (like me), which is a genetic trait, but prolonged exposure to the sun or chemical hair colors (environmental) could change my hair from brown to red or blonde.
The same thing goes for behavioral traits, you can breed retrievers to bring things back (genetic) or you could train them to shake and roll-over instead (environmental).
For people born with a predisposition to a medical condition like heart disease (genetic), eating healthy and exercising could reduce this risk (environmental).
What Kind Of Thumb Do You Have?
Try to bend your thumb back at the joint. Some people can bend their thumb back 45 degrees, that's called the Hitchhiker's Thumb (think Hitchhiker's Guide to the Galaxy). Other people have straight thumbs, which do not bend like this. Which kind of thumb do you have?
Scientists describe this set of genetic information for each type as a allele (pronounced uh-LEEL). The straight thumb allele is described with an "H" and the Hitchhiker's with an "h". Dominant genes are represented by capital letters and recessive genes are represented by lower case letters. (We'll get into the rules of dominance and recessiveness a little later on.)
Each of us has two alleles for the thumb extension trait. So basically, we all have one of these combinations.
Physical traits are characteristics of our physical make-up. These include hair color, eye color, and height.
Behavioral traits are characteristics of the way we act. A sheepdog's herding instinct and a retriever's desire to fetch are examples of behavioral traits.
Predisposition to a Medical Condition is an increased risk of contracting a certain type of disease, which is a type of trait that can be passed on from parent to child. Some examples of diseases include cancer, heart disease, and some types of mental illnesses.
The instructions encoded in our genes play a big part in which traits we acquire, but non-genetic or environmental influences also play a role. Sometimes they can even change a trait.
For example, with respect to physical traits, such as hair color, you could have brown hair (like me), which is a genetic trait, but prolonged exposure to the sun or chemical hair colors (environmental) could change my hair from brown to red or blonde.
The same thing goes for behavioral traits, you can breed retrievers to bring things back (genetic) or you could train them to shake and roll-over instead (environmental).
For people born with a predisposition to a medical condition like heart disease (genetic), eating healthy and exercising could reduce this risk (environmental).
What Kind Of Thumb Do You Have?
Try to bend your thumb back at the joint. Some people can bend their thumb back 45 degrees, that's called the Hitchhiker's Thumb (think Hitchhiker's Guide to the Galaxy). Other people have straight thumbs, which do not bend like this. Which kind of thumb do you have?
Scientists describe this set of genetic information for each type as a allele (pronounced uh-LEEL). The straight thumb allele is described with an "H" and the Hitchhiker's with an "h". Dominant genes are represented by capital letters and recessive genes are represented by lower case letters. (We'll get into the rules of dominance and recessiveness a little later on.)
Each of us has two alleles for the thumb extension trait. So basically, we all have one of these combinations.
Alleles for thumb extension trait...
You've probably already guessed that the trait in people with two of the same alleles, H + H, have straight thumbs, those with h + h will have Hitchhiker's Thumbs.
Scientists coined the word "homozygous" (HO-mo-ZY-gus) as the definition of when people have two of the same allele as a trait.
But what about people who have one of each? H + h...
When this happens, the alleles interact. So, if you have an H + h, you'll end up with a straight thumb. Here, the "H" alele is called dominant and the "h" alele is called recessive. Scientists coined the word "heterozygous" (HET-er-O-zy-GOUS) to describe having two different types of alleles as a trait.
Scientists coined the word "homozygous" (HO-mo-ZY-gus) as the definition of when people have two of the same allele as a trait.
But what about people who have one of each? H + h...
When this happens, the alleles interact. So, if you have an H + h, you'll end up with a straight thumb. Here, the "H" alele is called dominant and the "h" alele is called recessive. Scientists coined the word "heterozygous" (HET-er-O-zy-GOUS) to describe having two different types of alleles as a trait.
Here, the mom and the dad both have two different types of alleles for the thumb extension trait. If they have a child, the child receives one allele from each parent. This means, the child could receive "HH, Hh, or hh." If they have more than one child, each child could receive a different combination.
Not all traits are as simple as the thumb extension trait. Others are far more complex and not as easily tracked through the generations. Alleles can create incomplete dominance, which would be like crossing a white carnation with a red one to produce a pink one.
A trait that comes from just one gene is VERY rare. These are called single-gene traits. Most traits come from more than one gene, these are called Complex traits.
While there are countless numbers of differences that make each of us unique, we still share 99% of the same or identical DNA.
Not all traits are as simple as the thumb extension trait. Others are far more complex and not as easily tracked through the generations. Alleles can create incomplete dominance, which would be like crossing a white carnation with a red one to produce a pink one.
A trait that comes from just one gene is VERY rare. These are called single-gene traits. Most traits come from more than one gene, these are called Complex traits.
While there are countless numbers of differences that make each of us unique, we still share 99% of the same or identical DNA.