Human Biology Kaplan University Week 8 Project

Human Biology Kaplan University Week 8 Project

Use APA format and the graph below

Survey of Simple Human Genetic Traits

Although most human physical traits are coded for by more than one gene, some are not. These characteristic phenotypes (e.g., height, eye color) occur because of the products created by a single pair of alleles on each member of the chromosome pairs you possess.

You will carry two dominant alleles, two recessive alleles or one of each. If you have at least one dominant allele (commonly notated using capital letters) for the trait your phenotype is dominant and you will show the trait. For example, a person who can roll his/her tongue (a dominant trait) could be either RR (homozygous dominant) or Rr (heterozygous) for the genotype.

A person who could not roll his/her tongue would have recessive alleles (commonly notated using lowercase letters) and would have to have the rr (homozygous recessive) genotype.

Procedure

Work with another person (e.g., family members, friends, coworkers although this works best with at least one or two family members if possible) to determine your personal phenotype and possible genotype(s) for each of these human traits.

Record your findings in the Table below (cut and paste the table into a Word document. Save it and submit it to the Dropbox).

If you show the trait write the representative capital in the phenotype space.

If you do not show the trait write the representative lower case letter in the phenotype space. If you do not show the trait you can also be certain that your genotype may be a homozygous recessive condition represented by two small letters (e.g., xx). Write your genotype for each trait in the space provided.

If you show the trait, write XX and Xx in the space provided since you do not know for certain which set of alleles you possess.

Traits…just a few examples!

Tongue Rolling (T)

Tongue rolling is a dominant trait where the person can roll up the sides of the tongue and make it tube shaped while sticking it out. Recessive individual’s tongues will remain flat when extended.

Widow’s Peak (W)

A person with a Widow’s Peak, the dominant characteristic, will have the hairline across the forehead come to a V-shaped point approximately in the middle. The recessive characteristic is a straight hairline with no V-shaped point.

Detached Earlobes (E)

The dominant characteristic for this trait occurs when any part of your earlobe is not connecting to the side of your head. That is, you will have a loop on your earlobe of any size. People without a loop at the bottom of their earlobes have the recessive trait; attached earlobes.

Crossing of Thumbs (C)

The crossing of your thumbs may not seem to be important in the overall scheme of the survival of mankind but often the products of genes are used for more than one process in your body (see pleiotropy in the textbook). The product of the gene we see creating the phenotype of thumb crossing may be important for an as yet undiscovered body function, which could be crucial for our survival. To do this test hold your hands out in front of you and interlace your fingers. The dominant phenotype here is the left thumb being on top of the right thumb. Try putting your hands together in the opposite fashion, feels weird doesn’t it?

Hair on Mid-digit of Fingers (M)

Hold your hand in front of you with your fingers sticking straight up. Bend your fingers to that the middle segment is parallel to the floor (you can lay a dime on your fingers and it wouldn’t fall off). If there is at least one hair of any size on any of these middle segments of your fingers you have the dominant trait of mid-digital hair. If there are no hairs at all you have the recessive characteristic. The best finger to find the hair on is the ring finger; no we don’t know why.

Hitchhiker’s Thumb (h)

This trait is unusual because it is named for the recessive characteristic and not the dominant one, having a straight thumb. For this characteristic you need a nimble thumb and some loose tendons. Pretend like you were hitchhiking and have your thumb extended straight up. Bend the top part of the thumb back as far as you can. If your thumbnail is at a 60° degree angle or more bent out over the rest of your thumb, you have the Hitchhiker’s Thumb recessive trait. If your thumb doesn’t bend that far back or you can’t bend the tip of the thumb over your knuckle at all you possess the dominant trait or straight thumb.

Handedness (R)

The majority (85%) of the population is right-handed; the rest are left-handed.

Length of Big Toe vs. Second Toe (S)

Your big toe is also called your Hallux. If your second toe is longer than your big toe, congratulations you show the dominant characteristic. A longer Hallux means you are recessive for this allele.

Facial Dimples on the Cheeks (D)

Smile, that’s what you’ll need to do to detect this trait. If you have at least one dimple on your cheeks you possess this dominant phenotype. Having no dimples means you are a recessive.

Dimple of the Chin (K)

A family of famous movie stars is known for their chin dimples. This characteristic is due to the possession of the dominant allele. If you lack this feature, you are homozygous recessive.

Freckles (F)

These pigmented spots can show up on just about any part of your body. If you have freckles you possess at least one dominant allele.

Iris Pigment (I)

For people who have blue eyes there is a lack of pigment on the outer layer of your iris and you are homozygous recessive for this trait. Any color that shows up in your iris other than blue means that you have at least one dominant allele for eye pigment. The specific colors of your iris is controlled by other genes, which code for eye pigments of varying shades of brown, green, hazel, or a combination of colors. The “I” gene only determines whether your iris will or will not have color.

Red-Green Visual Deficiency (Red-Green Colorblindness)

The gene for this trait, unlike the other ones, is located on the X chromosome and is thus said to be sex-linked Remember that females carry two X chromosomes and males only one plus one Y chromosome, which has very few genes. For X chromosomes, alleles are represented by a capital X followed by a superscript letter for the trait. People with normal color vision, which is dominant, are either XRXR or XRXr for females or XRY for males. Females who are recessive and red-green deficient will carry the two recessive alleles, males will carry only one. Red-green deficient people are represented by XrXr for females and XrY for males.

Questions for consideration:

Would the person who could roll his/her tongue know their genotype for certain? Why?

What might determine whether a person who shows the dominant characteristic is homozygous dominant or heterozygous?

Now, knowing the details of red-green deficiency, please explain why males tend to show sex-linked traits more often than females? Can you think of any other sex-linked traits?

Summary of Personal and Class Genetic Traits

Trait
Possible Phenotype
Sample Size No. of people you tested
Dominant #
Recessive #
Personal Phenotype
Possible Genotype(s)

Tongue Rolling
T or t

Widow’s Peak
W or w

Detached Earlobes
E or e

Thumb Crossing
C or c

Mid-digit Hair
M or m

Hitchhiker’s Thumb
H or h

Handedness
R or r

Toe Length
S or s

Cheek Dimple
D or d

Chin Dimple
K or k

Freckles
F or f

Iris Pigment
I or i

Submitting Your Lab Assignment

Save your copy of the assignment in a location and with a name that you will remember. Be sure to use the “Save As” option to include your first and last name in the title of the document. For example, your assignment might be called Shawn_Edwards_Lab1.doc

When you are ready to submit it, click on the Dropbox and complete the steps below:

Click the link that says Submit an Assignment.

In the “Submit to Basket” menu, select Unit 8: Project 4

In the “Comments” field, include at least the title of your paper.

Click the Add Attachments button.

Follow the steps listed to attach your Word document.

To view your graded work, come back to the Dropbox or go to the Gradebook after your instructor has evaluated it. Click the Dropbox to access it.

Make sure that you save a copy of your submitted assignment.