1. Human Heredity
Biology

2. What single gene traits do you have?
Controlled by one dominant or recessive gene
Does dominant mean the same as most common?
Is it true that dominant phenotypes are always the most common in a population?

3. 1. Cleft chin - A noticeable indentation at the center of the chin.
Having a cleft chin is dominant to a smooth chin.
2. Pinky finger – having a bent pinky is dominant to having a straight pinky

4. 3. Hand folding - When the hands are folded either the left or right thumb will be on top.
Left thumb on top is dominant.
4. Mid-digital hair - Hair growing from the middle section of each finger.
Hair presence is dominant.

5. 5. Dimples - Round indentations in the cheeks when smiling, not lines or clefts.
Having dimples is dominant to not
6. Freckles - Small patches of darker pigmented skin on various parts of the body and most visible in those areas commonly exposed to the sun.
These may be present on both dark and light skinned individuals.
Freckles are a dominant trait

6. 7. Widow’s peak - the hairline of your forehead.
A widow's peak is dominant over a straight or curved hairline on the forehead
8. Hair whorling - These may be referred to as cowlicks. Areas in which hair grows from your scalp in a whorl instead of in a given direction.

7. 9. Ear lobes - Free ear lobe is dominant over attached ear lobe
10. Handedness - Right-handedness is dominant over left-handedness
11. PTC tasting – ability taste a certain harmless chemical
Tasters are less likely to be smokers
Studies suggest that there may be a link between the ability to taste PTC and preferences for certain types of foods.

8. 12. Tongue rolling - The ability to roll the tongue into a U-shape is dominant over the inability to roll the tongue
13. Big toe length – the big toe is shorter than your second one (dominant trait)

9. 14. Thumb – does it bend back at a 90 angle?
no hitchhiker’s thumb is dominant to hitchhiker’s thumb
15. Ear wiggling – the ability to wiggle your ears is dominant to not being able to wiggle your ears

10. Number of fingers/toes – Polydactyly is having more than five fingers and/or toes
If you have more you have the dominant condition.
If you have exactly 5 per hand/foot your phenotype is recessive.
S-methyl thioester smeller S-methyl thioesters are produced in the urine after consumption of asparagus.
Some individuals cannot smell this substance (dominant).
If you smell a strong odor on urination after eating at least 5 asparagas spears, you are an S-methyl thioester smeller (recessive).

11. Darwin tubercle - little bump on the inside of the ear
Having this is dominant to not having it
Index finger length – compare your index finger length to your ring finger
In males, a dominant allele causes the index finger to be shorter than the ring finger
In females, a dominant allele causes the index finger to be equal to or longer to the ring finger

12. Multi-factorial Hair color is determined by more than one gene
Thus hair color appears to vary on an almost continuous scale from black to brown to blond to red
The brown and black pigment is melanin
The red pigment is an iron containing molecule

13. Pigmented irises - When a person is homozygous for the recessive gene (p), there is no pigment in the front part of the eyes and a blue layer at the back of the iris shows through, resulting in blue eyes.
A dominant allele of this gene (P) causes pigment to be deposited in the front of the iris, thus masking the blue to various degrees.
A dark iris pigment (green/brown/black) is dominant over the light pigmentation. (gray/blue).