Download Variation

Variation
What is variation?
Variation Lab – Day 1
Variation Lab – Day 2
How does variation arise?
Variation - a difference or deviation
in structure or character from others
of the same species or group
Single-gene Traits – traits controlled
by a single gene that has two alleles

Examples – cleft chin, hitchhiker’s thumb, tongue
rolling, attached/unattached earlobes
Polygenic Traits– traits controlled by
two or more genes

Range of phenotypes

More than two genes

Examples – height, performance on IQ tests, skin color, eye
color
Variation Lab – Definitions

Species - a group of organisms capable of
interbreeding and producing fertile offspring

Population – groups of individuals of the same
species that interbreed

Gene Pool – all genes that are present in a population
Variation Lab – What will you be
doing?

Mealworms – LENGTH of
mealworm (mm)
Peanuts
– LENGTH of inside nut, or
cotyledon (mm)

Hand – LENGTH of hand spread
from thumb to little finger
Variation Lab - Predictions
Variation Lab - Graphing
Variation Lab – Graphing
Instructions

Label the x-axis (independent variable) and the y-axis
(relative frequency).

Determine the maximum and minimum values for each
variable and a standard width for each bar and set them
on your axes.

Draw a bar for each range of values that shows how
many organisms have a trait that measures within that
range. Repeat this for all ranges of measurements.
Mealworm (mm)
Size
<9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
>28
Number
Peanut (mm)
Size
<9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
>28
Number
Hand Size (mm)
Size
<14
15
16
17
18
19
20
21
22
23
24
25
>26
Number
Genetic Variations

Mutations


Due to mistakes in the replication of DNA or radiation or
chemicals in the environment
Gene Shuffling

Occurs during meiosis
Genetic Variations – Mutations:
Sickle Cell Anemia
Sickle Cell Anemia Mutation –
Harmful or Beneficial?
NN – normal round blood cells
 NS – normal round blood cells;
immune to malaria
 SS – sickle-celled blood cells
