Sweet pea phenotypes observed in the F2 Bateson and Punnett (1906)

PPLL (purple, long) x ppll (red, round)

F2

9:3:3:1)Purple, long (P- L-) 284 215

Purple, round (P- ll) 21 71

Red, long (pp L-) 21 71

Red, round (pp ll) 55 24

Total 381 381

cis-configuration

(coupling)

trans-configuration

(repulsion)

+

+

+

Metaphase I Telophase I Tetrads

Non-recombinant

Non-recombinant

Recombinant

Recombinant

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Meiosis.html#crossing_over

Five chiasmata in a tetrad of the grasshopper

df=3

Hermaphroditus

Son of Hermes & Aphrodite

From Greek Mythology Link: http://homepage.mac.com/cparada/GML/Hermaphroditus.html

XX

XOXX

2002

XRXR XrY

XR Xr Y

parents

gametes

gametes

F1

F2

XRXr XRY

XR Xr XR Y

XRXR XRYXRXr XrY

Queen Victoria(1819-1901)

Albert

Alexis (14)

Nicholasof Russia

Frederic IIIof Germany

Alfonso XIII

Edward VII

(31) (20)

(33) (23)

(31)

(3)

(56) (4) (20)

Questions

1 Answer the following questions about the Bateson and Punnett

study of sweet pea plants.

1) How would you explain the observed ratio?

2) By what process have the new combinations of characters, such

as red flowers and long pollen grains, come about?

2. Concerning the F2 result of a cross, prpr vgvg x pr+pr+vg+vg+,

1) Calculate the value of 2.

2) State the number of degrees of freedom that should be used for

reading the probability form the table.

3) What conclusion can be drawn from the test?

3. Explain what is meant by the term sex-linkage. Use examples to

illustrate your answer.

4. Why can a man not pass on an X-linked gene to his sons?

C1C1 C2C2

F1 C1C2

F2

C1C1 C1C2 C2C2

http://www.nlm.nih.gov/medlineplus/sicklecellanemia.htmlhttp://www.healthscout.com/ency/1/ImagePages/1494.html

A B 1

AB

ABO

IAIB

IBIB, IBi

http://www.hokkaido.bc.jrc.or.jp/laboratory/abo.htm

popo pbpb pypy

F2 (pypb)F2 (popb) F2 (pbpb)

Adamkewicz and Castagana (1988), Journal of Heredity 79, 15 (Figure 1).

shepherd’s purse, Capsella bursa-pastoris