mendel - Basic Mendelian Principles Mendels big...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Basic Mendelian Principles Mendel’s big ideas: --Particulate inheritance: the determinants of inherited traits are discrete units that are passed between generations unaltered, not blended together. --Count large numbers of offspring. The offspring ratios observed are imperfect reflections of underlying simple ratios like 3/4 : 1/4 , etc.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Experimental Organism Mendel worked with peas. Plants have sexual processes very similar to animals. --The male gamete, equivalent to the sperm, is the pollen grain. --The female gamete, equivalent to the egg, is the ovule. Pea plants have both sexes on the same plant, and they can be self-pollinated: pollen from one plant is used to fertilize ovules from the same plant. This is a closer cross than is possible with animals. He found 7 lines of peas that differed from each other for 7 distinct traits.
Background image of page 2
Mendel's Traits
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Monohybrid Cross We are first going to look at what happens when plants with different traits are crossed, then go through Mendel's explanation. Purple flowers vs. white flowers. The original parental lines are true-breeding , or pure-breeding. All offspring within the lines gave the same flower color for an arbitrary number of generations.
Background image of page 4
First Cross True-breeding purple x true-breeding white. All offspring are purple. The parent lines are the P generation; the offspring are the F1 (first filial) generation. All the F1's are purple regardless of which parent (father or mother) was purple and which was white. Note: no blending occurs. The purple F1 plants look exactly like the purple parentals. We say that purple is dominant because it appears in the F1 hybrid. White is recessive because it does not appear in the F1 hybrid.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Selfing the F1 Self-pollinate the F1 plants to get the F2 (second filial) generation. In animals with only 1 sex per individual, the equivalent would be a brother-sister mating. The F2 appear in a ratio of 3/4 purple to 1/4 white. Note: white has re-appeared in the F2, unchanged despite having been in a purple F1 plant. The genes are not affected by the organism that carries them.
Background image of page 6
Selfing the F2 Each F2 plant is selfed to produce a group of F3 offspring. The F3 offspring of the white F2's are all white.
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/24/2011 for the course STEP 1 taught by Professor Dr.aslam during the Fall '11 term at Montgomery College.

Page1 / 22

mendel - Basic Mendelian Principles Mendels big...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online