10-3GENE LINKAGE AND

POLYPLOIDY

WHY ARE CERTAIN TRAITS INHERTITED

TOGETHER?HOW CAN BERRIES BE GENETICALLY

ENGINEERED TO MAKE THEM TASTE SWEETER?

OBJECTIVES

• WHAT IS GENETIC RECOMBINATION?

• WHAT IS A CHROMOSOME MAP?

• HOW DOES MEIOSIS RESULT IN GENETIC RECOMBINATION?

GENETIC ENGINEERINGYES/ NO

• Some individuals are purists and consider genetically modified plants to be an aberration of nature. They prefer to grow plants the traditional way. For Example, when scientists release genetically modified roses into the marketplace, consumers might have a difficult time finding the traditional kinds of roses

that are not modified genetically.• Read more: The Disadvantages of Genetically Modified Roses:• eHow.com http://www.ehow

.com/list_7665137_disadvantages-genetically-modified-roses.html#ixzz1nXD7qoVB

UNEXPECTED CONSEQUENCES

• Those who plant genetically modified roses may find that these roses become too hardy and that the gardeners are unable to get rid of them using herbicides. This problem is an example of the unpredictable nature of genetically modifying plants and other organisms. Scientists do not always fully understand how genetically modifying a particular organism will affect that organism, and this tinkering might create undesirable side effects. While the initially modified roses might have desirable properties, when these plants reproduce, there is less certainty about which genes in the rose will be passed on to a new generation and which genes won't.

• Worldwide over 100 incidents of illegal or unlabelled GE contaminationhave been documented in 27 countries on 5 continents - and thoserepresent only the recorded incidents.

INTERNATIONAL CONCERNS

• http://www.gmcontaminationregister.org/

Genetic Recombination

• The new combination of genes produced by crossing-over and independent assortment is called Genetic Recombination

• Possible combinations can be calculated: 2 to the n power where n is the number of chromosome pairs.

• Example: Peas! 7 pairs of chromosomes• 2 to the 7th power = 128 possible combinations• Because any male gamete ( sperm) can potentially fertilize any

female gamete( egg) the total possibilities would be:• 127 x 127 or 16,384 potentially different combinations• Humans? 2 to the 23rd power x 2 to the 23rd power = 70

trillion possibilities! (and this is without crossing over)

Location Location Location

• Cromosomes contain genes• Chromosome pairs will contain gene pairs called

alleles (Dominant,D or Resessive,d)• Genes are made of sequences of DNA• DNA is made of pairs of bases ( A - adenine, T -

Thymine, G - Guanine, and C - Cytosine) A pairs with T (AT) and C pairs with G ( CG)

• The base pairs are inside the double helix, the sugar, deoxyribose and phosphate are on the outside

Gene Linkage

• Genes code for proteins• Genes that are close to each other on the same chromosome

are said to be “linked.”• Genes that are linked on the same chromosome usually do not

independently assort• Fruit fly was used to study linkage• When crossing over occurs, genes that are close together in

location on a homologous pair may be linked and cross to the other chromosome together

• A map shows the locations of genes on a chromosome.• A map shows “ relative position” and not exact distance.• One map unit is equivalent to 1% cross over

Polyploidy

• Polyploidy refers to multiple extra chromosomes• The most frequently found situation is diploid, or chromosomes

in pairs.• New designation for an extra sets of chromosomes: 3N• Rare in animals (Earthworms. Goldfish) - Lethal in Humans• 1/3 of flowering plants are polyploid• Wheat 6N, Sugar 8N• Genetically engineered for ability to survive ( vigor) or for size

and taste