Transcript BI0 10-3 P0WERPOINT

10-3
GENE 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 ENGINEERING
YES/ 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_disadvantagesgenetically-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