Genetics presentation ’10
-
Upload
lorraine-stratton -
Category
Education
-
view
225 -
download
0
Transcript of Genetics presentation ’10
Intro to Inheritance http://learn.genetics.utah.edu/content/begi
n/tour/inheritance.swf
04/14/232/3/03 10:39 AM 3
04/14/232/3/03 10:39 AM 4
Gregor Mendel (7/22/1822 - 1/6/1884)
“Father of Modern Genetics” Born in 1822 in Heinzendorf Moravia
in what is now the Czech Republic Born in Heinzendorf, Austria on July
22, 1822. He died in Brno, Austria January 6, 1884
Augustinian monk employed as high school natural science teacher for 20 years
04/14/232/3/03 10:39 AM 5
Gregor Mendel (7/22/1822 - 1884)
Experimented with garden peas Pisum sativum
Tested some 28,000 pea plants in 7 years Used artificial feritization Worked in limited space in monastery
garden First to consider single traits of
hybridization experiments results Devised precise mathematical pattern Did not understand biological process, eg.
chromosomes & DNA 1900 three botanists “discovered” his
papers while researching their own findings
Mendel, O.S.A., experimental garden (35x7 meters) in the grounds of the
Augustinian Monastery in Old Brno.Its appearance before 1922.
04/14/232/3/03 10:39 AM 6
Mendel’s Pea Plants Pisum sativum
Diploid Seven pairs of traits
• Axial / terminal flowers (Aa)
• Purple / white Flower coats (Pp)
• Tall / short (Tt)• Round / wrinkled (Ss)• Green / yellow seeds
(Gg)• Inflated / constricted
(Ii)• Green / yellow unripe
pods (Gg)
Mendel’s Pea Plants
Pisum sativum Mendel fertilized the
pea flowers and removed other underdeveloped reproduction parts before self-fertilization could take place.
04/14/232/3/03 10:39 AM 7
William Bateson, English Gave name genetics
based on Greek term "to generate"
Promoted Mendell's view of paired genes using term allelomorph, shortened to allele.
04/14/232/3/03 10:39 AM 8
04/14/232/3/03 10:39 AM 9
Basic Ideas Mendel used term unit
characters based on physical elements and occurring in pairs of allele. We now call these genes.
The paired genes (allele pairs) separate form one another and are distributed to different sex cells through meiosis
Mendel's 3 Laws1. The Law of
Dominance In a cross of parents
that are pure for contrasting traits, only one form of the trait will appear in the next generation. Offspring that are hybrid for a trait will have only the dominant trait in the phenotype.
04/14/232/3/03 10:39 AM 10
Mendel's 3 Laws2. The Law of
Segregation During the formation
of gametes (eggs or sperm), the two alleles responsible for a trait separate from each other.
Alleles for a trait are then "recombined" at fertilization, producing the genotype for the traits of the offspring.
04/14/232/3/03 10:39 AM 11
Mendel's 3 Laws3. The Law of
Independent Assortment Alleles for different
traits are distributed to sex cells (& offspring) independently of one another.
04/14/232/3/03 10:39 AM 12
04/14/232/3/03 10:39 AM 13
Terms Allele: an alternate form of a
gene. Variants that occur at the same locus.
Homozygous: having the same alleles for same trait
Heterozygous: having different alleles for same trait
Phenotype — physical looks of genes
Genotype — the actual genes Dominance — phenotypic
recognition Recessive —carriers
04/14/232/3/03 10:39 AM 14
Labeling:
The standard way of labeling the variation information of a trait in a particular organism is using two letters.
Capital letters represent information which is dominant.
Lowercase letters represent the recessive. The letter being used describes a variation (usually the recessive) of the trait.
GG stands for a plant where both pieces of color information are dominant - yellow. The plant is yellow.
Gg stands for a plant where one piece of color information is dominant - yellow, and the other is recessive - green. The plant is yellow.
Gg stands for a plant where one piece of color information is recessive - green, and the other is dominant - yellow. The plant is yellow.
gg stands for a plant where both pieces of color information are recessive - green. The plant is green.
04/14/232/3/03 10:39 AM 15
Pea Plant Traits
Trait:
Dominant
Expression:
Recessive
Expression:
1 Form of ripe seed Smooth Wrinkled
2 Color of seed albumen Yellow Green
3 Color of seed coat Grey White
4 Form of ripe pods Inflated Constricted
5 Color of unripe pods Green Yellow
6 Position of flowers Axial Terminal
7 Length of stem Tall Dwarf
04/14/232/3/03 10:39 AM 17
Examples of Phenotypes & Genotypes
Phenotypes for garden peas
Genotypes for garden peas
04/14/232/3/03 10:39 AM 18
Terms Codominance
Heterozygote expressing each allele equally
Semidominance Similar to codominance, but
not equal expression of both alleles
Filial Latin for progeny F1 -- F2 --
04/14/232/3/03 10:39 AM 19
Law of Probability The chance of two
or more independent events occurring together is the product of the chances for their separate occurrences.
04/14/232/3/03 10:39 AM 24
Monohybrid Cross, P1
Genotype Phenotype
Gg Green
Homozygous GreenX
Homozygous Yellow
04/14/232/3/03 10:39 AM 25
Monohybrid Cross, ƒ1
Genotype Phenotype
GG Green
Gg Green
gg Yellow
Heterozygous GreenX
Heterozygous Green
04/14/232/3/03 10:39 AM 26
Monohybrid Ratios
Genotypic Ratio 1:2:1
Phenotypic Ratio 3:1
# Genotype Phenotype #
1 GG Green 3
2 Gg Green
1 gg Yellow 1
04/14/232/3/03 10:39 AM 35
Dihybrid Punnett Square Genotypes
GGRR GGRr GgRR GgRr GGrr ggRR Ggrr ggRr ggrr
Genotypic Ratio 1:1:2:2:4:2:2:1:1
04/14/232/3/03 10:39 AM 38
Dihybrid Punnett Square
Phenotypes Green Round Green Wrinkled Yellow Round Yellow Wrinkled
Phenotypic Ratio 9:3:3:1
04/14/232/3/03 10:39 AM 40
Partial Dominance Example
Genotype Phenotype
RR Red
Rr Pink
rr White
Pink flowers
X
Pink flowers
04/14/232/3/03 10:39 AM 41
Epistiasis - two genes affecting property do not have equal vote
Example: melanin and melanin deposition (black, white, and brown coat of guinea pig). Black is dominant brown is recessive when melanin producing gene is present. Coat is white when no melanin is deposited.
04/14/232/3/03 10:39 AM 42
Collaboration - two genes interact to produce a novel phenotype Example: comb
types in chickens
04/14/232/3/03 10:39 AM 43
Multiple Gene Inheritance (polygenic)
Nilsson-Ehle's trigenic cross of wheat (10-8)
Frequency distribution (10-9)
04/14/232/3/03 10:39 AM 44
Sex-related Characteristics Holandric - genes
unique to Y chromosome, hair pinna on ears
Eye color in fruit flies Hemophilia Color blindness
04/14/232/3/03 10:39 AM 49
Webpage Links The Genetic Code - S.D. Black, U. of Texas Health Center at Tyler Table relating
nucleic acid triplet to the corresponding amino acid.
Molecular Biology - The Biology Project, Biology, University of Arizona Activities, Problems sets, and Tutorials: Molecular Genetics; Nucleic Acids; Recombinant DNA Technology; Eukaryotic Gene Expression
Prokaryotic Genetics and Gene Expression from the MIT Hypertextbook - M.I.T. Tools for studying prokaryotic genetics, biochemical genetics, Lac operation, etc.
The making of the nucleosome - D. Pruss Simplified images and a tour.
http://www.agen.ufl.edu/~chyn/age2062/lect/lect_10/lect_10.htm
http://www.borg.com/~lubehawk/mendel.htm
http://www.sonic.net/~nbs/projects/anthro201/disc/