what is genetics? a brief review.. greetings understanding genetics
TRANSCRIPT
What is Genetics?
A Brief Review..Greetings
Understanding Genetics
The study of how traits are passed on from one organism to it’s offspring.Each cell has chromosomes in the nucleus.Chromosomes contain DNA, which determine the genetic make-up of an organism.
Chromosomes
The Father of Genetics
• Gregor Mendel• Monk-liked pea plants• Bored with religion• Cross pollinated pea
plants• Tall = dominant (T)• Short = recessive (t)• Dominant more powerful
than recessive
Peas
Trait ExpressionTrait Expression• DominantDominant
• Stronger traitStronger trait• Seen most oftenSeen most often• Demonstrated Demonstrated
with a CAPITAL with a CAPITAL letterletter
• Expressed if Expressed if present with a present with a recessive generecessive gene
• RecessiveRecessive• Weaker traitWeaker trait• Seen less oftenSeen less often• Demonstrated Demonstrated
with a lower case with a lower case letterletter
• Not expressed if Not expressed if present with a present with a dominant gene, dominant gene, but not lost….but not lost….
Homo/Heterozygous Homo/Heterozygous TraitsTraits
Homozygous• Purebred• Can be
dominant or recessive
• Both genes are the same
• TT or tt
Heterozygous• Hybrid (mutt)• One dominant
gene, one recessive gene
• Both genes are different
• Tt
Heterozygous and Homozygous
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Genotype and Phenotype
Genotype The genetic makeup of
an organism For example
TTTttt
Phenotype The outward expression of a
gene For example
Tall or short Brown or blue eyes Straight or curly hair
Genotype and Phenotype
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Incomplete DominanceIncomplete Dominanceo Neither is stronger Neither is stronger
than the otherthan the othero Offspring is Offspring is
blended, a blended, a combination combination between both traitsbetween both traits
o For instance, red For instance, red flower mated with flower mated with white flower = pinkwhite flower = pink
Punnett Square Movie
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Punnett SquaresPunnett Squares Tall = (TT) X Short (tt)
t
t
Tt Tt
Tt Tt
T T
Punnett Squares Tall = (Tt) X tall (Tt)
T
t
TT Tt
Tt tt
T t
Punnett Squares Tall = (Tt) X Short (tt)
t
t
Tt tt
Tt tt
T t
The EndThe End Words to rememberWords to remember
DominantDominant RecessiveRecessive HomozygousHomozygous PurebredPurebred HeterozygousHeterozygous hybridhybrid Punnett SquarePunnett Square Incomplete Incomplete
DominanceDominance