Transcript Fundamentals of Genetics

Chapter 9 Lab Bio
Chapter 12 Honors Bio
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Brainstorm:
- define genetics
- define heredity
Anticipatory Set:
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How important is it to be able to find your own
answers to questions you may face?
Does education and learning end with your high
school or college years?
How do you plan to develop the skills to become a
life long learner?
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The study of how characteristics
are transmitted from parent to
offspring
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The transmission of
characteristics from parent to
offspring
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Chromosome: structure within nucleus, made
of DNA
Gene: unit of heredity found in DNA molecule
(words)
Allele: symbols (letter) used to represent genes
ex: T=tall, t=short
Dominant: trait/characteristic that are
expressed – represented with capital letter
Recessive: trait/characteristic that may not be
expressed (always lower case) ex: t=short
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Homozygous/pure: both alleles are alike ex:
TT or tt
Heterozygous/hybrid: alleles differ ex: Tt
Genotype: genetic make up ex: pure
)homozygous) tall, hybrid (hetero.) tall
Phenotype: what you see (physical appearance)
ex: tall, short
Cross: symbolic of reproduction ____ X _____
P: parent generation
F1: first generation
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Do you think that we could make as many
discoveries in science if we didn’t use animals?
Explain…..
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!
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Austrian Monk
Studied garden pea plants (Pisum
sativum)
1842 he entered the monastery in
Austria
1851 enetered Univ. of Vienna to
study science and mathematics
(statistics)
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Observed 7 characteristics each in 2 contrasting
traits:
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Long  short stems
Axial  terminal (flower position)
Green  yellow (pod color)
Inflated  constricted (pod appearance)
Smooth  wrinkled (seed texture)
Yellow  green (seed color)
Purple  white (flower color)
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He controlled how pea plants were
POLLINATED!!!
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SELF POLLINATION=pollen is transferred from
anthers (male) of a flower to stigma (female) of same
flower or flower on the same plant
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CROSS POLLINATION=involves flowers of 2
separate plants
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1. remove anthers from a flower
2. manually transfer the anther of a
flower on one plant to stigma of a
flower on another plant
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P1 (cross)
yellow x green
Law of Dominance
F1
ALL GREEN
F1 (cross)
green x green
Law of Segregation
F2
¾ GREEN, ¼ YELLOW
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Mendel hypothesized that the trait appearing
in the F1 generation was controlled by a
DOMINANT FACTOR because it masked, or
dominated, the other factor for a specific
characteristic.
RECESSIVE is the trait that did not appear in
the F1 generation but reappeared in the F2
generation.
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A pair of factors (alleles) is segregated (or
separated) during the formation of gametes
Each reproductive cell (gamete) receives only
one factor of each pair.
Crossed two heterozygous green plants!
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He also crossed plants with 2 different
characteristics
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Ex: flower color & seed color
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FACTORS FOR DIFFERENT CHARACTERISTICS
ARE DISTRIBUTED TO GAMETES
INDEPENDENTLY.
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Ex: Pure tall yellow x pure short green
TTYY
x
ttyy
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A GENE is the segment of DNA on a
chromosome that controls a particular trait.
Chromosomes are in pairs i.e.
Genes occur in pairs (each of several alternative
forms of a gene is called an ALLELE
MENDEL’S FACTORS ARE NOW KNOW AS
ALLELES!!!!!!
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CAPITAL = Dominant alleles
Lower case = recessive alleles
Example: G = green color (dom.)
g = Yellow pod color (rec.)
When gametes combine in fertilization
offspring receive ONE ALLELE for a given trait
from EACH PARENT!
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Helps us predict the likely outcome of
offspring!!
1. genotype: genetic make-up, consists of
alleles
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Ex: P=purple,
Pp = purple
PP = purple
White = pp
p=white
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2. Phenotype = appearance of an
offspring (what you see)
 Ex: purple flowers, white
flowers, hair color
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3. Homozygous = when both
alleles of a pair are alike
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tt, TT, PP, pp
 Homozygouse recessive = pp
 Homozygouse dominant = PP
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4. Heterozygous = two alleles in
a pair are different
 Ex:
Pp or Tt
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Law of Dominance
Law of Segregation
Test Cross
MENDEL’E RULES DO NOT APPLY TO:
Incomplete dominance
Multiple alleles
Codominmanmce
Polygenic inheritance
Pleiotyropy
Environmental influence
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Law of dominance
Law of segregation
Test cross
Incomplete dominance
Codominance
Independent assortment
Sex determination
Sex linkage
Multiple alleles