Transcript Genetics

Genetics
Who are you??
Different Traits







Widow’s Peak
Roman Nose
Bent little finger
Long Palmer Muscle
Pigmented Iris
Eye wink
Thumbs up
Genetics
 Study of how traits are
inherited through actions
of alleles
 Heredity = passing of
traits from parents to
offspring
 Traits are controlled by
GENES
 ALLELE = different
forms gene may have for a
trait
 Get one from each parent’s
sex cell
Gregor Mendel
 Austrian Monk
1856 – experimented with
garden pea plants
 Tried to predict what types
of flowers would be
produced from what he
know about parent plants
1866 – presented paper on his
findings
FATHER OF GENETICS
Gregor Mendel
 Purebred = organism that produces the same
traits
 Hybrid = two different alleles
 Tall x short = Tall
 What happened to the short?
 Dominant = covers up a recessive trait
 Recessive = trait that seems to disappear in a
population (will show with 2 recessive alleles)
Gregor Mendel
 Crossed plants from his tall x short cross
= 3 tall to 1 short
 3:1 ratio
 Studied 30,000 plants in 8 years
 Probability – helps you predict the
chance of something happening
 Repeatable patterns
Geno vs. Pheno
 Genotype = genetic makeup of organism
 Phenotype = physical trait that shows
Punnett Square
 Tool to predict results in Mendelian
genetics
 Capital letter = dominant trait ‘T’
 Lower case = recessive trait ‘t’
 Homozygous = same alleles TT or tt
 Heterozygous = different alleles Tt
Punnett Square
PARENT 2
PARENT 1
Punnett Square
T
TT x tt
Tall x short
t
t
T
Punnett Square
Tt x Tt
T
Tall x Tall
T
t
t
Since Mendel
 Incomplete Dominance = white
snapdragon x red snapdragon plants =
pink flowers
 Production of a phenotype intermediate
to those of 2 homozygous plants
Punnett Square
CHROMOBUGS
Since Mendel
 Multiple Alleles/Co dominance = trait
controlled by 2 or more alleles
 Blood type in humans
 A - dominant
 B - dominant
 O – recessive
 AB, OO, AA, AO, BB,BO
Since Mendel
 Polygenic Inheritance = group of gene pairs
act together to produce a single trait
 Eye-color
 Fingerprints
 Height, weight, skin color, etc
Sex Determination
Females have 2 ‘X’ chromosomes
Males have an
‘X’ and ‘Y’
chromosomes
Sex-Linked Trait
 Allele is carried on the
X chromosome
 Color blindness
 Hemophilia
X
Xc
X
XX
XXc
Y
XY
XcY
Recessive Genetic
Disorders
 Sickle-Cell Anemia
 RBC’s are sickle shaped
 Can’t deliver O2
 Can’t move easily
 Tissues may damage
 Cystic Fibrosis
 Thick mucus in lungs
 Hard to breathe
 Lung and pancreas damage
Chromosome
Mutations
 Nondisjunction = failure of
sister chromosomes to
separate during cell division
XX
XX
XX
X
X
X
X
XX
Chromosome
Mutations
 Trisomy
(3 chromosomes)
 Trisomy 21 =
Down’s Syndrome
X
X
X
X
X
XX
XX
XX
XXX
DNA Mutations
 Point Mutation
change in one base of the gene sequence.


The fat cat ate the wee rat.
The fat hat ate the wee rat.
 Frame-shift mutation
one or more bases are inserted or deleted


The fat cat ate the wee rat.
The fat caa tet hew eer at.
DNA Mutations
 Deletion: missing DNA


The fat cat ate the wee rat.
The fat ate the wee rat.
 Insertion
addition of extra


The fat cat ate the wee rat.
The fat cat xlw ate the wee rat.
DNA Mutations
 Inversion
an entire section of DNA is reversed


The fat cat ate the wee rat.
The fat tar eew eht eta tac.
Why are Mutations
Harmful?
 Too much, too little, or incorrect genetic
information =


Changes the message that goes to the ribosomes
Cannot make the correct proteins
Pedigrees
 Used to trace traits through a family
 Males =
 Females =
 Blank is normal
 All filled is affected
 Half filled = carrier
 Handout
Why is Genetics
Important?
 Genetic Engineering = science that
experiments with biological and chemical
methods to change DNA
 Produce medicine - insulin
 Genes inserted to change cell function
 Crop production
 Read page 143
Human Genome
Page 146