*Genetics* The Basics Slide 2 Humans have 23 pairs of
chromosomes Slide 3 Lets Examine This Karyotype! 1.Look at pair #19
2.Where do you think both of these chromosomes came from? 3.One
from your MOM and one from your DAD! 4.Hair color is determined by
genes found on chromosome #19 Slide 4 AllelesGenesand Traits oh
my!! 1.GENES Chemical factors found in DNA that determine our
traits! 2. Traits Characteristics that vary from individual to
individual (ex: hair color, eye color, skin color, widows peak.) 3.
Alleles Are different forms of genes. BLACK HAIR vs RED HAIR Slide
5 Alleles are represented in Biology by LETTERS. Lets Use Letter B
right now! (B)BIG LETTERS represent Dominant Traits Black hair is
dominant (b)LITTLE LETTERS represent Recessive Traits Red hair is
recessive Dominant RECESSIVE Slide 6 Each Person has 2 Alleles for
each trait! Question? Where did these 2 alleles come from? Answer:
1 came from MOM and 1 came from DAD BB bb Slide 7 Lets Remember
This Karyotype! 1.Look at pair #19 2.Keanu got one B allele for
hair color from his MOM and one B from his DAD BB Slide 8 GENOTYPE
vs PHENOTYPE Genotype =the genetic makeup of an organism (THE
LETTERS) There are only 3 options: BB, Bb, bb Homozygous- both
alleles same Heterozygous- alleles are different Phenotype = the
physical characteristic of the organism (WHAT YOU SEE) Tell me what
you see! Slide 9 A Widows Peak is a dominant trait! Lets represent
it with a W W=widows peak (D) w=no widows peak (R) Question: What
is the babys PHENOTYPE? Widows peak! Question: What is the babys
GENOTYPE? BB or Bb Slide 10 PRACTICE ONE MORE TIME! Question: What
are the phenotypes of these girls? Left and Right. Left-rolls
tongue Right-no rolling Question: There is only one girl that I
know the EXACT genotype. Which one is it? Right girl=rr Tongue
Rolling is a Dominant Trait! R=rolling tongue (D) r=no rolling (R)
Slide 11 Dominant traits show up more often! 2 Possible Genotypes
for a dominant trait RR or Rr Only 1 possible genotype for a
recessive trait rr Question? If you were Rr, what does that mean
for your kids? Slide 12 Keanu Reeves has black hair and a widows
peak Lets say Keanu is homozygous dominant (BB) for his black hair
but he is heterozygous (Ww)for his widows peak. What traits could
he give to his kids? Slide 13 Segregation Segregation is the
separation of alleles during gamete formation Gametes are
specialized cells involved in sexual reproduction Ww When Keanu
makes his sex cells (sperm) his alleles for widows peak will
separate W w Can Keanu give both his alleles to his kids? Slide 14
LAW OF INDEPENDENT ASSORTMENT Is Keanus black hair trait hooked to
his widows peak trait? NO WAY! Principle of Independent Assortment
Genes for different traits can segregate independently during the
formation of gametes Slide 15 Keanus Black Hair 1 B 2 B Keanus
Widows Peak 3 W 4 w There are 4 options! 1 with 3 BW 1 with 4 Bw 2
with 3 BW 2 with 4 Bw Is it possible for Keanu to have kids that
have red hair? What about a widows peak ? Slide 16 Probability and
Punnet Squares Punnet Squares can be used to predict the outcomes
of genetic crosses. Probability is the likelihood that a particular
event will occur. Slide 17 LETS PREDICT PROBLEM: A mom and a dad
decide to have a baby. Both mom and dad are HETEROZYGOUS for a
widows peak. *first you musts figure out the genotype of the
parents!!!! What are their chances (%) of having a child who has a
widows peak? What are the chances of having a child who doesnt have
a widows peak? Slide 18 W W w w WW Ww wwWw 75% Widows peak 25% No
widows peak
