Transcript The genotypic ratio is

Wednesday/Thursday 1/7-1/8/2015
Agenda: Welcome Back!!




Notes: Intro to Genetics
Activity: Brain Pop and Worksheet
Activity: Genetic Terms Review
Activity: Monster Genetics (due in class)
Homework/Class Work:
1. Monster Genetics due Today for 50 Points
(Grade Book)
2. Homework: Genetics Practice Problems
worksheet due Friday 1/9/2015 for 10
Points
1. Chimp’s & human’s DNA are 98% identical.
2. The father determines the sex of the offspring.
3. A genetic blood disorder can make your skin look blue.
4. A person may transmit characteristics to their offspring
which he/she do not show themselves.
5. Geneticists have created a potato that can self destruct.
6. We share 40-50% of our DNA with cabbages
7. Scientists estimate that 99.9 percent of the DNA of most
humans is identical.
8. Each parent contributes half of their child’s genetic make-up.
9. Henrietta Lacks was a woman with a mutation who had
immortal cells, who later died of cervical cancer (kidney injury)
10. Humans share 50% of their DNA with bananas.
Q3 WK1 D1
Jan. 7, 2013
THE FIELD OF BIOLOGY
DEVOTED TO
UNDERSTANDING HOW
CHARACTERISTICS
ARE PASSED FROM PARENT
TO OFFSPRING.
GREGOR MENDEL
(1823 – 1884)
• AUSTRIAN MONK WHO STUDIED MATH &
STATISTICS.
• HE BECAME KNOWN AS THE “FATHER OF
GENETICS”.
• HE CONDUCTED EXPERIMENTS ON PEA
PLANTS.
MENDEL’S PEA PLANT EXPERIEMENTS
• He observed 7 characteristics of pea plants
• each characteristic had only 2 contrasting traits.
- height
- flower position along the stem
- pod appearance
- pod color
- seed texture
- seed color
- flower color
MENDEL’S EXPERIMENT
1. GREW ONLY PLANTS THAT WERE PURE FOR EACH
TRAIT.
-he had plants self-pollinate for several
generations.
2. CROSS-POLLINATED CONTRASTING TRAITS.
-ex: he crossed a yellow pod plant with a
green.
3. THE 1ST CROSS WAS LABELED AS THE PARENTAL
GENERATION (P).
4. THE OFFSPRING WERE LABELED AS THE F1
GENERATION
5. MENDEL ALLOWED THE F1 GENERATION TO
SELF-POLLINATE & THOSE OFFSPRING
WERE THE F2 GENERATION.
MENDEL’S RESULTS
• AFTER CROSSING A PURE GREEN PODDED PLANT (P) WITH
A PURE YELLOW (P) ALL OF THE OFFSPRING WERE
GREEN.
• AFTER THESE OFFSPRING (F1) WERE CROSSED THE
RESULTING OFFSPRING (F2) CAME OUT TO A 3 TO 1 RATIO
FOR GREEN PODDED PLANTS.
MENDEL’S LAWS
• LAW OF SEGREGATION - two alleles for a character will separate when a gamete
is formed
• LAW OF INDEPENDENT ASSORTMENT:
-The factors for different characteristics
are not connected
QUESTION
EXPLAIN WHY MENDEL GOT THE
RESULTS HE DID WITH THE PARENTAL
GENERATION?
ANSWER
Because the green color is considered
dominant & it covers or masks the yellow
color trait (recessive)
QUESTION
If all of the offspring were green and
then they were cross pollinated, why
didn’t these offspring come out all
green?
ANSWER
Because the offspring from F1
generation carried a hidden
yellow factor that could be
passed on to the offspring of F2
generation.
The Testcross
• A genetic procedure devised by Mendel to determine an
individual’s actual genetic composition
• A purple-flowered plant can be homozygous dominant (PP)
or heterozygous (Pp)
• One cannot tell by simply looking at the phenotype
• One can tell from the results of a cross between the test plant and
a homozygous recessive plant
How Mendel used the testcross to detect heterozygotes.
BRAIN
POP:
HEREDITY
https://www.brainpop.com/science/cellularlifeandgenetics/heredity/
GENETIC TERMS
• Gene: a sequence of DNA that encodes for a certain trait
• Allele: one of two (or more) alternative forms of a gene (a
single letter)
• Dominant Allele: an allele that dictates the expression of a
trait (capital letter, ex: A)
• Recessive Allele: an allele whose trait is masked by the
presence of a dominant allele (lower case letter, ex: a)
TERMS
• Genotype: genetic make-up of an organism (letter
combination)
• Phenotype: physical appearance of an organism (its
outward appearance)
• Homozygous: both alleles in a gene pair code for the
same trait (ex: AA or aa)
• Heterozygous: the two alleles in a gene pair that do
not code for the same trait (ex: Aa)
TERMS
• Sex Chromosome: the chromosome that determines the sex
of an organism (the X and Y chromosome)
• Autosome: any chromosome that is not a sex chromosome
• Punnett Square: a chart which shows all possible gene
combinations in a cross of parents
• Monohybrid cross: a cross between two individuals for one
trait (ex: Aa x Aa)
• Dihybrid cross: crossing two different characteristics at the
same time (AaBb x AaBb)
Friday, January 9th, 2015
Agenda: Welcome Back!!
 Notes: Genotypic vs. Phenotypic Ratios
 Activity: Monohybrid Cross Practice
Homework/Class Work:
Genetic Practice Problems II Worksheet due
Monday 1/12/2015 for 15 Points
Genotypic Ratio VS Phenotypic
Ratio
• Genotypic Ratio: the number of times each genotype appears
in the offspring. Written from most dominant trait to the
recessive.
( # of AA, # of Aa, # of aa)
• Phenotypic Ratio: the number of times each phenotype
appears in the offspring. Written from the dominant trait to
the recessive.
(# of dominant, # of recessive)
Punnett Squares
• A Punnett square is a chart which shows all possible
gene combinations in a cross of parents.
• Horizontally across the top of the chart are the
possible gametes of one parent.
• Vertically down the side of the chart are the
possible gametes of the other parent.
• In the boxes of the chart are the possible genotypes
of the offspring.
TT x tt
T
T
t
Tt
Tt
t
Tt
Tt
LET’S TRY ONE!!!!
*Brown = dominant*
B= brown eyes
Bb x bb
b= blue eyes
The genotypic ratio is:
0:2:2
The phenotypic ratio is:
2:2
B
b
b
B b
b
b
B
b b
b
b
C= Straight hair
c= curly hair
GENOTYPIC RATIO:
1:2:1
CC:Cc:cc
Homozygous dominant:
Heterozygous:
Homozygous recessive
Monohybrid Cross:
two heterozygous
individuals
Cc x Cc
PHENOTYPIC RATIO:
3:1
Straight:curly
Dominant:Recessive
C
c
C
CC
Cc
c
Cc
cc