Transcript Intro to Mendelian Genetics ppt

Admit Slip:
Write question # and answer in journal
• 1. You toss a coin in the air, what are the odds that it will
land on heads?
• 2. You toss a coin in the air, what is the probability that
it will land on tails?
• 3. You toss a coin in the air twice, what is the probability that it will
land on tails both times?
• 4. A couple is about to have their first child. What is the probability
that it is going to be a boy?
• 5. A couple has two children, both girls. What are the chances that
their next child is also going to be a girl?
• 6. What is another term for probability?
• 7. What is the likelihood that a couple will have a girl after their first
four tries resulted in boys?
• 8. If you toss a coin 4 times and it lands on tails all 4 times. What is
the chance that it will land on heads the fifth time?
Date
1/5/16
Topic
Page
Intro to Mendelian Genetics ???
Admit Slip: Complete the probability handout
Homework: Spongebob Genetics Handout
Content objectives: SW demonstrate their understanding of
inheritance as a game of chance
Language objectives: Define inheritance, probability,
hemophilia, acquired
Today’s Agenda:
1. Pass back old work!!!
2. Discuss Science Fair
3. Mendelian Genetics Notes
4. Punnet Square Practice
5. Spongebob Genetics handout
Outcome: Students will discover their luck in the inheritance game
Exit Slip: Students recall
Eye Dominance
Aim Here!
Gregor Mendel
• Modern genetics began in the mid1800s in an abbey garden
• Gregor Mendel documented
inheritance in peas
– used experimental method
– used quantitative analysis
• collected data & counted them
Gregor Mendel
• Father of Genetics
• Studied pea plant
• Genes come in pairs
– You get one from each
parent
• 1. Law of segregation
(as cells divide, pairs of
chromosomes separate)
• 2. Law of independent
assortment
(chromosomes line up
randomly during cell
division)
Traits
• Traits - characteristics or features
that make up the individual.
– Examples: eye color, hair type, nose shape etc.
Traits are inherited as discrete units
• For each characteristic
(ex. hair color)…
– an organism inherits 2 alleles, 1 from
each parent (diploid organism only)
– diploid organism
• inherits 2 sets of chromosomes,
1 from each parent
• homologous chromosomes
• like having 2 editions of encyclopedia
– Encyclopedia Britannica
– Encyclopedia Americana
Genes
• Genes - section of DNA that control your
genetic make up.
–
–
–
–
Determine your traits
Located on chromosome
Inherited in pairs
One from each parent
Genotype
• Genotype- the alleles that an organism has
– Genotype is the letters that represent a trait
– Upper case letters indicate dominance
• TT, BB
– Lower case letters usually indicate recessiveness
• tt, bb
Phenotype
• Phenotype- the physical representation
of the genotype (what you can see)
• So if someone has the genotype BB for hair
color…
• The phenotype is brown hair
• (It’s the physical outcome of the genes)
Allele
• Alleles are the different versions of a gene
– The gene for tallness is represented by letters
TT, Tt, and tt.
– The alleles are either “T” or “t”
– Ex. “T” or “t”
Homozygous
• When both alleles (versions of a gene) are
identical.
• The genotype is said to be
– homozygous (homo = same)
– Examples: TT, tt, BB, RR, yy
Heterozygous
• When the two alleles
(versions of a gene) are different.
– The genotype is said to be
– heterozygous (hetero = different)
• Examples: Tt, Bb, Rr, Yy,
Dominant Genes
• A dominant allele is expressed
regardless of other allele
– Ex: TT = Tall, Tt =Tall
Recessive Gene
• A recessive traits are only expressed
when both alleles are present.
– tt = short
– bb = blue
Note: “gene” “allele” and “trait” all
pretty much mean the same thing!
Punnett Squares
• A Punnett square is a table used to predict
the outcome of a cross
– A basic square has 4 boxes
• Genotypes of parents are shown
– One parent is on the top
– One parent is on the left side
Mendelian Cross: TT x TT
• T = tall plant, t = short plant
• List the 4 possible parental
gametes (alleles)
• Complete the punnett
square
• List the % of tall plants
• List the % of short plants
Mendel Cross: TT x tt
• List the 4 possible parental
gametes (alleles)
• Complete the punnett
square
• List the % of tall plants
• List the % of short plants
• List the genotype of the F1
Mendelian Cross: Tt x Tt
• List the 4 possible parental
gametes (alleles)
• Complete the punnett
square
• List the genotypes of the F1
generation (meaning first
generation):
Lets Practice Some More
• In some flowers, purple (P) is dominant and
white (p) is recessive.
• Use a Punnett square to predict the chances
of two heterozygous parents producing a
white-flowered offspring.
More Practice
• In humans, brown eyes (B) are dominant to
blue eyes (b).
• A heterozygous man and a blue-eyed
woman have a son. What is the probability
that he has brown eyes?
Recessive
Dominant
Dominant
Recessive
Dominant/Recessive
• https://www.youtube.com/watch?v=mnSkz
8s-b44
SpongeBob Genetics Practice