Transcript Living Things - Ms. D. Science C.G.P.A.
Genetics and DNA: The Science of Heredity Ms. De Los Rios 7th Grade 12.3 Probability and Heredity
Essential Question:
Why Don’t Offspring always look like their Parents?
How is Probability Related to Inheritance?
What Are Phenotype and Genotype?
Pgs. 420-425
Probability and Heredity – Vocabulary
Probability
– A number that describes how likely it is that a particular event will occur
Punnett square
– A chart that shows all the possible combinations of alleles that can result from a genetic cross
Pedigree
– A chart that shows the presence or absence of a trait according to the relationships within a family across several generations
Phenotype
– An organism’s physical appearance, or visible traits
Genotype
– An organism’s genetic makeup, or allele combinations
Homozygous
– Having two identical alleles for a particular gene
Heterozygous
– Having two different alleles for a particular gene
My Planet Diary p.420
Storm on the Way?
Have you ever watched a hurricane form? Weather forecasters at the National Hurricane Center (NHC) in Miami, Florida, have. From May 15 to November 30, the NHC Operations Area is staffed around the clock with forecasters. They study data from aircraft, ocean buoys, and satellites to develop computer models. These models predict the probable paths of a storm. If the probability of a certain path is high, the NHC issues a warning that helps save lives and reduce damage
.
Probability and Heredity – My Planet Diary p.420 Storm on the way?
Local weather forecasters often talk about the percent chance for rainfall. What do you think they mean?
_________________________________________________ _________________________________________________ _________________________________________________
What is probability?
Pg.421
• Probability will occur is a number that describes how likely it is that an event • Ex: probability that a tossed coin will land on heads = 50% • The laws of probability predict what is
likely
to occur, not what
will
occur • The more trials you do, the closer your actual results will be to those predicted by probability • When tossing a coin, one toss does not affect the result of the next toss – each event occurs independently
Do the math!
Step 1: write the comparison as a fraction 3 out of 5 = 3/5 Step 2: Calculate the number value of the fraction Step 3: multiply this number by 100% 3/5 = 0.6
0.6 x 100% = 60%
Punnett Squares and Pedigrees P.422-423
• A Punnett square is a chart that shows all the possible ways alleles can combine in a genetic cross • In a genetic cross, the combination of alleles that parents can pass on to an offspring is based on probability • The boxes in the Punnett square show the possible combinations of alleles that the offspring can inherit • A pedigree is a chart or “family tree” that shows the presence or absence of a trait according to the relationships within a family across several generations • Doctors us pedigrees to trace and diagnose genetic disorders
Probability and Heredity – Figure 1 p. 422-423 1. Determine the probability that an offspring will have wrinkled seeds.
____________________________________ 2. Determine the probability that an offspring will have round seeds.
____________________________________
Assess Your Understanding pg. 423
1a. Review- What is probability?__________________________
___________________________________________________ b. Apply Concepts- What is the probability that a cross between a hybrid pea plant with round seeds and one with wrinkled seeds will produce offspring with wrinkled seeds? (Draw a punnett square on another paper to find the answer) ___________________________________________________ I get it! Now I know that the combination of alleles parents can pass to offspring ___________________________________ ___________________________________________________
What are Phenotype and Genotype
p.424
phenotype genotype
An organism’s
phenotype
is its
physical appearance or, visible traits
Identical Alleles
SS or ss Homozygous
An organism’s
genotype
is its
makeup
or
allele
genetic
Different alleles
S s Heterozygous
An organism that has two
identical alleles
for a trait is said to be
homozygous
for that trait. An organism that has two different alleles for a trait is said to be
heterozygous
for that trait. Ss Recall that Mendel used the term
hybrid
to describe heterozygous
What are Phenotype and Genotype
p.424
The allele
for smooth pea pods
(
S
) is dominant. Therefore those with the
phenotype of smooth pods can have two genotypes
, SS or Ss The plants with a
phenotype of pinched pod
s would only only have one genotype, ss
Apply it! p. 425
Mendel ’s principles apply to many other organisms.
Example: In guinea pigs, black fur color (B) is Dominant over white fur color (b). Suppose a pair Of black guinea pigs produces several litters of Pups during their lifetimes. The graph shows the Phenotypes of the pups. Write a title for the graph.
1.How many black pups were produced? How many white pups?
______________________________________ 2.
What are the possible genotypes of the offspring?
____________________________ 3.
What can you conclude about the genotypes of the parent guinea pigs? Explain your answer
.
______________________________________________________________________ ______________________________________________________________________
Assess Your Understanding pg. 425
2a. Relate Cause and Effect- Explain how two organisms can have the same phenotype but different genotypes.
_________________________________________________________ ___________________________________________ b. Challenge- In their lifetime, two guinea pigs produce 40 black pups and 40 white pups. On a separate sheet of paper, make a Punnett square and find the likely genotypes of these parents. __________________________________________ ___________________________________________________
I get it, Now I know that phenotype and genotype are terms that describe
__________________________________________ ___________________________________________________