Unit Four: The Continuity of Life
Part One: DNA, RNA, and Protein Synthesis (Ch. 12)
Part Two: Mendelian Genetics (Ch. 11)
Part Three: Biotechnology (Ch. 13 & 14)
Part Four: Evolution and the Origins of Life (Ch. 15, 16 & 17)
Part Two: Mendelian Genetics
Chapter 11: pages 263 – 283
Objectives:
1. Describe Gregor Mendel, his experiments, and his conclusions
2. Demonstrate your understanding of Genetics by completing one factor and two factor crosses using
Punnett squares.
3. Explain how geneticists use the principles of probability.
4. Explain what a test cross is by completing a problem.
5. Describe the process of meiosis: the process, the results, and how it differs from mitosis
Assessments:
See Assessment sheet 
Vocabulary:
Genetics
Fertilization
True-breeding
Trait
Hybrid
Gene
Allele
Gamete
Punnett square
Homozygous
Heterozygous
Phenotype
Genotype
Polygenic traits
Homologous
Diploid
Haploid
Meiosis
Tetrad
Crossing over
DF
Unit Four: The Continuity of Life
Part Two: Mendelian Genetics
Name: ________________________________
Mr. DePhillips
Genetics Assessments
You Earned:
Vocabulary
Everyone must take the Root Word Pre-Quiz
12 pts
________ pts
Activities & Labs
Everyone must complete “Dragon Genetics” lab
40 pts
Everyone must complete “Coin Flip” lab
30 pts
Everyone must complete “Investigating Human Traits” lab
Bonus Anchor: Tri-Hybrid Cross
20 pts
________ pts
________ pts
________ pts
+10
Homework & Practice
Punnett Square Practice Sheet
Human Characteristics
2 Factor Punnett Square Practice
10 pts
10 pts
15 pts
________ pts
________ pts
________ pts
Review
Everybody MUST COMPLETE the Genetics Problems Review
20 points
________ pts
Formal Assessments
Everyone must take the Pop-Quiz
Everyone must take a PSSA-based Exam
15 pts
75 pts
________ pts
________ pts
DF
Unit Four: The Continuity of Life
Part Two: Mendelian Genetics
Name: _________________________
Mr. DePhillips
Introduction to Genetics Notes
Who is Gregor Mendel? What did he study? Name his important ideas.
Plant cells can reproduce in two ways…
____________ = male pollen fertilizes a female ovum from the same flower
____________ = male pollen and female ovum are from different individuals/flowers
What is a pure breed (true breed)?
Mendel decided to cross ‘pure plants’. He received surprising results…
Pea color
Pure yellow peas X Pure yellow peas = _______________(what color seeds?)
Pure green peas X Pure green peas = ________________
Pure green peas X Pure yellow peas = ________________
Pea shape
Pure round peas X Pure wrinkled peas = ________________ (what shape peas?)
What is the name of an offspring that has different traits than its parents?
When Mendel crossed the pure plants having different traits…he observed something…one trait is covered up!!
The trait that covers up another trait is known as _____________________
The trait that is covered up is known as _______________________
What are the factors that control traits?
Define ‘allele’:
Examples…
Trait
=
Alleles =
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When making offspring, each parent gives half the total number of chromosomes to the child.
Example:
Humans have 46 chromosomes total. We have 23 pairs of chromosomes.
We get one set of chromosomes (23) from ‘mom’ and one set of pairs (23) from ‘dad’.
Each of the chromosomes can have a different allele for on trait. For example…
In pea plants…
Y = yellow
y = green
A plant can be…
YY
(yellow-yellow)
Pure yellow
_____________
Yy
(yellow-green)
Hybrid yellow
_____________
yy
(green-green)
Pure green
_____________
The Y in the hybrid plant is dominant over the recessive y. The plant is all yellow.
Define ‘Homozygous’
Define ‘Heterozygous’
Label the blanks in the above example as either ‘homozygous’ or ‘heterozygous’
Complete the ‘Should This Dog Be Called Spot” worksheet…for more information and problems…
Punnett Square Instructions
To figure out the probability (chances) of the traits an offspring can inherit from its parents, we need to figure out
the possible allele combinations the parents can give…so we use a Punnett Square…
In pea plants, for pea color…
Y = dominant = Yellow
y = recessive = Green
Two pea plants are mated. The ‘father’ is Yy (yellow), and the mother is also Yy (yellow)
(I MUST always give this bold info to you for any problem you need to complete!!)
The new plant can get a Y or a y from ‘dad’, and a Y or a y from ‘mom.
We need to set up a Punnett Square to see all the combinations the offspring can get.
1.
2.
3.
4.
5.
Place the father’s two alleles along the top of the chart, one on each column.
Place the mother’s two alleles along the side of the chart, one next to each row.
Complete the chart by placing the two letters (one from the top, one from the side) in each box
Be sure each box has 2 letters…one from mom and one from dad.
Write your results outside the box…count up Genotype and Phenotype.
Results: (Also…define these words…)
Genotype:
Phenotype:
DF
Unit Four: The Continuity of Life
Part Two: Mendelian Genetics
Name: _____________________________
Mr. DePhillips
How to do a “Two Factor Cross”
When the individuals you need to cross have TWO DIFFERENT traits, then you need to complete a larger two
factor Punnett square. “Dihybrid” refers to 2 parents who are both heterozygous (hybrid) for 2 traits.
In pea plants…
Y = Yellow = Dominant
y = green = recessive
R = Round = Dominant
r = wrinkled = recessive
PROBLEM: Cross two parent pea plants, both of who are heterozygous for Yellow, Round seeds.
How many letters does each parent usually have for one trait? _____
How many traits are we looking at for these plants? _____
What is the total numbers of letters one parent/individual will have for this problem? _____
1
Write the parents’ genotype.
- both of these parents are the same.
- both are heterozygous for BOTH traits.
2
Find all the possible gametes.
- when using one trait…how many letters give one parent give? _______
- now that we are using two traits, how many letters will each parent give? ________
For color…what are the two possible allele choices that one of these parents can give? ___ or ___
For shape…what are the two possible allele choices that one of these parents can give? ___ or ___
Branching Tree Method
F.O.I.L. Method
3
Write the gametes on the top and on the side of a 16 block Punnett Square.
- see the prepared Punnett Squares on the back of this page!!!
4
Fill in the Punnett Square.
- How many letters will be in each block? _____
5
Count the PHENOTYPES of the offspring. Counting genotypes would drive you crazy!
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