Clarification on Testable Material

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Welcome back to IB 150...
Johns Hopkins Applied Physics Lab
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James Scholar Projects

• I will have two different projects
• a field-based exercise that will partly be done
  as a group
• NCBI based research papers
• Please email me for details or see me before or
  after class on Wednesday
• Prof. Hu may have opportunities to work in his
  lab - contact him if you are interested

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Integrative Biology Honors Program

• Full details at http//www.life.uiuc.edu/sib/honor
  s.htm
• Intensive core courses with small class sizes (30
  maximum) and heavy faculty participation.
• Emphasis on all areas of biology. Three core
  courses are Evolution of Molecules and Cells,
  Organismal Biology, Ecology and Evolution
• Upper division requirements can be met with both
  IB and MCB courses

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How To Sign Up

• Informational Meetings Tues. Feb. 7 and Wed. Feb
  8 at 7 PM in Burrill 140
• Applications due Feb. 17
• Interviews Feb. 22-24
• Successful applicants will be notified at the end
  of February.
• Attend either meeting. If you have questions
  before then please let me know

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Clarification on Testable Material

• Discussion material also testable (my mistake)
• All lecture material (all slides and statements I
  make) - unless I state specifically otherwise
• Lecture is about concepts - we can bring in other
  examples to illustrate concepts
• What I said is that topics in the text that I
  dont cover AT ALL wont be on the test

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An Example of Material that I Did Not Discuss

• Chapter 13 - entire chapter is assigned reading
• Figure 13.3 - Research Method - Preparing a
  Karyotype. This is not on the objectives and we
  did not mention this topic at all in lecture
• I told you that I would not test you on examples
  like this because I WANT YOU TO LEARN OTHER
  THINGS VERY THOROUGHLY

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An Example You DEFINITELY NEED TO KNOW

• How Meiosis Results in Variable Offspring
• Listed On The Objectives for the Lecture
• Mentioned several times in lecture
• Summary Slide - Not Much Detail
• Textbook has lengthy section on this topic - you
  NEED to read this to fill out the picture

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Some Really Important Conclusions Are Only Made
Verbally

• Last time - evolution of sex
• Talked about long-term advantage of sex and short
  term disadvantage - this was an important point.
• Didnt put this down on a slide - wanted you to
  think about it.

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Exam Questions

• Some will test basic facts - In what stage of
  mitosis do the sister chromatids separate?
• Others test for understanding, ability to
  transfer concept to a particular situation - A
  scenario in which sexual and asexual organisms
  colonize - ask for an interpretation of what
  happens.

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Lecture 6 Simple patterns of inheritance
Assigned Readings Ch. 14 Overview, 14.1, 14.2
What is Genetics? three different questions The
Basic Genetic Model is Based on
Meiosis particulate inheritance, segregation,
allele Some Genetic Terminology genotype,
heterozygote, homozygote, phenotype, dominant,
recessive Interactions Between Genes Dominance,
Influence of other loci, the environment  
Describe the sex life of a pea plant - read
textbook carpel stamens self-pollination
cross-pollination true-breeding
hybridization Understand Mendels experimental
design. Parental Generation F1 Generation F2
Generation, monohybrid cross Relate Mendels Law
of Independent Assortment to events that occur
during meiosis - Dihybrid Cross Understand how
Mendelian inheritance reflects laws of
probability. Rule of Multiplication Rule of
Addition
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What is Genetics?

• What does a gene do?
• How are genes passed from one individual to
  another?
• How do genes interact with one another to produce
  something?

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Genetics As A Tool

• Genetics is the growth industry of biology
• Tools of molecular genetics are used in many
  disciplines
• Proper use of those tools requires understanding
  of principles of genetics

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Question 1 What does a Gene do?
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Question 3 - How do genes interact with one
another?

• Interactions between alleles
• Interactions between loci
• Gene regulation
• Interaction with the environment
• Can get very complicated very quickly

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Question 2 - How are genes passed from one
individual to another?

• General Answer
• Genes are found at loci
• Diploid organisms have 2 copies of each locus
• Different versions of a gene are called alleles
• How does meiosis relate to the inheritance of
  genes?

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Genetics and Meiosis
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What are the Implications of this Model of
Inheritance?
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• Particulate Inheritance
• Two Copies
• Different Forms
• Random Segregation

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How Do You See What Will Happen?

• Coin Flip Experiment

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Testing the Model With Peas
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What Happened?

• Were the results what you expected?

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Some Terminology

• Heterozygote
• Homozygote
• Dominant
• Recessive
• Genotype
• Phenotype

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Dominance is one way that alleles interact with
one another

• Not necessarily the most common or typical way
• Easiest type of interaction for understanding
  Mendelian inheritance

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Genotype and Phenotype in Peas
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Dominance

• Flower color - dominant allele produces pigment,
  recessive allele does not
• Not the only way to have dominant and recessive
  alleles
• More next time

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Moving Mendel into the 21st century The
Mendelian gene that controls stem length in peas
is formally called Le. The two alleles are Le
and le le/le is a dwarf pea plant. This gene has
been recently sequenced. A single base change
changes a single amino acid in an enzyme that is
part of the chain of reactions that makes the
plant growth hormone gibberellin.
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The chemical pathway for gibberellin synthesis.
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How does this work, in more detail
Chemical Y
Chemical X
Gibberellin
Le makes a better enzyme 3, that makes a lot of
Gibberellin, and le makes much less. But Le/le
makes enough to grow normally.
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What does A gene for mean?

• Hypothetical graph of height in T/T, T/t, and t/t
  plants
• Gene influences height but is actually one of
  many factors that goes into that complex trait

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one coin toss genotype of one gamete
probability that two PP alleles will come
together at fertilization probability that two
coin tosses land heads up 1/2 x 1/2
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Heredity and Probability
Same laws that apply to coin tosses, dice
rolls Each toss or roll is independent Probabili
ties range between 0 and 1 MULTIPLY individual
probabilities to obtain the overall probability
of one or more events occurring together - when
there is an AND , use the Rule of
Multiplication ADD individual probabilities to
obtain the overall probability of an event that
can occur two or more different ways - when there
is an OR, use the Rule of Addition
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P (A and B) P(A) x P(B)
What is the probability that a woman who gives
birth 2 times will have 2 daughters?
P (first birth is a girl and second birth is a
girl) P (first birth is a girl) x P (second
birth is a girl)
Given that the probability of a daughter at any
birth is 1/2
P (A and B) 1/2 x 1/2
P (A and B) 1/4
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P (A or B) P (A) P (B)
In a cross between two heterozygous tall pea
plants, what is the probability that an offspring
will be tall (TT OR Tt)?
Heterozygotes are Tt and tall TT homozygotes are
also tall tt homozygotes are short
P (tall) P (Tt or TT) P (Tt) P (TT) P (Tt
or TT) 1/2 1/4 3/4
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What is the pattern of inheritance for alleles at
2 different loci?
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Lecture 6 Simple patterns of inheritance
Assigned Readings Ch. 14 Overview, 14.1, 14.2
What is Genetics? three different questions The
Basic Genetic Model is Based on
Meiosis particulate inheritance, segregation,
allele Some Genetic Terminology genotype,
heterozygote, homozygote, phenotype, dominant,
recessive Interactions Between Genes Dominance,
Influence of other loci, the environment  
Describe the sex life of a pea plant - read
textbook carpel stamens self-pollination
cross-pollination true-breeding
hybridization Understand Mendels experimental
design. Parental Generation F1 Generation F2
Generation, monohybrid cross Relate Mendels Law
of Independent Assortment to events that occur
during meiosis - Dihybrid Cross Understand how
Mendelian inheritance reflects laws of
probability. Rule of Multiplication Rule of
Addition