Heredity
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Transcript of Heredity
Biology 1BChapters 11 and 14
Heredity
1. Define heredity and identify the units of heredity.
2. Discuss the design, results and conclusions of Mendel’s monohybrid cross experiment.
3. Explain the principle of dominance and the
principle of segregation
Section 11.1 Objectives
From the same root word as “inherit”
Heredity describes the passing of traits from parents to offspring
Give examples of traits shared with family members:
Heredity
ProblemHow are traits passed from parents to offspring?
Many children resemble an aunt, uncle or grandparent more than they do their parents.
Some traits seem to “skip generations”Often traits are expressed in children that are
not observed in any other family member
ANY ACCEPTABLE HYPOTHESIS SHOULD BE ABLE TO ACCOUNT FOR THESE OBSERVATIONS
More Background
Alternative Hypotheses:Traits are inherited
from only one parentThis seems true in
many cases, because many children have a strong resemblance to either their mother or their father
Traits are inherited from both parentsThis seems true in
many cases also, because many children resemble both parents, and often have one trait similar to their father and another trait similar to their mother
Gregor Mendel – Historical PerspectiveMendel was an
Austrian monk in the mid 1800’s
Monks make contemplation and study a lifestyle.
Life at the monastery is largely self-sufficient. It is common for Monks to grow their own food.
Gregor Mendel’s ExperimentsMendel grew peas
for food at the monastery, and observed that the pea plants had a variety of distinct traits, such as flower color, that appeared to be inherited traits.
Inherited Traits in Pea Plants
Mono = oneHybrid = cross breedMendel picked one trait at a time (“mono”)
for his experiments, and cross bred (“hybrid”) pea plants for each trait to see what would happen
To track the effect of inheritance from one parent compared to the other, the parents must be different with regard to the trait being studied (“hybrid”)
The first generation in the experiment is labeled “P1”
P for Parents, 1 for 1st generation
“Monohybrid Cross”
Monohybrid Cross – P1 Generation
• This is a “hybrid” cross, because the parents are different for the trait being studied.
• What trait is being examined in this experiment?
Resulting offspring (F1)F1, F for filial (greek
for brothers) and 1 for 1st generation
In a cross between one purple flower parent and one white flower parent, all the offspring had purple flowers.
What hypothesis does this support?
4. Use punnett squares to predict the probability of genetic crosses
5. Discuss the design, results and
conclusions of Mendel’s dihybrid cross experiment.
6. Explain the principle Independent Assortment
Section 11.2 Objectives
7. Explain the following forms of inheritance: Incomplete dominance Codominance Multiple alleles Polygenic inheritance
8. Use pedigrees to analyze inheritance of alleles within families
9. Explain ABO blood type and Rh factor, and explain the inheritance of both traits
Section 11.3 Objectives:
10. Define the terms haploid and diploid. Relate the terms to the life cycle of plants and animals.
11. Describe the process of meiosis.
12. Explain what is happening in each stage of meiosis 13. Use the chromosome theory to contrast between “linked”
genes and those inherited by independent assortment
14. Compare and contrast mitosis and meiosis
Section 11.4 Objectives: