Fundamentals of Genetics (Ch.9.1 + 9.2)

Genetics is the field of biology devoted to understanding how characteristicsare transmitted from parents to offspring.

Objectives 1. Explain the significance of Mendel'sexperiments and observations, and the lawsderived from them.1.1 Explain the concept of independent events.1.2 Understand that the probability of anindependent event is not altered by theoutcomes of previous events.1.3 Describe Mendel's experiments andobservations.1.4 Describe the relationship between genotypeand phenotype. 1.5 Use the concept of the gene to explainMendel's laws.1.6 Describe the ideas of dominant and recessivetraits with examples.1.7 Consider the value of the punnett square bycreating examples of mono and dihybridcrosses.1.8 Explain the law of segregation.

THINK, PAIR UP, AND SHARE!Think, Pair, Share

2.10 Discuss the similarities and differences

between sex chromosomes and somatic

chromosomes.2.11 Using examples from

living organismsdiscuss the importance of

asexual and sexualreproduction to their growth

and survival.

Independent Events

If events happen independently of each other they...

If events were to be dependent on each other they...

Mendel the Monk

Gregor Mendel was an Austrian Monk, who specialized in statistics.

Heredity – transmission of characteristics from parents to offspring.

Traits – a category in which alternate characteristics can be observed

Mendel's Crosses and Results

Mendel's Laws

Law of Segregation – a pair of factors is segregated or separated during the formation of gametes.

Law of Independent Assortment – factors for different characteristics are distributed to gametes independently.

WHAT DO THESE MEAN EXACTLY?

Genes and Alleles

Gene is a segment of DNA on a chromosome that controls a particular hereditary trait.

Alleles are the different types of characteristics the gene can express.

These alleles are represented by letters.G = capital means dominantg = lower case means recessive

Genotype vs Phenotype

Genotype – its “genetic type” or make-up Phenotype – its visible appearance – what we see

Dominant – will reflect appearance regardless of the other trait's characteristics.

Recessive – only will reflect appearance if paired with another recessive.

Punnett Squares – Monohybrid and Dihybrid Crosses

P1 Generation –

Parental F

1 Generation – Fillial

(offspring) Pure – breed only a

specific trait Strain – plants that are

pure for a specific trait

Y = Dominant Yellow Genotypes: 2 Yy, 2 yyy = Recessive Green Phenotypes:

2 yellow, 2 green

Dihybrid Cross

R - roundr – wrinkled

Y – yellowy - green

Homozygous vs Heterozygous

Homozygous – allele is with the exact same allele as itself.

GG

Heterozygous – allele is paired with a different allele (characteristic).

Gg

Dominance

Complete Dominance-one allele “pwns” the other. You only see the one phenotype.

Incomplete Dominance -two or more alleles influence the phenotype.

Codominance-both alleles are expressed independently. Blonde (B) + brown (B') hair.

Assignments + Practice

Test Cross – if you know something expresses a certain phenotype, but want to know its genetype for a trait, cross is with a purebreed and observe the results!

9.1 9.2 Punnett Square

Problems

ObjectivesAchieved?

1. Explain the significance of Mendel'sexperiments and observations, and the lawsderived from them.1.1 Explain the concept of independent events.1.2 Understand that the probability of anindependent event is not altered by theoutcomes of previous events.1.3 Describe Mendel's experiments andobservations.1.4 Describe the relationship between genotypeand phenotype. 1.5 Use the concept of the gene to explainMendel's laws.1.6 Describe the ideas of dominant and recessivetraits with examples.1.7 Consider the value of the punnett square bycreating examples of mono and dihybridcrosses.1.8 Explain the law of segregation.