Punnet Square

http://www.youtube.com/watch?v=GbhsayzxNoQ

JTPS (Think pair share) - IBE

• Two parents are expecting a baby. They already have a boy. What’s the probability they will have a girl?

J-TPS (Justify –Think Pair Share)

THINK PAIR

SHARE

The inheritance of traits follows the rules of probability.

Punnett squares illustrate genetic crosses

• The Punnett square is a grid system for predicting all possible genotypes resulting from a cross.

Punnett squares illustrate genetic crosses.

• The Punnett square is a grid system for predicting all possible genotypes resulting from a cross.

F F

F

f

Homozygous

Heterozygous

F F F F

F Ff f

A monohybrid cross involves one trait.

• Monohybrid crosses examine the inheritance of only one specific trait.– Homozygous dominant (FF) X Homozygous recessive (ff)– Outcome: all heterozygous, with dominant phenotype (purple)

• Heterozygous (Ff) X Heterozygous Cross (Ff)

Phenotype outcome: 3:1 ratio 3 purple and 1 white

Genotype outcome: 1:2:1 ratio 1 FF, 2 Ff, 1 ff

• A testcross is a cross between an organism with an unknown genotype (FF or Ff) and an organism with the recessive phenotype (ff)

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FF Ff√

F

f

A dihybrid cross involves two traits

• Mendel’s dihybrid crosses with heterozygous plants yielded a 9:3:3:1 phenotypic ratio.

A dihybrid cross involves two traits.

• Mendel’s dihybrid crosses led to his second law, the law of independent assortment.

• The law of independent assortment states that alleles on the same chromosome separate independently of each other during meiosis.

Law of independent assortment

• Allele pairs separate independently of each other during gamete formation, or meiosis. That is, different traits appear to be inherited separately

Heredity patterns can be calculated with probability

• Probability is the likelihood that something will happen.

• Probability predicts an average number of occurrences, not an exact number of occurrences.

Meiosis and 1st Mendel’s law

• http://www.sumanasinc.com/webcontent/animations/content/independentassortment.html

JTPS -

• Two parents are expecting a baby. They already have a boy. What’s the probability to have a girl?

Review(Vocabulary)

Homologous Chromosomes

• Chromosomes that are similar in shape and content and which are donated by each parent

Homozygous

• Organisms that have two identical alleles for a particular trait such as TT or tt are said to be homozygous

Heterozygous

• Organisms that have two different alleles for the same trait are heterozygous such as Tt

Genotype

• Genotype is the genetic makeup of an organism usually represented as; the genotype– Homozygous Dominant (such as TT)– Homozygous Recessive (such tt) – Heterozygous (such as Tt)

Phenotype

• Phenotype are the physical (visible) characteristics of an organism such as seen when:– Tall (when the genotype is TT)– Tall (when the genotype is Tt)– Short (when the genotype is tt)

Law of Segregation• Segregation is the separation of alleles during gamete

(sex cell) formation.

Law of Independent Assortment• The principle of independent assortment states that

genes for different traits can separate (segregate) independently during the formation of gametes.

Crossing Over• Chromosomal crossover (or crossing over) is the process by

which two chromosomes pair up and exchange sections of their DNA

Video