Punnett Squares

Quick Review The most important organelle in a eukaryotic cell is the ________. The nucleus has one job, and that is to store the ______. nucleus nucleus DNA 2

Quick Review DNA is packaged into a very long molecule called a _____________. When you talk about chromosomes you need to realize that you are talking about ______. chromosome DNA Human Chromosomes 3

The sequence is what holds the information! The instructions or __________ for making proteins are found in the ______. The information is carried in the _________________________. blueprint DNA sequence of nitrogen bases

The combination of genes in a person is known as his/her __________. The sequences of DNA that helps to create and regulate proteins are known as a ______. This includes the sections of DNA used to create all 3 major types of ______. The combination of genes in a person is known as his/her __________. gene RNA genotype messenger RNA (mRNA) transfer RNA (tRNA) ribosomal RNA (rRNA)

Humans have ____ different types of chromosomes, and they have ___ of each type. This means that they have a total of ____ chromosomes in all. In humans, the first 22 pairs are called ___________, but the 23rd pair of chromosomes is called the _____ chromosomes. If a person has the karyotype XY, the person is a ______. If a person has the karyotype XX, the person is a ________. 23 2 46 autosomes sex male female male female

Phenotype for Fur Color Because every person has ___ copies of every gene, we name them using lowercase and capital letter to show how they interact. Because of how the sequences of DNA that create and regulate _________ production interact, we say that some of them are __________ while others are __________. What we mean has been illustrated below: 2 protein dominant recessive Subject A Subject B Subject C Genotype for Fur Color GG Gg gg Phenotype for Fur Color Gray Fur White Fur

The genotype of these girls is what determines their phenotypes! We name genes based on the __________ they create. We call the different versions of a gene ________. You would find the hair color gene in the same place for everyone, but some people have the _______ for blond hair and some people have the _______ for black hair. We call the physical appearance that results from the proteins the organism’s ____________. proteins alleles allele allele phenotype Photo by Bahar Photo by Marc Davis The genotype of these girls is what determines their phenotypes!

Phenotype for Fur Color Dominant genes are always __________. This means that they always appear as the phenotype. Recessive traits are only expressed if they receive the recessive version (allele) from both parents. Recessive traits remain ____________ if the other gene is dominant, as with subject B. expressed unexpressed Subject A Subject B Subject C Genotype for Fur Color GG Gg gg Phenotype for Fur Color Gray Fur White Fur

same different joined together Use your vocabulary reference sheet to define the following prefixes and suffixes. What does homo- mean? ______________ What does hetero- mean? ______________ What does –zygous mean? ________________________ Define homozygous: _______________________________________________ Define heterozygous: _______________________________________________ Circle the following genotype(s) that are homozygous: GG Gg gg Circle the following genotype(s) that are heterozygous: same different joined together Homozygous means the same alleles have joined together Heterozygous means different alleles have joined together

BB Green eyes bb Blue eyes Bb Green eyes Allele Trait Type G Solid gray fur Dominant g Striped gray fur Recessive B Green eyes b Blue Eyes T Long tail t Short tail E Large ears e Small ears Use the information above to answer the following questions and to complete the table below. 1. What is the genotype of an animal that is homozygous dominant for eye color? _____ What would this animal’s phenotype be? __________________ 2. What is the genotype of an animal that is homozygous recessive for eye color? _____ 3. What is the genotype of an animal that is heterozygous for eye color? _____ BB Green eyes bb Blue eyes Bb Green eyes

GG Solid gray fur gg Striped gray fur Gg Solid gray fur Allele Trait Type G Solid gray fur Dominant g Striped gray fur Recessive B Green eyes b Blue Eyes T Long tail t Short tail E Large ears e Small ears 4. What is the genotype of an animal that is homozygous for solid gray fur? _____ What would this animal’s phenotype be? __________________ 5. What is the genotype of an animal that is homozygous for striped gray fur? _____ 6. What is the genotype of an animal that is heterozygous for fur? _____ GG Solid gray fur gg Striped gray fur Gg Solid gray fur

tt Short tails Ee Large ears tt Short tails Tt Long tails bb Blue eyes Allele Trait Type G Solid gray fur Dominant g Striped gray fur Recessive B Green eyes b Blue Eyes T Long tail t Short tail E Large ears e Small ears Description Genotype Phenotype Homozygous recessive for tail length Heterozygous for ear size Homozygous for short tails Heterozygous for tail length Homozygous for blue eyes Homozygous dominant for fur Homozygous for striped gray fur Heterozygous for eye color Homozygous for long tails tt Short tails Ee Large ears tt Short tails Tt Long tails bb Blue eyes GG Solid gray fur gg Striped gray fur Bb Green eyes TT Long tails

Just like we can ________ the possible gamete cells of an individual, we can also predict the possible ___________ and ___________ of the offspring a set of parents might create. We do this using a tool called a _______________. predict genotypes phenotypes Punnett square b b G g B b Green eyes Bb Green eyes Bb G g Solid Fur GG Solid Fur Gg Blue eyes bb Blue eyes bb Solid Fur Gg Striped fur gg

GG (male) × Gg (female) G G G To use a Punnett square, we start by placing the genotype of the _______ (♂) across the top of the Punnett square and placing the genotype of the ________ (♀) down the side of the Punnett square. Even though this is the conventional placement of the genotypes, mixing this up will not keep you from getting the correct answer. male female G G G g GG (male) × Gg (female)

You fill the boxes by writing male alleles down each ________ and filling in the female alleles across each _____. column row G G G g G G G G g g GG (male) × Gg (female)

1 gamete gamete G G G G G G G g g Since each gamete cell will only have ___ of these parental genes, each box represents a possible combination of genes that might be created when one of the possible male _________ cells fuses with one of the possible female ________ cells. 1 gamete gamete G G G g G G G G g g g G GG (male) × Gg (female)

G G G G G G G g g percentage 25% 100% You can discuss the outcome of a Punnett square in one of two ways. First, you can calculate the average ____________ (%) of offspring that will have a certain genotype or phenotype. Since there are 4 boxes, each box is worth _____. The Punnett square above shows that ______ of the children will have solid gray fur (G). percentage 25% 100%

G G G GG GG Gg Gg genotypes phenotypes 50% 100% Solid Fur Solid Fur G g GG GG Solid Fur Solid Fur Gg Gg It is important that you pay attention to whether the question is asking about __________or ___________. genotypes phenotypes What percentage of the offspring would be expected to have a heterozygous genotype? ______ 50% What percentage of the offspring would be expected to have a solid gray fur? ______ 100%

greatest common factor 2:2 is reduced to 1:1 using a factor of 2. The second way is to discuss the ________ of genotypes or phenotypes. In the Punnett square, the ratio of homozygous dominant to heterozygous is ____to____ also written as ____. We always reduce our ratios using the _______________________ (GCF). ratio 1 1 1:1 greatest common factor G G 2:2 is reduced to 1:1 using a factor of 2. G g G G G G g g

Complete the following Punnett squares and answer the questions go with each cross. Use the tables of information on each page to answer the questions.

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