Can 2 Red-Eyed Flies have a Purple-Eyed Baby? + = ?

Can 2 Brown-Eyed Parents have a Blue-Eyed Baby? + = ?? UNDERSTANDING HEREDITY WHITE Copy WHITE

IMPORTANT NOTE Think back to the activity yesterday… Are there any intermediate characteristics for human traits? Look on P.11, #2 Ex: Eye color– are there only 2 eye colors? Light and Dark? Please Read the Important Note! Think back to the activity yesterday… Are there any intermediate characteristics for human traits? Look on P.11, #2 Ex: Eye color– are there only 2 eye colors? Light and Dark? Please Read the Important Note!

Before we begin, we need to understand how babies are made!  Egg and sperm come together to make a zygote…  The DNA in the egg & sperm determines what DNA goes in the zygote. Zygote: Cell made when egg & sperm join

 Chromosomes come in HOMOLOGOUS PAIRS The other matching half comes from the MOTHER. The other matching half comes from the MOTHER. Half the chromosomes comes from the FATHER. Half the chromosomes comes from the FATHER. matching Gender

Before we begin, we also need to understand importance of language  The Genetics Unit is almost completely language-based.  You will be learning 10+ words a week!  You will be doing vocab homework for this unit, instead of a MARG.  If you want to make flashcards, come to Office Hours!!!

In genetics, there are 2 ways to describe individuals…

Phenotype:  The physical traits that an organism has. (PHENOtype --> type of PHYSICAL features) In genetics, there are 2 ways to describe individuals… (1) Can you list 3 traits of my phenotype?

More practice… List 2 differences in their Phenotype: A) and B) and

Genotype:  The genes that an organism has.  Represented by letters.  The genes that an organism has.  Represented by letters. (GENotype --> type of GENES) In genetics, there are 2 ways to describe individuals… (2)

More practice… Do these have the same Genotype? Hint: DNA (genes)  RNA  PROTEIN  TRAIT A) and B) and TRICK QUESTION! Flamingos change color based on ENVIRONMENT! TRICK QUESTION! Flamingos change color based on ENVIRONMENT!

Genotype (cont.)  There are different versions of the same gene, called alleles.  For every trait, you have 2 alleles. - One version from your father (through sperm) - One version from your mother (through egg)  There are different versions of the same gene, called alleles.  For every trait, you have 2 alleles. - One version from your father (through sperm) - One version from your mother (through egg) There can different versions of the same gene… Mom’s version Dad’s version

X Normal Human Karyotype Eye color

Let’s look at a person’s pair of Chromosome #15… Gene for Eye Color Allele from egg Allele from sperm

X Y Normal Human Karyotype - Male Eye color

We will only be looking at 2 types of alleles for now: DOMINANT ALLELES and recessive alleles

Dominant Allele:  Its trait is expressed all the time.  Represented by a capital letter. (Example: B = brown eyes)  Its trait is expressed all the time.  Represented by a capital letter. (Example: B = brown eyes) The 2 types of alleles we are looking at… (1)

Recessive Allele:  Its trait is expressed ONLY if there is no dominant allele.  Represented by a lowercase letter. (Example: b= blue eyes)  Its trait is expressed ONLY if there is no dominant allele.  Represented by a lowercase letter. (Example: b= blue eyes) (2) The 2 types of alleles we are looking at…

Dominant vs. Recessive Ssh! I’ll speak for both of us!

Let’s look at zygosity – the 2 alleles the zygote has. Gene for Eye Color Allele from sperm Allele from egg

Homozygous:Homozygous:  Homo = “Same” Having 2 of the same alleles for the same gene  Homozygous = Having 2 of the same alleles for the same gene  Homo = “Same” Having 2 of the same alleles for the same gene  Homozygous = Having 2 of the same alleles for the same gene “Zygosity”– Looking at the 2 alleles that the zygote has… Recessive Dominant “Homozygous Dominant”“Homozygous Recessive”

Heterozygous:Heterozygous:  Hetero = “Different” Having 2 different alleles for the same gene  Heterozygous = Having 2 different alleles for the same gene  Hetero = “Different” Having 2 different alleles for the same gene  Heterozygous = Having 2 different alleles for the same gene Recessive (r) Dominant (R) “Zygosity”– Looking at the 2 alleles that the zygote has…

Learning Log 1/22 – Page 12 WONDERWALL – NO STAMP Go water your plants first! El Chupacabra – Page 18 WONDERWALL – NO STAMP Go water your plants first! El Chupacabra – Page 18

IF…. B= brown eyes (dominant) b= blue eyes (recessive) GenotypePhenotype HeTeRoZyGoUs HOMOzygous DOMINANT homo zygous recessive Bb BB bb Brown eyes Blue eyes

So how do we use this information?? What are the possible genotypes for eye color for the children of …a dad that is homozygous recessive and …a mom that is heterozygous? Dad’s Body cell Mom’s Body cell meiosis Possible SPERMS made by Dad Possible EGGS made by Mom r r R r Zygote As you see, there are many combinations… A Punnett Square will make this easier!

Four Easy Steps to Solve PUNNETT SQUARES! From Mom From Dad 1.Make a square with 4 boxes 2.Put Mom’s genotype in 2 eggs (left) 3.Put Dad’s genotype in 2 sperms (top) 4.Drop the top, Drag the left

Homozygous Dominant Mom × Homozygous Dominant Dad Genotypic Ratio= Phenotypic Ratio=

Heterozygous Mom × Homozygous Dominant Dad Genotypic Ratio= Phenotypic Ratio=

Heterozygous Mom × Heterozygous Dad Genotypic Ratio= Phenotypic Ratio=

Bbbb Bbbb Bb b b What color eyes do you think the younger brother has? bb ? ? Bb

bb Bbbb Bb b b ? ? ? ? ? ? NOTE: The probability resets for every baby!

Vocabulary Squares Textbook DefinitionDefinition in Your Own Words PictureExample – or – In a Sentence Homozygous Describes an individual that has identical alleles for a trait on both homologous chromosomes. When someone has two of the same version for a gene. Jack has BB, so he is homozygous dominant. I’ll speak for both of us! No! I’ll speak too!

Possible other Vocabulary for your squares:  Punnett Square  Probability  Zygote  Trait  Heredity  Dihybrid cross  Polygenic Possible other Vocabulary for your squares:  Punnett Square  Probability  Zygote  Trait  Heredity  Dihybrid cross  Polygenic