GENETICS

OBJECTIVE

Take a class survey on genetic traits.

Distinguish between: dominant and recessive alleles homozygous and heterozygous allele pairings genotype and phenotype

Rolled TongueWidow’s Peak

Straight hairline

Dimples!!Cleft Chin

CLASS SURVEY OF GENETIC TRAITS

GENE: a unit of DNA that controls a trait of a particular organism (ex. Freckles)

ALLELE: an alternative form a gene (one member of a pair) that is located at a specific position on a specific chromosome.

Homologous Chromosomes

Allele #1 Allele #2

Gene

DOMINANT alleleAn allele that can “mask over” a recessive allele. Only the dominant trait is expressed.

It is generally represented by a CAPTIAL letter

Ex. “B”

RECESSIVE alleleAn allele that can only be expressed if a dominant allele is absent.

It is generally represented by a LOWER CASE letter

Ex. “b”

HOMOZYGOUS(purebred)

A term used to describe a pair of alleles that are IDENTICAL or the SAME.

Ex. BB or bb

HETEROZYGOUS(hybrid)

A term used to describe a pair of alleles that are DIFFERENT.

Ex. Bb

GENOTYPE

The description of the gene pair.

Ex. BB, Bb, bb

PHENOTYPE

The observable trait that results from the action of an allele pair.

Ex. Brown eyes Brown eyes or blue eyesblue eyes

Genotype(s):

Phenotype:

Genotype:

Phenotype:

REVIEW

1. A ____________________ allele “masks” recessive alleles.

2. Another word for purebred is ____________________.

3. You have two ___________________ for eye color.

4. Bb is homozygous or heterozygous?

5. What is the difference between genotype and phenotype?

OBJECTIVES

To simulate the process of fertilization and determining the genotypes and phenotypes of potential offspring

To be able to use a punnett square to predict the genotype and phenotype probabilities of future offspring.

HOW TO SET UP YOUR PUNNETT SQUARE

1. Read the word problem. Identify the dominant and recessive traits.

2. Make a key to represent the dominant and recessive alleles.

3. Determine the alleles of the parents. 4. Place the alleles of the parents along the

top and left side of the punnett square. 5. Cross the alleles inside the boxes. 6. Determine the ratios of the offspring.

CROSS A HOMOZYGOUS PURPLE FLOWER WITH A WHITE FLOWER. PURPLE IS DOMINANT TO WHITE.

PHENOTYPIC RATIO:

GENOTYPIC RATIO:

CROSS TWO HETEROZYGOUS BROWN HAIRED PARENTS. BROWN IS DOMINANT TO BLONDE.

PHENOTYPIC RATIO:

GENOTYPIC RATIO:

A HETEROZYGOUS TALL PLANT IS CROSSED WITH A HOMOZYGOUS SHORT PLANT.

PHENOTYPIC RATIO:

GENOTYPIC RATIO:

OBJECTIVE

To trace the genotype and phenotypes of a particular trait through a family pedigree.

FACEBOOK MESSAGE ON MAY 24TH 2012

Dear family and friends,

As many of you already know, a few weeks ago our family were given the most devastating news parents could ever receive.

Our son Oliver, at only 25 months old, has been diagnosed with an incredibly rare genetic disorder called metachromatic leukodystrophy. Our lives have been shattered and we’re simply at a loss for words.

We know that many of you have been asking after Oliver and how he’s been doing and since we are not comfortable posting any details on facebook and we simply do not have the strength to call and retell the same bad news and updates to everyone we have decided to start a blog that we will help keep everyone informed on what is going on with us.

There is not much there yet, but I will post in the next few days to bring everyone up to date. Thank you all for your unending love and support, it means the world to us.

Sincerely, Katie, Chris and Ollie

Here is our blog: http://www.oliversteam.blogspot.com/

HTTP://WWW.OLIVERSTEAM.BLOGSPOT.COM/ Blog #1: May 30th Have A Cookie Or Three

Blog #2: August 22nd Yah, Equipment!

Blog#3: November 7th Kohl’s Woman

Blog #4: January 20th Failing

PEDIGREE ANALYSIS Male = Female = Marriage =

 

Sibling = Fraternal Twins = Identical Twins =

(Non-identical)

Organization Rules:1. Generations are numbered using Roman numerals, I,

II, III, etc.  2. Children are placed in birth order starting from the

left side.

PEDIGREEKEY = healthy

= MLD

PEDIGREEKEY = brown eyes

= blue eyes

I.

II.

III.

KEY

Immune to poison ivy (R) =

Susceptible to poison ivy (r) =

KEY

Six-fingered (F) =

Five-fingered (f) =

OBJECTIVE

Use a Punnett square to predict the genotypic and phenotypic probability of offspring for:Incomplete dominanceCo-dominance

INCOMPLETE DOMINANCE: A type of inheritance when a heterozygous geneotype expresses a blending phenotype.

R= redW= white

#1 Cross a snapdragon white flower with a pink flower.

R= redW= white

#2 Cross a snapdragon pink flower with a pink flower.

R= curly hairr = straight hair

#3 Cross a wavy haired person with a straight haired person.

Co-Dominance: Co-Dominance: 2 alleles are equally dominant and expressed.

There are 3 alleles for blood typing: A, B, O A and B alleles are co-dominant O allele is recessive• Even though “O” is capitalized, it is still considered a

recessive allele.

PHENOTYPE GENOTYPE

“A” blood AA, AO

“B” blood BB, BO

“AB” blood AB

“O” blood OO

EACH BLOOD TYPE HAS A DIFFERENT PROTEIN

#1 CROSS A PERSON WITH HOMOZYGOUS “A” BLOOD AND A PERSON WITH HOMOZYGOUS “B” BLOOD.

#2 CROSS AN “O” BLOOD PERSON WITH A “AB” BLOOD PERSON.

#3 CROSS A HETEROZYGOUS “A” BLOOD PERSON WITH A HETEROZYGOUS “B” BLOOD PERSON.

DONATING BLOOD

http://www.redcrossblood.org/learn-about-blood/blood-types

OBJECTIVE

Use a Punnett square to predict the genotypic and phenotypic probability of sex-linked traits.

COMPLEX INHERITANCE SEX-LINKED: A type of inheritance where certain

alleles are found only on one sex chromosome (X) Ex. color-blindness, hemophilia, werewolf syndrome

TEST# 1TEST# 2

RED-GREEN COLOR BLINDNESS

GREEN-YELLOW COLOR BLINDNESS

BASIC SEX DETERMINATION PUNNETT SQUARE

PHENOTYPE GENOTYPE

Normal Female XBXB

Normal Female XBXb (carrier)

Abnormal Female XbXb

Normal Male XBY

Abnormal Male XbY

#1 CROSS A COLORBLIND MALE WITH A NORMAL FEMALE.

#2 CROSS A COLORBLIND MALE WITH A NORMAL FEMALE CARRIER.

#3 CROSS A NORMAL MALE WITH A NORMAL FEMALE (THAT HAS A COLORBLIND FATHER).

KEY

Normal =

Colorblind =