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Topic: GeneticsAim: Why do offspring look similar to their parents?Do Now:1.) List the similarities you notice amongst the family members
2.) State why they may have the same features
What is Genetics?
The study of how variations of traits are inherited (or passed down) through living organisms Key Words gene
Alleles Parent & offspring
DNAChromosomes
Heredity
How are organisms genetically structured?
Living organisms contain ___________________ inside of their nucleus which are made up of strands of ___________. This carries the hereditary information for the organism. Sections of the ____ code for a particular ________ that makes a specific trait.
chromosomes
DNA
DNA
gene
Who was the Father of Genetics?
Gregor Mendel1822-1884
•He was a monk and gardener who studied Math and Science•He was the 1st to study heredity in pea plants •He was 1st to trace one trait passed down through several generations
How did Mendel study pea plants?
•He pollinated two parent pea plants and observed and recorded the traits of the new plant He referred to the
traits as: Dominant- Seen often (Common) or Recessive- Not seen often(Uncommon)
Why Pea plants to study traits?
•Pea plants have fewer traits
•Can grow in a large amount (quantity)•He could control the plants he desired to mate in his experiment
Topic: GeneticsAim: How can we examine the inherited traits found in offspring?
How do scientist today tracetraits?
•One or more genes found at the same point on the chromosomes represents a trait•Each person has a pair of genes for each trait
•One Allele from MOM•One Allele from DAD
Alleles
•Each trait is represented by two versions called alleles
•One person may have two of the same version or one of each version•The dominant allele is represented by a CAPITAL letter and the recessive is represented by a lower case letter
EXAMPLE:
ALLELES
TRAITDimples
Dimples no dimples
Dominant
Recessive
Principles of Genetics• Traits are passed on from one generation to the
next.• Traits are controlled by genes.• Organisms inherit genes in pairs (2 alleles for
every trait, 1 on each strand).• Some genes are dominant, some are recessive.• Dominant genes hide recessive genes when both
are inherited by an organism.• Some genes are neither dominant nor recessive
(incomplete dominance)
What do scientists study in understanding a trait?
PhenotypeIs the physical appearance (___________) expressed (__________)by the organism because of their genotype
featureshown
Genotype It is the combination of alleles (genes) in the chromosomes that determine a specific characteristic (trait)
There are many types of Alleles for a traitAlleles can be _____________ or_____________
Dominant
Recessive
1 mom & 1 dad
When the dominant allele is present the recessive trait is
not seen in the phenotype
BrownEyes
BrownEyes
Blue Eyes
How many ways can alleles be represented?
Heterozygous
Two different alleles present in the organism
Homozygous
Two of the same alleles present in the organism
Homozygous Dominant
Homozygous Recessive
How do the genotype help determine the phenotype in human organisms?
It is based upon the variations of alleles found on the __________________that each parent gives the offspring during the process of _______________________.
chromosomes
Fertilization
TOPIC: GeneticsAIM: What are Punnett Squares?
DO NOW:Explain the difference
between genotype and phenotype
PunnettSquares
• Special chart
• Shows probability of possible gene combinations of offspring between 2
organisms
What isprobability
?
The possibility that an event may or may not happen
• ¼ = 25%• 2/4 = 50%• 3/4 = 75%• 4/4 = 100%
Steps to using a Steps to using a Punnett SquarePunnett Square
Step # 1 – Draw Step # 1 – Draw Punnett squarePunnett square
Step # 2 – Apply maternal and paternal genotypesStep # 3 – Move alleles into appropriate boxes
Steps to Steps to reading a reading a Punnett Punnett SquareSquareStep #1- Classify Genotypes
Step # 2- Tally genotypes and phenotypes
Step # 3-Calulate ratios and percentages Homozygous
Dominant Heterozygous
Heterozygous HomozygousRecessive
Genotypes Phenotype
1 BB2 Bb1 bb
Trait – Hair colorAllele – Purple (Dom), Yellow (Rec)
3 Purple1 Yellow
Heterozygous X Heterozygous
Heterozygous X Homozygous recessive
Heterozygous X Homozygous recessive
Homozygous Dominant X Homozygous Recessive
Is the range of differences between a male and female
Biologically, male and females differ in ___________which are determined by____________________
sex traits
genes
Whether you are a male or female depends on the presence or absence of certain chromosomes.
FEMALE
MALE
The sex chromosomes are the X chromosome and the Y chromosome. Chromosomes determine gender.
Human cells contain 23 pairs of chromosomes for a total of 46.
MOM
DAD
A technique that involves a photograph of the chromosomes from a nucleus that are paired and arranged in size order.
The first 22 pairs are called autosomes and the last pair are sex chromosomes.
When the chromosomes are different they are an X and a Y therefore it is a male