Download trait

Topic: Genetics
Aim: 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
DNA
Chromosomes
Parent &
offspring
Heredity
How are organisms
genetically
structured?
Living organisms contain
chromosomes
___________________
inside
of their nucleus which are
made up of strands of
___________.
This carries the
DNA
hereditary information for
the organism. Sections of the
DNA
____ code for a particular
gene
________
that makes a
specific trait.
Who was the
Father of
Genetics?
Gregor Mendel
1822-1884
•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: Genetics
Aim: How can we examine the inherited traits
found in offspring?
How do scientist
today trace
traits?
•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:
TRAIT
Dimples
ALLELES
Dimples Dominant
no dimples 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?
Phenotype
Is the physical
appearance
(___________)
feature
expressed
(__________)by
the
shown
organism because of
their genotype
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 trait
Alleles can be
Dominant
_____________
or_____________
Recessive
1 mom & 1 dad
When the dominant allele is present the
recessive trait is not seen in the
phenotype
Blue Eyes
Brown
Eyes
Brown
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
It is based upon the
help determine the
variations of alleles found
phenotype in human
on the
organisms?
chromosomes
__________________that
each parent gives the
offspring during the proces
of
Fertilization
_______________________.
TOPIC: Genetics
AIM: What are Punnett Squares?
DO NOW:
Explain the difference
between genotype
and phenotype
Punnett
Squares
• Special chart
• Shows
probability of
possible gene
combinations of
offspring
between 2
organisms
What is
probability?
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
Punnett Square
Step # 1 – Draw Punnett
square
Step # 2 – Apply maternal
and paternal genotypes
Step # 3 – Move alleles
into appropriate boxes
Steps to reading a
Punnett Square
Trait – Hair color
Allele – Purple (Dom), Yellow (Rec)
Step #1- Classify Genotypes
Step # 2- Tally genotypes
and phenotypes
Step # 3-Calulate ratios
and percentages
Genotypes
Phenotype
1 BB
2 Bb
1 bb
3 Purple
1 Yellow
Homozygous
Dominant
Heterozygous
Heterozygous
Homozygous
Recessive
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
traits
differ in sex
___________which
are
determined
by____________________
genes
Whether you are a male or
female depends on the
presence or absence of
certain chromosomes.
FEMALE
MALE
Human cells contain 23
pairs of chromosomes
for a total of 46.
The sex chromosomes are the X
chromosome and the Y
chromosome. Chromosomes
determine gender.
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