Download 3.6 Genetics pp - 7th-grade-science-mississippi-2010

Bellringer
• The offspring of asexual reproduction
are
a)Identical to the parent organism
b)Similar to a parent organism
c)A combination of two parent
organisms
d)Prokaryotic
Agenda
•
•
•
•
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Anticipatory Set
Input (notes on genetics)
Guided Practice
Independent Practice
Closing
Objective
• SWBAT identify the effects
of dominant and recessive
traits in offspring.
3.6 Genetics Class Notes
Mendel
- Mendel discovered that traits
are passed or inherited from
one generation to the next.
Gene inheritance
Organisms inherit one gene for
a trait from each parent. As a
result, an organism can have
two different genes for the
same trait.
Let’s Practice
1.Who is Mendel?
2.Can you have two different
genes for the same trait?
Some genes are dominant,
while others are recessive.
“Stronger”
traits are called
dominant.
“Weaker” traits
are called
recessive.
Let’s Practice
1.What is the difference
between dominant and
recessive traits?
Geneticists use letters to represent
the different forms of a gene.
Dominant traits are represented by
a capital letter.
Yellow seeds are
dominant……..
Y
Recessive genes (for the same
trait) are represented by THE
SAME lower case letter.
Green seeds are
recessive……….
y
Dominant (yellow) = Y
Recessive (green) = y
Let’s Practice…
1.Are dominant traits
represented by capital letters
or lower case letters?
2.Are recessive traits
represented by capital letters
or lower case letters?
Let’s Practice…
1.If purple petal color is
dominant, will the
symbol for purple color
be P or p?
 In pea plants,
tall is dominant
over short. The
letter used to
represent the
tall gene is T.
The short gene
is represented
by t.
Tall =T
Short = t
In humans, brown eyes are dominant over
blue.
Brown = B
Blue = b
Dominant genes hide recessive
genes when both are inherited by an
organism.
 Y + y = yellow seeds
(yellow is dominant)
T + t = tall plant (tall
is dominant)
B+ b = brown eyes
(brown is dominant)
Let’s Practice…
1.If yellow seeds (Y) are
dominant and green seeds (y)
are recessive, and an
organism has one Y gene and
one y gene, what color seeds
will the organism have?
Q1
If you cross a green cobra with a yellow cobra,
and there are 5 green baby cobras and 2
yellow baby cobras, which trait is dominant?
a)Yellow color
b)Green color
c) Yellow and green stripes
d)Orange color
Q2
If you cross a big viper
with a medium viper, and
all the baby vipers are
medium size, which trait
is recessive?
Q3
If you cross a blue dragon and
a red dragon, and you get 3
blue dragons and one red
dragon which trait is
recessive?
Q4
If one parent has detached
earlobes and the other parent
has attached earlobes, and all
of their children have detached
earlobes, which trait is
dominant?
Q5
If you cross a blue eyed dog
with a brown eyed dog, and
all the puppies have brown
eyes, which trait is
recessive?
Q6
If a short tail is dominant,
will the symbol for a
short tail be T or t?
Q7
If small ears are recessive,
will the symbol for small
ears be S or s?
Q8
1.If brown hair (B) is dominant
and red hair (b) is recessive,
and an organism has one B
gene and one b gene, what
color hair will the organism
have?
3.6 Independent Practice