Transcript Mendel Discovers “Genes” 9-1

9-1
How come you look like
you?
http://www.jic.bbsrc.ac.uk/germplas/pisum/zgs4f.htm
It’s in your genes!
Transmission of characteristics from
parents to offspring is called
___________________.
The STUDY of how those
characteristics are passed on from
one generation to the next is called
___________________
http://www.jic.bbsrc.ac.uk/germplas/pisum/zgs4f.htm
The Father of Genetics is
_________________,
a monk whose study of
genetic traits was the beginning of
our understanding about how
genes work.
Mendel designed experiments using
_________________________.
He looked at different observable
CHARACTERISTICS or
______________
Pea Characteristics
http://mac122.icu.ac.jp/BIOBK/BioBookgenintro.html
A plant that ALWAYS produces
offspring with a certain trait are
called ___________ for that trait.
Remember all body cells have 2
copies of every gene, so to breed
pure the 2 parent gene choices
must be the_________.
_______ red flower
alleles
PURE white
flowered plants
have ______
WHITE flower alleles
Mendel combined genes from 2
PURE parent plants and
recorded the kinds of
___________ produced.
In his experiments the 1st plants
crossed were called the ____
generation. ( P is for parental)
GENETIC EXPERIMENTS
____ generation
(parental)
____ generation
(filial=offspring)
___ generation
GENETIC EXPERIMENTS
Image modified from:
http://www.laskerfoundation.org/rprimers/gnn/timeline/1866.html
http://www.accessexcellence.org/AB/GG/mendel.html
When Mendel crossed PURE PLANTS
with 2 choices for a trait:
He found
_____trait showed in the F1 generation
1.Only
___________________________________
BUT
Missing trait reappeared in the
2. ___________________________________
F2 generation in a ________ ratio
Mendel decided that there
must be a_______ of
“factors” controlling each
trait and that one factor
must be able to _______ the
other.
We now know that Mendel’s
“factors” are _________ carried
on the pair of________________
_________________
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
_______________
are different gene
choices for a trait.
__________________ = An allele
that MASKS the presence of
another allele
__________________ = An allele
that IS MASKED BY the
presence of another allele
WHAT DOES MEIOSIS HAVE
TO DO WITH IT?
MENDEL’S LAWS
LAW OF ____________________
The pair of factors is
segregated
(or separated)
during the formation
of gametes.
Image modified from:
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
LAW OF
__________________________
the factors are distributed to gametes
independently of other factors
Image modified from:
http://anthro.palomar.edu/mendel/mendel_1.htm
MENDEL’s LAWS of
SEGREGATION
&
INDEPENDENT
ASSORTMENT
happen because of the
way the chromosomes
move during
__________________
http://www.tokyo-med.ac.jp/genet/anm/mimov.gif
GENETIC CROSSES
9-2
DOMINANT/RECESSIVE
Dominant gene is represented by a
____________ letter.
(usually the first letter of the trait)
Recessive gene is represented by the SAME
_________________ letter.
EX: Tall = ______
Short =______
NOT S for short
HOMOZYGOUS
HETEROZYGOUS
When both alleles in the pair are the
SAME the organism is
_______________ or __________
EX: TT
or tt
When both alleles in the pair are
DIFFERENT the organism is
_________________ or _____________
Ex: Tt
PHENOTYPE/GENOTYPE
The genetic makeup of an organism is
its _____________
The appearance of an organism is
its _____________
Animation from:
http://www.people.virginia.edu/~rjh9u/monohyb.html
PUNNETT SQUARES
are used to show possible offspring
of a cross between 2 parents
Parent genes go at
top and on left side
Boxes show
possible
combinations
____________________
is the likelihood that a
specific event will occur
It can be written as a:
Fraction 1/4
Percent 25%
Ratio 1:3
IN PEA
PLANTS
Tall is dominant over short
TALL = ____
SHORT = ____
PURE TALL parent
What genes can it give?
TT

T
_________

T
T
T
PURE SHORT parent
What genes can it give?
tt

t
_________

t
T
t
t
T
ALL of the
offspring
4/4
100%
will be
GENOTYPE _____ PHENOTYPE _______
HYBRID TALL parent
What genes can it give?
Tt

T
_________

t
T
t
T
t
T
TT
Tt
t
Tt
tt
GENOTYPES
¼ = _____
½ = _____
¼ = _____
PHENOTYPES _______ ____________
_______ ____________
MAKING A CROSS with
only ONE gene trait =
____________________
A Punnett square for
a MONOHYBRID
CROSS looks like
this:
TESTCROSS
used to tell what genes an organism has
Cross an UNKNOWN parent with a
____________________________
and see results
Offspring give a clue about the
unknown parent’s genes
TESTCROSS
used to tell what genes an organism has
Example: The genes of a TALL
PARENT are UNKNOWN
- COULD HAVE _____
- COULD HAVE _____
http://mac122.icu.ac.jp/BIOBK/BioBookgenintro.html
TESTCROSS
T
T
t
t Tt
Tt
t Tt
tt
Tt
t
Tt
t
tt
T
All offspring will
be TALL
Tt
50% will be TALL
50% will be SHORT
DEAF DOGS
Deafness in dogs is DOMINANT (D)
over the ability to hear (d)
A deaf dog could have 2 possible
GENOTYPES
______
______
How do we tell which one it is?
TESTCROSS
DEAF PARENT WITH PURE HEARING PARENT
D
D
d
Deaf
Deaf
d
d
Deaf
Deaf
d
D
d
Deaf
Hearing
Deaf
Hearing
If you get some hearing puppies, you know parent was Dd.
GENES are more complicated
than MENDEL thought
Some traits have more than
two allele choices
EX: eye color
GENES are more complicated
than MENDEL thought
Some traits are determined by
more than one gene
EX: Human height
http://www.bcps.org/offices/lis/models/life/images/grow.JPG
GENES are more complicated
than MENDEL thought
Traits determined by more than
one gene have lots of “in-between”
phenotypes
There aren’t just SMART people
and DUMB people….
there is a whole range
of intelligences in-between
http://www.newtonswindow.com/problem-solving.htm
GENES are more complicated
than MENDEL thought
KINDS OF DOMINANCE
____________________
____________________
____________________
COMPLETE DOMINANCE
Dominant allele masks
the recessive one
Recessive allele returns
in a 3:1 ratio in the F2
generation
INCOMPLETE DOMINANCE
Don’t see expected 3:1 ratio in F2
generation
Organisms with one dominant and
one recessive allele show a
blended in-between trait
INCOMPLETE DOMINANCE
ALLELES BLEND
to produce an
INTERMEDIATE
PHENOTYPE
Don’t see the expected
3:1 ratio in the F2
generation
CO-DOMINANCE
Both traits are expressed at same time
(NO BLENDING) in heterozygote
Has BOTH
RED hair and
WHITE hair
CO-DOMINANCE
Both traits are expressed together
(NO BLENDING) in heterozygote
Persons with an A gene
AND a B gene have
blood type AB
BLOOD TYPES
have more than 2 allele choices
Proteins with SUGARS
attached help cells
recognize ___________
• Called
_______________
http://www.mannanw.com/super-sugars.htm
BLOOD TYPES
have more than 2 allele choices
The protein and sugar that is
attached is determined by genes
Allele choices are:
_____ ____ ____
BLOOD TYPES
An A gene tells
the cell to put
“A” glycoproteins
on its surface
BLOOD TYPES
An B gene tells
the cell to put a
different “B”
glycoprotein
on its surface
BLOOD TYPES
An O gene tells
the cell NOT to put
anything on the
surface
A and B are CO-DOMINANT
A cell with
an A and a B gene
has BOTH
“A” and “B”
glycoproteins on its
surface
BLOOD TYPES & ALLELES
ALLELE
AA
AO
BB
BO
OO
AB
BLOOD TYPE
A
A
B
B
O
AB
BLOOD TYPES
YOU’RE NOT
DIFFERENT
FROM ME!
Body images modified from:
http://www.new-fitness.com/images/body_shapes.jpg
YOU ARE NOT ME!
IMMUNE SYSTEM
ATTACKS!
BLOOD TYPES
YOU’RE NOT
DIFFERENT
FROM ME!
Body images modified from:
http://www.new-fitness.com/images/body_shapes.jpg
YOU ARE NOT ME!
IMMUNE SYSTEM
ATTACKS!
BLOOD TYPES
YOU’RE
LIKE ME!
Body images modified from:
http://www.new-fitness.com/images/body_shapes.jpg
YOU ARE NOT ME!
IMMUNE SYSTEM
ATTACKS!
BLOOD TYPES
YOU’RE NOT
DIFFERENT
FROM ME!
Body images modified from:
http://www.new-fitness.com/images/body_shapes.jpg
O can donate to
EVERY BLOOD TYPE
= UNIVERSAL DONOR!
Nothing on surface to
recognize as “NOT SELF”
BLOOD TYPES
AB can RECEIVE FROM
EVERY BLOOD TYPE
= UNIVERSAL RECIPIENT
Body image modified from:
http://www.new-fitness.com/images/body_shapes.jpg
BLOOD TYPE FREQUENCY
IN USA
A
B
AB
O
40%
10%
4%
46%
http://www.reachoutmichigan.org/funexperiments/agesubject/lessons/newton/BldTyping.html
OTHER BLOOD TYPES
+
Rh
Rh
OTHER BLOOD TYPES
NO PROBLEMS IF:
MOM & BABY are both
+
Imagea modified from:
http://www.wsd1.org/lessonplans/images/Body.gif
MOM is
+ & BABY is -
OTHER BLOOD TYPES
PROBLEMS IF: MOM is - & BABY is +
1st baby OK but few baby cells
entering mom’s bloodstream
put mom’s immune system on
alert for + cells.
Next + baby, mom’s immune
system can attack baby as it is
growing
Shot after 1st birth prevents alert
Imagea modified from:
http://www.wsd1.org/lessonplans/images/Body.gif
DIHYBRID CROSSES
(2
traits)
http://mac122.icu.ac.jp/BIOBK/BioBookgenintro.html
MAKING A CROSS with
TWO gene traits =
____________________
A Punnett square for
a DIHYBRID
CROSS looks like
this:
HOMOZYGOUS
ROUND YELLOW
R RYY
X
HOMOZYGOUS
WRINKLED GREEN
rryy
POSSIBLE GAMETES?
POSSIBLE GAMETES?
ry
ry
ry
ry
RY
RrYy
RrYy
RrYy
RrYy
RY
RrYy RrYy
RrYy
RrYy
RY
RrYy
RrYy
RrYy
RrYy
RY
RrYy
RrYy
RrYy
RrYy
100% of offspring = _______ genotype
_______________________ phenotype
HETEROZYGOUS
ROUND YELLOW
X
RrYy
HETEROZYGOUS
ROUND YELLOW
RrYy
POSSIBLE GAMETES?
RY
RY
Ry
Ry
rY
ry
____ Round &
Yellow
____ Round &
green
rY
____ Wrinkled
& yellow
ry
____ wrinkled
& green
Sign of a heterozygous dihybrid cross is a
_____________ ratio in offspring.
____ DOMINANT TRAIT 1 ; DOMINANT TRAIT 2
____ DOMINANT TRAIT 1; RECESSIVE TRAIT 2
____ RECESSIVE TRAIT 1; DOMINANT TRAIT 2
____ RECESSIVE TRAIT 1; RECESSIVE TRAIT 2
9:3:3:1