Mendels Laws of Genetics

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14 Δεκ 2012 (πριν από 4 χρόνια και 8 μήνες)

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the study of patterns of
inheritance and variations
in organisms.



GENES
: control each
trait of living thing by
controlling the
FORMATION
of an
organisms
PROTEINS.




Chromosomes are
DIPLOID

(
A PAIR OF
CHROMOSOMES
) therefore,
each cell contains
TWO
GENES

for each
TRAIT
.


One from
MOM


One from
DAD



Genes may be the
SAME
or they
could be
DIFFERENT


Produce
DIFFERENT
CHARACTERISTICS

of each
TRAIT


EXAMPLE: gene for plant height
might occur in
TALL

or
SHORT

form.


Different forms of a gene
are called
ALLELES


The
TWO ALLELES

are
SEGREGATED

during
GAMETE FORMATION
(MEIOSIS II)


Dominant allele: allele that
is E
XPRESSED


Recessive allele: allele that
is
ONLY EXPRESSED w
hen
there is no dominant allele
present.


Modern Genetics: Based
on
GREGOR MENDEL’S

explanations for the
patterns of
HEREDITY

in
garden
PEA PLANTS.



CROSSING

different
PEA PLANTS


Crossing: to mate or
BREED
two
INDIVIDUALS


Pea plant with
PURPLE FLOWERS

with a type that has
WHITE
FLOWERS
.


ALL OFFSPRING HAD PURPLE
FLOWERS




Mendel
CROSSED

those
OFFSPRING
and produced some
WHITE FLOWERS

and some
PURPLE FLOWERS.


(
THE WHITE FLOWERS CAME BACK!)


1. Every trait (like flower color, or
seed shape, or seed color) is
controlled by
two "heritable
factors".

[We know now that
these are
genes

-

we each have
two copies of every gene].


2. If the two alleles
differ
, one
is
dominant
and one is
recessive. Dominant

traits
mask the appearance of
recessive

traits.




3.
Alleles

are randomly donated from
parents to offspring
-

the factors
(alleles)
separate

when the gametes
are formed by meiosis, allowing all
possible combinations of factors to
occur in the gametes.


3.
Gene Composition is known as
GENOTYPE


The expression of the genes is
PHENOTYPE


EXAMPLE: if a person has attached
earlobes, the phenotype is “attached
earlobes” if a person has free earlobes, the
persons
PHENOTYPE IS FREE EARLOBES




a.
EXAMPLE: if a person has attached earlobes, the phenotype is

attached earlobes


if a person has free earlobes, the persons
PHENOTYPE IS FREE EARLOBES


It’s was you
SEE




a.
EXAMPLE: if a person has attached earlobes, the phenotype is

attached earlobes


if a person has free earlobes, the persons
PHENOTYPE IS FREE EARLOBES

b. two paired
ALLELES
in
an organism’s
genotype may be
IDENTICAL,
HOMOZYGOUS.


a.
EXAMPLE: if a person has attached earlobes, the phenotype is

attached earlobes


if a person has free earlobes, the persons
PHENOTYPE IS FREE EARLOBES

c.
The two paired
ALLELES

in
an organism can also be
DIFFERENT,
HETEROZYGOUS.



DOMINANT

trait is
EXPRESSED


a.
EXAMPLE: if a person has attached earlobes, the phenotype is

attached earlobes


if a person has free earlobes, the persons
PHENOTYPE IS FREE EARLOBES


Mendel’s Law of
DOMINANCE
: When an
organism has
TWO
DIFFERENT

ALLELES
for a
trait,
ONE ALLELE IS
DOMINANT.



a.
EXAMPLE: if a person has attached earlobes, the phenotype is

attached earlobes


if a person has free earlobes, the persons
PHENOTYPE IS FREE EARLOBES


Mendel’s Law of
SEGREGATION
:

During
GAMETE

formation by a
DIPLOID

organism, the pair of
ALLELES

for a trait
SEPARATE,

during
MEIOSIS
.



a.
EXAMPLE: if a person has attached earlobes, the phenotype is

attached earlobes


if a person has free earlobes, the persons
PHENOTYPE IS FREE EARLOBES



Mendel’s Law of
INDEPENDENT
ASSORTMENT:

The members of
a
GENE PAIR SEPARATE

from
one another
INDEPENDENTLY
from the members of the other
GENE PAIRs
.

NAME MENDELS 3 LAWS OF GENETICS


1.


2.


3.


5. Using a
PUNNETT SQUARE
: to
PREDICT

the
PROBABLE GENETIC
COMBINATIONS

in the
OFFSPRING

that result from different
PARENTAL
ALLELE COBINATIONS

that are
INDEPENDENTLY
assorted.



MONOHYBRID CROSS examines the
inheritance of ONE TRAIT.


HOMOZYGOUS
-
HOMOZYGOUS



HETEROZYGOUS
-
HETEROZYGOUS



HETEROZYGOUS
-
HOMOZYGOUS



HETEROZYGOUS
-
HOMOZYGOUS



EXAMPLE: trait for height


T= DOMINANT TALL


t= RECESSIVE SHORT


The
suare

shows the following
GENOTYPES:


PARENTS ARE THE F1 GENERATION
resulting in offspring as F2
GENERATION


The square shows the following
GENOTYPES:


1:4 RATIO of__________________ ____%


1:4 RATIO of__________________ ____%


2:4 RATIO of__________________ ____%



The square shows the following
PHENOTYPES:


3:4 RATIO of__________________ ____%


1:4 RATIO of__________________ ____%


a
PEDIGREE

is a family
history that shows
HOW A
TRAIT is INHERITED

over
several
GENERATIONS
.


a.
can help answer questions
about
THREE

aspects of
inheritance




1
. SEX LINKAGE



2. DOMINANCE



3. HETEROZYGOSITY


b. males have
ONE X AND
ONE Y CHROMOSOME
.


PROCESS OF REPLACING
SPECIFIC GENES IN AN
ORGANISM IN ORDER TO
ENSURE THAT THE
ORGANISM EXPRESSES A
DESIRED TRAIT.


a. Take specific genes from
ONE ORGANISM

and
place them
INTO
ANOTHER ORGANISM.


1. CLONING:

an
IDENTICAL

copy of a gene or an entire organism is produced.

1. CLONING: an
IDENTICAL

copy of a
gene or an entire organism is
produced.


scientists
INSERT
a normal gene
into an
ABSENT OR
ABNORMAL GENE
. Once
inserted the normal gene begins
to produce
CORRECT

proteins or
enzymes. This
ELIMINATES

the
cause of the disorder

3. Results of genetic engineering
may include:

a. the development of
PLANTS

that
make their own
INSECTICIDES.

b. the development of
ANIMALS

that are
BIGGER, FASTER,
RESISTANT TO DISEASE.


9. SELECTIVE BREEDING:
method of artificially
SELECTING

and
BREEDING

only organisms with a
DESIRED
TRAIT

to produce the next
generation.


a. inbreeding:
CROSSING
INDIVIDUALS THAT ARE
CLOSELY RELATED.



1.
NOT THE BEST
OPTION: DISEASE
DEVELOPS EASILY.


b. HYBRIDIZATION: choosing
and breeding organisms that
show
STRONG EXPRESSION

for
TWO DIFFERENT TRAITS

in
order to produce their offspring
that express the desired traits.