Transcript 4.1 Intro to Genetics

Intro to Genetics
Mr. Mah
Living Environment
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Think for a second
about the most crazy
thing you have ever
seen…
Imagine in the future…
when something like THIS
could be possible…
The future is now…
How did the
scientists do
it?
INTRO TO
GENETICS
GENETICS:
the study of how
traits are passed
from one generation
to the next
TRAIT:
a characteristic
Examples:
Plant size, seed color, pod
shape
GENE:
the factors that
control traits
(found on chromosomes)
*can be passed down from one
generation to another
CHROMOSOME:
tightly coiled strands
of DNA stored in the
NUCLEUS
* genes = segments of
chromosomes
ALLELES:
different forms
of a gene
GENES
Each feature of the pea plants is controlled by a
gene. It may have a gene that controls its color,
another for size and another for shape.
Above you see chromosomes. The
circled area is a gene on chromosome
#22. The absence of this gene causes
velo-cardio-facial syndrome (VCFS)
which may cause ADD and mental illness
ALLELES
Each gene comes in different forms called alleles,
so the gene that controls flower color may
come in two alleles: purple and white.
GREGOR MENDEL
•
•
•
•
The “father” of genetics
Lived from 1822-1884
Austrian Monk
Published his work in
1866, but no one took
him seriously until 1900.
• Studied Pea Plants!
MENDEL’S
EXPERIMENTS
Mendel experimented with
7 different characteristics
How can we
determine what
the offspring are
going to be?
DOMINANT traits:
allele that is always
expressed
(TT or Tt = tall)
RECESSIVE traits
allele that is expressed
only when
homozygous
(tt = short)
HOMOZYGOUS
organism with two
identical alleles for
the same trait
(TT or tt)
HETEROZYGOUS
organism with two
different alleles for
the same trait
(Tt)
GENOTYPE
the genetic makeup
(TT, TtHh)
*depends on the genes you
inherit
PHENOTYPE
physical
characteristics
(Tall, Brown)
*depends on genes BUT can be
affected by environmental factors
A child has brown hair and brown eyes. His father
has brown hair and blue eyes. His mother has red
hair and brown eyes. The best explanation for the
child having brown hair and brown eyes is that
(A) A gene mutation occurred that resulted in
brown hair and brown eyes
(B) Gene expression must change in each
generation so evolution can occur
(C) The child received genetic information from
each parent
(D) Cells from his mother’s eyes were present
in the fertilized egg
A child has brown hair and brown eyes. His father
has brown hair and blue eyes. His mother has red
hair and brown eyes. The best explanation for the
child having brown hair and brown eyes is that
(A) A gene mutation occurred that resulted in
brown hair and brown eyes
(B) Gene expression must change in each
generation so evolution can occur
(C) The child received genetic information
from each parent
(D) Cells from his mother’s eyes were present
in the fertilized egg
In a particular variety of corn, the kernels turn red
when exposed to sunlight. In the absence of sunlight,
the kernels remain yellow. Based on this information, it
can be concluded that the color of these corn kernels is
due to
(A) A different type of DNA that is produced when
sunlight is present
(B) A different species of corn that is produced in
sunlight
(C) The effect of sunlight on the number of
chromosomes inherited
(D)The effect of environment on gene expression
In a particular variety of corn, the kernels turn red
when exposed to sunlight. In the absence of sunlight,
the kernels remain yellow. Based on this information, it
can be concluded that the color of these corn kernels is
due to
(A) A different type of DNA that is produced when
sunlight is present
(B) A different species of corn that is produced in
sunlight
(C) The effect of sunlight on the number of
chromosomes inherited
(D)The effect of environment on gene expression