INHERITANCE

INHERITANCE
Interest Approach
Pea plants

Different colored flowers
What was different about each plant??
History of Genetics
1670’s


Scientists believed
that each sperm
contained a “little
man” that would
develop into a
human
Then mother only
served as an
incubator
History of Genetics cont.
1750’s

“Blending of Inheritance Theory”
Example:
 Black animal mated to a white animal would
produce a gray animal
History of Genetics cont.
1850’s
Gregor Mendel


Austrian monk and worked in the
monastery garden mating pea plants
Determined that characteristic were
inherited by discrete factors that would
eventually become know as genes
Gregor Mendel
Discovered many principles


Principle of segregation
Principle of independent assortment
Principle of Segregation
Every individual carries pairs of factors for
each trait and that the members of the genes
segregate at random during the formation of
gametes
Since segregation is random, predictable
ratios of traits are found in the offspring
During segregation, chromosomes go from a
pair (2n or diploid) to singles (1n or haploid).
Good way to remember:
“Hap a diploid is 1n”
Principle of Independent
Assortment
Members of each pair of genes are
distributed independently when the gametes
are formed and are unaffected by other gene
pairs on other chromosomes
When pairs of genes on different chromosomes
separate, they have an equal chance or probability
of going to an individual gamete
No predetermined order for the dividing pairs
EVERY GENE FOR ITSELF
Chromosomes
Located in the nucleus of the cell and
contain all of the genetic material in the
cell
Arranged in pairs
Made up of a substance called DNA
Two Types of Chromosomes
Haploid

Half the diploid or
somatic (non-sex cell
or gamete) number
of chromosomes (n
or 1n)
Diploid


Number of
chromosomes found
in the somatic or
body cells (2n).
Twice the number of
chromosomes found
in the gametes
Chromosomes in Animals
1n
2n
Cattle
30
60
Sheep
27
54
Goat
30
60
Swine
40
80
Horse
30
60
Human
23
46
DNA
Deoxyribonucleic Acid
Three Components
 Deoxyribose sugar
 Phosphate
 Four nitrogenous
bases
 Adenine (A)
 Thymine (T)
 Guanine (G)
 Cytosine (C)
Nucleotides
Combination of the deoxyribose,
phosphate and one of the four bases


Nucleotides bond together to form one
strand of the DNA molecule
Two of the strands wind around each other
in a double helix to form the DNA molecule
In the two pairs of DNA
C
is always paired with
G
AND
A is always paired with T
The Gene
Genes are points of activity found in
each chromosome that govern the way
in which traits develop. Genes are
specific areas on each chromosome and
are made up of DNA
Protein Synthesis
RNA (ribonucleic acid) is a group of
molecules in charge of “reading” and
“translating” the genetic code for the
formation of new proteins
RNA uses the DNA as a template to
read the code in order to produce the
right protein with the correct order and
number of amino acids.
Three Types of RNA
Transfer RNA (t RNA)

Plays a key role in protein
synthesis (building). Each tRNA
molecule can combine with one
amino acid and can transport the
a. a. to the new protein building
site in the cytoplasm of the cell
Three Types of RNA cont.
Ribosomal RNA (rRNA)

Also plays a key role in protein
synthesis. It helps control the
connecting of the parts of the protein
(the amino acids) together.
Three Types of RNA cont.
Messenger RNA (mRNA)
Helps complete the building of the
protein
Physically sequencing the amino acids that
were carried to the building site by the tRNA
and chemically connected by the rRNA
The mRNA directs the sequence based on the
order it obtains from the DNA molecule
In RNA Translation. . .
C is paired with G
T is paired with A
A is paired with U
Activity: Building DNA
Materials Needed:

Several of each:
 Four different colored gumdrops or other
material that a toothpick can be inserted
into
 Toothpicks
Activity cont.
Instructions:




Designate each color of gumdrops a different base
(A=red, T=green, for example)
Designate the toothpicks as the bonds between
the bases
Give the students a list of bases that ranges from
10 to 15 bases long
The students will then lay out the sequence using
the gumdrops and the sticking toothpicks into the
sides
Activity Instructions cont.


The students must then decide the
complimentary pair for each base and
connect it to the given base
(to make a double helix other toothpicks
must be used on the outer sides of the
bases to connect the pairs of bases
together in a rotating matter)
Example
Given
Gumdrops
Toothpicks to hold bonds
together in rotating matter
T
A
A
C
Toothpicks
T
G
Complimentary Gumdrops