Transcript Designer Dogs!!

Hello Mr. Schooner’s 7th
Grade Class!!
* DNA contain genes that occupy a
specific place on a chromosome.
* A chromosome is a rod- shaped
structure made of DNA and proteins.
* DNA determines a specific trait in
the organism, like eye color or
gender.
* Dogs have 78 chromosomes: 38
pairs of autosomes and 2 sex
chromosomes.
* Sex chromosomes determine the
differences between male and
female (X or Y). Males have X and Y
chromosomes while females have
two X chromosomes.
* Autosomes have the information for
the traits that both male and female
have.
* An allele is an alternative form a
gene that determines a
characteristic.
* Alleles are represented by
letters. Capital for dominant
alleles and lowercase for
recessive alleles.
* For example, D can mean the
dog will have dark fur and d can
mean the dog will have light fur.
* Sex cells receive one
chromosome from each pair and
when combined, the offspring
will get one allele from each
parent.
* Homozygous is to have the
same from of the gene
represented by letters. i.e.
TT (dominant), tt (recessive)
* Heterozygous is to have
different froms of genes
represented by one capital
letter and one lower case
letter. i.e. Tt
Tall or Short
Eye Color
* A dominant trait is a trait that
overpowers a recessive trait
represented by a capital letter on
paper.
* A recessive trait can be
masked/hidden by the dominant
trait. It is represented by a
lowercase letter of the first letter
for the dominant trait.
* i.e. If the dominant trait is brown
eyes and the recessive trait is
blues eyes, the dog is more likely
to have brown eyes. But it is still
possible for the offspring to have
blue eyes.
* A Phenotype is the
Code
for
physical characteristic/
trait of an organism that
can be detected using any
of the five senses. i.e. big
ears
* The genotype is the actual
genes on the chromosomes
that can’t be detected
with five senses. They are
represented by letters on
paper i.e. TT, Tt, tt
* Genotypes code for
Phenotypes!!
* Meiosis is a process of nuclear
division that reduces the number
of chromosomes in new cells to
half the number in the original
cell.
* The cells made are sex cells:
sperm in males and egg in
females.
* When a baby is made one cell from
the father (sperm) joins with one
cell from the mother (egg).
* The new cell that is formed
(zygote) contains information
stored in DNA to make a new
puppy.
•
Punnett Squares are used
to predict the possible
outcomes of the puppy.
•
The center boxes
represent fertilized eggs.
•
The two columns and rows
represent the female
chromosomes and the male
chromosomes.
•
i.e. If the parents have
genotypes Aa x Aa, the
Punnett Square will look
like this. -----------
A
a
A
AA
Aa
a
Aa
aa
* Natural Reproduction is the
mating of two different types
Bulldog/
of dogs. (mutts)
Dalmatian *Selective Breeding is controlled
Hybrid
mating between two of the
same type of dog.
* Natural Reproduction increases
Purebred
Beagle
genetic variation because it
introduces new genes to the
breed.
* Selective Breeding decreases
genetic variation because it
doesn’t introduce new genes to
a breed.
* Dog trainers use Selective
Breeding to put their dogs in dog
shows and make money off pure
bred puppies (very expensive)
* If they keep doing this there will
be no new genes in the
bloodline, which can cause
health problems for future
offspring.
* Selective Breeding has large
impacts on genetic variation.
 It can cause offspring to
get a genetic condition
like heart disease, blood
disorders, immune
system disease, etc.
 For example, large dogs,
like the Great Dane are
at a higher risk of getting
bone cancer because
their bones are so
stressed by all the
weight they have to
carry.
Bone Cancer
Vizsla with
skin
disease
known as
atopic
dermatitis
Chronic eye
irritation
from excess
skin folds
* A Pedigree shows how a
trait is inherited over
several generations. Kind of
like a family tree!
* If two parents of the same
breed are carriers of a
genetic disease, it is likely
that the puppy will be born
with a genetic condition.
* These diseases and illnesses
can be passed through the
pedigree, which can be fatal
to the breed.
* Information about genetics from:
Postlethwait, John H., and Janet L. Hopson. "Ch. 9
Fundamentals of Genetics." Modern Biology. Orlando: Holt,
Rinehart and Winston, 2006. 172-86. Print.
* Information about Selective Breeding from:
"Dogs That Changed the World - Selective Breeding Problems
- Genetics | Nature | PBS." PBS: Public Broadcasting Service.
Web. 04 Mar. 2011.
<http://www.pbs.org/wnet/nature/episodes/dogs-thatchanged-the-world/selective-breeding-problems/1281/>.
* Pictures from Google Images