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Study Guide: DNA and Gene Technology Assessment
DNA:
 Structures from largest to smallest: cell → nucleus→ chromosome → DNA → gene
 A gene is a set of instructions for each trait.
o Genes are found on chromosomes.
o Chromosomes are made up of DNA.
 Rosalind Franklin was able to create images of DNA molecules
using X-Rays and discover that DNA was spiral shaped.
 Watson and Crick made models to determine DNA’s “twisted ladder”
or double helix structure.
 According to Chargaff’s rules Adenine always pairs with Thymine and Cytosine always pairs
with Guanine. A-T and C-G
 The complementary strand of:
ATTGCCG
TAACGGC
is
(because A goes to T and G always goes to C)
 The picture above is the basic structure of DNA and it is made of nucleotides.
 A nucleotide (pictured to the right) in a DNA molecule is
made up of a sugar, a phosphate, and a base.
 In a DNA nucleotide, the middle of the “ladder” is made of
four different nitrogen bases and the sides of the “ladder”
are made of sugar and phosphate molecules.
 In DNA there are four different bases: Adenine, Thymine, Cytosine, and Guanine
Genetic Engineering
 Cloning- process of making an identical copy of another organism using its DNA.
 Dolly, the sheep, is the first successfully cloned mammal because of genetic engineering.
Mutations:
 A change in the order of bases in DNA is called a mutation.
 A mutation could be caused by x-rays, radioactivity,
ultraviolet rays.
 A mutation in DNA could result in no change,
death or a genetic disorder.
 Your phenotype (physical appearance) can be affected
by heredity and the environment.
• The environment can have an effect on a person’s genes:
•
o Ultraviolet radiation from the sun is known to cause
mutations in skin cells that can lead to cancer
o Smoking cigarettes can cause mutations in lung cells.
Most genetic disorders (albinism, sickle cell anemia, etc.)
are due to a recessive gene.
Pedigree Chart:
 In a pedigree, squares represent males and circles represent females.

A solid black square or circle indicates that the person has a certain trait.
 A blank square or circle indicates that a person DOES NOT have a certain trait.
 A half-filled square or circle indicates that the person is a carrier of a certain trait but does
not show the trait.