DNA & Genetics in Biotechnology

What is a DNA?
o A
that carries the genetic information in the cell and
is capable of self-replication and synthesis of RNA.
o DNA consists of two long chains of nucleotides twisted into a
and joined by hydrogen bonds between the complementary bases
o The sequence of
hereditary characteristics.
determines individual

What is a Nucleotide?
o A single molecule of DNA comprised of 2 basic parts made from 3 distinct
molecules.



Sugar/Phosphate Backbone
o Comprised of
o Forms a
bond that creates the backbone of a DNA strand
o EXACTLY THE SAME IN ALL DNA

Nitrogenous Base
o Bond with complimentary bases in other nucleotides to form the rungs of the
DNA ladder (zip DNA together)
o Only 4 types in all DNAo Adenine and Thymine bond only with each other
o Cytosine and Guanine bond only with each other

DNA form
o
o Nucleotides bond at two spots
 Sugar/Phosphate molecules form the backbone (
)
 Nitrogenous bases bond in the middle by hydrogen bonds (
)
 Hydrogen bonds between nitrogenous bases are MOST EASILY BROKEN
o
Characteristics of DNA
 DNA
o Accounts for all genetic variation between different individuals and organisms by
the use of different:
 Sequences of nitrogenous bases
 Lengths of DNA segments
 Numbers of Chromosomes and amounts of DNA in an organism
o The amount of DNA in an organism DOES NOT relate to the size or complexity
of an organism.

DNA Replication
o The process



The double helix structure allows DNA to easily unzip down the center
between nitrogenous bases.
Free floating nucleotides attach to each of the separated DNA strands
forming 2 new strands of DNA, each an exact copy of the original.
Mutations
o A mutation is
o Mutations are
in most organisms (especially simple organisms)
though only a small percentage produce noticeable changes in organisms.

Genetic Hierarchy
o A group of nucleotides=a gene/allele=45-150 base pairs
o A group of genes=1 strand of DNA
o Several condensed strands of DNA=1 chromosome
o 2 chromosomes=1 chromatid pair
o All possible gene forms in a population=Genome

Gene Mapping
o Mapping the genome of a species allows scientists to
, and is
the first step in determining the location of specific genes on chromosomes.
 Changes in the genome of a species occur slowly in response to
environmental changes.

Transferring of DNA
o DNA is passed to offspring during sexual reproduction through single
chromosomes.

Human Genetics
o Almost all humans have
.
 Individuals with Down Syndrome have one extra chromosome.
o Humans generally differ from each other by approximately 3 million nitrogenous
base pairs, or 0.1% of the total gene sequence.

Genetic Disorders
o Diseases or other problems resulting from errors in the transmission of genetic
information, or the expression of certain negative gene sequences.
o Most genetic disorders are
, and thus cannot be predicted
without genetic analysis
 Recessive disorders are transmitted by carriers-parents with one dominant
gene (normal) and one recessive gene (disorder)
 Example-Tt
o Certain disorders are more common in certain populations
 Example: The occurrence of sickle cell in African Americans.

Common Genetic Disorders
o Inherited Disorders
 Examples: Tay-Sachs, Sickle Cell Anemia, Hemophilia
o Mutations
 Cancer Treatment must destroy mutated cells

Genetic Mutations
o Sudden unexpected changes in the genetic code of an organism which appear
most often during the process of replication
o
o Stresses includeo Almost all mutated cells die immediately, or never impact living organisms
 Most mutations in humans are harmful such as cancer
 A small fraction of noticeable mutations are beneficial, such as Chimeras
which are used to give us variegated plants.
o Most mutations occur in developed plants and animals, affecting isolated groups
of cells.
o Mutations are most devastating when the occur in the early development of
organisms. (STEM CELL STAGE)

Types of Mutations
o Point mutation

o Frameshift
