N5315 Advanced Pathophysiology
Genetics
Core Concepts and Objectives with Advanced Organizers
Genetics
1. Analyze the pathological processes which alter the structure and role of the DNA and RNA
molecules.
a. Describe the structure and function of the DNA molecule and its clinical significance.
● DNA (double strand) Genes are composed of DNA and most important is the 4 types of
nitrogenous bases (adenine, cytosine, guanine, thymine). Adenine pairs with thymine, and
guanine pairs with cytosine. A T and GC
● Each DNA consist of one deoxyribose molecule, one phosphate group, one base called a
nucleotide.
● DNA serves as the blueprint of proteins in the body, genes ultimately influence all aspects
of body structure and function
b. Evaluate the process of DNA replication and describe how it is altered by mutations.
● DNA replication consist of the breaking of the weak hydrogen bonds between the bases,
leaving a single stand with each base unpaired.
● Complementary base pairing is the pairing of adenine with thymine and guanine with
cytosine. This is the key to accurate replication. This means the unpaired base will attach
to a nucleotide only if has the complementary base.
● When replication is complete a new identical strand will be formed. This new strand is
called a template by which is built from the complementary molecule.
● Proteins are involved in the replication by one protein unwinds the double helix, one
holds the strands apart, and other have different functions. The most important protein is
the enzyme called DNA polymerase; the enzyme travels along the DNA strand, adding
the correct nucleotide, the DNA polymerase performs a proofreading procedure.
● The DNA polymerase checks that the base is complementary to the template base. If it
not the correct nucleotide it will replace it with the correct one.
● Mutation is an inherited alteration of genetic material.
○ Base pair substitution- one base pair is replaced by another (missense mutation)
because the “sense” of the codon produced after transcription of the mutate gene
is altered which results in chase in amino acid sequence b/c of the redundancy of
the genetic code, it may have no consequence.
○ Profound consequence- when an amino acid sequence is altered by a base pair
substitution
○ Frameshift mutation- insertion/deletion of one or more basic pairs to the DNA
molecule-change the entire “reading frame” of the DNA sequence b/c codons
consist of groups of three base pairs.
c. Describe the structure and function of the RNA molecule and its clinical significance.
1
, N5315 Advanced Pathophysiology
Genetics
Core Concepts and Objectives with Advanced Organizers
RNA (a single strand)- a type of nucleic acid chemically similar to DNA. Bases of RNA :
(adenine, cytosine, guanine, uracil)- A U and GC
RNA transmits genetic information from DNA to proteins produced by the cell. RNA
carries out the instructions encoded in DNA. RNA is similar to DNA except thymine is
replaced by uracil. RNA occurs in a single strand.
d. Explain the processes of translation and transcription.
Transcription (occurs in nucleus)
Process by which RNA is synthesized from a DNA
template result formation for messenger RNA
(mRNA) from the base sequence specified by the
DNA molecule
Transcription of a gene begins when enzyme RNA
polymerase binds to a promoter site of DNA
Promoter site- a sequence of DNA the specifies the
beginnings of a gene
Transcription factors (protein) bind to Transcription
factor binding sites (DNA sequences) near genes to
regulate the timing of transcription as well as the
specific tissues in which genes are actively
transcribed ie. Clotting factor VIII primarily in
hepatocytes
Transcription factors can either activate or repress
expression of genes and sometimes up-regulated by
the binding of nearby DNA sequenced called
enhancers
RNA polymerase pulls portion of DNA strands apart
from one another-allowing unattached DNA bases to
be exposed
One of the DNA strands then provides template for
sequence of mRNA nucleotides
Sequence of bases in mRNA is complementary to that of template strand with the exception of
the presence of uracil instead of thymine
Transcription continues until a DNA called termination sequence is reached RNA
polymerase detaches from DNA and transcribed mRNA is freed to move out of nucleus into
cytoplasm
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