NU 545 Advanced pathophysiology
Chapter 4 Outline Genes and Genetic
Diseases Study Guide with Questions &
Complete Details | Latest 2025/2026
Update |
• DNA, RNA, and Proteins: Heredity at the Molecular Level Chromosomes
contain genes.
• Genes are the basic unit of inheritance and are composed of DNA.
• DNA subunit or nucleotide contains Ø one pentose sugar (deoxyribose).
Ø one phosphate group.
Ø one nitrogenous base.
• Cytosine (C), thymine (T), adenine (A), guanine (G)
DNA has a double helix structure.
• DNA as the Genetic Code
• DNA provides the code for all body proteins.
• Proteins are composed of one or more polypeptides.
• Polypeptides are composed of amino acids; there are twenty (20) amino acids:
Ø The sequence of three bases (codons) direct the production of amino acids.
Ø Termination and nonsense codons stop the production of protein.
Replication of DNA
• The DNA strand is untwisted and unzipped.
Ø Single strand acts as a template.
• DNA polymerase pairs the complementary bases.
1
, Ø Adenine-thymine; cytosine-guanine
• DNA polymerase adds new nucleotides and “proofs” the new protein; if not correct,
the incorrect nucleotide is excised and replaced.
Question 1
Which information is correct regarding DNA polymerase? DNA polymerase functions to:
1. signal the end of a gene.
2. pull apart a portion of a DNA strand.
3. add the correct nucleotides to a DNA strand.
4. provide a template for the sequence of mRNA nucleotides.
Rationale: This enzyme functions to add correct nucleotides to the DNA strand, to edit
incorrect nucleotides, and enhance the accuracy of DNA replication.
1. Termination or nonsense codons signal the end of a gene.
2. RNA polymerase binds to a promoter site on DNA and pulls apart a portion of the DNA
strand.
4. One of the DNA strands exposed by the action of RNA polymerase provides a template for
the sequence of mRNA nucleotides.
Mutation
• Is any inherited alteration of genetic material.
Ø Chromosome aberrations in number or structure Ø
Base pair substitution or missense mutation
• One base pair is substituted for another; may result in changes in
amino acid sequence.
• May or may not cause disease or problems. Ø Frameshift mutation
• Involves the insertion or deletion of one or more base pairs to the DNA
molecule.
• Mutagens: Are agents, such as radiation and chemicals, that increase the frequency of
mutations.
2
, From Genes to Proteins
• DNA is formed in the nucleus; protein is formed in the cytoplasm.
• Transcription and translation: DNA code is transported from the nucleus to the
cytoplasm, and protein is subsequently formed.
• Ribonucleic acid (RNA) mediates both processes.
Ø RNA is a single strand.
Ø Uracil rather than thymine is one of the four bases; all the rest are the same as
DNA.
Transcription
• RNA is synthesized from the DNA template via RNA polymerase.
Ø RNA polymerase binds to the promoter site on DNA.
• DNA specifies a sequence of mRNA.
• Transcription continues until the termination sequence is reached.
• mRNA then moves out of the nucleus and into the cytoplasm.
• Gene splicing occurs.
Ø Introns and exons
Translation
• Is the process by which RNA directs the synthesis of a polypeptide via the interaction
with transfer RNA (tRNA).
• tRNA contains a sequence of nucleotides (anticodon) complementary to the triad of
nucleotides on the mRNA strand (codon).
• Ribosome is the site of protein synthesis.
Ø Ribosome helps mRNA and tRNA make polypeptides.
Ø When ribosome arrives at a termination signal on the mRNA sequence,
translation and polypeptide formation cease.
Question 2
3
Chapter 4 Outline Genes and Genetic
Diseases Study Guide with Questions &
Complete Details | Latest 2025/2026
Update |
• DNA, RNA, and Proteins: Heredity at the Molecular Level Chromosomes
contain genes.
• Genes are the basic unit of inheritance and are composed of DNA.
• DNA subunit or nucleotide contains Ø one pentose sugar (deoxyribose).
Ø one phosphate group.
Ø one nitrogenous base.
• Cytosine (C), thymine (T), adenine (A), guanine (G)
DNA has a double helix structure.
• DNA as the Genetic Code
• DNA provides the code for all body proteins.
• Proteins are composed of one or more polypeptides.
• Polypeptides are composed of amino acids; there are twenty (20) amino acids:
Ø The sequence of three bases (codons) direct the production of amino acids.
Ø Termination and nonsense codons stop the production of protein.
Replication of DNA
• The DNA strand is untwisted and unzipped.
Ø Single strand acts as a template.
• DNA polymerase pairs the complementary bases.
1
, Ø Adenine-thymine; cytosine-guanine
• DNA polymerase adds new nucleotides and “proofs” the new protein; if not correct,
the incorrect nucleotide is excised and replaced.
Question 1
Which information is correct regarding DNA polymerase? DNA polymerase functions to:
1. signal the end of a gene.
2. pull apart a portion of a DNA strand.
3. add the correct nucleotides to a DNA strand.
4. provide a template for the sequence of mRNA nucleotides.
Rationale: This enzyme functions to add correct nucleotides to the DNA strand, to edit
incorrect nucleotides, and enhance the accuracy of DNA replication.
1. Termination or nonsense codons signal the end of a gene.
2. RNA polymerase binds to a promoter site on DNA and pulls apart a portion of the DNA
strand.
4. One of the DNA strands exposed by the action of RNA polymerase provides a template for
the sequence of mRNA nucleotides.
Mutation
• Is any inherited alteration of genetic material.
Ø Chromosome aberrations in number or structure Ø
Base pair substitution or missense mutation
• One base pair is substituted for another; may result in changes in
amino acid sequence.
• May or may not cause disease or problems. Ø Frameshift mutation
• Involves the insertion or deletion of one or more base pairs to the DNA
molecule.
• Mutagens: Are agents, such as radiation and chemicals, that increase the frequency of
mutations.
2
, From Genes to Proteins
• DNA is formed in the nucleus; protein is formed in the cytoplasm.
• Transcription and translation: DNA code is transported from the nucleus to the
cytoplasm, and protein is subsequently formed.
• Ribonucleic acid (RNA) mediates both processes.
Ø RNA is a single strand.
Ø Uracil rather than thymine is one of the four bases; all the rest are the same as
DNA.
Transcription
• RNA is synthesized from the DNA template via RNA polymerase.
Ø RNA polymerase binds to the promoter site on DNA.
• DNA specifies a sequence of mRNA.
• Transcription continues until the termination sequence is reached.
• mRNA then moves out of the nucleus and into the cytoplasm.
• Gene splicing occurs.
Ø Introns and exons
Translation
• Is the process by which RNA directs the synthesis of a polypeptide via the interaction
with transfer RNA (tRNA).
• tRNA contains a sequence of nucleotides (anticodon) complementary to the triad of
nucleotides on the mRNA strand (codon).
• Ribosome is the site of protein synthesis.
Ø Ribosome helps mRNA and tRNA make polypeptides.
Ø When ribosome arrives at a termination signal on the mRNA sequence,
translation and polypeptide formation cease.
Question 2
3
