Mutations and Pedigrees
A mutation that changes one nucleotide is called what?
Substitution
What are the three components of a DNA nucleotide?
Deoxyribose sugar, phosphate group, nitrogen base
What process copies DNA into mRNA?
Transcription
What is the end result of DNA replication?
2 strands of DNA
What is the START codon? What amino acid does is code for?
AUG; Methionine
Describe the following individual on a pedigree:
-Shaded Square
Affected Male
Which nitrogen base is found in RNA but not in DNA?
Uracil
Where does transcription occur? Why?
Nucleus; location of DNA
Why is DNA considered semi-conservative?
Each new DNA molecule contains one original (parent) strand and one newly synthesized strand.
A scientist replaces all thymine bases in a DNA strand with uracil. What molecule has he created?
RNA
Two unaffected parents have an affected child. What is the most likely inheritance pattern?
Autosomal Recessive
What are the complementary base pairs of DNA?
A-T; C-G
What codons code for Valine?
GUG; GUA; GUC; GUU
Replicate the following DNA sequence:
A A T C G A T C C
T T A G C T A G G
Why does changing a single nucleotide not always change the amino acid sequence?
Because the genetic code is redundant; multiple codons can code for the same amino acid (silent mutation).
What is the pattern of inheritance?
Autosomal Recessive
List two structural differences between DNA and RNA.
-DNA contains deoxyribose; RNA contains ribose
-DNA has thymine; RNA has uracil
-DNA is double-stranded; RNA is single-stranded (any two)
Transcribe the following DNA sequence:
A T T C G A A
U A A G C U U
When does DNA replicate? Be specific.
Before cell cycle; interpahse; S-Phase
Original DNA: TAC GGA TTT ACC GAA
Mutated: TAC GGT TTA CCG AA
What type of mutation occurred? Why are so many amino acids affected?
Deletion (frameshift); The deletion shifts the reading frame, changing every codon downstream from the mutation.
Explain why a frameshift mutation is often more severe than a substitution mutation.
A frameshift changes every codon after the mutation, potentially altering many amino acids and drastically changing the protein.
What would happen to DNA structure if hydrogen bonds between nitrogen bases did not form?
The two strands would not hold together properly, preventing stable double-helix formation.
Translate the following RNA Sequence:
UUA AUG AAA CCU UAG UGG
Amino Acids: Met-Lys-Pro- stop
Why do cells replicate prior to cell division?
To ensure all cells have the same DNA
In a pedigree, two unaffected parents have a child with a genetic disorder. The disorder appears in both males and females equally.
What is the expected GENOTYPE of the unaffected parents?
Carriers --Aa