GENE - MUTATION

GENE MUTATION

  • Gene mutations are alterations in the DNA sequence that can lead to changes in protein function and contribute to the development of various diseases.

  • An error that occurs in the DNA

  • Gene mutations are permanent alterations in the deoxyribonucleic acid (DNA) sequence that make up a gene. These changes can range from a single nucleotide base pair to larger segments of a chromosome.

  • They can lead to changes in the protein product encoded by the gene, potentially altering its function, making it non-functional, or preventing its production entirely. This can contribute to the development of various genetic diseases or predispose individuals to certain conditions.

  • Mutations can occur spontaneously due to errors during DNA replication or recombination, or they can be induced by external factors called mutagens (e.g., radiation, certain chemicals).

DNA Template: TAC CCT GCT CCA TCG ATC

Complementary Strand: ATG GGA CGA GGT AGC TAG

mRNA Translations: A > U, T > A, C > G, G > C

Amino Acids - Building blocks of protein

Insertion - Is the mutation of inserting one or more nucleotides into the DNA sequence

ex.

Original DNA Sequence: TAC GAT CCG AAT TGC CGA

Mutated DNA Sequence: ATG CTA  AGG CTT AAC GGC T

Deletion - Is the mutation where a nucleotide is deleted in the DNA sequence

ex.

Original DNA Sequence: TAC GCT ATC CGA ACG ACT

Mutated DNA Sequence: AGC GAC AGG CTT GCT GA

Substitution - Mutation where another nucleotide base replaces a nucleotide base.

ex.

Original DNA Sequence: TAC AAA CGA

Mutated DNA Sequence: ATG TAT GCT

Gene: Segments of DNA

Alleles - Letters

  • Dominant: Uppercase

  • Recessive: Lowercase

Genotypes: Homozygous Dominant (TT), Heterozygous (Tt), Homozygous Recessive (tt)

Punnet’s Square

  • A tool used to predict offspring's possible geno and phenotypes

Genotypes - Are the letters representing the Dominant and Recessive characteristics, also called Alleles

ex. TT, Aa, Pp

Phenotypes - Identifying the dominant characteristics of the Genotypes

ex. Tt > Tall, pp > Yellow

DNA Replication 

  • Process of making an exact copy of DNA before cell division ensures each new cell gets the same genetic info.

  • Happens during the S Phase of the cell cycle

  • Purpose: so that cells can have their own complete set of DNA

Helicase - unzips the DNA strands

Primes - starting point of replication

DNA Polymerase - Builds new complementary nucleotides

Ligase - Glues the DNA fragments together.

DNA > RNA > Protein

Protein Synthesis

  • cells make proteins using information from the DNA

  • occurs in two steps: Transcription and Translation

Transcription

  • Occurs in the nucleus

  • DNA is copied into mRNA

  • RNA Polymerase builds mthe RNA strand

Translation

  • Occurs in the ribosome

  • mRNA in groups of three called codons

  • tRNA brings amino acids to match codons

  • rRNA links amino acids into a protein chain

Types of RNA

mRNA - messenger RNA - carries the genetic code from DNA

tRNA - transfer RNA - brings amino acids

rRNA - ribosomal RNA - forms ribosomes

A mutation can be beneficial, harmful, or neutral/no effect

Types of Mutations

Missense Mutation - Changes one amino acid

Nonsense Mutation - Stops protein early

Frameshift Mutation - Change entire sequence

Gregor Mendel

  • “Father of Genetics”

  • Augustinian monk

  • Discovered how traits are inherited using pea plant experiments

Three Laws (according to Gregor Mendel)

Law of Dominance - The dominant allele overrules the recessive alleles

Law of Segregation - Alleles separate during meiosis, giving each gamete one copy of a gene

Law of Independent Assortment - Genes for different traits