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Learn about the structure of DNA and chromosomes, including the different types of chromosomes. Explore chromosomal and gene mutations and their effects at the nucleotide level.
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DNA & Chromosomes Notes • DNA is tightly coiled up with proteins to make chromosomes • DNA is made of repeating monomers called nucleotides • 4 DNA Nucleotide Bases: A, T, C, G • These nucleotide bases are what code for certain characteristics by creating for proteins • Chromosome structure breakdown:
Chromosomes • 2 Types: • Sex Chromosomes – contain genes that determine the sex of individuals • Autosomes – contain all other genes for an individual • Humans have 46 chromosomes • 2 Sex chromosomes (X & Y) • 44 autosomes • Sex is determined by the sex-chromosome in the sperm • Egg always has X; sperm has 50% chance of X or Y • Some genes are “linked” to the sex chromosomes
Mutations 1. Chromosomal Mutations – involves changing of pieces of actual chromosomes - Deletion - Duplication - portion of chromosome - portion doubledtotally removed and added - Translocation - Inversion - Parts of chromosomes - Piece is removed are switched and flipped backward - Nondisjunction - Chromosomes don’t separate during cell division
Mutations 2. Gene Mutations – affect genes at the nucleotide level (bases) • Substitution – 1 base swapped for another • Insertion - 1 base is added, causing a frame shift mutation • Deletion - 1 base is deleted, causing a frame shift mutation • Frame Shift – a change in the 3 DNA bases being read