ALL THE DNA THINGS DNA Structure DNA Replication

ALL THE DNA THINGS! DNA Structure DNA Replication DNA mutation Wobble Theory Chromosome structure Chromosome mutation DNA packing

ALL THE DNA THINGS! Quick review! DNA – deoxyribonucleic acid Made of nucleotides Genetic code A-T G-C <= base pairs Sugar phosphate backbone Double helix aka Twisted ladder

ALL THE DNA THINGS!

ALL THE DNA THINGS! DNA Structure 5' Carbon is the top Carbon on one side of the strand. 3' Carbon is top on the other side of the strand Presents a flip flopped double strand

ALL THE DNA THINGS! DNA replication Helicase unzips DNA and relieves torsion on the DNA strand preventing it from snapping DNA polymerase fills in the coordinating nucelotides and proofreads for errors. DNA ligase ties (ligates) the copies together into a new DNA strand

ALL THE DNA THINGS! DNA Polymerase add only to the 3' end. This leads to a lagging strand in one of the DNA strands. The DNA is copied in segments. These segments are called Okazaki fragments.

ALL THE DNA THINGS! Errors in proofreading lead to genetic mutations. Genetic mutations can be harmful, neutral, or positive. Body mutations can affect the organism. Gamete mutations can affect offspring.

ALL THE DNA THINGS! Multiple codons (set of 3 nucleotides) can code for a single amino acid. This allows the chance that an error/point mutation will not be harmful.

ALL THE DNA THINGS! Wobble theory! The first 2 nucleotides code for the actual amino acid. Some sway is allowed on the third nucleotide so that the entire amino acid does not change

ALL THE DNA THINGS! DNA is organized into chromosomes.

ALL THE DNA THINGS! Chromosome Structure

ALL THE DNA THINGS! Much like mutations happen in DNA replication, mutations can happen on the chromosome level. Each letter represents a particular gene or sequence.

ALL THE DNA THINGS! A karyotype is used to map out chromosomes to determine proper count and if any mutations have occurred.

ALL THE DNA THINGS! DNA packing tends to prevent gene expression If DNA is packed tightly, RNA polymerase can not access the genetic code to make m. RNA for protein synthesis. DNA is also packed tightly so that there is lesser chance of genes being lost in transport for mitosis and meiosis. DNA packing also is found with X chromosomes for “dosage compensation” Since the X chromosome is so large, only one is needed to be functional. One is shut down to prevent an overload of genetic information

ALL THE DNA THINGS! DNA wraps around histones. Histones with DNA form beads called nucleosomes. Nucleosomes form tight helical fibers These fibers form supercoils into chromosomes

ALL THE DNA THINGS! DNA packing affects gene expression

ALL THE DNA THINGS! TASKS! Discuss the structure of DNA and chromosomes Discuss the process of DNA replication Discuss DNA mutations and Chromosomal mutations How does DNA packing affect gene expression and how is it useful in other genetic processes?