Aim: DNA & RNA structure Enter Date Aim: DNA & RNA structure Warm-up: HW:

Watson and Crick … and others… 1953 | 1962 Watson and Crick … and others…

The Double Helix Rosalind Franklin used an X-ray diffraction machine to photograph DNA She found that DNA is twisted like coils and that there were two strands present

Nucleic Acids Examples DNA RNA DeoxyriboNucleic Acid RiboNucleic Acid

Nucleic Acids Function: genetic material stores information genes blueprint for building proteins DNA → RNA → proteins transfers information blueprint for new cells blueprint for next generation DNA proteins

Nucleic acids 5 different nucleotides Building block = nucleotides nucleotide – nucleotide – nucleotide – nucleotide 5 different nucleotides different nitrogen bases A, T, C, G, U Nitrogen bases I’m the A,T,C,G or U part! phosphate sugar N base

Differences between DNA & RNA phosphate sugar N base DNA double-sided double helix A, T, G, C RNA single-sided A, U, G, C phosphate sugar N base strong bonds phosphate sugar N base phosphate sugar N base RNA

Nitrogenous Bases Adenine – A Guanine – G Cytosine – C Thymine – T These two are purines, they have two rings. These two are pyramidines, they have one ring

Paired bases RNA bases that go together DNA bases that go together A pairs with T A : T G pairs with C G : C RNA bases that go together A pairs with U A : U G pairs with C G : C

A T C G Genes (DNA) are needed to run bodies every day… to make you and me… to make new cells… to make babies!

DNA Double strand twists into a double helix weak bonds between nitrogen bases join the 2 strands the two strands can separate when our cells need to make copies of it It’s a helix or B sheet within a single region. Can have both in one protein but a specific region is one or another weak bonds

Copying DNA Matching bases allows DNA to be easily copied

Making new DNA Copying DNA DNA starts as a double-stranded molecule matching bases (A:T, C:G) then it unzips…

DNA replication Strands “unzip” at the weak bonds between bases

DNA replication Enzyme DNA polymerase adds new bases DNA bases in nucleus Enzyme DNA polymerase adds new bases DNA polymerase

Copying DNA Build daughter DNA strand use original parent strand as “template” add new matching bases synthesis enzyme = DNA polymerase DNA Polymerase

DNA Sequences If a strand of coded DNA read ATGGCGTAGTAGA It’s complimentary strand would say TACCGCATCATCT

New copies of DNA Get 2 exact copies of DNA to split between new cells polymerase DNA polymerase

Copied & Paired Up Chromosomes centromere

DNA must be duplicated… chromosomes in cell 4 single-stranded chromosomes nucleus cell DNA in chromosomes nucleus cell duplicated chromosomes duplicated chromosomes 4 double-stranded chromosomes

Chromosomes Since DNA is so long, the body designed a way to tightly wind it up. Chromosomes are strands of DNA that are tightly wound together

Chromosome Packing In order to make a chromosome, DNA winds around a histone protein. The DNA strand is pulled closer together and eventually makes up a chromosome.

double-stranded human chromosomes ready for mitosis DNA RAP