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

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

3. 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

4. Nucleic Acids Examples DNA RNA DeoxyriboNucleic Acid RiboNucleic Acid

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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!

11. 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

12. Copying DNA
Matching bases allows DNA to be easily copied

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

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

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

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

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

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

19. Copied & Paired Up Chromosomes
centromere

20. 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

21. 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

22. 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.

23. double-stranded human chromosomes ready for mitosis
DNA RAP