DNA. Deoxyribose Nucleic Acid

Size: px
Start display at page:

Download "DNA. Deoxyribose Nucleic Acid"


1 DNA Deoxyribose Nucleic Acid

2 Biomolecules Remember 1. Carbohydrates 2. Lipids 3. Nucleic acids hold genetic information; code for proteins 4. Proteins

3 History of DNA

4 Who Discovered DNA Rosalind Franklin Took X-ray diffraction images In 1953 James Watson & Francis Crick Used Franklin s image Developed the 1 st accurate model of DNA

5 Nucleic Acids Overall Importance to Organisms Stores and transmits genetic hereditary information Codes for proteins Gene- specific segment of DNA

6 Nucleic Acids DNA double stranded genetic molecule RNA single stranded genetic molecule

7 Basic Building Block- Nucleotide

8 Sugar part of Nucleic Acids DNA RNA

9 Base pairs in DNA: A T and G C Hydrogen bonds


11 Held together by H bonds


13 DNA Double Helix Twisted Ladder Rungs of ladder are Nitrogenous base pairs held together by weak Hydrogen bonds Adenine with Thymine Guanine with Cytosine Side of ladder Alternating Sugar and phosphate backbone

14 DNA is Antiparallel

15 Parallel Strands Antiparallel Strands

16 Nucleosome

17 DNA histones nucleosomes chromosomes Organization of DNA In chromosomes, DNA is wound around histones A nucleosomes is a cluster of 8 histones

18 Reason for Packaging DNA must be tightly wound in order to fit inside the nucleus or nucleoid region of a cell Uncoiled human DNA is about 6 feet long!

19 Summary of DNA Structure 1. DNA is made of nucleotides as building blocks Nucleotides consist of deoxyribose (sugar), phosphate and a base 2. DNA has a antiparallel double helix shape 3. DNA is held together by hydrogen bonds 4. DNA consists of two strands joined by complementary base pairs Adenine and Thymine (A-T) Guanine and Cytosine (G-C) 5. A segment of DNA is called a gene, which codes for proteins

20 DNA Replication

21 Replication Replication copying DNA for new daughter cell Occurs during S phase of cell cycle S for DNA Synthesis

22 Replication copying DNA Replication copying DNA to supply new cells with DNA copy DNA instructions to make proteins and specialized cells

23 Base sequence The sequence of bases codes for proteins Ex. The strand you see now is ACAGGACGAC which may be the gene for the protein, keratin, in your fingernails That sequence of DNA would be the gene for keratin

24 Human DNA (As Chromosomes) 23 pairs of chromosomes 25, 000 genes

25 Replication is used to provide new cells with copy of DNA when new cells divide for Healing Replacement Growth increase # of cells

26 Cancer uncontrollable growth of cells Defect in their DNA that tells them to keep growing and dividing

27 Cancer Cells under Microscope

28 DNA Replication What do you see?

29 Terms of Replication Helicase enzyme that unwinds DNA DNA Polymerase enzyme that adds nucleotides to DNA Parent strand original DNA double helix Daughter DNA DNA copies with one side from parent strand and one new side Replication fork where DNA is unwound and separated into 2 single strands

30 Steps of DNA Replication S phase 1. Helicase carefully unwinds double helix of DNA, revealing replication fork 2. DNA Polymerase adds complimentary nucleotides to the two original strands of unwound DNA 3. Hydrogen bonds hold Adenine to Thymine, and Cytosine to Guanine 4. Two new strands of DNA are formed, one for original cell, and one for new cell

31 Can you label the parts?

32 Helpful Videos eplication1.swf Flash DNA Replication 3D animation mechanism-of-replication-advanced.html Overview of DNA structure and replication

33 Mutations Mistakes made during replication Most mutations have no affect! Types of Mutations Point Mutations Deletions Substitutions Frame Shift

34 Mutations on Chromosomes