1. Nucleic Acids Unit: Nucleic Acids Nucleus DNA structure DNA replication

2. All living things… What are the characteristics of all living things?

3. Deoxyribonucleic Acid (DNA) One of several nucleic acids Contained in the cell nucleus (eukaryotes) Hereditary information (passed on parent to child) Copied before cell division Codes for proteins – the building blocks for all cell materials, activities, and traits

4. Nucleic Acids Nucleic acids are long chains of nucleotides Nucleotides are molecules with a five-carbon sugar, a phosphate functional group, and a nitrogen-containing base Nucleotides are building blocks

5. Nucleotides: Two main groups Deoxyribose Nucleotides Deoxyribonucleic acid (DNA): chromosomes Ribose Nucleotides Ribonucleic acid (RNA): protein synthesis Adenosine triphosphate (ATP): energy

6. Deoxyribonucleic Acid (DNA): Structure Four nucleotides (deoxyribose sugar, phosphate group, nitrogenous base) arranged in a double helix pattern (twisted ladder) Purines Adenine (A) Guanine (G) Pyrimidines Cytosine (C) Thymine (T)

7. Deoxyribonucleic Acid (DNA): Structure Bases pair up like rungs in the center with a weak hydrogen bond (attraction between a positive and negative charge) A sugar/phosphate backbone forms each side of the ladder What do you notice about the base pairing? A-T, C-G are the complementary base pairs

8. Deoxyribonucleic Acid (DNA): Prokaryotes Prokaryote Single, circular DNA molecule called the chromosome and has all the information for functioning Plasmid is a separate, very small circle of DNA used for special information like antibiotic resistance Reproduction? Asexual by binary fission (divide in two, similar to mitosis) Pili? Conjugation allows bacteria to exchange information like plasmids

9. Deoxyribonucleic Acid (DNA): Eukaryotes Eukaryote Much more DNA enclosed in nucleus Varying number of chromosomes Humans: 23 pairs of chromosomes (46 total) Approximately 3 billion base pairs

10. DNA: Variation and Specialization All living organisms have DNA based on the same four base pairs Sequence of base pairs determines proteins produced (all traits!) Specialization of cells determines which part of the DNA is active in each unique cell (every cell in an organism has the same DNA) Try this!

11. DNA: In the cell

12. DNA: Nucleus Three major parts: Nuclear envelope Chromatin Nucleolus

13. DNA: Nucleus Nuclear envelope (membrane) – Selectively permeable double membrane (allows small molecules through but large molecules go through a protein gate) Chromatin – DNA and associated proteins that forms long strands called chromosomes; condenses for cell division Nucleolus – site of ribosome synthesis

14. DNA: Cell Division Mitosis StageActivityDefinitions InterphaseDNA is in relaxed form called chromatin. During S phase it is replicated. Chromatin: DNA of eukaryotic cells ProphaseDNA already copied. It begins to condense to form chromosomes (paired chromatids). Spindle fibers attach to kinetochore of each sister chromatid Sister chromatid: One of two identical strands of DNA that forms a duplicated chromosome, joined at centromere MetaphaseSister chromatids line up in the middle AnaphaseSister chromatids are pulled apart becoming independent daughter chromosomes Chromosomes: DNA double helix together with proteins. TelophaseChromosomes return to relaxed chromatin form

15. DNA: Helix to Chromosome Watch Here

16. DNA: Replication During S phase of interphase DNA is copied so there will be one identical set for each new daughter cell Replication of DNA depends on the complementary base pairs 1.Unwind the DNA 2.Match complementary base pairs to each side 3.Two new identical DNA strands produced

17. DNA: Replication 1.Unwind the DNA DNA helicases – enzymes pull the DNA apart by breaking hydrogen bonds between the base pairs

18. DNA: Replication 2. Match complementary base pairs to each side DNA polymerases – enzymes move along each parent DNA strand and match complementary nucleotides

19. DNA: Replication 3. Two new identical DNA strands produced Semi-conservative process – Each daughter DNA strand has half parental DNA and half new DNA and winds back together to form the double helix

20. DNA: Replication Mistakes? Very rare but can happen Mistakes are called mutations and can be fatal, indifferent, or good depending on what they do to protein synthesis  Point mutation (one base pair wrong)  Insertion mutation (extra base)  Deletion mutation (lose base)  Inversion (piece of DNA cut out and moved into a gap)  Translocation (piece of DNA removed and attached to another chromosome)