Cell division 2 DNA Replication NOTES
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DNA replication makes copies of DNA and is essential for cell division. It occurs through a semi-conservative process where the double helix structure of DNA unwinds and each strand serves as a template for a new complementary strand. This results in two new DNA molecules that each contain one original strand and one newly synthesized strand. Key enzymes like helicase and DNA polymerase facilitate accurate copying of the genetic material according to the base pairing rules to ensure each cell receives an identical copy of the DNA blueprint.
Cell division 2 DNA Replication NOTES
- 1. CELL DIVISION 2: DNA Replication ppt. by Robin D. Seamon
- 2. N U C L E I C A C I D S • Made of nucleotides • Make up macromolecules of DNA 1. DNA Replication (makes copies of itself) 2. Encodes information (for proteins to be made) 3. Controls & instructs cells 4. Mutations (molecule of heredity) 2
- 3. D N A Deoxyribonucleic Acid double helix structure containing genetic information SIZE: (in each cell) 3 billion base pairs 6 feet long 10- 30 trillion cells in body!!
- 4. Prokaryotes- DNA is in the cytoplasm; during binary fission, DNA forms round structure called plasmids Eukaryotes- DNA is inside the nucleus; double- helix structure
- 5. VOCABULARY • chromosomes- threadlike structure of nucleic acids containing genetic information in the form of genes • genes- unit of heredity transferred from parent to offspring; a distinct sequence of nucleotides • nucleotides- A, T, C, G
- 6. DNA Strands per human cell: • 23 base pairs of chromosomes A – T C – G • each chromosome has 2 strands of DNA (double helix)
- 7. • DNA is in all living things • fundamental language of all of life (all life forms can read it) • Plants, animals, bacteria, protists, fungi, some viruses • these coded instructions are read (translated) by ribosomes and then used to build proteins (transcripted) for the body
- 8. COMMON LANGUAGE OF LIFE
- 9. genome: complete set and pattern of genes present in a cell; each species has its own pattern/genome example: HUMANS • 99.9 % genes identical to every one else • 0.1% makes us unique
- 10. • Every cell in a living organism’s body (except red blood cells) have a copy of their species genome written in the code. • Different genes (pieces of DNA) are turned on or off where they are needed 10
- 12. **DNA (chemical basis of heredity) is in genes **Genes are ON chromosomes Chromosomes (made of two sister chromatids) • A “packaged structure” made of DNA & proteins • single strand of tightly coiled DNA • too thin to see without a microscope • become short and fat & pairs up with a sister chromatid to make an X shape during mitosis
- 13. Chromatin: long, thin nuclear strands Chromatid: after chromatin are copied, they are called sister chromatids Chromosome: the sister chromosomes combine to make an x-shaped chromosome package Chromosomes (made of two sister chromatids) • single strand of tightly coiled DNA • too thin to see without a microscope • become short and fat & pairs up with a sister chromatid to make an X shape during mitosis
- 14. C CC C C P Nitrogen base DNA Structure nucleotide- monomer • sugar + phosphate + Nitrogenous base • Groups of nucleic acids make strands of the polymer DNA
- 15. C CC C C P Nitrogen base
- 16. Nitrogen Bases: PURINES • Adenine (A) BIG • Guanine (G) BIG PYRIMIDINES • Cytosine (C) (small) • Thymine (T) (small) C CC C C P Nitrogen base BASE
- 17. Nitrogen base
- 18. Backbone: sugar
- 20. Base-pairing rule: purines pair with pyrimidines and are held together with hydrogen bonds • sequence: order of bases A pairs with T C pairs with G codon: 3 base pairs A T T G C T C A T T A A C G A G T A
- 21. Double helix - Twisted ladderDNA Structure PAIRS: Number of A will = number of T Number of G will = number of C
- 22. genes • one gene makes one protein • the gene is the instruction sequence for the production of that protein protein • carries out a function example: hemoglobin carries oxygen GENE EXPRESSION:
- 24. Mutations: a change in the coding of a gene -can occur through: 1. Deletion: cell accidentally omits a piece of the DNA 2. Duplication: cell accidentally makes an extra copy of the DNA piece 3. Insertion: cell accidentally adds a piece of DNA 4. Substitution: putting in the wrong letter 5. Translocation: cell accidentally puts a piece of genetic sequence in the wrong place. 24
- 25. ACTIVITY • THE OLD RED DOG WAS TOO BIG FOR HIS BED • Deletion that would delete the D in OLD… • THE OLR EDD OGW AST OOB IGF ORH ISB ED • Inversion of the word DOG... • THE OLD RED GOD WAS TOO BIG FOR HIS BED 25 FRAME SHIFT- confuses the whole message: bad mutation less of a problem
- 26. mutation example: • one mutation in the gene for hemoglobin (change T to A) causes sickle cell anemia
- 28. DNA REPLICATION 1. Helicase- enzyme unzips the double helix 2. Hydrogen bonds break 3. DNA polymerase- enzyme builds the new DNA • Selects the new nucleotide (matches it) • Makes sure it is correct • Forms a new bond
- 29. Enzyme Substrate
- 30. Semi-conservative: DNA replication makes 2 new DNA strands with ½ the old strand and ½ the new strand
- 31. Two new strands
- 32. The specific pairing of bases allows for an EXACT copy of the DNA to be made.
- 33. Double helix = Twisted ladder