DNA

1
DNA

• Structure and Replication
• DNA Rap Song
• http//www.youtube.com/watch?vd1UPf7lXeO8

2
Student Expectations

• B 6.A1
• Identify components of DNA.

3
DNA Structure

• DNA stands for Deoxyribonucleic Acid
• Shape Double helix
• Monomers Nucleotides (has 3 parts)
• Sugar, (deoxyribose),
• phosphate
• nitrogenous base
• Bases are held together by hydrogen bonds.

4
Four Nitrogenous Bases

• Adenine (A)
• Guanine (G)
• Cytosine (C)
• Thymine (T)
• Purines (double ring) Adenine and Guanine
• Pyrimidines (single ring) Cytosine and Thymine
• Chargaffs rule
• Adenine pairs with thymine. A T T A
• Guanine pairs with cytosine. G C C G

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Nucleotides
Purines
Pyrimidines
Adenine
Guanine
Thymine
Cytosine
Thymine
Cytosine
Phosphate group
Sugar Deoxyribose
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Build a DNA molecule

• http//learn.genetics.utah.edu/content/begin/dna/b
  uilddna/

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A Closer Look at DNA Page 294
Nucleotide
Hydrogen bonds
Sugar-phosphate backbone
Key Adenine (A) Thymine (T) Cytosine (C) Guanine
(G)
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A closer look at DNAHow DNA condenses
Chromosome
Centromere
Supercoils
DNA double helix
Histones
Chromatin
9
Student Expectation

• B 5.A1
• Describe the stages of the cell cycle,
  including deoxyribonucleic acid (DNA)
  replication.

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What is Replication?

• The process of copying DNA during S phase of
  interphase in the nucleus
• Makes sure that a daughter cell will have a
  complete set of chromosomes
• Original strand of DNA serves as a template for 2
  new strands
• Template a pattern an original model
• Each new strand will be identical to the original
  strand because of Chargaffs rule.

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How does replication work?

• 1) Helicase unwinds the double helix, forming a
  replication fork, where replication takes place
• 2) DNA polymerase bonds the necessary nucleotides
  to the original DNA strand to complete 2 new DNA
  molecules
• 3) DNA polymerase also proofreads the new DNA
  strand to make sure it is an exact copy of the
  original DNA

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DNA Replication Facts

• DNA polymerase can only work in one direction so
• 2 new strands of DNA are made in opposite
  directions
• One strand is made in sequence of nucleotides
• The other strand is what we call the lagging
  strand because nucleotides are added in fragments

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DNA Replication Page 298
Original strand
DNA polymerase
New strand
Growth
DNA polymerase
Growth
Replication fork
Replication fork
Nitrogenous bases
New strand
Original strand
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Videos

• http//www.youtube.com/watch?NR1featurefvwpvb
  W5JnYZImJA
• http//www.youtube.com/watch?v5VefaI0LrgEfeature
  related