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DNA and Replication. Test: Friday Nov. 19 Covers Viruses and DNA/Replication. DNA- Deoxyribonucleic Acid. DNA codes for genes which carry your genetic information. History of DNA. 1953 Watson and Crick proposed the double helix, or spiral staircase, structure of the DNA molecule

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dna and replication

DNA and Replication

Test: Friday Nov. 19

Covers Viruses and DNA/Replication

dna deoxyribonucleic acid
DNA- Deoxyribonucleic Acid
  • DNA codes for genes which carry your genetic information.
history of dna
History of DNA
  • 1953
    • Watson and Crick proposed the double helix, or spiral staircase, structure of the DNA molecule
    • They were awarded the Nobel prize for this discovery
dna discovery
DNA Discovery
  • The Hershey-Chase Experiment
    • Bacteriophages: a virus that attacks bacterial cells. They inject genetic material and take over the cell
    • Radioactive markers: tag and stick to certain parts of the bacteriophage
hershey chase experiment pg290
Hershey-Chase Experiment-pg290

Bacteriophage with phosphorus-32 in DNA

Phage infectsbacterium

Radioactivity inside bacterium

Bacteriophage with sulfur-35 in protein coat

Phage infectsbacterium

No radioactivity inside bacterium

hershey chase experiment pg2901
Hershey-Chase Experiment-pg290

Bacteriophage with phosphorus-32 in DNA

Phage infectsbacterium

Radioactivity inside bacterium

Bacteriophage with sulfur-35 in protein coat

Phage infectsbacterium

No radioactivity inside bacterium

hershey chase experiment pg2902
Hershey-Chase Experiment-pg290

Bacteriophage with phosphorus-32 in DNA

Phage infectsbacterium

Radioactivity inside bacterium

Bacteriophage with sulfur-35 in protein coat

Phage infectsbacterium

No radioactivity inside bacterium

structure of dna
Structure of DNA

Chargaff’s Rules

*base pairing rule of

A+T & C + G

Source of DNA A T G C

Streptococcus 29.8% 31.6% 20.5% 18.0%

Yeast 31.3% 32.9% 18.7% 17.1%

Herring 27.8% 27.5% 22.2% 22.6%

Human 30.9% 29.4% 19.9% 19.8%

x ray evidence of dna
X-Ray Evidence of DNA
  • Rosalind Franklin
  • Suggested a twisted double helix
dna structure
DNA Structure
  • DNA structure is made up of nucleotides
  • Each nucleotide is made up of three parts:
    • Sugar (deoxyribose)
    • Phosphate
    • Nitrogenous Base
      • (Adenine, Thymine, Guanine, Cytosine)
structure of dna1
Structure of DNA

Nucleotide

(3 parts)

Hydrogen bonds

(connect bases)

Sugar/phosphate

Backbone (sides)

Key

Adenine

Thymine

Cytosine

Guanine

Deoxyribose sugar is attached to all bases

base pair rule
Base-Pair Rule
  • In a DNA molecule bases pair up in predictable ways
    • Adenine always pairs with Thymine
    • Guanine always pairs with Cytosine
    • A = T
    • G = C
base pair rule1
Base Pair Rule

One side:     A   T   A      T   C   A      T   G   C      G   GG

Other side:

how the code works
How the Code Works

The combination of A,T,G,C determines what traits you might have, for ex.

C A T C A T   =  purple hair

T A C T A C  =  yellow hair

think of the bases of dna like letters letters form words words form sentences endless combinations
Think of the bases of DNA like letters.Letters form words....Words form sentences....              *endless               combinations
slide16

All the activities of the cell are controlled by DNA.

DNA is located in the nucleus of the cell.

Just before cell division DNA coils to form chromosomes.

A Chromosome

is tightly coiled DNA.

When a chromosome is unraveled, it reveals DNA’s double helix shape.

dna replication
DNA Replication
  • When a cell divides each cell needs its own DNA
  • DNA must replicate and produce two identical strands of DNA in order for this to happen
process of dna replication
Process of DNA Replication
  • An enzyme “unzips” the existing DNA strand
  • Free floating nucleotides attach themselves to each side
  • TWO new strands of DNA are formed for each new cell
slide19

This “double helix structure” makes it possible for DNA to make an exact copy of itself.

T

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1

DNA “unzips itself.”

2

Free-floating nucleotides attach themselves to each side.

DNAPolymerase

This is known as

replication.

dna replication video
DNA Replication Video

http://www.youtube.com/watch?v=hfZ8o9D1tus

dna fingerprinting
DNA Fingerprinting
  • The only difference between your DNA and the DNA of the person sitting next to you is the order of the DNA base pairs
  • Every person has a different sequence
  • DNA fingerprinting is a way to identify and distinguish among individual human beings