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DNA Structure. By the early 1900’s it was known that the chromosomes carry the genetic (hereditary) information Chromosomes consist of DNA (deoxyribonucleic acid). I. Chemical Structure of DNA. Nucleotide: 1. Thousands of repeating units that make up the DNA (DNA is a polymer).

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Dna structure


I chemical structure of dna
I. Chemical Structure of DNA carry the genetic (hereditary) information

  • Nucleotide:

    1. Thousands of repeating units that make up the DNA (DNA is a polymer)


Dna structure

  • a phosphate group carry the genetic (hereditary) information

  • a deoxyribose molecule (5-carbon sugar)

  • a nitrogenous base

    adenine, thymine, guanine, cytosine

    (There are four different types of nucleotides, depending on which of the four bases is present- A, T, C, or G)


Ii the watson crick model of the structure of dna
II. The Watson-Crick Model of the Structure of DNA carry the genetic (hereditary) information

DNA consists of two chains of nucleotides in a ladder-like structure which is twisted

(Double Helix)


James watson francis crick
James Watson & Francis Crick: carry the genetic (hereditary) information

  • Used data of M.H.F. Wilkins and Rosalind Franklin, early 50’s

  • Wilkins and Franklin studied the structure of DNA crystals using X-rays.

  • The X pattern suggested the structure of DNA was a helix.

    Distance between the two “backbones” of DNA

    is constant along the length of the molecule


Dna structure

  • Used data of carry the genetic (hereditary) informationErwin Chargaff, 1940’s and early 50's

  • Chargaff’s Rule: His data showed that in each species, the percent of A equals the percent of T, and the percent of G equals the percent of C.


Watson and crick 1953
Watson and Crick (1953) carry the genetic (hereditary) information


Watson and crick model
Watson and Crick Model: carry the genetic (hereditary) information

  • The sides of the ladder are made up of alternating molecules of phosphate and deoxyribose

    B. The bases make up the rungs of the ladder


Dna structure

C. The bases that make up the rungs of the ladder are attracted by a weak chemical bonds called hydrogen bonds


Base pairing rule
Base Pairing Rule attracted by a weak chemical bonds called hydrogen bonds

Adenine (A) pairs with Thymine (T)

Guanine (G) pairs with Cytosine(C)


Structure of dna animations
Structure of DNA Animations attracted by a weak chemical bonds called hydrogen bonds

  • http://207.207.4.198/pub/flash/24/menu.swf

http://www.pbs.org/wgbh/nova/genome/dna.html#


Watson and crick s double helix model explained
Watson and Crick’s Double Helix Model explained: attracted by a weak chemical bonds called hydrogen bonds

1. How replication of DNA during mitosis produces exact copies for the daughter cells

2. How DNA acts as a code, specifying how proteins are made by the cell


Dna replication
DNA Replication attracted by a weak chemical bonds called hydrogen bonds


Dna structure


Dna structure

2 along the weak hydrogen bonds between the base pairs. Free nucleotides that are present in the nucleus attach themselves by hydrogen bonds to the exposed bases

(A-T, C-G)


Dna structure

3. Two identical strands form from each strand of DNA along the weak hydrogen bonds between the base pairs


Dna replication animations
DNA Replication Animations along the weak hydrogen bonds between the base pairs

http://www.lewport.wnyric.org/JWANAMAKER/animations/DNA%20Replication%20-%20long%20.html

http://www.johnkyrk.com/DNAreplication.html


Dna structure


Dna structure

TCCAATGACGTG along the weak hydrogen bonds between the base pairs


How does dna act as a code
How Does DNA Act As A Code? along the weak hydrogen bonds between the base pairs

  • The order of bases on the DNA strand instructs the ribosomes how to synthesize proteins


Dna structure

  • Gene along the weak hydrogen bonds between the base pairs: portion of DNA that codes for the production of a specific polypeptide


Dna structure

  • Polypeptide along the weak hydrogen bonds between the base pairs: building block of a protein


In terms of decreasing size
In terms of decreasing size: along the weak hydrogen bonds between the base pairs

Nucleus → Chromosome → Gene → DNA