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Aim: What is a chromosome?

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Presentation on theme: "Aim: What is a chromosome?"— Presentation transcript:

1 Aim: What is a chromosome?
Human Chromosomes Text p

2 Electron Micrograph

3 Chromosome Structure Section 12-2 Nucleosome Chromosome DNA double
helix Coils Supercoils Histones Go to Section:

4 Key Idea 2 Organisms inherit genetic information in a variety of ways that result in continuity of structure and function between parents and offspring. 2.1 f In all organisms, the coded instructions for specifying the characteristics of the organisms are carried in DNA, a large molecule formed from subunits arranged in a sequence with bases of four kinds (represented by A, G, C and T). The chemical and structural properties of DNA are the basis for how the genetic information that underlies heredity is both encoded in genes (as a string of molecular “bases”) and replicated by means of a template.

5 Bases (rungs of the ladder) in DNA
Purine Bases Adenine (A) and guanine (G)are the larger of the two types of bases found in DNA.

6 Bases (rungs of the ladder) in DNA
Pyrimidine Bases

7 The DNA backbone is a polymer with an alternating deoxyribose sugar-phosphate sequence
DNA (deoxyribonucleic acid) is a double-stranded molecule that is twisted into a helix like a spiral staircase

8 Base Pairing in DNA A with T: the purine adenine (A) always pairs with the pyrimidine thymine (T) C with G: the pyrimidine cytosine (C) always pairs with the purine guanine (G) Give instructions to make the DNA molecule

9 DNA Nucleotides Purines Pyrimidines Adenine Guanine Thymine Cytosine
Section 12-1 Purines Pyrimidines Adenine Guanine Thymine Cytosine Phosphate group Deoxyribose Go to Section:

10 Structure of DNA Nucleotide Hydrogen bonds Sugar-phosphate backbone
Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Go to Section:

11 Transcription – making RNA
Section 12-3 Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNA polymerase RNA DNA Go to Section:

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