Presentation on theme: "Aim: What is a chromosome? Human Chromosomes Text p.291-294."— Presentation transcript:
Aim: What is a chromosome? Human Chromosomes Text p
Chromosome Structure Chromosome Supercoils Coils Nucleosome Histones DNA double helix Section 12-2 Go to Section:
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.
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.
Bases (rungs of the ladder) in DNA Pyrimidine Bases
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
Base Pairing in DNA A with T: the purine adenine (A) always pairs with the pyrimidine thymine (T)purine pyrimidine C with G: the pyrimidine cytosine (C) always pairs with the purine guanine (G)
Purines Pyrimidines AdenineGuanine Cytosine Thymine Phosphate group Deoxyribose DNA Nucleotides Section 12-1 Go to Section:
Hydrogen bonds Nucleotide Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Structure of DNA Go to Section:
RNADNA RNA polymerase Transcription – making RNA Section 12-3 Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) Go to Section: