Introduction to genetics
- Created by: une-meduse
- Created on: 17-05-14 20:49
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- Introduction to Genetics
- DNA as the Genetic Material
- 1900 Chromosomes = likely carriers of genes
- Chromosomes = DNA and protein - protein varied from cell to cell
- Therefore protein = genetic material - DNA lacked diversity
- Each daughter cell = same chromosome number in each species
- Experimental proof:
- Hershey and Chase
- Bacteriophage and E. coli
- McLeod, McCarthy, Avery
- S and R strains of S. pneumoniae and mice
- Hershey and Chase
- DNA Structure: The Double Helix
- 1953
- Watson, Crick and Franklin
- 3D structure of DNA
- Watson, Crick and Franklin
- Double stranded, antiparallel helix of complementary bases
- Head = 3' Tail = 5'
- B form = right handed twist
- Purines
- Adenine and Guanine
- Pyrimidines
- Thymine and Cytosine
- 1953
- Genes and Proteins
- Genes are in the DNA, they are made up of DNA nucleotide sequences
- There are different types of proteins
- Structural
- Pores in membranes
- Receptor proteins
- Enzymes
- Mutant genes give rise to defective proteins
- A mutant enzyme can be harmful or have a neutral effect
- Phenylketonuria
- Alkaptonuria
- A mutant enzyme can be harmful or have a neutral effect
- Inborn errors of metabolism (Garrod)
- From these, hereditary diseases arise due to a defect in enzymes
- Gene Expression: The Central Dogma
- The genetic code for protein is found in one strand only
- Proteins consist of one or more polypeptide chains
- 1.5% of the gene is contributed to coding for protein
- Unsure on what the rest is for - most likely regulatory, controlling the activity of the gene
- DNA codes for protein indirectly DNA --> RNA --> Protein
- This is known as the central dogma for genetics
- There are 20 different amino acids
- There are 4 base combinations
- There are 64 possible 3-base sequences
- Therefore the genetic code is degenerative
- Three codons do not code for amino acids - they code for 'STOP'
- UAA, UAG. UGA recognised by protein factors - NOT tRNA
- Three codons do not code for amino acids - they code for 'STOP'
- Therefore the genetic code is degenerative
- There are 64 possible 3-base sequences
- There are 4 base combinations
- RNA contains ribose sugar instead of deoxyribose (as in DNA)
- There are 3 types of RNA
- transfer RNA
- messenger RNA
- ribosomal RNA
- There are 3 types of RNA
- DNA as the Genetic Material
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