Inheritance and the Structure of DNA
-
Upload
kermit-wooten -
Category
Documents
-
view
23 -
download
0
description
Transcript of Inheritance and the Structure of DNA
Inheritance and the Structure of DNA
Deoxyribonucleic Acid
DNA Discovery• 1928-Frederick Griffith– transforming factor
• 1944-James Watson and Francis Crick – discovered that DNA was the transforming factor
• 1952-Rosalind Franklin and Maurice Wilkins – took x-ray photographs of the DNA molecule
• 1953-Watson and Crick – created a three-dimensional 3-D model of DNA
• 1962-Watson, Crick, and Wilkins – received the Nobel Prize in Medicine
What is DNA?• Genetic material used to express traits• Nucleotide units– Deoxyribose (sugar)– Phosphate– Base• Purines (double ring)
– Thymine ( T ) – Cytosine ( C )
• Pyrimidine (one ring)– Adenine ( A )– Guanine ( G )
Complementary Strands• Order of bases on the nucleotides in one
strand of DNA complements the order of bases on the opposite strand– base sequence
DNA Replication
• DNA stores and transmit information that tells cells which proteins to make and when to make them.
• DNA located in the nucleus and cannot leave.• Duplication of DNA
DNA Helicase and DNA Polymerase
RNA (Ribonucleic Acid)• RNA differs from DNA– Sugar is ribose– The nitrogen base THYMINE is replaced by URACIL– RNA is single-stranded
• There are three types of RNA– Messenger RNA (mRNA)– Transfer RNA (tRNA)– Ribosomal RNA (rRNA)
RNA• Messenger RNA (mRNA)– copies the information from the DNA in the
nucleus
• Transfer RNA (tRNA)– reads the information from mRNA– carries amino acids to the ribosome
• Ribosomal RNA (rRNA)
• Transcription – DNA to mRNA – in nucleus
• Translation – mRNA to tRNA and rRNA to make proteins– in cytoplasm
Transcription
• Reading the gene• RNA polymerase (mRNA)
Translation• RNA to proteins• Cytoplasm– tRNA, rRNA, and mRNA– assemble proteins
• Genetic Code– Three letter word (codon)– Codon codes for amino acid– 64 mRNA
Translation
• Specific amino acid on one end of each tRNA. – anticodon on tRNA is complementary codon on
mRNA.
• mRNA joins with a rRNA and tRNA– first tRNA is released from the ribosome– Amino acids bond creating a polypeptide chain– This process is repeated until one of three stop
codons is reached