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Inheritance and the Structure of DNA. Deoxyribonucleic Acid.

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Presentation on theme: "Inheritance and the Structure of DNA. Deoxyribonucleic Acid."— Presentation transcript:

1 Inheritance and the Structure of DNA

2 Deoxyribonucleic Acid

3 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

4 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 )


6 Complementary Strands Order of bases on the nucleotides in one strand of DNA complements the order of bases on the opposite strand – base sequence

7 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

8 DNA Helicase and DNA Polymerase 5”  3” refers to location of carbon on sugar, bases added to C with OH attached, work forward from there, refer to DNA handout. Bases attach to C #2, C#5 Phosphate

9 Deoxyribose vs Ribose sugars 2-Deoxy-Ribose in DNA is replaced by Ribose in RNA. The difference is a hydroxy group ( -OH ) in RNA versus a single proton ( -H ) in DNA. The extra -O- in the ribose backbone prevents formation of stable double-helices in RNA.

10 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)

11 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)

12 Transcription vs Translation Transcription – DNA to mRNA – in nucleus Translation – mRNA to tRNA and rRNA to make proteins – in cytoplasm


14 Transcription Reading the gene RNA polymerase (mRNA)

15 Translation RNA to proteins Cytoplasm – tRNA, rRNA, and mRNA – assemble proteins Genetic Code – Three letter word (codon) – Codon codes for amino acid – 64 mRNA


17 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


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