1. nitrogenase base
2. deoxyribose sugar
3. phosphate

1. Adenine
2. Thymine
3. Cytosine
4. Guanine

• 2 H-bonds link A-T
• 3 H-bonds link C-G

2 antiparallel (one strand 5' to 3' & one strand 3' to 3') chains are held together by complementary base pairing

1. DNA unzips
2. Nucleotides are linked by enzymes

       -bi-directional: enzymes replicate in opp directions

        (always 5' -> 3') 

   3. Process is semi-conservative

       -each of the 2 new copies contains 1 of the original strand of DNA and 1 new strand

1. Helicase binds DNA at the Origin of Replication
2. Primase lays down a short RNA primer
3. DNA Polymerase III adds DNA nucleotides to the RNA primer
4. Leading Strand: Continuous in the direction of the replication fork - 5' to 3'
5. Lagging Strand: Discontinuous opposite of the replication fork 

-Discontinuous Synthesis: DNA polymerase cannot add nucleotides 3' to 5'

-DNA is synthesized in short(Okazaki) fragments

-RNA Primer is removed & filled in with DNA nucleotides by DNA polymerase I

-DNA ligase joins the fragments together

Pattern of flow

DNA -> (transcription) -> RNA -> (translation) -> protein 

RNA (ribonucleic acid)

• Sugar is ribose
• N-Bases are A, U, G, C
• Short Single Strands
• Read to produce proteins according to instructions from DNA
• 3 Types of RNA
•   rRNA – Part of the Ribosome

         tRNA - transfers amino acids to ribosome bound to                    mRNA

         mRNA - messenger between the DNA and the                            ribosome

DNA (deoxyribonucleic acid) 

• Sugar is deoxyribose
• N-Bases are A, T, G, C
• Long double strands linked by H-Bonds
• Stores the genetic code in genes
• Each human cell has 46 DNA (chromosomes)
• Bacteria have 1 circular chromosome

1) Portion of protein unzips

2) 1 strand of DNA is used as template

3) nucleotides of mRNA are free in the cytoplasm

4) They complimentary base pair w/ DNA to form single strand of mRNA (RNA polymerase)

5) mRNA pulls away

6) DNA zips back up (3 products)

    -tRNA & mRNA

*ONLY LEADING STRAND (NO LAGGING)

1) Initiation

• RNA polymerase binds to promoter(ID gene to be transcribed)
• sigma factor = guide to promoter

2) Elongation

• chain of RNA nucleotides formed
• RNA polymerase copies mRNA in 5' to 3'
• "copy stage"

3) Termination

• RNA synthesis ends 
• when RNA polymerase reaches a terminator at end of gene, mRNA is released 
• signals end of gene

1. mRNA
2. tRNA
3. rRNA

1. Initiation

• Initiation complex forms
• 30S binds to mRNA---50S joins = 70S
• AUG signals start

1. Elongation 

• amino acids are joined in a long chain
• ribosome moves from A-site to P-site (translocation of tRNA)
• old tRNA in P-site is ejected via E-site
• continues forming new peptide bonds

1. Termination

• translation stops
• release factors free polypeptide chains
• ribosome dissociates from mRNA & can be reused 

1. Sense codon- code for amino acid
2. Start codon- designates beginning of translation
3. Stop codon- code for end of translation
4. Anticodon- triplet complementery to codons and found on tRNA

Prokaryotic

• simpler 
• mRNA not modified
• transcription/translation coupled = FAST

Eukaryotic

• more complex
• mRNA modified before leaving nucleus
• transcription - nucleus
• translation - cytoplasm

DNA binding proteins that bind to promoters blocking RNA polymerase

(must be turned on/off)

-must be activated

-response to an over-abundance of end-product

-block transcription for repressed genes

-changes shape of repressor

-deactivate repressors

-response to availability of a specific substrate