Nucleotides and Nucleic Acids

Nucleotides (3 components)

1.) Phosphate

2.) sugar: Deoxyribose (DNA) or Ribose (RNA)

3.) Nitrogenous base: Purines (Adenine (A) and Guanine (G)) and pyrimidines (Uracil (U) (RNA), Thymine (T) (DNA), and Cytosine (C))

4.) if phosphate group is removed it is called a NUCLEOSIDE

DNA structure

double stranded alpha helix, 2 strands run antiparallel

DNA Bonds

1.) Nucleotides within 1 strand = phosphodiester bonds

2.) Base pairs between complimentary strands = hydrogen bonds (easily broken)

DNA Base pairing

1.) A + T

2.) G + C

3.) enzyme: Dnase

DNA Replication (S phase)

1.) Location: nucleus

2.) DNA doubling 46 → 92 chromosomes

3.) Enzyme: Topoisomerase (Helicase) unwinds DNA strands

4.) Enzyme: DNA Polymerase makes new DNA from parent DNA (acts as a template)

5.) mitosis: splits the doubled 92 chromosome DNA into two identical 46 Chromosome daughter DNA sets

Transcription (RNA synthesis 5’ to 3’)

1.) location: Nucleolus → only the segment of DNA with the specific region to be transcribed unwinds

2.) Enzyme: RNA POLYMERASE binds to promoter site, begins to make RNA primer strand from DNA template

3.) DNA template is read 3 bases at a time, RNA polymerase reaches a special section of DNA called termination sequence, polymerase and RNA primer strand both fall of the DNA which then rewinds itself

4.) RNA now leaves the nucleus and goes to work in the cytoplasm

Messenger RNA (mRNA)

Holds the information to determine AA sequence order

Ribosomal RNA (rRNA)

Main component of the ribosomal unit which moves along mRNA

Transfer RNA (tRNA)

Jumps on and off the rRNA carrying amino acids with it

Translation (protein synthesis)

1.) mRNA binds to ribosome before translation can occur

2.) 3 bases in the mRNA code for one amino acid

3.) anticodon: tRNA has 3 bases that is complementary to specific codon

4.) tRNA anticodon binds to mRNA codon and brings AA to ribosome, AA on tRNA forms a peptide bond with the AA on the tRNA next door (Enzyme: peptidyl transferase)

5.) tRNA leaves ribosome to get another AA, Enzyme: amino acids is attached to tRNA by Aminoacyl-trna synthase

Translation base pairing (RNA)

1.) A + U

2.) G + C

Start codon

AUG

3 Stop codon

UAA, UAG, UGA

(DNA to mRNA to Protein)