NUCLEOTIDES AND NUCLEIC ACIDS

CHONP

pentose sugar , phosphate group, nitrogenous base

DNA: deoxyribose

RNA: ribose

• Condensation reactions form strong phosphodiester bonds between a sugar of one nucleotide and the phosphate group of another (sugar-phosphate backbone).

• Hydrolysis reactions use a molecule of water to break these bonds.

• Enzymes catalyse these reactions

• Molecule twists to form double helix of 2 deoxyribose polynucleotide strands (so there are 2 sugar-phosphate backbones).

• H-bonds form between complementary base pairs (AT & GC) on strands that run antiparallel

adenine C5H5N5

guanine C5H5N5O

two-ring molecules

cytosine

thymine

uracil

• 2 H-bonds between adenine (A) + thymine (T)

• 3 H-bonds between guanine (G) + cytosine (C)

• 2 H-bonds between adenine (A) + uracil (U)

• 3 H-bonds between guanine (G) + cytosine (C)

• Strands from original DNA molecule act as templates.

• New DNA molecule contains 1 old strand & 1 new strand

Breaks H-bonds between base pairs to form 2 single strands, each of which can act as a template

1. DNA helicase breaks the H bonds between the 2 polynucleotide DNA strands

2. This causes the helix to unzip and form 2 single strands

3. Each original strand now acts as a template for a new strand

4. Free nucleotides attach to exposed bases by complementary base pairing.

5. DNA polymerase joins adjacent nucleotides on new strand in a 5' → 3' direction via condensation reactions to form phosphodiester bonds.

6. H-bonds form between the bases on the original and new strand

7. This causes it to twist into a double helix

• Non-overlapping= each triplet is only read once.

• Degenerate= more than one triplet codes for the same amino acid (64 possible triplets for 20 amino acids).

• Universal= same bases and sequences used by all species.

Consists of base triplets that code for a specific amino acids.

• Produces mRNA

• Occurs in nucleus

• RNA polymerase detaches at terminator region.

• H-bonds reform & DNA rewinds

• Splicing removes introns from pre-mRNA in eukaryotic cells.

• mRNA moves out of nucleus via nuclear pore & attaches to ribosome

• Produces proteins

• Occurs in cytoplasm on ribosomes (which are made of protein + rRNA)

• Has a pentose sugar Ribose

• Has a nitrogenous base Adenine

• Has 3 inorganic phosphate groups

- nucleotide derivative of adenine

- has a pentose sugar (Ribose)

- has a nitrogenous base ( adenine)

- has 2 inorganic phosphate groups

• An alteration to the DNA base sequence.

• Mutations often arise spontaneously during DNA replication

phosphodiester bond

• Messenger RNA

• It carries the genetic code from the DNA out of the nucleus and transfers it to the ribosomes where the code is for protein synthesis

• Transfer RNA

• Its found in the cytoplasm

• It has an amino acid binding site at one end and an anticodon at the other

• It carries amino acids to ribosomes

• ribosomal RNA

• Its found in the ribosome

• It helps catalyse the formation of peptide bonds between amino acids during translation

A complex molecule containing the genetic information that makes up the chromosomes.

A single-stranded nucleic acid that passes along genetic messages.

Nitrogenous bases that have a double ring of carbon and nitrogen atoms

- adenine and guanine.

Nitrogenous bases that have a single ring of carbon and nitrogen atoms

- cytosine and thymine (Uracil)

Adenosine triphosphate

Provides energy for chemical reactions in the cell

A polymer consisting of many nucleotide monomers in a chain; nucleotides can be those of DNA or RNA.

- the type of bond that links the nucleotides in DNA or RNA.

- joins the phosphate group of one nucleotide to the hydroxyl group on the sugar of another nucleotide

- Breaks the hydrogen bonds between the two polynucleotide DNA strands.

- Unzips the double helix to form 2 single strands during DNA replication

A sequence of DNA nucleotides that codes for a polypeptide

The three nucleotides of DNA which code for one amino acid.

A specific sequence of three adjacent bases on a strand of DNA or RNA that provides genetic code information for a particular amino acid

A group of three bases on a tRNA molecule that are complementary to an mRNA codon

codon that signals to ribosomes to stop translation

An enzyme that catalyses the formation of phosphodiester bonds between nucleotides during the synthesis of a new DNA strand.

sections of DNA that code for amino acid sequences.

An enzyme that catalyses the formation of phosphodiester bonds between nucleotides during the synthesis of a new RNA strand.

An enzyme that unwinds and winds coils of DNA that form during replication and transcription.

places a primer to tell DNA polymerase to stop working

an enzyme that eventually joins the sugar-phosphate backbones of the Okazaki fragments

DNA topoisomerase

DNA helicase

DNA primase

DNA polymerase

DNA ligase

Helicase

RNA polymerase

hydrogen bonding between complementary base pairs on two antiparallel DNA polynucleotides

5’ to 3’