Nucleic Acids

Cells + viruses

• cells - use DNA, cells are living

• viruses - not living, use DNA or RNA

Nucleic acids + Nucleotides

• nucleic acids - polymers + macro molecules

• nucleotides -monomers + building blocks, has a negative charge

nucleotide structure drawing + components for DNA

• phosphate group

• nitrogenous base

• pentose sugar

• covalent bond - CH2

what is the pentose sugar called in DNA and RNA

• DNA - deoxyribose

• RNA - ribose

what are the nitrogenous bases for DNA + RNA

• DNA - Adenine, Thymine, Guanine, Cytosine

• Adenine, Uracil, Guanine, Cytosine

DNA vs RNA strands

• DNA - double stranded or single stranded, long strands, antiparallel

• RNA - single stranded, short strands

Nucleotide to nucleic acid

• condensation reaction - every time a new bond form (chemical reaction) a water molecule is produced

• sugar phosphate bond/ phosphodiester bond

• anti parallel strands of nucleotides

sugar phosphate backbone

alternating deoxyribose sugars and phosphate groups bonded together

messenger RNA (mRNA)

formed in the nucleus and transported to the ribosomes in the cytoplasm

transfer RNA (tRNA)

is responsible for transporting amino acids to ribosomes during protein synthesis

ribosomal RNA (rRNA)

forms part of ribosomes

double Helix DNA

• antiparallel strands of nucleotides are held together by hydrogen bonds between complementary base pairs

what are the complementary base pairs for hydrogen bonding in DNA

• A-T : 2 hydrogen bonds

• G-C : 3 hydrogen bonds

drawing DNA vs RNA

• OH → RNA

• H → DNA

Roles of complementary bonding

• in gene expression

• in DNA replication

• Genetic code is universal

Roles of complementary bonding in gene expression

• a strand of DNA is converted to complementary mRNA this is then read by complementary tRNA molecules

• the tRNA is then split into groups which are 3 bases each.

• each group codes for one amino acid

DNA → mRNA → tRNA

• A → U → A

• C → G → C

• G → C → G

• T → A → U

role of complementary bonding in DNA replication (inheritance)

• each DNA strand is separated.

• original DNA strand acts like a template

• complementary nucleotides/bases build new strands → ľ identical DNA molecules.

DNA base sequence capacity

can hold limitless information

role of complementary bonding - Genetic code is universal

• all organisms + cells use the DNA base sequence + express it in the same way

• the genetic code evolved very early in the evolution of life in a last universal common ancestor from which all living species developed