Chem: Ch 21: DNA and RNA Part II

Base sequences

The primary structure carries the genetic

information for the nucleic acid, and is read

from the 5’ phosphate toward the 3’ hydroxyl

RNA

replaces thymine with uracil

DNA’s double helix

DNA’s nucleic acids are arranged as a double helix, with

complementary nucleotides arranged opposite of one another

A-T and G-C

held together by hydrogen bonds

RNA

makes up most of the nucleic acid found in the cell.

• transmits genetic information from DNA to operate the cell.

The sugar in RNA is ribose

The base uracil replaces thymine

RNA molecules are single stranded

RNA molecules are much smaller than D NA molecules

synthesizes protiens

DNA

the sugar in DNA is deoxyribose.

DNA molecules are double stranded

Genetic code

consists of sets of three nucleotides (triplets) in mRNA called codons that

specify the amino acids and their sequence in the protein

Protein Synthesis

the essential two-step cellular process—transcription and translation—by which cells build proteins from amino acids based on DNA instructions

mutation

a change in the nucleotide sequence of DNA

genetic defect

When a mutation severely alters proteins or

enzymes, the new cells may not survive or the

person may exhibit a disease or condition that is a

result of a

point mutation

the replacement of one base in the template strand of DNA with

another; this may cause a different amino acid to be inserted into the polypeptide

silent mutation

occurs when a point mutation does not change the amino acid

deletion mutation

a base is deleted from the normal order of bases

in the template strand of DNA

insertion mutation

base is

inserted into the normal order of bases in the template strand of DNA.