Nucleic acids & DNA

Bio C5

DNA

double stranded molecule that occurs in the nucleus of eukaryotic cells

Similarities in DNA vs RNA:

-both are made of long strands of a repeating unit made from a sugar and a phosphate group

-monomer is called a nucleotide

-the sugar group of one unit joins the phosphate group to another to form a long chain —> sugar phosphate backbone

Differences in DNA vs RNA:

-sugar: DNA = deoxyribose sugars & has one less oxygen atom compared to ribose sugars, RNA = contains ribose sugars

What are the three ‘parts’ of RNA:

-mRNA

-tRNA

-rRNA

What are proteins composed of?

Amino acids

Splicing:

-the process of intron removal to produce mRNA

What is transcription?

-The DNA directed synthesis of RNA

RNA synthesis:

-is catalysed by RNA polymerase (pries the DNA strands apart and hooks together the RNA nucleotides)

-follows the same base-pairing rules as DNA

What is translation?

-The RNA-directed synthesis of a polypeptide

-The decoding of mRNA into a protein

Translation involves:

-mRNA

-rRNA

-tRNA

-codons

What are codons?

-three base code for the production of a specific amino acid (the sequence of three/four different nucleotides)

Transfer RNA:

-carriers a specific amino acid on one end, and an anticodon on the other

-brings amino acids to the ribosomes

What are mutagens?

-Chemical or physical agents that impact with DNA to cause mutations

What are point mutations?

-Involve alterations in the structure or location of a single gene

-Generally only one or few base pairs involves

-Can significantly affect protein structure & function

What are the types of point mutations?

-Substitutions (replacement of one nucleotide & its partner with another pair of nucleotides)

-Insertions or deletions (Additions or losses of nucleotide pairs in a gene)

Base pair substituions

-Silent (changes a codon, but codes for the same amino acid)

-Missense (Substitutions that change a codon for one amino acid into a codon for a different amino acid)

-Nonsense (Substitutions that lead to the premature ending of protein synthesis)

Insertions and deletions:

-Additions or losses of nucleotide pairs in a gene

-May produce frameshift mutations that will change the way a gene sequence is read