two nucleic acids: – deoxyribonucleic acid (dna) – ribonucleic acid (rna) monomers:...
TRANSCRIPT
• Two nucleic acids:– Deoxyribonucleic acid (DNA)– Ribonucleic acid (RNA)
• Monomers: ‘Nucleotide’– 5-carbon sugar (ribose or deoxyribose)– Phosphate group– Nitrogen base (cytosine, guanine, thymine,
cytosine)
• Phosphorus covalently bonded to deoxyribose sugar which is bonded to the nitrogen base• Sugar-Phosphate backbone
• Nitrogen base pairs with the complementary base on the other (complementary strand of DNA)
• Base pairing rules:– G pairs with C– T with A
• Same structure except:– 5-carbon sugar is ribose– Uracil replaces thymine – Single stranded, not
double stranded
• Segments of DNA contain genes
• Genes contain the information to code for the production of polypeptides on the surface of the ribosome.
• Before a proteins can be built: – DNA must undergo replication– Helicase separates the strands
of DNA– DNA polymerase assembles
the nucleotides
• Occurs during Interphase
• DNA copied for the new cells
• Replicate this strand of DNA– AAGCCGTTA
– Animation
• Information from DNA must be transported to the ribosomes
• DNA unwinds and is copied by RNA– mRNA
• mRNA moves out of the nucleus (pores) and attaches to the ribosomes
• Transcribe this stretch of DNA– AAA TGC
• Animation• Animation II
• Pre-mRNA will lose non-coding sequences called introns– Formally know as junk
DNA
• The important information in a gene will be preserved– Exon
• Amino acids are assembled on the surface of a ribosome and a polypeptide is formed.
• Amino acids are brought the surface of the ribosomes by tRNA
• Bond with sequences in the mRNA called codons– Anticodon on tRNA bonds
with codon on mRNA
• The codon sequences of mRNA may be translated into amino acids using the genetic code
• Always read from the mRNA!
• UCA = Ser• Animation
• A single stand of mRNA can produce hundreds of the same polypeptide in a short period of time.