4. Genetic information, variation and relationships between organisms Flashcards
how is DNA stored differently in eukaryotes and prokaryotes
Eukaryotic DNA: long, linear tightly coiled into chromosomes
Prokaryotic DNA: short, circular
What’s a gene?
sequence of DNA bases that codes for an amino acid sequence of a polypeptide
what’s a DNA triplet?
sequence of 3 bases coding for a specific amino acid
What are the 3 natures of the genetic code?
Universal
Non-overlapping
Degenerate
how is the genetic code universal?
the same specific DNA base triplets (codons) will code for the same amino acids in all organisms.
how is the genetic code non-overlapping?
each base can only be used once and only in one triplet
how is the genetic code universal?
the same amino acid can be codes by more than one base triplet
what is an allele
different version of the same gene
what’s a genome?
the complete set of genes in a cell
where does transcription occur?
the nucleus
what happens at transcription?
production of mRNA from DNA
what is the purpose of mRNA
acts as a template for translation in the cytoplasm
purpose of tRNA molecule?
attaches to and transports amino acid, in relation its anticodon
two tRNAs bring amino acids together for the formation of peptide bonds
what’s the structure of a tRNA molecule?
3 leafed clover shape
held together by hydrogen bonds
What is the similarity between the structure of mRNA and tRNA molecules?
they are both polynucleotides
what are differences between the structure of mRNA and tRNA molecules?
Describe the process of transcription
1) DNA helix is unzipped by DNA helicase, and hydrogen bonds are broken
2) RNA nucleotides line up next to the complementary base pairs, forming temporary hydrogen bonds
3) RNA polymerase joins the adjacent nucleotides together through a condensation reaction forming phosphodiester bonds
4) When RNA polymerase reaches the stop codon, the mRNA detaches
5) mRNA leaves via nuclear pore
Describe the process of translation
1) at the ribosome, tRNA anticodons bind to the complementary codon on the mRNA
2) two amino acids joined together via a condensation reaction, forming a peptide bond
3) tRNA detaches (without the amino acid) ribosome moves along the mRNA and detaches when it reaches the stop codon
4) polypeptide chain is released
what is the role of ribosomes in translation?
attaches to the mRNA allowing codon-anticodon
complementary base pairing
allows peptide bonds to form between amino acids
Exons
Coding regions
Introns
Non-coding regions
Role of ATP in translation
-Hydrolysis of ATP → ADP + Pi releases energy
-For peptide bond formation between amino acids
Role of tRNA in transcription
- Attaches to, and transfers, a specific amino acid in relation to its anti codon
- tRNA complementary base pairs to mRNA anticodon
- 2 tRNAs bring 2 amino acids together for the formation of peptide bonds
Role of ribosomes in translation
- Attatches mRNA and houses tRNA allowing codon anticodon complementary base pairing
- allows peptides bonds to form
