14. Protein Synthesis Flashcards
(11 cards)
What is a gene?
Base sequence of DNA that codes for an amino acid sequence and a functional RNA.
It is a section of DNA located at a particular site on a DNA molecule called a locus.
What 3 words describe the genetic code?
- Universal: same triplets always code for same amino acids in all species.
- Degenerate: More than 1 triplet for each amino acids
- Non Overlapping: each base is only part of 1 triplet they don’t overlap.
Whats the difference between prokaryotic and eukaryotic DNA?
Prokaryotic is short, circular, and not associated with proteins.
Mitochondria and Chloroplasts DNA is same as prokaryotic.
Eukaryotic is longer, linear and associated with proteins (called histones) and contains introns.
Prokaryotic cells produce mRNA directly but eukaryotic produce pre-mRNA then mRNA.
What are exons and introns?
Exons: within gene only 3 base sequences code for an amino acid sequence.
Introns: separate exons and are non-coding sequences of base sequence.
Whats a genome and preteome? And hows can variation within species be measured?
Genome: complete set of all genes in a cell.
Proteome: Full range of different proteins that cell can produce as coded for by its DNA.
Variation can be measured using differences within base sequences code of DNA or in Amino acid sequence of DNA.
What difference between mRNA and tRNA?
-mRNA is longer has more nucleotides
- mRNA is straight molecule whereas tRNA is folded into clover leaf shaped molecule.
- mRNA contains no paired bases so no hydrogen bonds but tRNA has some hydrogen bonds.
- mRNA has codons, tRNA has anticodons.
- mRNA doesn’t have amino acid binding site but tRNA does.
Whats Transcription?
- DNA helicase unwinds a section of DNA by breaking hydrogen bonds to expose a template strand.
- Free RNA nucleotides align next to exposed bases via complementary base pairs (Adenine and Thymine, Adenine and Uracil, Cytosine and Guanine.)
- RNA polymerase joins adjacent mRNA nucleotides together via condensation reaction forming phosphodiester bonds forming pre-mRNA.
- introns removed from pre-mRNA by splicing to form mRNA which leaves the nucleus.
What is Translation?
-mRNA associates with a ribosome and ribosome attaches to mRNA.
- ribosome move to start codon (AUG)
- tRNA brings specific amino acid to ribosome.
- anticodon on tRNA binds to complementary codon on mRNA
- amino acids join by peptide bonds via condensation reaction using ATP
- ribosome moves along to the next codon until the stop codon forming a polypeptide chain.
(EXTRA: the more copies of mRNA for a specific protein in cell the more that protein that will be produced.)
What is a mutation and what is non disjunction?
Mutation is change in DNA sequence.
Non disjunction is change in number of chromosomes due to non sister chromatids not separating or homologous pair chromosomes not separating.
What are the 3 different mutations?
- Substitution Mutation: Change in DNA nucleotide changes mRNA sequence changing the polypeptide chain, changing tertiary structure of protein. Due to the degenerate nature of genetic code not all substitutions result in mutation or change in sequence as multiple mRNA codons can encode the same amino acid.
- Addition or Deletion: cause a frameshift where all the following codons are changed. Diff base sequence DNA, Diff codon on mRNA, diff sequence amino acid, tertiary structure protein changes.
What can mutagenic agents do and what does it include?
Mutagenic agents increase rate of gene mutation.
Includes: high energy radiation (e.g. x-rays/gamma rays) which damage DNA molecules and Chemicals (.e.g. benzene) that alter DNA structure/interfere with DNA replication.
