2B: proteins and genetic Flashcards
what are proteins
chains of amino acids
- amino acid
monomers linked by peptide bonds in condensation reactions
what is the structure mononucleotides
deoxyribose or ribose sugar linked to a phosphate and a bases with phospodiester bonds
what is the structure of DNA
two strands of mononucleotide chains ( a polynucleoride) in a double helix structure
what is the structure of RNA
one strand of mononucleotide chain (a polynucleotide)
how do mononucleotides link together to form polynucleotides
condensation reactions
what are the four main structures of a protein
- primary
- secondary
- tertiary
- quaternary
what is the basic structure of an amion acid
a carbon attached to a R group, a carboxyl group and a amine group
how to differiate amino acids
by their R groups
what is a proteins primary structure
sequence of AA in polypeptide chains - linked via peptide bonds
what is a proteins secondary structure
alpha helix and beta pleated sheets formed when hydrogen bonds form between the AA chains
what is a proteins tertiary structure
the chains are further coiled/folded as more bonds form inbetween the polypeptide chains (hydrogen & ionic, maybe disulfide) and their 3D structure is formed
what is a proteins quaternary structure
multiple polypeptide chains (tertiary) assembled together - final 3D structure
how significant is primary protein structure
determines 3D structure and properties
- determines which bonds will form and how the protein will fold
what are the 2 types of 3D structures of a proteins
globular and fibrous
what is the globular structure of a protein
round, compact proteins
- polar hydrophylic parts of the chain on outside of molecule
- hydrophobic parts of the chain face inwards of the molecule
- soluble due to hydrophylic outerlayer
what is the fibrous structure of a protein
long insoluble chains coiled around each other in a rope
- triple helix of polypeptide chains held by H+ bonds
what are the two parts of protein synthesis
transcription and translation
what happens during transcription
an mRNA copy of gene(DNA) is made
- RNA polymerase attach to DNA and H+ bonds between the double helix strands break
- the strands separate and one strand is copied and used as a template for an mRNA copy
- free mononucleotides (bases) are lined next to the copy strand and complimentary base paring takes place forming a complete copy
- strands are joined together with RNA polymerase forming mRNA molecule
- RNA polymerase meets stop codon and will detatch from DNA
- mRNA moves out of the nucleus via the nuclear pore and attatches to a ribosome in the cytoplasm to be translated
what happens during translation
protein AA sequence is translated
- transfer RNA carry AA to the ribosomes
- tRNA w/ a anticodon connect to complementary codon
- amino acids are then joined together with peptide bonds
- tRNA moves away and ribosome moves to next codon and the process repeats
- AA join together to form polypeptide chain
what is the degenerate code
more codons than corresponding AA therfore some genetic mutations may not have an effect due to AA codons
- similar structure
- code for same AA
- not at the active site therefore has no effect
