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Nucleic Acids and Proteins - Coggle Diagram
Nucleic Acids and Proteins
Proteins
Levels of Protein structure
Primary
Amino acids are joined together via. peptide bonds forming a linear polypeptide chain
Secondary
Hydrogen bonding forming within the polypeptide chain to create alpha helices, beta pleated sheets and random coils
Tertiary
Involved R group interactions (Disulphide bridges, ionic bonding, hydrogen bonding and hydrophobic interactions), forms a polypeptide into a 3D functional shape
Quaternary
Two or more polypeptide chains to form a functional protein
Functional diversity of proteins
Toxins, hormones and chemical messengers
Maintaining cell structure (Cytoskeleton)
Markers for cellular recognition
Receptors
Transport proteins
Enzymes
How are polypeptide chains synthesised?
Undergoes condensation polymerisation, forming covalent peptide bonds between the amino acids to form a linear polypeptide chain; water becomes a byproduct of the condensation polymerisation reaction
Nucleic Acid
Structure of DNA
contains Thymine instead of uracil
Deoxyribose sugar
Double stranded- double helix
Located in the nucleus of the cell
Structure of RNA
Contains Uracil which is complementary to adenine
Ribose sugar
Single stranded
Located in the cytoplasm
Bonds that are formed when a condensation polymerisation reaction occurs?
Phosphodiester
Gene expression
Transcription
1.RNA polymerase attaches to the promoter region and starts unwinding the DNA double helix strand exposing the template strand to RNA nucleotides
RNA polymerase synthesises an mRNA strand complementary to the template strand of DNA, where mRNA synthesis occurs in a 5' to 3' direction
RNA polymerase reads the terminator sequence and disassociates with the DNA strand and the complete pre-mRNA
Translation
Ribosomes attach to the 5' end of mRNA and the ribosomes read the mRNA molecule in a 5' -3' direction and translates the start codon
tRNA binds to the mRNA codon via. its complementary anticodon, whilst suppling the corresponding amino acid to form peptide bonds with the growing polypeptide chain
Ribosomes reads the stop codon and detaches from the mRNA molecule and the polypeptide chain
Degeneracy of the triplet code
Post transcriptional modification
The introns are removed and the exons are spliced together
A 5' methyl cap is added to the 5' end of the pre-mRNA
A poly adenine tail is added to the 3' end of the pre-mRNA molecule and mature mRNA is complete
Gene regulation and structure:
Purpose of gene regulation
Allow cellular specialisation and differentiation in multicellular organisms
Saves metabolic energy
Different types of genes
Structural genes
Codes for functional proteins that are necessary for biochemical processes within the cell
Regulatory genes
Codes for transcription factors that regulate the transcription of structural genes
Lac Operon
Lactose present
Allolactose is present, so a 3d conformational change in the shape of the repressor changes and thus unbinds from the operator. As a result transcription of the genes that code for enzymes that breakdown lactose are transcribed
Lactose absent
When no alloctose is present, a 3D conformational shape of the repressor does not change thus it still remains on the operator. As a result the genes that code for the enzymes that break down lactose are not transcribed.