5. Proteins and nucleic acids Flashcards
Which macromolecules are responsible for setting the potential function and which responsible for the actual function fo proteins?
Potential function is encoded in DNA - nucleic acids the macromolecules code for amino acid sequences
The actual function (function, phenotype) is completed by proteins - cover 50% of the dry mass of cells - enzymes in chemical reactions as catalysts - the final functional product of mRNA transcription
What are the types of proteins by function?
- enzymatic: enzymes as catalysts
- storage: storage of am a - caseine in milk stores am a for mammal babies
- defensive: antibodies
- transport: hemogloben, sodium potassium pumps
- hormonal: coordinate activities - insulin - regulates sugar levels
- receptor proteins: responf to chemical stimuli - synapsis
- contractile and motor: muscle contraction actin and myosin, movement of flagella and cilia
- structural: keratin - hair, horns, skin, silk, collagen - animal conncetive tissues
ESS Tvirtai Dauzo CM Heart Rate
Explain amino acids
20 am a - linked in unbranched polymers - polypeptides ← peptide bonds
Common am a structure → variable group makes the different am a → different properties: hydrophobic / hydrophilic, polar / non-polar, acidic / basic - chemical and physical properties determine the unique characteristics and influence the structure of the functional protein
Define protein
Protein - a biologically active macromolecule which can be made up from 1 or many polypeptides folded into a specific structure
Explain the formation of a peptide bond
Dehydration (condensation) reaction - removal of water
Polypeptide backbone (purple), side chains sticking out (green / yellow)
Two ends always free - N-terminus (amino group) and C-terminus (carboxylic group)
What are the possible models for representing proteins?
- Space filling model
- Ribbon model
What are the levels of protein structure?
- Primary structure: amino acid chain
- Secondary structure: comes from binding of O and H of the backbone (not R groups) → alpha helices and beta pleated sheets
- Tertiary structure: folds due to side chain (R groups) interactions: hydrophobic / H bondig / van der Waals / disulphide bridges
- Quaternary structure: several polypeptides join together
Explain sickle cell disease
Base substitution: Glu to Val - haemoglobin is fibrous not globular → deformed → sickled RBC → worse at carrying O → clog in blood vessels
But better at fighting malaria
What environmental effects affect protein structure?
Physical: temperature - irreversible
Chemical: pH, salt conc - reversible
The protein loses shape - loses function - DENATURATION
Protein misfolding can also lead to diseases (Alzheimers)
What is the role of nucleic acids?
Nucleic acids store, transmit and help express hereditary and genetic information
What is the dogma of life?
Information flows from DNA → RNA → protein - GENE EXPRESSION
Explain the strcuture and composition of nuleic acids
Nucleic acids are polymers of nucleotides
Nucleotide: 5C sugar, pentose, N base (base because takes a proton from the solution), phospate group
Pyramidines: C, T and U
Purines: G and A
DNA and RNA differ by a sugar: deoxyribose and ribose
What is the reaction of forming DNA and RNA?
Linking nucelotides into polynucleotides involves DEHYDRATION (condensation) - phosphodiester link - links the sugars of the nucleotides → creates repeating patter → sugar-phospate backbone
Two different ends - phosphate group 5’ end - OH group 3’ end
Bases are attached to sugars
H bonds between complementary bases - double helix around an imaginery axis, sugar phosphate backbone run in opposite directions - antiparallel - allows to reproduce itslef → pass on hereditary info into identical daughter cells - structure allows to happen
RNA - single strand, U instead of T, ribose
What are genomics and proteomics?
Being able to sequence genomes allowed genomics and proteomics to develop → evolution, paleontology, medical science (diseases)
