Week 2 Flashcards
Nucleic acids
Polymers that store, transmit and express genetic info
How genetic info is stored
Encoded in the sequences of monomers
2 types of nucleic acid
DNA
RNA
DNA function
Stores and transmits genetic info
Used to specify the amino acid sequences of proteins
RNA role
Certain specialised RNA play role in metabolism
Uses DNA info to specify the amino acid sequences
Nucleotide makeup
Nitrogen containing base
Pentose sugar
One to theee phosphate groups
Pyrimidines
Cytosine
Thymine
Uracil
Purines
Adenine
Guanine
Pyrimidine makeup
Six membered single ring
Purine makeup
Fused double ring structure
Phosphodiester bond
When the pentose sugar of the old chain and phosphate of the new chain undergo condensation reaction
DNA bases
Adenine
Guanine
Thymine
Cytosine
RNA bases
Adenine
Guanine
Cytosine
Uracil
Dhow base pairs are held together
Hydrogen bonds
Hydrogen bond strength
Relatively weak by cause there are so many provide considerable amount of force
Hydrogen bond - breaking
Not as strong as multiple covalent bonds so base pairs are easy to separate with modest energy
RNA makeup
Single strand
Many single stranded fold up to 3D
Folds back to form double stranded helix
RNA folding - outcome
3D surface for bonding and recognition of other molecules
DNA makeup
Double strand
2 separate polynucleotides that run in opposite directions
Form ladder that twists into double helix
Sugar phosphate groups form side and bases form rungs on inside
Ways of DNA reproduction
DNA replication
Transcription
DNA replication
Replicated by polymerisation using existing strand as base pair template
Transcription
DNA copied into rna
Translation
Nucleotide sequences in most rna can be used to specify sequences of amino acids in proteins
Enzymes
Catalyse biochemical reactions
Defensive proteins
Recognise and respond to substances that invade the organism
Hormonal and regulatory proteins
Control physiological processes
Receptor proteins
Receive and respond to molecular signals from inside and outside organism
Storage proteins
Store chemical building blocks for later use
Structural proteins
Provide physical stability and enable movement
Transport proteins
Carry substances within organism
Genetic regulatory proteins
Regulate when, how and to what extent a gene is expressed
Functional groups of amino acids
Nitrogen containing amino group
Carboxyl group
Peptides
Amino acid polymers of 20
Polypeptide formation
Via the sequential addition of new amino acids to the end of existing chains
The amino group of the new amino reacts with the carboxyl group of the end amino to form peptide bond
Primary structure of proteins
Established by covalent bonds
Protein secondary structure
Regular repeated spatial patterns
Secondary structure - alpha helix
Right handed coil that turns in same direction
R groups extend outward from peptide backbone
Secondary structure- beta pleated sheet
Two or more sequences are extended and aligned
Stablilised by hydrogen bonds
Protein structure - tertiary
Bent a specific sites and folded back and forth
Definite 3D shape
Tertiary proteins - exposed surface
Resent functional groups capable of interacting with other molecules in the cell
What determines tertiary structure
Interactions between r groups
What determines secondary structure
Hydrogen bonding between n-h and c=o groups within and between chains
What changes protein structure
Environment
Interactions with other molecules
Environmental conditions that affect protein
Increase in temp
Concentration of h+
High concentrations of polar substances
Non polar substances
Enzyme function
Lowers activation energy by enabling reactants to come together and react easily
Active site
Where substrate bind to the enzyme
Competitive inhibitor
Inhibitor and substrate compete only one can bind to the active site
Non competitive inhibitor
Bonds to a site away from active site, changing the enzymes shape so the subrate can no longer fit
