Biology Flashcards
How do Proteins function and operate?
Proteins fold to give distinct structures and they require the correct folding to function . They operate in vivo as catalysts (enzymes), structural molecules (cytoskelaton, collagen), receptors (membrane protein), and transporters.
Proteins structures and its stability
Protein structure is stabilized by:
H bond
salt bridge
hydrophobic effect
metal ion binding
disulfide bridge
Amino Acids
Amino Acids are classified as
non polar (hydrophobic)
polar charged
polar uncharged
depeding on the basis of the nature of side chain
isoelectric point
amino acids and proteins are insoluble at that pt
net charge zero
no migration to electric field
Acid base titration of amino acid (Lys)
Carbohydrates
General formula
there two forms
General formula (CH2O)n
monosacharides 3 to 6 C atoms
there two forms linear and cyclic forms
Hemiacetal and Hemiketal
Hemiacetal aldose sugar and Hemiketal ketose sugar
Glucose
different polymers of glucose differ in their connectivity:
carbon centers connected via oxygen
configuration of anomic center
polysacharides
they are polymers of monosacharides which can be linear or branched
Enzyme
are biological catalysts that increase the rate of the metabolic reaction. the active site of an enzyme acts as a catalyst. The substrate turns into the product when a rxn involves an enzyme.
Cofactor
Cofactors are small molecules or ions that associate with (bind to) proteins to provide them with chemical activity (e.g. oxidation, reduction, methylation) that is not available from the standard repertoire of amino acids.
They generally comprise an active chemical functional group, plus additional segments that are used for binding to the active site of a protein.
Metabolism
is the chemical process that takes place in a living cell that provides energy for vital processess and for synthesizing organic material.
Metabolic pathways
a sequence of chemical steps that converts starting materials into products.
where does a metabolic pathway occurs
A metabolic pathway usually occurs in a specific location within the cell (compartment/organelle).
Catabolic pathway
Metabolic pathways that involve ‘breaking down’ complex molecules into smaller ones, with the release of energy, are termed catabolic.
anabolic pathway
Metabolic pathways that involve ‘building up’ complex molecules, with the consumption of energy, are termed anabolic.
Metabolites
Metabolites are small molecules that are formed in cells and organisms by the catalytic activity of enzymes as part of a metabolic pathway
receptors
It is an organ or a specialized cell that can detect the change that is causing the stimulus
cellulose structure
Amylose structure
Carbohydrates role
to supply the body with energy
Lipids structure
Lipids are amphipathic – (relatively) small hydrophilic headgroup and (relatively) large hydrophobic fatty acyl chains.
Because of this amphipathicity, they spontaneously form bilayers in water, diameter (headgroup to headgroup) 4–8 nm.
Lipids role
Store energy
structural componen of cell membranes
Fatty acids
Fatty acids: long chain carboxylic acids. Can be saturated (no alkene groups) or unsaturated (one or more alkenes, normally in cis configuration).
(Note numbering of fatty acyl chains: n system is 1 at carbonyl etc. In italics is bond position from carbonyl; ω system – 1st C of C=C from end of chain).
Headgroups
Headgroups: choline (PC), ethanolamine (PE), inositol (PI), serine (PS), glycerol (PG), no additional group (PA).
PC and PE are neutral lipids (no net charge) at physiological pH (7.4). PG, PS, PI and PA are negatively charged.
Glycerophospholipids structure
Glycerophospholipids – based on glycerol. Phosphate + headgroup at one position (3), fatty acyl groups at other 2 positions.
Sterols structure
Cholesterol has a large hydrophobic tetracyclic hydrocarbon group, and a small polar headgroup and therefore readily inserts into bilayer.
Archidonic linoleic and oleic acid
Nucleoside
Nucleoside = base + sugar (ribose or deoxyribose).
Nucleotide
DNA bases structure
DNA
In DNA, there are 2 chains, running antiparallel in a double helix.
Bases pair in centre of double helix: A-T (2 H-bonds); C-G (3 H-bonds).
DNA carries genetic information.
RNA
RNA rarely forms double helices. Intrastrand base pairing forms hairpins (stems + loops), and bulges. RNA forms more complex 3° structures than DNA.
RNA is used to process this information (transcription and translation)
Prokaryote
dimension
component genetic material
Eukaryote
dimension
component genetic material
Cytosol (cytoplasm):
Cytosol (cytoplasm): fluid filled (aqueous) inner compartment of cells
Rough ER
Rough ER: double membrane sheets, continuous with the outer envelope of the nucleus. Studded with ribosomes (the particles visible in EM)
Smooth ER:
Smooth ER: membrane tubules connected to the nuclear envelope. protein synthesis (30-50 nm)
Nucleus
Nucleus: store of genetic information in eukaryotes. Has a double membrane. (contains DNA and Protein)
Nucleolus
Nucleolus: site of ribosome assembly
Golgi apparatus
Golgi apparatus: membrane stacks. Protein sorting, e.g. for secretion or transport to the membrane. Not continuous with the ER. (2-5 micro m)
Vesicle/Vacuole
Vesicle/Vacuole: particle with an fluid-filled (aqueous) interior and a single membrane. Vesicles small (< 200 nm), vacuoles large (> 200 nm) {ball park numbers}
Lysosomes and Secretory Vesicles are examples in animal cells. Plants also usually contain a large central vacuole.
Cell (plasma) membrane
Cell (plasma) membrane: not really an organelle, but crucial to the structural integrity of the cell and its organelles. Formed of a double layer of lipids.
