Importance of proteins in control of processes and responses in organisms Flashcards
Transcriptional factors
1) Each TF has a DNA binding site that is specific to a particular gene.
2) When a specific protein is required, the gene is stimulated by the specific TF.
3) This initiates synthesis of the protein by binding to the DNA at the specific base sequence - the promoter sequence.
4) Stimulates transcription.
5) Pre-mRNA produced, spliced into mRNA before being translated into a protein.
Enzymes in digestion
1) Saliva enters mouth from salivary glands, mixed with food during chewing.
2) Catalyses hydrolysis of glycosidic bonds in starch, produces disaccharide maltose.
3) Food swallowed, amylase in saliva denatures in stomach acid, preventing further digestion of starch.
4) Food passed into ileum, mixed with pancreatic juice (contains pancreatic amylase).
5) Catalyses hydrolysis of starch to maltose.
6) Smooth muscle in ileum pushes food along, epithelial lining produces maltase.
7) Maltase catalyses hydrolysis of maltose into glucose disaccharide.
8) Molecule can then be absorbed into epithelial cells.
No amylase/maltase = no glucose = no uptake for respiration = no ATP for other metabolic processes like muscle contractions.
Information passing from one neurone to the next across a cholinergic synapse
1) Impulses cause calcium ion channels to open, calcium ions diffuse into synaptic knob.
2) Vesicles move towards AND fuse with presynaptic membrane.
3) Acetylcholine is released via exocytosis.
4) Acetylcholine diffuses across synaptic cleft.
5) Acetylcholine binds with receptors on Na+ channels in postsynaptic membrane.
6) Na+ channels open, Na+ diffuse into postsynaptic membrane.
7) Depolarisation of postsynaptic membrane.
8) If above threshold, action potential produced
Action potential for muscle contraction (synaptic transmission)
1) Depolarisation of sarcolemma.
2) Action potential passed to T-tubule (if above threshold).
3) Calcium ions released from sarcoplasmic reticulum.
4) Calcium ions bind to troponin and cause tropomyosin to move.
5) Exposes myosin binding sites on actin.
6) Myosin head binds to actin.
7) Form actinmyosin cross bridge.
8) Myosin head power stroke.
9) Actin filament moves relative to myosin.
10) Hydrolysis of ATP causes re-cocking of myosin head.
11) Myosin head binds to actin further along actin.
12) Repeated for muscle contraction.
Humoral immunity
1) Pathogens enters blood stream, phagocytosis occurs.
2) Specific B lymphocytes engulf foreign antigens.
3) Foreign antigen displayed on surface of B lymphocytes.
4) Activated T helper cells bind to presented foreign antigens.
5) Activated T helper cells activate B lymphocyte to divide by mitosis.
6) Clones differentiate to form plasma B and memory B lymphocytes.
7) Plasma B cells produce thousands of specific antibodies.
8) Antibodies released into blood stream and bind with antigens, forming antigen-antibody complexes. PRIMARY RESPONSE.
9) Memory B cells remain are are used for repeated invasions by same pathogen. SECONDARY RESPONSE.
Light independent reaction: Calvin cycle
1) CO2 diffuses into leaf through stomata into the stroma of the chloroplast.
2) Using an enzyme (Rubisco), CO2 binds to 5-carbon sugar ribulose bisphosphate.
3) Produces 2 molecules of 3-carbon glycerate 3-phosphate, which are activated.
4) Reduced NADP from light-dependent reaction reduces 2x GP to 2x triose phosphate. Uses ATP from light-dependent reaction.
5) TP goes through reactions to regenerate the ribulose bisphosphate. Reduction of ATP to ADP and Pi provides phosphate needed.
6) 2x TP combine to form one 6C glucose molecule.
7) Glucose molecules combine via condensation to produce larger complex molecules e.g. starch. Used in respiration to produce ATP (plant uses this to produce glucose, and for it to synthesise other organic compounds the plant needs for growth like cellulose, proteins).
