slide set 2

rosalind franklin = real DNA hero

transcription DNA sequence is enzymatically copied by an RNA polymerase to produce mRNA

• transcription = price that leads to translation of genetic code into a functional peptide or protein
• DNA is unwound by DNA helices
• RNA polymerase binds and recognizes the start site
• RNA nucleotides (uracil rather than thymine) base pair with the DNA
• form chain of mRNA

• transcription factors
• proteins that assist the RNA polymerase in recognizing promoters

• transcription factors are divided into 2 types
• 1. gene specific transcription = activate specific genes
• ex. estrogen receptors = estrogen target gene specific
• 2. general transcriptions factors = required to activate all genes

cAMP response element modulator - CREM is a transcription factor

• CREM null mice = infertile
• CREM required to make sperm

• 1 gene activation
• 2.transcription
• 3.mRNA processing
• 4. translation
• 5. post-translational modification

• Channel proteins (create a water filled pore)
• can be classified into:
• 1. gated channels
• 2. open channels

• Carrier proteins (never form an open channel between the 2 sides of the membrane)
• can be classified into
• 1. uniport carriers (Glu goes thru)
• 2. symport carriers (Na and Glu go thru)
• have cotransporters
• 3. antiport carriers (Na goes in and K goes out)(ATP needed)
• have cotransporters

require energy (ATP) from cells

• Transport by pumps
• pump are membrane transporters that move a substance again the concentration gradient
• ex. Ca pumps, Na-K pumps

• Transport by vesicles
• allows substances to enter or leave the interior of a cell without actually moving through its plasma membrane

• Extracellular fluid
• ↑ Na  and ↓K

• Intracellular fluid
• ↓ Na and ↑ K

• Mecanism of the SGLT transporter
• 1. Na binds to the carrier
• 2. Na creates a site for Glucose
• 3. Binding of glucose changes the carrier confirmation
• 4. Na is released into the cytosol. Glucose follows

• epithelium is either leaky or tight
• capillaries - all dissolved molecules can pass through
• kidney - held by tight barrier
• substances must enter cell and pass through it

selectively regulates exchanges of ions and nutrients 

• absorptions = from external to internal
• secretion = from internal to external

transporting epithelial characteristics = thicker membrane modifications, cell junctions, mitochondria

• exocrine glands =  release into the external environment, skin, airways, digestive
• release into ducts

endocrine glands = release hormone into the blood stream

• 1. plasma proteins are concentrated in the caveolae, which then undergo endocytosis and form vesicles 
• 2. vesicles cross the cells with help from the cytoskeleton
• 3. vesicle contents are released in the interstitial fluid by exocytosis

• alvins symptoms:
• chronic cough, diarhea, wheeze
• runny nose
• SALTY SKIN

pathophysiology of CF = characterized by defective epithelial ion transport

• abnormal transport of Cl and Na across epithelium in all exocrine tissues, leading to think viscous secretions in the lungs, pancreas, liver, intestine and reproductive tract
• ↑ salt content in sweat glands secretions

• faulty gene = on chromosome 7
• malfunction of gene coding for the CF transmembrane conductance regulator (CFTR)
• malfunction leads to defective cAMP activated Cl-Na channel on the surface of epithelial cells
• NaCl becomes trapped in cell
• pulls the water in and results in dehydrated mucus
• lungs are the most affected organs
• 70-80% of patients lack receptor?*

• airway clearance therapy
• antibiotics
• bronchial dilators
• vitamin supplements
• enzyme to aid digestion

• structural proteins
• enzymes
• membrane receptor proteins

• transporters
• channel proteins
• carrier porteins

ligand = binds to a cell membrane receptor protein

ligand-receptor complex = triggers intracellular response

• Phagocytosis
• cell engulfs bacterium or other particle into phagosome

• Endocytosis
• the plasma membrane "traps" some extracellular material and brings it into the cell in a vesicle
• active process that can only be non selective (pinocytosis) or highly selective
• potocytosis = uses cavaolae
• receptor mediated uses clathrin coated pits

• 1. Phagocytosis
• "condition of cell eating"
• large particle are engulfed by the plasma membrane and enter the cell in veiscles
• vesicles fuse with lysosomes, where the particles are digested

• 2. Pinocytosis
• "condition of cell drinking"
• fluid and substances dissolved in it enter the cell

• 1. ligand brings to receptor
• 2. receptor ligand migrates to clathrin coated pit
• 3. endocytosis
• 4. vesicle loses clathrin coat
• 5. receptors and ligands separate
• 6. ligands go to lysosome or Golgi for processing
• 7. transport vesicle with receptors
•  moves in the cell membrane
• 8. transport vesicle and cell membrane fuse (membrane recycling)

then it restarts again

• Exocytosis
• process by which large molecules love the cell even though they are too large to move out through the plasma membrane
• enclosed in many vesicles, pulled by the cytoskeleton to the plasma membrane, where the contents are released