Exam 2 Material Flashcards
T/F: enzymes are not efficient
False. They are very efficient.
How can we regulate amount of enzymes?
Increase enzymes = more products
Decrease enzymes = less products
Three methods of regulating enzyme activity are:
Regulating access to cofactors
Phosphorylation
Proteolytic Cleavage
How does the method of regulating access to cofactors work?
The cell adds an extra step in process of metabolism by making enzyme require a cofactor
What is a cofactor or coenzyme?
Organic molecule usually from a vitamin that’s required to produce the product.
Example from class: towel needed to connect w people vs just holding hands
What happens if you don’t have enough cofactors in the metabolic process?
Slows down process
How does Phosphorylation work?
Kinases add phosphate group to molecules,
Phosphatases remove phosphates from molecules
Is a reaction with kinase anabolic or catabolic?
Anabolic bc it requires energy
Is a reaction with Kinase encergonic or exergonic?
Endergonic
How does Proteolytic Cleavage regulate enzymes?
Amino acids temporarily block active site = Pepsinogen (inactive) then unfold to form pepsin (active)
what are hydrolase enzymes?
Catalyze a hydrolytic reaction
Types of hydrolytic enzymes
Nuclease, protease, lipase
Prefix = what they break down by hydrolyzing
What does ATPase do?
Catalyzes hydrolysis of ATP or ADP, liberating energy possibly used by the cell
Membrane transport mechanisms:
How does simple diffusion work?
No energy required, molecules follow their concentration gradient
What is net diffusion?
Mass movement of material from high concentration to low
T/F: net diffusion is constant
False. It stops once concentration gradient reaches equilibrium (molecules spread out)
Fick’s Law (rate of net diffusion equation)
What’s does D stand for?
Diffusion coefficient - depends on size of molecule
Fick’s Law (rate of net diffusion equation)
What does A stand for?
Surface area of membrane
Fick’s law (rate of net diffusion equation)
What does 🔺C mean?
Concentration difference across membrane
Fick’s law (rate of net diffusion equation)
What does d mean?
Thickness of membrane
What is facilitated diffusion?
Door or window is inserted to aid hydrophilic molecules cross membrane, no energy required, still following concentration gradient
What are carrier proteins?
Membrane transporters, have binding sites for the transported molecule
What is acute regulation?
Changed quickly
What is chronic regulation?
Changed over time
T/F: facilitated diffusion is highly elective to one or few specific solutes
True
T/F: facilitated diffusion is regulated by enzymes
False. It’s regulated by membrane proteins
What do channels do?
tunnel through membrane, specific for each ion
T/F: channels allow passage for all ions
False. Each channel is made for one ion. Selective based on ion size and charge
What’s it called when channels can be opened or closed?
Channel gating
What is a constitutively open (or passive) channel?
Material can always cross when following concentration gradient
What is a ligand-gated channel?
Opens only for specific ligand
What is a phosphorylation-gated channel?
Open/closed according to whether channel protein is phosphorylated or not
What is voltage-gated channel?
Open/closed depending on change in membrane potential (charge)
What is mechanically-gated channel?
Open/closed depending on sensory receptors, stretching or pulling forces
What is the electrical concentration gradient?
Ion floats along membrane bc of separation of charges
What is membrane potential?
Result of separation of charges across membrane
What is the electrical gradient?
Separation of charges across membrane
What is active transport?
Molecules move against concentration gradient, requires membrane protein, requires energy
How does Na/K Pump work?
primary active transport,2 K+ binding sites,3 N+ binding sites, requires 1 ATP, every 3 Na ions pushed out = 2 K ions pulled in
What is secondary active transport?
Two molecules passing membrane, one is hitchhiking so doesn’t require extra energy
What does a vesicle do?
Pod that carries stuff doesn’t interact w stuff inside cell. does exocytosis, endocytosis, transcytosis, and substance trafficking = all require energy
How does vesicular trafficking work?
Kinesin and Dynein walk loaded vesicles along microtubules
Epithelial tissues are vascular or non?
Non
2 types of epithelial tissue:
Cover and lining, glandular
Basic properties of epithelial tissues
Avascular, inncervated (lots of nerves), regenerative (quickly replaces lost cells)
What is a tight junction?
Forms an impermeable junction encircling cell, prevents molecules from passing between adjacent cells, looks like a net
What are the cell-cell junctions?
Tight, gap, adherens, desmosome
What is adhesion junction?
Attack on inside of each cell like velcro, helps epithelial surfaces resist separation during muscle contraction
What are desmosomes?
Act like “spot welds”, attached to cytoskeleton, tie all cytoskeletons together, reduces chance of tearing
What is the only type of cell-matrix junction?
Hemidesmosome
What is a Hemidesmosome?
Half a desmosome, anchor cellular sheet to underlying connective tissue
What are gap junctions?
Connects cytoplasm of 2 cells, passes ions and small polar molecules, mostly btw nerve and muscle cells
Where is the apical surface?
Exposed to body cavity
Where is basal surface?
Attached to connective tissue
3 types of covering and lining epithelia
Epithelium, endothelium, mesothelium
What is epithelium?
Covers body surfaces, lines lumens of digestive, respiratory, and urogenital tracts
What is endothelium?
Lines chambers of heart and lumen of BV and lymph vessels
What is mesothelium?
Covers serous membranes
What are epithelial membranes?
Combo of covering and lining epithelial cheer and its underlying connective tissue
4 types of epithelial membranes
Mucous, serous, cutaneous, and synovial
What is mucous membrane?
Lines body cavities open to exterior
Where is serous membrane?
Peritoneum, pleura of lungs, pericardium
Where is cutaneous membrane?
Skin
What is synovial membrane?
Line joint cavity of synovial joints, similar to serous fluid
Where to find simple epithelia
Places of absorption and filtration, areas that are already protected, single layer
Where to find stratified epithelia
Places under constant stress, 2+ layers, not for absorption
What do enzymes do?
They are catalysts. So they speed up metabolic reactions without being affected
Describe capillaries
Simple squamous epithelium cells bound together like tile floor
What kind of junction does central nervous system have?
Tight, for keeping stuff out to protect itself
What makes up the epithelial membrane?
Covering and lining epithelia + its underlying connective tissue
Functions of simple cuboidal epithelial
Secretes and absorbs
Functions of simple columnar epithelia
Secretion and absorption
What are goblet cells and where are they found?
Produce mucous, found in stomach and upper respiratory tract
Describe pseudostratified columnar epithelia, what are the functions?
Single layer but looks like more than one, secretion partially of mucous
How do you know if an epithelia is for protection or not?
Simple is not bc its one thin layer, stratified are bc they’re multiple layers
What does squamous mean?
Flattened
How do you name stratified epithelia?
shape of apical cells?
Function of glandular epithelia
Produces a secretion
Why Classify glandular epithelia as endocrine..
(Inside cell to blood stream) It secretes into extra cellular fluid then straight into blood stream
Why classify glandular epithelia as exocrine?
(Inside cell to lumen of stomach) Secretes onto body’s surface or into body then into lumen of stomach
What are cytogenetic glands?
Secretes whole cells, only in germline cells
What is a hormone?
Ligand made by endocrine gland, carried through blood, finds its target cell and binds
Are endocrine glands vascular?
Yes, very. Bc it secretes from inside cell directly to blood stream
What’s the only important unicellular exocrine gland?
Goblet cells
Structure of multicellular exocrine glands
Made of duct and secretory unit
Difference in structure of exocrine and endocrine glands
Endocrine doesn’t have a duct attached to the secretory unit bc its its attached to blood vessels
What are myoepithelial cells?
Contractile cells like a net that squeeze salivary and mammary glands to push stuff out
Mode of secretion: how does merocrine work?
Products are secretes by exocytosis
Mode of secretion: how does apocrine work?
Secretory product accumulates at apical surface and pinches off
Modes of secretion: how does halocrine work?
Products are secreted by rupture of gland cells
