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Biol 111 Exam 3
| Question | Answer |
|---|---|
| What cleave RNA into miRNAs and siRNAs? | Dicer enzymes |
| What happens when miRNAs bind to mRNA | Prevent translation |
| How is a peptide translated? | 1. Sigmal sequence recognized by signal recognition particle (SRP) 2. SRP drags peptide to RER 3. Complex docks at a receptor in an RER channel; translation continues 5. Final polypeptide released through the channel into the lumin of the RER |
| How does polypeptide release occur once it is docked at the RER | 1. During translation the signal sequence is cleaved 2. peptide enters the lumin of the RER through the receptor via translocation 2. |
| What are the first steps to make a polypeeptide functional in post translational processing? (5) | Cleavage/proteolysis; glycosylation; phosphorolation; ubiquination; acetylation |
| Define proteolysis | cleavage into smaller peptides |
| Define glycosylation, phosphorolation, and acetylation | Add sugars; add phosphorous; add acetyl groups |
| Define ubiquination | Add ubiquitin (small protein groups) to a polypeptide chain |
| What is the effect of proteolysis/cleavage in post translational processing | Activate enzymes and hormones |
| What is the effect of ubiquination in post translational processing | target for destruction in proteosome (get rid of things) |
| Define primary protein structure | Sequence of amino acid; determined by gene information |
| Define secondary protein structure | Folding of the polypeptide backbone |
| What are the two types of secondary protein structures | Alpha-helix: coil/rigid rods Beta sheets: planar sheets/ more flexible |
| What are motifs | repeated secondary protein structures |
| Define tertiary protein structure | The 3D shape, including the arrangement of the alpha-helices and beta-sheets in space |
| Define quaternary protein structure | Multiple poly peptides interacting |
| What is a tetramer | 1 protein with 4 polypeptides |
| How can protein structure be stabalized (5) | 1. Hydrogen bonding; 2. electrostatic attractions between chargesd R-groups; 3. Disulfide bridges; 4. Van der Waals (nonpolar, weak) attractions 5. Hydrophobic exclusion |
| What is denaturation and why would it occur | When proteins lose their shape, causeing them to lose activity in response to the environment (temperature, pH, or ionic changes) |
| What are chaperone proteins (orig. heat shock) | Capped enzymes that fold proteins and preserve the function of the cell under stress using ATP |
| Which of the following can be denatured/renatured: a. Quaternary b. DNA c. Tertiary Proteins d. Primary protiens e. Secondary proteins | BCE.. sometimesA |
| Alzheimer's is a result of the accumulation of misfolded ______________________ producing an excess of _____________ that accumulate around neurons in the brain intracellularly | 1. amyloid beta protein 2. beta sheets |
| What does tau protein hyperphosphorylation result in? | An excess of alpha-heliceies forming protein clumps |
| How might protein function be restored? (2) | 1. May happen spontaneously under ideal conditions 2. May need assistance of chaperone proteins to sheild from the environment |
| What is the mechanism for cell communication | Signal transduction: convert info in a signaling molecule into a cellular response |
| What are the two main requirements for cell communication | Ligand & receptor |
| Define ligand | signalling molecule |
| Define receptor | molecule on the surface or inside a cell that the signal binds to |
| What are the five ways of signalling for cells? | 1. Cell to cell contact via gap junctions/surface receptors 2. Autocrine 3. Paracrine 4. Endocrine 5. Synaptic chemical signals released by neurons across a gap/synapse to a target cell |
| Differentiate between autocrine, paracrine, and endocrine | Auto: signaling to itself Endo: systematic signal via hormones & circulation (far away cells) Para: cell signalling to nearby cells |
| What are the two receptor types? | 1. Cytoplasmic (intracellular) 2. Membrane (cell surface) |
| What are the signals for cytoplasmic receptors | Hydrophobic hormone (steroids) or small molecule that pass through the plasma membrane |
| How do membrane/ cell surface receptors function | Signals cannot pass through the plasma membrane; receportors are transmembrane proteins that transmit the signal |
| What is the goal, location, and site of action for steroid hormone receptors? | Goal: change patterns of gene expression ( part of transcription factor) Located in cytoplasm Site of action is in nucleus |
| What is the mechanism for steroid hormone receptors | 1. Hormone crosses membrane by diffusion 2. Bind to receptor in cytoplasm 3. Hormone/receptor moves into nucleus to find DNA 4. Joins with transcription factor to regulate gene expression |
| What are the three types of membrane receptors | 1. Channel-linked; 2. Enzymatic; 3. G-Protein coupled |
| How do channel linked receptors function | 1. Ligand binds to receptor 2. Channel opens/closes causing a membrane potential |
| What is a membrane potential | Charge difference of the inside of the cell relative to the outside |
| What can activate a receptor by binding adaptor proteins | Autophosphorolation |
| What's an example of a catalytic receptor and what does it do | Protein/receptor tyrosine kinase (RTK); adds PO4 to amino acid tyrosine in proteins |
| How is a receptor bifunctional | 1. Extracellularly it binds to a ligand 2. Intracellularly is changes the cell activity |
| What is a 2nd internal messenger | Indirect receptor - receptor conveys info and messenger leads to response |
| What is the common structure of G-Protein coupled receptors | 7 transmembrane domains |
| What is the mechanism for G-Protein Coupled Receptors | 1. Ligand activates the receptor by binding 2. Receptor activates G protien 3. When inactive G proteins bind to GDP; when activated exchange GDP for GTP 4. This activates an effector protein or produces a 2nd messenger |
| What are the two discussed effectors and their function? | 1. Adenylyl cyclase: catalyzes ATP to cAMP which turns on protein kinase A 2. Phospholiphase C: converts POP2 to IP3 + DAG; IP3 causes release of intracellular calcium ions |
| What are two examples of 2nd messengers | cAMP; Ca2+ |
| Pharmaceuticals can be agonist or antagonists. What does this mean? | Agonist: mimic action of ligan; antagonist: prevent action of ligand |
| About 50% of pharmaceuticals target ___________________________. | Transmembrane receptors |
| What are the stages of development (6) | 1. gametogenesis 2. fertilization to produce a zygote 3. Cleavage into morula and blastula 4. Gastrulation 5. Neuulation 6. Organogenesis |
| What are the main components of gastrulation | Cell movement and shpae change leading to germ layer differentiation |
| What is neurulation | Neurule of the embryo undergoes dorsal ectoderm movement to form the neural plate |
| What is organogenesis | organ formation |
| Are eggs symetrical? | No, they have polarity important for function |
| In which pole of an egg is the nucleus found? | Animal |
| Where is the important structural information about the organizm found in the egg? | Both the animal and vegetal poles |
| How were scientist able to determine that the animal and vegetal poles differ | If the third cleavage was vertical development was the same; if it was horizontal problems occured in development (without one of the poles) |
| How is early development regulated | Maternal genes |
| How did we discover the role of maternal genes in development prior to fertilization? | Treated frog eggs with Actinomycin D(AMD. AMD shut off RNA synthesis after a little bit implying there was initially some mRNA in the egg cytoplasm from the mother |
| What mRNA is unique to the vegetal pole and what is its function? | Vegl - vegetal localized maternal RNA which stimulates dorsal lip formation |
| What are morphogens | diffusable proteins that affect developmental location by forming a gradient and setting up a map for the cells |
| What do the two sets of morphogen gradients determine? | 1. Anterial-Posterior axis 2. Dorsal-Ventral axis |
| What are bicoids and what do they do? | Morphogens (proteins) that activate gap geps which control other genes to segement the cell and form the anterior and posterior structures |
| What are segment polarity genes and how are they expressed? | Establish head, thorax, and abdomen segments; bicoid -> gap --> pair-rule --> segment polarity genes |
| What is the hierarchy of genes? | 1. Maternal genes - establish the gradient 2. Zygote genes: refine information & initial segmentation 3. Homeotic genes - specify segment fate |
| What do homeotic genes do? | Regulate gene expression in segments to establish specific fate |
| What is the hox gene and what does it do | Homeobox containing gene that specifies the identity of a particular body part. *The location corresponds to the body part identity and is very important |
| Define morphogenesis | The creatino of cell shape via cell movement (gastrulation) and cell shape changing (neurulation) |
| Define cell differentiation | Cells take on identity via changes in gene expression |
| What is induction and how does it occur in the lens | Cells affect the fate of other cells. The lens will not develop unless the optic vescile is properly formed and located |
| What is apoptosis and why would it be important in development? | Programmed cell death; cartiladge remodeling in the individual fingers as opposed to webbing |
| What are stem cells | Undifferentiated cells that can give rise to many different types of tissues |
| What are the three different types of stem cells? | Totipotent, pleuripotent, multipotent |
| Define and give an example of totipotent | Can become any type of cell or tissue; zygote/early blastula & embryonic stem cells |
| Define and give an example of pleuripotent | Can become most types of cells or tissue; late blastula & gastrula (after segmentation begins) |
| Define and give an example of multipotent | Can become a few different types of cells or tissues; adult stem cells & bone marrow |
| What are the two control systems in animals? | Endocrine and nervous |
| What system are the hormones and receptors a part of | endocrine |
| What does the nervous system do | interpret information about the body and the environment and decides whether and how to responds |
| What is the PNS and it's two types of neurons | Peripheral nervous system; contains sensory and motor neurons |
| What is the difference between sensory and motor neurons | sensory: bring info TO the brain; motor: take info away from brain and to the effector location (muscle,s organs, glands) |
| What is the central nervous system, what does it do, and how is it developed? | Brain and spinal cord; receives and integrates info from the body and direct appropriate response; developed from outpouching of neural tube |
| Define neuron | signal conducting cells in the CNS |
| What are the three parts of the neuron and their function? | 1. Dendrites: ;receive signal from other cells and conduct info to 2. cell body which maintains the cell followed by 3. axon which conducts the signal to the other nerve cells or effector organs |
| Define neuromuscular junction | connection between neuron and muscles |
| define synapse | connection to other neurons |
| Describe the structure of the axon | Made of schwann cells that wrap around to insulate conduction and provide support in a myelin sheath. The open areas between the schwann cells are the nodes of ranvier. |
| _______________ in the PNS conduct infor to ___________ in the CNS to produce and appropriate output by ___________ in the PNS | sensory neurons; inter neurons; motor neurons |
| What does nerve function depend on | membrane potential |
| What is action potential | The basis of nerve impulse via rapid depolarization of membrane and propagation of voltage spike along axon |
| Which are more highly concentrated inside/outside of the cell? a. Na+ b. K+ c. Cl- d. proteins | a. out; b. in; c. out; d. in |
| Define membrane potential | Charge difference (gradient) across a membrane |
| What is the sodium/potassium pump | Antiportor that pumps 3 Na+ out and 2 K+ in using ATP to maintain a concentration difference of sodium & potassium across the neural membrane |
| What are the 3 types of ion channels | Non gated, voltage gated, chemically gated |
| Differentiate betwen the two different types of sodium channel gates | 1. Activation: fast & on extracellular side 2. Inactivation: slow and on intracellular side |
| Differentiate betwen the two different types of potassium channel gates | Only 1 activation gate that is slow |
| What happens during the rising phase of action potential | Once threshold potential reached, sodium activation gate opens, the cell depolarizes, and the channels reach action potential |
| What happends at action potential | Sodium inactivation gate closes; potassium gate opens; falling phase leads to repolarization |
| Differnetiate between hyperpolarization and depolarization | Hyper: membrane potential becomes more negative; de: becomes more positive |
| During the resting phase what is the condition of the sodiumm channel | the activation gate is closed while the inactivation gate is open |
| *Review action potential graphs and processes | |
| Define nerve | Bundled acomany neurons that may have different properties |
| Efflux of K+ __________ the membrane | repolarizes |
| Why does a hyperpolarization dip occur during action potential | The time it takes to slowly close the potassium channel |
| Why does popagation of action potential only occur in one direction? | The region it previously fired is refractory (unable to respond to a second potential) |
| How can you increase the speed of conductance? | 1. increase the diameter of the axon (invertebrates); 2. insulate the axon with myelin (vertebrates).. because conduction jumps beween nodes of ranvier |
| What's the relationship between axon diameter and resistance | Inverse; large diam = low resistance |
| What happens when the action potential reaches teh axon terminal? | 1. Calcium channels open; 2. Influx of Ca++ causes neurotrasmitter to diffuse in; 3. Neurotransmitter may exite or inhipit the post synaptic cell |
| What are neurotransmitters? | Chemical signals released by neurons into the synaptic cleft which bind to receptors in postsynaptics cells causing charge changes |
| What may neurotransmitters do to the post synaptic cell? | 1. exite: depolarize and cause to fire; 2. inhibit: hyperpolarize and inhibit firing |
| Define synaptic cleft | Intracellular space between the neuron and its target |
| What is a post synaptic cell | The reciving cell that a neurotransmitter binds to via receptors to transmit nerve impulses |
| What is the portion of the muscle that the neuron communicates with refered to as | motor-end plate |
| What is the effect of the neurotransmitter binding to the motor-end plate | depolarization of the muscle |
| A wave of depolarization can be propogated deep into muscle through ______________. | transverse (T) tubules |
| Define sarcoplasmic reticulum | Special type of endoplasmic retiulum in muscles which stores calcium needed to regulate muscle contraction |
| What are the three types of muscle | Cardiac, smooth, & skeletal |
| What are two characteristics of cardiac muscle | 1. communicates electrically rather than chemically 2. created early in development, prior to nervous system |
| What are two characteristics of smooth muscle | 1. involuntary contractions 2. lines digestive tract and blood vescles |
| What is the structure of a muscle | During development cells fuse to produce fibers; A muscle cell contains bundled myofibrils ( each of the fibers fused by myocyte fusino during development) |
| What are the 4 proteins that make up myofibrils and their function | Actin & myosin for structure; troponin & tropomyosin for regulation |
| Differentiate between actin/myosin and troponin/tropomyosin interactions in contraction. | Actin/myosin: produce contraction; Troponin/tropomyosin: control contraction |
| Myofibrils are organized into ________ that are the actual unit of conctraction in a muscle. | sarcomeres |
| Differientate between thin and thick filaments in a sarcomere | Thin are made of globular actin prtein with tropomyosin and troponin wrapped around to cover the actin pit; thich are twisted chains of myosin with globular club-shaped heads |
| What is a cross bridge | The physical interaction of actin pit and myosin head |
| In the sliding filament model ________ is slide relative to ________ | actin; myosin |
| What changes between actin and myosin in the sliding filament model of muscle contraction | Their degree of overlap; NOT length |
| What changes in length during muscle contraction and by how much (um) | Sarcomeres; 2.5 um --> 2 um shortened |
| What is the Z line | Where actin attaches to proteins in a sarcomere |
| What are the molecular events of muscle contraction? | 1. Myosin hydrolizes ATP; 2. Head resets & tropomyosin is pulle daway from actin binding site by troponin; 3. Myosin binds to actin; 4. Myosin head released in ADP during powerstroke; 5. Mysoin binds to ATP & releases actin (breaking cross bridge) |
| What is the process of shortening the sarcomere in the sliding filament model refered to as | powerstroke |
| What controls troponin | Ca++ from the sarcoplasmic reticulum binds to it allowing it to move tropomyosin |
Created by:
jkmccord11
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