Molecular Review (Zaidi)

Question 1

Gated, Transmembrane, and Vesicular Transport

Answer 1

Gated - between nucleus and cytosol (active transport and free diffusion)

Transmembrane - from cytosol across organelle membrane (protein translocators)

Vesicular - between various compartments via vesicles (membrane-enclosed transport)

Question 2

Protein Sorting Signals

Answer 2

• on N or C terminus or within protein sequence
• signals both necessary and sufficient for protein targeting
• recognized by complimentary receptors

Question 3

Nuclear Transport

Answer 3

• bidirectional, selective, gated

- sorting signals = nuclear localization sequence (lysine/arginine-rich)

Question 4

Nuclear Import and Export

Answer 4

1. Import - Ran-GDP dissociates from receptor; receptors binds with cargo, and passes through NPC
2. Export - Ran-GTP binds to receptor; receptors bind cargo, pass through NPC, cargo and Ran-GDP dissociate

Question 5

Outer Mitochondrial Membrane Translocators

Answer 5

1. TOM complex

2. SAM complex

Question 6

Inner Mitochondrial Membrane Translocators

Answer 6

1. TIM22 complex
2. TIM23 complex
3. OXA

Question 7

TOM Complex

Answer 7

• required for import of ALL nuclear encoded proteins

- inserts them in Outer Membrane

Question 8

TIM 22 and 23

Answer 8

22 - mediates insertion of specific subclass of proteins

23 - transports soluble proteins into matrix and helps insert membrane proteins in inner membrane

Question 9

SAM Complex

Answer 9

translocates and inserts/folds beta barrel proteins in OUTER membrane

Question 10

OXA Complex

Answer 10

insertion of all proteins synthesized IN MITOCHONDRIA

• also some proteins already present in matrix brought from outside

Question 11

Ribosomes to ER membrane

Answer 11

• SRP binds to signal sequence of growing peptide
• pauses translation and binds to SRP receptor
• protein translation continues into translocator
• SRP dissociates and recycles

Question 12

Rab and SNARE in vesicle targeting

Answer 12

Rab proteins - direct vesicles to specific spots on target membrane

SNARE - mediate fusion of vesicle with membrane

Question 13

MP6 and lysosomal hydrolases

Answer 13

• receptors in TGN recognize mannose-6-phosphate (attached to lysosomal hydrolases in CGN)
• packaged into clathrin-coated vesicles, which are delivered into endosomes and then to lysosomes

Question 14

Pellets in Centrifugation

Answer 14

• low speed pellet = whole cells, nuclei, cytoskeletons
• medium speed pellet = mitochondria, lysosomes, peroxisomes
• high speed pellet = microsomes, small vesicles
• very high speed pellet = ribosomes, viruses, large macromolecules

Question 15

Ion-Exchange, Gel-Filtration, and Affinity Chromotography

Answer 15

Ion - charged beads attract molecules of certain charge

Gel - small molecules trapped in porous beads

Affinity - beads with covalently attached substrate bind certain enzymes

Question 16

3 Restriction Endonucleases (HaeIII, EcoRI, HindIII)

Answer 16

HaeIII - cuts between G and C

EcoRI - cuts between G and A

HindIII - cuts between A and A

Question 17

Agarose Gel Electrophoresis

Answer 17

• different than SDS-PAGE (DNA is already CHARGED)

Question 18

How can genes be cloned?

Answer 18

• by using bacteria

- insert clone segment into circular, DS plasmid vector

Question 19

Homologous proteins are functionally what?

Answer 19

INTERCHANGEABLE

Question 20

Ectoderm, Endoderm, Mesoderm

Answer 20

Ectoderm - precursor of nervous system and epidermis

Endoderm - precursor of gut, lung, liver

Mesoderm - precursor of muscles and CT

Question 21

Gastrulation

Answer 21

transformation of blastula, a hollow sphere of cells, into a layered structure with a gut

Question 22

What makes one organism different from another?

Answer 22

non-coding DNA sequences

• coding sequences in DNA similar in most organisms

Question 23

Cell Fates (determined, completely undetermined, committed)

Answer 23

Determined - fated to develop into specialized cell type DESPITE changes in environment

Undetermined - cells that rapidly change due to alterations in environment

Committed - cells have some attributes of particular cell type but can change with environment

Question 24

What are the most important environmental cues?

Answer 24

signals from neighboring cells

INDUCTIVE SIGNALING = induction of different developmental program in select cells in a homogonous group leading to altered character

Question 25

morphogen

Answer 25

- long range inductive signal that imposes pattern on a field of cells - exert graded effects by forming gradients of different concentrations (may direct target cells into different developmental pathway)

Question 26

3 phases of neural development

Answer 26

Phase I - different cell types develop independently at widely separate locations Phase II - axons/dendrites grow along routes, setting up provisional but orderly networks of connection Phase III - connections adjusted and refined through interactions with distant regions

Question 27

CNS and PNS development

Answer 27

CNS - from neural tube (brain, spinal cord, retina) PNS - neural crest (nerves, sensory neurons)

Question 28

Radial Glial Cells

Answer 28

what neurons travel on - older neurons are closer to layers of cortical neurons (closer to origin)

Question 29

Growth Cones

Answer 29

- behavior dictated by cytoskeletal machinery - throw out filopodia and lamelopodia - Rho/Rac (GTPases) control assembly/disassembly of actin filaments, controlling movement of growth cone

Question 30

Growth Cone Migration

Answer 30

- travel towards targets along PREDICTABLE ROUTES | - sense extracellular matrix environment and chemotactic factors

Question 31

Netrin, Slit, Semaphorin

Answer 31

Netrin - attractor Slit/Semaphorin - repellants

Question 32

Neurotrophic Factors

Answer 32

- axonal growth cone reaches target - signals from target tissue regulate which growth cones synapse and where - produce limited amount of specific neurotrophic factors needed for survival (those that do not get enough die)

Question 33

Synaptic Remodeling rules that create spatial order

Answer 33

1. axons from different regions compete for tectal neurons | 2. axons from neighboring sites excited at the same time collaborate and strengthen synapses with tectal neurons

Question 34

Characteristics of Stem Cells

Answer 34

- not terminally differentiated - can divide without limit - renew themselves - slow division, ability to remain stem cell or become differentiated

Question 35

Totipotency, Pluripotency, Multipotency

Answer 35

Totipotency - cell gives rise to all cells of organism (Zygote) Pluripotency - cell gives rise to all cells of embryo and adult tissues (embryonic stem cell) Multipotency - cell gives rise to different cells types of given lineage (adult stem cells)

Question 36

Skin Layers (outer to inner)

Answer 36

1. squame - flakes 2. keratinized squames 3. granular cell layer (waterproof barrier) 4. prickle cell layer 5. basal cell layer (only dividing cells in epidermis) 6. basal lamina

Question 37

Renewal of Epidermis

Answer 37

- self-renewing process - stem cells provide indefinite supply of fresh differentiated cells - basal layer has stem cells

Question 38

Somatic Nuclear Transfer (SCeNT)

Answer 38

- nucleus taken from somatic cell of patient and injected into oocyte of donor replacing the oocyte nucleus - blastocyst generated from this hybrid oocyte and ES cells isolated