Chapter 7-Bio 202

What motor protein dynein helsp cilia and flagella move?

Dynein -it forms the arms between doublets and changes shape when ATP is hydrolyzed to walk up the microtubule

Protein-importin complex enters nucleus and then binds to what?

Ran-GTP

Protein dissociation?

Ran-GTP binds to importin = importin releases cargo = Ran-GTP moves importin to nuclear pore and helps importin out = GTP goes to GDP = import in released

All cells contain...

Ribosomes for protein synthesis

Pulse-Chase Experiment

used to track protein movement (way to see things move through a cell and helped figure out sequence of cellular events in a process) -Idea is to mark a population of molecules at a particular interval and follow their fate over time

NLS on protein binds to what?

Importin

Prokaryotic Cells

(1) Have one supercoiled circular chromosome found in the nucleoid (consists of large DNA molecule associated with a small number of proteins). Genetic material is organized by clustering loops of DNA into distinct domains. (2) Contain small, supercoiled DNA molecules call plasmids. (3) Contain ribosomes for protein synthesis (4) Extensive internal membranes perform photosynthesis (5) Bacterial Organelles perform many tasks (6) Protein filaments form basis of cytoskeleton (7) Cell wall protects the cell (8) Bacteria interact with the environment via structures that grow from the plasma membrane (flagella and fimbriae)

All cells have:

(1) Nucleic acids that store and transmit information (2) Proteins that perform most of the cell's functions (3) Carbs that provide chemical energy, carbon, support, and identity (4) A plasma membrane, which serves as a selectively permeable membrane barrier (separates outside of cell from the inside)

Moving from the ER to Golgi

(protein is not in fully-folded form) 1.Ribosomes deposit protein in ER 2. Protein exits ER 3. Protein enters Golgi for processing (cis face) 4. Protein exits Golgi (trans face) 5. Protein exits cell

Filaments:

-All cells have all three types of cytoskeleton filaments, and all are polymers of protein -The shape of an animal cell is determined by organization of filaments -Actin filaments and microtubules are easy for cells to disassemble and rebuild them, serve as tracks for other items to be transported along in cell

Golgi Apparatus

-Where proteins are modified and sorted 1. Formed by a series of stacked flat membranous sacs (cisternae) 2. Receives products (proteins) from the rough ER, processes them and sends them to the cell surface in vesicles 3. Has distinct polarity (Cis side faces nucleus, trans side faces plasma membrane) 4, Golgi receives produce on the cis face and sends them from the trans face

The Signal Hypothesis

-synthesis of proteins destined to be secreted or embedded in membranes begins in ribosomes free in the cytosol -synthesis of amino acids that will move proteins into the ER lumen is their molecular zip code

Nuclear proteins are synthesized by ribosomes in the cytosol

-they contain a molecular address tag that marks them for transport through the nuclear pore complex (address tags allow the nuclear pore complex to open in a way that permits larger proteins and RNA molecules to pass through)

Actin proteins aren't symmetrical

-two distinct ends of an actin filament are referred to as plus and minus ends and the structural difference between the two results in different rates of assembling new actin subunits (plus grows faster than minus end)

Mitochondria

1. ATP production (bulk is generated through cellular respiration) 2. Have a double membrane-the inward membrane folds inward to make cristae (cristae increases surface area) 3. Each mitochondrion has many copies of small, circular chromosome

How you recycle material in the lysosome through autophagy?

1. Damaged organelles are surrounded by a membrane (autophagosome) 2. They get delivered to the lysosome (lysosomes move to the autophagosome) 3. Small molecules are recycled into the cytosol (normal process that occurs in cells and can increase in times of extreme stress)

Process of the signal hypothesis:

1. Endomembrane address is a signal sequence at the terminus of the ribosome (ribosome synthesizes the ER signal sequence) 2. Signal sequence binds to a signal recognition particle that is a complex of RNA and protein and causes protein synthesis to stop 3. Translocon associates with a receptor for SRp 4. Protein is pushed into the ER 5. Signal sequence clips off 6. Signal sequence folds into the final form in the ER

Four key differences between eukaryotic and prokaryotic cells:

1. Eukaryotic chromosomes are found inside a nucleus (membrane-bound) 2. Eukaryotic cells are much larger than prokaryotes -diffusion only allows for rapid movement across very small distances in these cells 3. Eukaryotic cells contain extensive amounts of internal membranes 4. Eukaryotic cells feature a diverse and dynamic cytoskeleton

Cytoskeleton

1. Extensive system of protein fibers 2. Give the cell its shape and structural stability but also involved in moving the cell itself 3. Organizes all the organelles and other cellular structures into a cohesive whole

Cell Wall

1. Fungi, algae, and plants have a stiff outer cell wall that protects the cell and provides structural support 2. Very important in protecting and fusing 2 cells together - very strong adhesion

Chloroplast

1. In most plant and algal cells 2. Grow and divide independently, have a double membrane, and contain chlorpolast DNA 3. Contain everything required for photosynthesis

Microtubules

1. Largest cytoskeleton component 2. Subunits: alpha and beta tubulin dimers 3. Are a hallow tube 4. Maintain cell shape by resisting compression, move cells via flagella or cilia, move chromosomes during cell division, assist formation of cell plate during plant cell division, move organelles, provide tracks for intracellular transport

How do you recycle material in the lysosome through receptor mediated endocytosis?

1. Macromolecules bind to receptors 2. Endocytic vesicle forms 3. Endocytic vesicle fuses with early endosome; protons lower pH 4. Early endosome matures; digestive enzymes received 5. Mature lysosome macromolecules digested 6. Cell basically turns into a lysosome

Rough Endoplasmic Reticulum

1. Network of membranous tubes and sacs studded with ribosomes for protein synthesis 2. Ribosomes associated with the rough ER synthesize proteins that will be inserted into the plasma membrane, secreted to the cell exterior, or shipped to an organelle 3. Interior of the rough ER = lumen 4. Many of the rough ER products are packaged into vesicles and transported to various destinations

Different types of peroxisomes specialize in different types of oxidation:

1. Oxidative breakdown of long-chain fatty acids 2. Catalase breaks down hydrogen peroxide

Smooth Endoplasmic Reticulum

1. Parts of the ER that are free of ribosomes 2. Contains enzymes that catalyze reactions involving lipids-may synthesize lipids needed by the organism or break down lipids and other molecules that are poisonous 3. Functions as a reservoir for calcium ions that act as a signal triggering a wide array of activities in the cell 4. Function of the smooth ER is somewhat cell type specific: primary site for lipid metabolism; hydrophobic toxins can easily get into cells, but because they don't react with water it is hard for the cell to break them down

How you recycle material in the lysosome through phagocytosis?

1. Plasma membrane detects a smaller cell or food particle and begins to engulf it 2. The resulting membrane-bound vesicle = phagosome 3. Phagosome is delivered to a lysosome, which takes it in and begins digesting it 4. Small molecules from the digested food particles are released into the cytosol (most cells can do phagocytosis if they have correct stimulus)

How proteins are modified and sorted in the Golgi?

1. Proteins products pass through the golgi apparatus in cistern containing enzymes for specific glycosylation reactions, before exiting on the far side of the golgi 2. Proteins are sorted into distinct vesicles in the golgi apparatus, and additional molecular tags direct golgi proteins to final destination

Ribosomes

1. Scattered throughout the cytoplasm 2. Some ribosomes associate with the rough ER and some ribosomes seem to freely float around 3. Eukaryotic ribosomes are complex macromolecular machines that manufacture proteins

Peroxisomes

1. Single membrane bound globular organelles where oxidation reactions occur; originate as buds from the ER 2. Located toward the periphery of the cell 3. Products of reactions in peroxisomes often include hydrogen peroxide, which is highly reactive -releases

Vacuoles

1. Storage in plants and some fungi 2. Are ways for plant cells to store water, they will grow and shrink depending on the environments 3. Act like lysosomes in plants

Actin Filaments

1. Subunit: actin 2. Strands are in a double helix 3. Smallest cytoskeleton elements 4. Often interact with myosin to cause movement 5. Cyotokinesis 6. Cytoplasmic Streaming 7. Cell Crawling

Intermediate Filaments

1. Subunits: Keratins, Lamens, or others (different cells make it out of different proteins) 2. Fibers are wound into thicker cables 3. Not polar-each filament is identical 4. Serve a purely structural roll; maintain cell shape by resisting tension (pull), anchor nucleus and some other organelles 5. All cells build a type of intermediate filament inside the nucleus out of lamins, which keep nucleus structure and organization 6. Provide structural support for the cell and hold the nucleus in place 7. Epithelial cells' intermediate filaments act like ropes and are responsible for giving them their shape and resiliency

Lysosomes

1. The cells recycling center 2. Animal lysosomes have an an acid interior and contain digestive enzymes 3. Molecules resulting from acid hydrolysis leave the lysosome via transport proteins in the organelle's membrane

Cells....

1. are specialized for certain tasks, and its structure correlates with those tasks 2. Cells are dynamic 3. The dominate forces are charge or polarity based electrostatic attractions between molecules and their energy of motion

Molecules shuttle to and from the nucleus through the nuclear pores

1. each pore consists of over 50 different proteins 2. DNA is used to synthesize RNA inside the nucleus, (exported through the nuclear pores of cytoplasm) 3. The nuclear pores experience a lot of traffic

Bacterial Organelles....

1. store calcium ions or other key molecules 2. help cells sense a magnetic field and swim in a directed way 3. Organize enzymes responsible for synthesizing complex carbon compounds from carbohydrates 4. Sequestering enzymes that generate chemical energy from ammonium ions

Proteins destined for the nucleus have how many amino-acid nuclear localization signals (NLS)?

17

Nucleus

All eukaryotes have a large nucleus that is surrounded by a double-membrane nuclear envelope. It has loosely packed sections of chromosomes and densely packed sections.

Nucleolus

Area with higher density of RNA's in the nucleus. This is where RNA molecules found in ribosomes are manufactured and the large and small ribosomal subunits are assembled. Also, administrative center for information storage and processing

What does kinesin do?

Converts chemical energy in ATP to mechanical energy in the form of movement; when ATP is hydrolyzed by kinesin, the protein moves along microtubules toward the plus end

Endoplasmic Reticulum

ER membrane is continuous with the nuclear envelope

How does kinesin bind?

Head region binds to microtubule, while tail region binds to transport vesicle

GTP is hydrolyzed to?

GDP, where the importin dissociates

Endomembrane System:

Golgi apparatus lysosomes and the ER (system is a center for producing, processing, and transporting proteins and lipids in eukaryotic cells)

How do microtubules grow?

Grow from one end and shrink from the other -kinesins tend to move toward the + end, and each interacts with a different cargo

Axoneme

Inside a microtubule, its a series of microtubule doublets with one or two in the center -dynein causes them to bend, which results in beating motion

Flagella

Large protein complexes that cross into the cytoplasm and the base of the structure is embedded in the plasma membrane. Allows cell to move through water.

Kinesin

Motor protein that generates vesicle movement

Tubulin Dimers

Polymerize from head to tail to form filaments that interact with one another to create relatively large, hallow tubes -alpha one one (minus) end -beta on one (plus) end

Cytokinesis

Process of cell division: actin-myosin interactions pinch the membrane in two

What does the cell wall do?

Protects the cell, gives them shape and structure, and resists the osmotic pressure difference between the hypertonic cytoplasm and the environment outside the cell. It resists rapid changes in turgor pressure (osmosis). Surrounds the plasma membrane

____ form the basis of the cytoskeleton and helps the cell maintain its shape.

Protein Filaments

Fimbriae

Protrusions from the cell that allow the cell to anchor down and may even secrete the material that it is going to attach to. It is often distributed over the entire surface of the cell

What are the major differences between prokaryotes and eukaryotes?

STRUCTURAL

Cisternae

Series of stacked flat membranous sacs

If substrates are used up in a particular part of the organelle they can be replaced with what?

Substrates that only have a short distance to diffuse

Endosymbiosis Theory

The ancestors of modern eukaryotes ingested bacteria. bit ousted of destroying them, established a mutual beneficial relationship with them. This led to chloroplasts and mitochondria (explains structure and DNA)

Define cytoskeleton:

The cytoskeleton gives the cell shape and aids cell movement and transport of materials within the cell; also helps in anchoring organelles

How do you recycle material in the lysosome through bulk phase endocytosis?

Tiny vesicles are used elsewhere in the cell and are likely involved in recycling lipids deposited on the plasma membrane during exocytosis

Microtubule organizing centers

Where all microtubules originate from -Called a centrosome in animals, and contains two bundles of microtubules called centrioles -Microtubules that radiate from the organizing center stiffen the cell by resisting compression forces

Lumen

Where newly manufactured proteins undergo folding and other types of processing

Myosin

a motor protein -head bends when myosin binds and hydrolyzes to ATP -when head attaches to actin and moves, the actin filament slides -After repeated rounds of the contraction cycle, the myosin progressively moves towards plus end of filament

Differential centrifugation

allowed researchers to isolate particular cell components and analyze their chemical composition. (based on breaking cells apart to create a complex mixture and separating components in a centrifuge)

Autophagy

bringing materials from inside the cell (lysosomes)

Phagocytosis

bringing materials from outside the cell in (lysosomes)

Groups of enzymes that work together....

can be clustered with or on the the membranes of organelles

Receptor mediated cytosis

cells brings in one type of material at a time

Plasmids

contain genes but are physically independent of the cellular chromosomes (these genes help cell adapt to unusual circumstances and aren't required)

Stroma

contains enzymes that use chemical energy made by thylakoids to produce sugars

Most bacteria have a _____.

cytoskeleton

Large volume inside a eukaryotic cell is compartmentalized into many small bins =

cytosol is only a fraction of the total cell volume. This allows incompatible chemical reactions to be separated in order for them to take place, and allows chemical reactions to become more efficient.

Cytoplasmic Streaming

directed flow of cytosol and organelles without plant cells -actin-myosin interactions move cytoplasm around the cell

Proteins have different primary structures, but fold up and are structurally similar to filaments found in _______ ___.

eukaryotic cells

"pulse" of PC Experiment

exposes experimental cells to a high concentration of a modified amino acid for a short time

Importin-

has a shape complementary to the NLS and then it binds to the nuclear pore and complex is delivered into the nucleus

Cytosol

fluid between the plasma membrane and the organelles in eukaryotic cells

Rib0somes

function as protein-manufacturing centers (have both large and small subunit and contain both RNA and protein molecules)

Substrates required for a particular reactions can be localized and maintained at ___ concentrations within organelles

high

Extensive surface area provided by internal membranes allow more photosynthetic reactions to occur =

increases cell's ability to make food

Thylakoids

interior of the chloroplast that is made of membrane-bound, flattened, sac-like structures. Have stacks called grans: many pigments, enzymes, and macromolecular machines responsible for photosynthesis are embedded in the thylakoid membrane.

Flagella

long projections that move cells -In eukaryotes flagella are made of microtubules and wave back and forth to propel cells through a fluid environment

NLS folds up in a unique shape which identifies that it needs to go to the....?

nucleus

Cell Crawling

occurs when groups of actin filaments grow, creating bulges in the plasma membrane that extend and move the cell

To get to the right location, each ____ has to have an address tag and a transport and delivery system?

protein

Cilia

short microtubule-based structures that wave fluid over the surface of cells -basically shorter version of flagella that beat to move -anchored in the cell and beat to have fluid flow over them -Non-motile cilia may help send or receive signals

Overall ___, _____, and ______ of a cell correlate with its function

size, shape, and composition

Bulk phase endocytosis

small fluid-filled vesicles brought into a cell

Mitochondrial Matrix

solution enclosed within the inner membrane of the mitochondria

Nuclear envelope

studded with pore-like openings and the inside surface is linked to fibrous proteins that form the nuclear lamina (stiffens the structure and maintains its shape)

"chase" of PC Experiment

the pulse ends by washing away the modified amino acid and replacing it with the normal version of the same molecule