BIO1011 Lecture Notes - Lecture 7: Endoplasmic Reticulum, Nuclear Pore, Nuclear Membrane

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11 May 2018

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Bio1011

Eukaryotic Cells

Details of the Eukaryotic Cell

Nucleus !

•The nucleus is generally the most prominent organelle in eukaryotic cells.

•It is surrounded by a double membrane known as the nuclear envelope and

communicates with the cytosol via nuclear pores.

Endoplasmic Reticulum

•The outer nuclear membrane is continuous with the membrane of the endoplasmic

reticulum.

•The ER is the major site of synthesis of new membranes in the cell.

•The rough ER has ribosomes

•The smooth ER lacks ribosomes.

Golgi Apparatus

•The Golgi apparatus, which is usually situated near the nucleus, receives proteins and

lipids from the ER, modiﬁes them and then dispatches them to other destinations in the

cell.

Lysosomes

•Small sacs of digestive enzymes called lyosomes digest worn out organelles, as well as

macromolecules and particles taken into the cell by endocytosis.

•On their way to lysosomes, endocytosed materials must ﬁrst pass through a series of

compartments called endosomes, which sort the ingested molecules and recycle some

of them back to the plasma membrane.

Peroxisomes

•Peroxisomes (also called microbodies) are small organelles that contain enzymes used

in a variety of oxidative reactions that brea down lipids and destroy toxic molecules.

•Bound by a single membrane, several hundred in each cell

•Bud off from ER not Golgi

•Contain enzymes that produce H2O2 (hydrogen peroxide) as a by-product

•Some peroxisomes use oxygen to break down fatty acids to be used as fuel

•Also involved in detoxiﬁcation and therefor are found in liver cells

•Peroxisomes are NOT part of the endomembrane system

Cytoskeleton

•Cytoskeletal ﬁlaments provide tracks for moving the organelles around and for directing

the trafﬁc of vesicles between one organelle and another.

•Microﬁlaments:

-has the smallest diameter

-is a polymer of actin

-maintains and changes cell shape

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Document Summary

Eukaryotic cells: the nucleus is generally the most prominent organelle in eukaryotic cells, it is surrounded by a double membrane known as the nuclear envelope and communicates with the cytosol via nuclear pores. Golgi apparatus: the golgi apparatus, which is usually situated near the nucleus, receives proteins and lipids from the er, modi es them and then dispatches them to other destinations in the cell. Cytoskeleton: cytoskeletal laments provide tracks for moving the organelles around and for directing the traf c of vesicles between one organelle and another, micro laments: Muscle contractions - myosin is the motor protein that pulls on the actin. Tubulin is highly dynamic - it can be rapidly assembled at one end whilst being disassembled at the other. The main structure of cilia and agella. States that chloroplasts and mitochondria derive from ancestral prokaryotes that became symbiont via symbiosis. They both clearly have prokaryotic dna, which means that they were absorbed into a cell.

Related Questions

One effective learning strategy when trying to learn largeamounts of factual information is to group items, or âchunkâ. Youshould include all important structures of the cell (this includescell membrane and membrane adaptations as well as organelles).Examples of general categories could be location, function,morphology, etc. Your categorization groups must tell the viewersomething about the structures. Once your structures are groupedaccording to the characteristics they share, you should include ashort phrase about what differentiates them from each other withinthe group. Citation of your source material must be present.

List of Organelles:

Nucleus, Nuclear envelope/membrane, Nucleolus, Ribosomes,Endoplasmic reticulum, Golgi apparatus, Mitochondria, Plasmamembrane, Cytoskeleton, Transport/secretory vesicles,Phagosomes/endosomes-including sorting & recycling endosomes,Lysosomes, Peroxisomes, Lipid droplets, Glycogen granules

I started this assignment and was going to go withfunction and morphology. Below is what I have so far, but I'mhaving a difficult time coming up with a short phrase for each anddistinguishing between the organelles that can change shape/morphand those that cannot. I am open to changing the categories that Ihave chosen to chunk. I've never used this technique before so it'sa new concept for me.

Function

Protein Synthesis â Nucleus, Nuclear envelope, Nuclear porecomplex, Ribosomes, Rough endoplasmic reticulum, Golgi apparatus,Plasma membrane

Energy Production â Mitochondria, Lipid droplets, Glycogengranules

Transportation â Transport vesicles, Phagosomes,Cytoskeleton

Metabolism â Lysosomes aid in digestion, Peroxisomes oxidizefatty acids

Morphology

Ability to change shape â Mitochondria, Cell membrane, Nuclearenvelope,

Inability to change shape â Nucleus, Nuclear envelope,

erinporpoise390

QUESTION 30

The function of centrosome is:

	1.	Microtubule initiation and organization in animal cells
	2.	Organization of thin filaments
	3.	Depolymerization of microtubules
	4.	Organization of intermediate filaments

2.5 points

QUESTION 31

The destinations of proteins synthesized on "free" ribomsomes include:

	1.	Endoplasmic reticulum
	2.	Nucleus
	3.	Mitochondria
	4.	Lysosomes

2.5 points

QUESTION 32

Microtubules can be assembled and disassembled quickly in response to the cellular changes is because:

	1.	Cells synthesize tubulin proteins very fast.
	2.	Cells can turn other cytoskeletal filaments into microtubules
	3.	Microtubules have an instable plus end and microtubules are probably organized by weak non-covalent interactions
	4.	The motor proteins of microtubules can organize the microtubules in response to the cellular changes

2.5 points

QUESTION 33

Both signal recognition particle and a translocon in rough endoplasmic reticulum membrane can recognize and bind to the signal sequence of a secretory protein, so they play the exact same role during protein co-translational translocation.

True

False

2.5 points

QUESTION 34

Rough endoplasmic reticulum is so named is because:

	1.	It has many proteins associated with its surface.
	2.	It has ribosomes associated with its cytosolic surface.
	3.	It is associated with nuclear membrane.
	4.	It has vesicles budding off its surface.

2.5 points

QUESTION 35

The membrane vesicles that transport materials between membrane compartments have a protein coat. The protein coat has similar functions in different vesicles. These functions include:

	1.	Help the enclosed material fold correctly.
	2.	Help degrade the protein in the vesicles
	3.	Maintain the internal pH of the vesicles
	4.	Function as mechanical device to form a vesicle and select the components to be carried by a vesicle.

2.5 points

QUESTION 36

Lysosomes are important for:

	1.	Receptor-mediated endocytosis.
	2.	Breaking down foreign particles brought into the cells by endosomes
	3.	Regulating the process of organelle turnover.
	4.	Protein trafficking between membrane compartments

2.5 points

QUESTION 37

Which of the following is correct about membrane biosynthesis?

	1.	Membranes are synthesized in Golgi Complex.
	2.	Membranes arise from preexisting endoplasmic reticulum membranes.
	3.	Membranes are synthesized on ribosomes.
	4.	Membranes of all organelles have the same composition of proteins and lipids, since they all originate from endoplasmic reticulum.

2.5 points

QUESTION 38

During skeletal muscle contractions, the shortening of the muscle fibers is because of:

		The shortening of the thin and thick myofilaments.
		The shortening of the cytoskeletal filaments.
		The kinesin proteins moving over microtubules.
		The actin and myosin filaments sliding over each other.

2.5 points

QUESTION 39

The assembly and disassembly of microtubules is regulated by rate of growth and shrinkage of the plus end.

True

False

2.5 points

QUESTION 40

The functions of Golgi complex include:

	1.	O-linked oligosaccharides and most of a cellâs complex polysaccharides are assembled in Golgi complex
	2.	Cis Golgi complex sorts proteins
	3.	Trans Golgi complex segregates proteins in different types of vesicles for dilevery.
	4.	N-linked oligosaccharides are further processed in Golgi complex

ochrecoyote721

The vesicles that transport materials from donor membranes to acceptor membranes include:

	1.	COP-II coated vesicles
	2.	COP-III coated vesicles
	3.	COP-I coated vesicles
	4.	Clathrin coated vesicles

2.5 points

QUESTION 11

During skeletal muscle contraction, the roles of ATP include:

	1.	ATP is not required for forming the crossbridges between myosin and actin filaments.
	2.	ATP is utilized as a structural linker to mediate the interaction between myosin and actin filaments
	3.	Hydrolysis of ATP provides energy for myosin head to move along actin filaments and the binding of ATP to myosin head allows the detachment of myosin fromactin filaments.
	4.	ATP binds to actin filaments to drive the power stroke of myosin head.

2.5 points

QUESTION 12

One of the functions of smooth endoplasmic reticulum is

	1.	Synthesizing steroid hormone in the endocrine cells of the gonad and adrenal cortex
	2.	Serves as the starting point of the biosynthetic pathway
	3.	Synthesizing secretory proteins
	4.	Degrading cell debris

2.5 points

QUESTION 13

The function of COP-II coated vesicles is mainly:

	1.	Transporting materials from endosomes to Golgi complex
	2.	Moving materials from the ER to the ERGIC and Golgi complex.
	3.	Transporting materials from Golgi complex back to endoplasmic reticulum.
	4.	Involved in receptor-mediated endocytosis.

2.5 points

QUESTION 14

Which of the following processes is completed in rough endoplasmic reticulum?

	1.	Chaperones help misfolded proteins fold correctly.
	2.	Proteins that target to nucleus are synthesized in rough endoplasmic reticulum.
	3.	O-linked glycosylation occurs in rough endoplasmic reticulum.
	4.	Misfolded proteins are destructed in rough endoplamic reticulum.

2.5 points

QUESTION 15

Kinesin is the motor protein that coorporates with microtubules. It has the following functions:

	1.	It uses GTP as energy source.
	2.	It can hydrolyze ATP and use the energy to drive cargo along microtubules from minus end to plus end.
	3.	It has a globular head that can act as GTPase
	4.	The tail of kinesin is more diverse and binds to cargo

2.5 points

QUESTION 16

For correct segregation and trafficking, lysosomal proteins are tagged in the cis-Golgi with phosphorylated mannose residues, and then the tagged lysosomal enzymes are recruited to clathrin coated vesicles by mannose 6-phosphate receptors.

True

False

2.5 points

QUESTION 17

The process that specialized cells, such macrophages, engulf relatively large particles is:

	1.	Called pinocytosis
	2.	Called phagocytosis
	3.	Mediated by COP-II coated vesicles
	4.	Called autophagy

2.5 points

QUESTION 18

Proteins synthesized on rough endoplasmic reticulum and smooth endoplasmic reticulum are imported co-translationally to their destinations

True

False

2.5 points

QUESTION 19

Treatment of cells with a drug that promotes microtubule disassembly disperses Golgi complex into separate stacks of membrane compartments, suggesting that:

	1.	Golgi complex is made of microtubules.
	2.	Microtubules are important for the organization of Golgi complex.
	3.	Microtubules are transported into Golgi complex
	4.	Golgi complex is composed of tubulin proteins

2.5 points

QUESTION 20

Which of the following is correct about signal sequence of a secretory protein?

	1.	It is an âaddress codesâ for protein trafficking pathways
	2.	It is usually located at the C-terminus.
	3.	It targets the ribosome and the protein that is being synthesized to endoplasmic reticulum.
	4.	It is removed in Golgi complex.

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BIO1011 Lecture Notes - Lecture 7: Endoplasmic Reticulum, Nuclear Pore, Nuclear Membrane

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