The various parts of the endomembrane system serve different functions in the cell. In this activity, you will identify the roles of each part of the endomembrane system.
A.) Smooth ER
B.) Rough ER
C.) Golgi Apparatus
D.) Lysosomes
1. protein synthesis
2.
A.) Smooth ER: lipid synthesis, calcium storage, poison detoxification
B.) Rough ER: protein synthesis
C.) Golgi apparatus: protein modification, sorting, cisternal maturation
D) Lysosomes: macromolecule digestion, autophagy
Endoplasmic Reticulum
The endomembrane system is critical for the synthesis, processing, and movement of proteins and lipids in the cell.
Smooth ER
lipid synthesis and processing
Rough ER
site of secretory protein synthesis
All proteins are synthesized by ribosomes in the cell. Some ribosomes float freely in the cytosol, while others are bound to the surface of the endoplasmic reticulum. Most proteins made by free ribosomes function in the cytosol. Proteins made by bound rib
Most proteins that function in the cytosol (such as actin) or in the nucleus (such as DNA polymerase) are synthesized by free ribosomes.
Proteins that function within the endomembrane system (such as lysosomal enzymes) or those that are destined for secre
What is the path a secretory protein follows from synthesis to secretion?
As they are being synthesized, secretory proteins enter the lumen of the endoplasmic reticulum. From the ER, vesicles transport these proteins to the Golgi, where they are sequentially modified and concentrated in a cis-to-trans direction. Secretory vesic
Pulse-chase Experiment
The pulse-chase experiment is similar to fitting newly synthesized proteins with identification collars, much as one would do in the field to track animals. By using a chase, this cohort of newly synthesized proteins can be tracked as they move to differe
phatocytosis
Some cells ingest smaller particles
Pulse-chase experiments and protein location
Scientists can track the movement of proteins through the endomembrane system using an approach known as a pulse-chase experiment. This experiment involves
the "pulse" phase: Cells are exposed to a high concent
The cells in this experiment were macrophages. These immune system cells have many lysosomes for the destruction of bacteria and other invaders brought into the cell via phagocytosis.
The enzymes (hydrolases) that carry out this catabolic activity are syn
Part A - Animal cell structures and functions
To understand how cells function as the fundamental unit of life, you must first become familiar with the individual roles of the cellular structures and organelles.
Drag the labels on the left onto the diagra
a. synthesizes lipids
b. assembles ribosomes
c. defines cell shape
d. produces secretory proteins
e. modifies and sorts proteins
f. digests proteins
g. generates ATP
The eukaryotic cell has well-defined structures that serve discrete functional roles. An
Part B - Comparing eukaryotic and prokaryotic cells
Two fundamental types of cells are known to exist in nature: prokaryotic cells and eukaryotic cells (like the one shown in the Tour of an Animal Cell animation). Both prokaryotic and eukaryotic cells car
Prokaryotic only: nucleoid
Eukaryotic only: Lysosome, Mitochondria, Nucleolus
Both: Ribosomes, Plasma membrane, Flagella
Only bacteria and archaea have prokaryotic cells, which lack a nucleus and other membrane-enclosed organelles. Prokaryotic cells are s
1. In eukaryotic flagella, the fibers that slide past one another due to the activity of dynein proteins are __________ .
microtubules
Many cell organelles, most notably the nucleus, are anchored by ___________ which are assembled from a diverse class of proteins.
intermediate filaments
Centrosomes are sites where protein dimers assemble into __________
microtubules
The extension of pseudopodia in amoeba is due to the regulated assembly and destruction of ______________.
microfilaments
The only cytoskeletal fibers not associated with intracellular movement or whole cell locomotion are the ______________ .
intermediate filaments
During muscle contractions, myosin motor proteins move across tracks of ______________
microfilaments
Plant cell structures
Cellulose cell wall, Chloroplast, Central vacuole
Animal Cell Structures
Centriole
Plant and Animal Cell Structures
Nucleus, Plasma membrane, Mitochondrion, Cytoskeleton, Endoplasmic reticulum, Golgi apparatus
Which statements are true for chloroplasts? Select the three that apply.
They are the sites of reactions that convert solar energy into chemical energy.
Their inner membrane has infoldings called cristae.
Their matrix contains enzymes that function in cel
They are the sites of reactions that convert solar energy into chemical energy.
They contain the green pigment chlorophyll.
They have membranous sacs called thylakoids that are surrounded by a fluid called stroma.
Which organelle plays a role in intracellular digestion?
lysomsome
The cilia and flagella of eukaryotic cells are composed of _____.
microfilaments
demosomes
membrane protein complexes that strengthen adhesion between cells like rivets to protect against
plasmodesmatas
Small channels between cells that are otherwise surrounded by walls; enable movement of water and solutes between plant cells
tight junctions
Membrane proteins that create a watertight seal between animal cells to connect them and to keep fluid from crossing barriers
gap junctions
Small channels that form across the plasma membranes of adjacent animal cells; especially important in intercellular communication; help coordinate activities of adjacent cells
cellulose
A polysaccharide that is used to synthesize plant cell walls, which protect cells and help maintain their shape
collagen
Long fibers of protein found in the extracellular matrix that provide structural support for animal cells
1 meter = _____ centimeters.
100
What cell junctions form a barrier to the passage of materials?
tight junctions
The primary role of _____ is to bind animal cells together.
desmosomes
_____ aid in the coordination of the activities of adjacent animal cells.
Gap (communicating) junctions
Pancreatic cells, which secrete a large amount of digestive enzymes, are labeled with radioactive leucine and then chased for several hours with nonradioactive leucine. Photographic emulsions are prepared at different times during the chase. Where would t
exterior of cell
What path does a protein in the secretory pathway take, starting from its site of synthesis?
Rough ER, Golgi apparatus, secretory vesicles, plasma membrane
During a pulse-chase experiment, photographic emulsions were prepared at different times during the chase, and radioactive spots were detected at the following times and locations: 5 minutes: rough ER; 10 minutes: Golgi apparatus; 40 minutes: endosomes; 7
The final destination of the proteins was the lysosome.
What scientific hypotheses can be tested by a pulse-chase experiment?
Movement of molecules through a cell over time
True or false? Proteins produced during the "chase" phase of a pulse-chase experiment are labeled with radioactive material
False, during the chase phase, cells are provided with a large amount of nonradioactive material, so they are not labeled.
What is the first step in a pulse-chase experiment?
Incubating cells with a labeled molecule
Which molecules do not normally cross the nuclear membrane?
DNA
Which of the following statements about the nuclear envelope is false?
1.) Nuclear pores are made up of a group of proteins that are collectively called the nuclear pore complex.
2.) The nuclear envelope is continuous with the Golgi apparatus.
3.) The nuc
The nuclear envelope is continuous with the Golgi apparatus.
True or false? Large proteins containing a nuclear localization signal (NLS) bind to the nuclear pore and enter the nucleus without any expenditure of energy
False, cytoplasmic proteins called importins bind to large proteins containing an NLS and mediate their transport across the nuclear membrane through an active transport (energy-requiring) process.
A small protein (molecular weight = 25,000 daltons) is injected into a cell and observed in the nucleus a short time later. What type of transport has taken place?
Passive transport, a 25,000-dalton protein is small enough to diffuse through nuclear pores without any expenditure of energy.
In experiments to test whether a protein can enter the nucleus, why would proteins be labeled with fluorescent molecules?
To make the proteins easy to see
Nucleoplasmin is a nuclear protein. This protein was divided into two segments and linked to the same large cytoplasmic protein, generating two fusion proteins. After injecting these fusion proteins into a cell, one of the proteins was found in the nucleu
Only one of the two fusion proteins possesses a nuclear localization signal
Both the volume and the surface area for three different cells were measured. These values are listed in the following table:
Volume Surface Area
Cell 1 9.3 ?m3 26.5 ?m2
Cell 2 12.2 ?m3 37.1 ?m2
Cell 3 17.6 ?m3 40.6 ?m2
Using data from the table above, se
Cell 2 since it has the highest surface area-to-volume ratio which facilitates the exchange of materials between a cell and its environment.
A biologist wants specifically to examine the surfaces of different types of cells in kidney tubules of small mammals. The cells in question can be distinguished by external shape, size, and 3-D characteristics. Which of the following would be the optimum
scanning electron microscopy
A biologist ground up some plant leaf cells and then centrifuged the mixture to fractionate the organelles. Organelles in one of the heavier fractions could produce ATP in the light, whereas organelles in the lighter fraction could produce ATP in the dark
chloroplasts and mitochondria
Gaucher disease is the most common of lipid storage diseases in humans. It is caused by a deficiency of an enzyme necessary for lipid metabolism. This leads to a collection of fatty material in organs of the body including the spleen, liver, kidneys, lung
The lysosomes lack sufficient amounts of enzymes necessary for the metabolism of lipids.
A newspaper ad for a local toy store indicates that a very inexpensive microscope available for a small child is able to magnify specimens nearly as much as the much more costly microscope available in your college lab. What is the primary reason for the
The toy microscope magnifies a good deal, but has low resolution and therefore poor-quality images.
Athletes can apply for an exception to use a banned substance if it is used for medical purposes. Which of the following athletes is most likely to be allowed to use meldonium if she or he is using it for its original intended purpose?
1.) An Olympic spee
A professional runner using it for a heart condition.
It is believed that meldonium works on which of the following?
mitochondria
In which of the following countries would it likely be easiest to obtain meldonium?
Russia
Why would a professional athlete be interested in using meldonium?
enhance endurance
The NBA decides to look into the use of meldonium in the league following the same protocol as the WADA. Which of the following will be randomly tested?
urine
Which of the following choices correctly matches a tool and its proper application?
1.) cell fractionation to study the function of specific organelles
2.) transmission electron microscopy (TEM) to study the surfaces of preserved cells
3.) light microscop
cell fractionation to study the function of specific organelles
Which of the following clues would tell you if a cell is prokaryotic or eukaryotic?
1.) The presence or absence of a rigid cell wall.
2.) The presence or absence of ribosomes.
3.) Whether or not the cell contains DNA.
4.) Whether or not the cell carries o
whether or not the cell is partitioned by internal membranes
Which of the following correctly matches an organelle with its function?
1.) ribosome-manufacture of lipids
2.) central vacuole-storage
3.) mitochondrion-photosynthesis
4.) nucleus-cellular respiration
5.) lysosome-movement
central vacuole-storage
_____ are surface appendages that allow a bacterium to stick to a surface
Fimbriae
What is the function of a bacterium's capsule?
protection
Where is a bacterial cell's DNA found?
nucleoid region
In a bacterium, where are proteins synthesized?
ribosomes
What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?
cell wall
The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell.
plasma membrane
Which statement correctly describes the nuclear envelope of a eukaryotic cell?
1.) The nuclear envelope is a single membrane, consisting of a phospholipid bilayer.
2.) Plasmadesmosomes in the nuclear envelope permit the exchange of macromolecules between
The nuclear envelope is continuous with the endoplasmic reticulum.
A cell has formed a food vacuole as it ingested a food particle. Which of the following events is associated with the breakdown of that food particle?
Digestion of the food particle occurs in a vesicle enclosed by a membrane that separates the digestion from the cytoplasm.
Which of the following are common traits of chloroplasts and mitochondria?
A. Both are found in plant and animal cells.
B. Both are surrounded by a single membrane.
C. Both have their own DNA.
D. Both reproduce by meiosis.
E. Proteins for both are
synthes
C. Both have their own DNA.
Mitochondria and chloroplasts contain their own DNA and ribosomes.
Mitochondria are found in _____.
plant and animal cells
Which of the following functions is NOT associated with the cytoskeleton in eukaryotic cells?
A. the contraction of muscle cells in animals
B. maintaining the position of the nucleus in the cell
C. the beating of cilia or flagella
determining the shape of
Movement of RNA molecules from the nucleus to the cytoplasm, RNA molecules exit the nucleus via nuclear pores.
Where is most of cell's DNA?
nucleus
mitochondrion
an organelle in EUKARYOTIC CELLS where CELLULAR RESPIRATION occurs. Enclosed by two membranes, it is where most of the cell's ATP is made
Chromosomes/chromatin
Composed of DNA and proteins; found in the nucleus; tightly packed during cell division and dispersed during normal cell operations
Ribosomal subunits are manufactured by the _____.
nucleoulus
ribosomes
site for protein synthesis
Which of these manufactures cellular membranes by adding membrane proteins and phospholipids to its own membrane?
A. lysosomes
B. ribosomes
C. nucleolus
D. Golgi apparatus
E. rough endoplasmic reticulum
rough ER
Where is calcium stored?
smooth ER
Which of these are hollow rods that shape and support the cell?
A) plasma membrane
B) microtubules
C) chloroplasts
D) microfilaments
E) peroxisomes
microtubules
_____ is/are identical in structure to centrioles.
1) Mitochondria
2) Nuclear envelopes
3) Chromatin
4) Microfilaments
5) Basal bodies
5
Which of these organelles produces H2O2 as a by-product?
1) mitochondrion
2) nucleus
3) centrioles
4) flagellum
5) peroxisome
5
Which statement about extracellular structures (plant cell walls and the extracellular matrix of animal cells) is correct
A. Extracellular structures store energy in the form of polysaccharides for subsequent metabolism by the cell.
B. Proteins and lipids
Information can be transmitted from these extracellular structures to the cytoplasm.
The diameter of a typical eukaryotic cell is approximately ten times the diameter of a typical prokaryote. What is the ratio of the volume of typical eukaryotic:prokaryotic cells?
1000:1
Which statement correctly describes an endomembrane function?
A. Products of the ER are usually modified during their transit from the CIS to the TRANS region of the Golgi Apparatus.
B. The lumen of the endoplasmic reticulum (ER) is continuous with the ce
A
Select the correct statement describing the cellular structure or function:
A. Plant and animal cells both carry out cellular respiration, producing ATP.
B. Only plant cells contain chloroplasts, and only animal cells contain mitochondria.
C. Mitochondria
A
Choose the best description of the cell cytoskeleton.
A. The cell cytoskeleton is a dynamic network of fibers that can be quickly dismantled and reassembled to change cell shape and the position of cell components.
B. The cell cytoskeleton serves as perma
The cell cytoskeleton is a dynamic network of fibers that can be quickly dismantled and reassembled to change cell shape and the position of cell components.
Identify the correct statement about differences between rough and smooth endoplasmic reticulum (ER).
A. Rough ER consists of a network of membranous tubules and sacs called cisternae, whereas smooth ER is less complex.
B. The outer surface of smooth ER l
B