Chapter 7 Inside the Cell Flashcards
1
Q
Differential centrifugation
A
Procedure for separating cellular components according to their size and density by spinning a cell homogenate in a series of centrifuge runs. After each run, the supernatant is removed from the deposited material (pellet) and spun again at progressively higher speeds.
2
Q
Why is differential centrifugation important?
A
Because it allowed researchers to isolate particular cell components and analyze their chemical composition
3
Q
What is the difference between Differential centrifugation and electron microscopy?
A
Differential centrifugation splits cells into parts that are analyzed independently and electron microscopy gives a fixed “snapshot” of the cell or organism being observed.
4
Q
These gate-like structures extend through both inner and outer nuclear membranes, they connect the inside of the nucleus with the cytosol
A
Nuclear Pore
5
Q
true or false
Passage though the nuclear pore is selective
A
true
6
Q
Most ribosomal RNAs are manufactured in the ______________ where they bind to proteins to form _________________, which are exported to the ______________.
A
nucleolus;ribosomes;cytoplasm
7
Q
Explain the inbound and outbound traffic of the nuclear envelope.
A
messenger RNAs carry information required to manufacture protein out to the cytoplasm. Nucleoside triphosphates that act as building blocks for DNA & RNA enter the nucleus
8
Q
Nuclear pore
A
An opening in the nuclear envelope that connects the inside of the nucleus with the cytoplasm and through which molecules such as mRNA and some proteins can pass.
9
Q
A large complex of dozens of proteins lining a nuclear pore, defining its shape and transporting substances through the pore.
A
Nuclear Pore Complex
10
Q
Virus
A
A tiny intracellular parasite that uses host cell enzymes to replicate; consists of a DNA or RNA genome enclosed within a protein shell (capsid). In enveloped viruses, the capsid is surrounded by a phospholipid bilayer derived from the host cell plasma membrane, whereas nonenveloped viruses lack this protective covering.
11
Q
Nuclear localization signal (NLS)
A
A short amino acid sequence that marks a protein for delivery to the nucleus.
12
Q
Name 3 cytoskeleton elements
A
1) Actin Filaments
2) Intermediate Filaments
3) Microtubules
13
Q
In animal cells, _________________ is often the most abundant of all proteins.
A
actin
14
Q
How does actin filament form?
A
when individual actin molecules polymerize
15
Q
What is treadmilling?
A
the addition and deletion of actin subunits
16
Q
Why does actin filaments tend to grow at the plus end?
A
because polymerization occurs fastest there
17
Q
What is myosin?
A
a motor protein
18
Q
What is the structure of actin filaments?
A
strands in a double helix with a + and - end
19
Q
What are the subunits of actin filaments?
A
Actin
20
Q
What are the functions of actin filaments?
A
1) maintain cell shape by resisting tension (pull)
2) move cells via muscle contraction or cell crawling
3) divide animal cells in two
4) move organelles and cytoplasm in plants, fungi, and animals
21
Q
What happens when the “head” region of myosin protein interacts with ATP?
A
Myosin attaches to actin and it changes shape. The movement cause the actin filaments to slide.
22
Q
___________ serve purely as a structural role in eukaryotic cells.
A
intermediate filaments
23
Q
Tubulin dimers polymerize to form the large, hollow tube called a ___________.
A
microtubules
24
Q
What is the structure of intermediate filaments?
A
Fibers wound into thick cables
25
What are the subunits of intermediate filaments?
keratin or vimentin or lamin
26
What are the functions of intermediate filaments?
1) maintain cell shape by resisting tension (pull)
| 2) anchor nucleus and some other organelles
27
What is the structure of microtubules?
a hollow tube
28
What are the subunits of microtubules?
a- and b- tubulin dimers
29
What are the functions of microtubules?
1) maintain cell shape by resisting compression (push)
2) move cells via flagella or cilia
3) move chromosomes during cell division
4) assist formation of cell plate during plant cell division
5) move organelles
6) provide tracks for intracellular transport
30
Actin Filament
A long fiber, about 7 nm in diameter, composed of two intertwined strands of polymerized actin protein; one of the three types of cytoskeletal fibers. Involved in cell movement. Also called a microfilament. Compare with intermediate filament and microtubule.
30
Name a class of proteins whose major function is to convert the chemical energy of ATP into motion. Includes dynein, kinesin, and myosin.
Motor protein
31
What is the division of the cytoplasm to form two daughter cells. Typically occurs immediately after division of the nucleus by mitosis or meiosis.
Cytokinesis
32
Cytoplasmic Streaming
The directed flow of cytosol and organelles that facilitates distribution of materials within some large plant and fungal cells. Occurs along actin filaments and is powered by myosin.
33
Cell Crawling
A form of cellular movement involving actin filaments in which the cell produces bulges (pseudopodia) that stick to the substrate and pull the cell forward. Also called amoeboid motion.
34
Intermediate Filaments
A long fiber, about 10 nm in diameter, composed of one of various proteins (e.g., keratins, lamins); one of the three types of cytoskeletal fibers. Form networks that help maintain cell shape and hold the nucleus in place. Compare with actin filament and microtubule.
35
Microtubules
A long, tubular fiber, about 25 nm in diameter, formed by polymerization of tubulin protein dimers; one of the three types of cytoskeletal fibers. Involved in cell movement and transport of materials within the cell. Compare with actin filament and intermediate filament.
36
Centrosome
Structure in animal and fungal cells, containing two centrioles, that serves as a microtubule-organizing center for the cell’s cytoskeleton and for the spindle apparatus during cell division.
37
Centrioles
One of two small cylindrical structures, structurally similar to a basal body, found together within the centrosome near the nucleus of a eukaryotic cell.
38
A _______________ is like a delivery truck that carries transport vesicles along microtubule tracks.
kinesin molecule
39
Any one of a class of motor proteins that use the chemical energy of ATP to transport vesicles, particles, or chromosomes along microtubules.
Kinesin
40
Bacterial flagella are mad of a protein called _______________; eukaryotic flagella mare constructed from _________________.
flagellin;microtubules(tubulin)
41
Bacterial flagella move the cell by ___________ and eukaryotic move the cell by________________.
rotating like a ships propeller; undulating (they whip back and forth)
42
Bacterial flagella are mad of a protein called _______________; eukaryotic flagella mare constructed from _________________.
flagellin;microtubules(tubulin)
43
Bacterial flagella move the cell by ___________ and eukaryotic move the cell by________________.
rotating like a ships propeller; undulating (they whip back and forth)
44
____________ re surrounded by a plasma membrane and are considered an organelle and ________________ are not.
eukaryotic flagella; bacterial flagella
45
Bacterial flagella are mad of a protein called _______________; eukaryotic flagella mare constructed from _________________.
flagellin;microtubules(tubulin)
46
Bacterial flagella move the cell by ___________ and eukaryotic move the cell by________________.
rotating like a ships propeller; undulating (they whip back and forth)
47
____________ re surrounded by a plasma membrane and are considered an organelle and ________________ are not.
eukaryotic flagella; bacterial flagella
48
Where is a bacterial cell's DNA found?
Bacteria lack a nucleus; their DNA is found in the nucleoid region.
49
What is the function of a bacterium's capsule?
A bacterium's capsule has a protective role.
50
_____ are surface appendages that allow a bacterium to stick to a surface.
Pili enable bacterial cells to stick to a surface
51
In a bacterium, where are proteins synthesized?
Ribosomes are involved in the manufacture of polypeptides (proteins).
52
What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?
The cell wall is a rigid supporting structure.
53
The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell.
The plasma membrane is selectively permeable.
54
In animal cells, name the organelle that carries out cellular respiration, the process of converting the chemical energy of sugars and other molecules to chemical energy in the form of ATP.
mitochondrion
55
In animal cells name the appendage that propels the cell
flagella
56
In animal cells, Which large organelle contains most of the genes that control the cell?
nucleus
57
In animal cells, What is the double membrane that encloses the nucleus?
nuclear envelope
58
In animal cells, what is the name given to the strands containing DNA (genes) along with associated protein?
chromatin
59
In animal cells, where are ribosomal subunits made?
nucleolus
60
In animal cells, what small structures serve as the sites of protein synthesis?
ribosomes
61
In animal cells, can you identify the membranous tubules and sacs where secretory proteins and membranes are manufactured?
rough ER
62
In animal cells, what acts as a selective barrier, allowing passage of oxygen, nutrients, and wastes?
plasma membrane
63
In animal cells, can you identify the portion of the endomembrane system important in lipid synthesis, detoxification, and calcium storage?
smooth ER
64
In animal cells, which organelle modifies, stores, and repackages products of the ER, mostly for secretion?
golgi apparatus
65
In animal cells, where would you find a stockpile of digestive enzymes, important in breaking down nutrients, destroying bacteria, recycling, and development?
lysosomes
66
In animals, what are the rods that shape and support the cell, and serve as tracks along which other organelles can move?
microtubules
67
In animals, which cell components are identical in structure to basal bodies?
centrioles
68
In animals, which organelle carries out diverse metabolic processes and produces hydrogen peroxide (H2O2) as a by-product, which it converts to water (H2O)?
peroxisom
69
In animal cells, What are thin, solid protein rods, especially numerous in muscle cells, involved in cell support and movement?
microfilaments
70
Which organelle carries out cellular respiration?
Mitochondria convert the chemical energy of organic molecules to chemical energy in the form of ATP.
71
The _____ is composed of DNA and protein.
Chromatin is composed of DNA and protein.
72
Ribosomal subunits are manufactured by the _____.
Ribosomes are manufactured by the nucleolus.
73
_____ are the sites of protein synthesis.
Ribosomes are the site of protein synthesis.
74
This manufactures cellular membranes by adding membrane proteins and phospholipids to its own membrane?
As membrane proteins grow from ribosomes on rough ER, the proteins are embedded into the rough ER membrane.
75
The _____ is a selective barrier, regulating the passage of material into and out of the cell.
The plasma membrane regulates the passage of material into and out of the cell.
76
Where is calcium stored?
In addition to storing calcium, the smooth ER also plays a role in detoxification and lipid synthesis.
77
This structure stores, modifies, and packages products?
The Golgi apparatus modifies, stores, and packages products of the ER
78
These are hollow rods that shape and support the cell?
Microtubules are rods that also play a role in organelle movement.
79
_____ is/are identical in structure to centrioles.
Basal bodies and centrioles have identical structures.
80
This organelle produces H2O2 as a by-product?
Peroxisomes produce hydrogen peroxide as a by-product of their metabolic processes.
81
What provides the cell with structural support?
Microfilaments are a component of the cytoskeleton.
82
_______________ are responsible for cell locomotion and the cell’s structural characteristics.
Microfilaments
83
_______________ serve as intracellular highways for transporting vesicles and organelles; they are also required for cellular locomotion via flagella and cilia.
Microtubules
84
___________________ are rope-like structures that anchor organelles and intercellular junctions called desmosomes. They are specialized for bearing tension.
Intermediate filaments
85
In eukaryotic flagella, the fibers that slide pas one another due to the activity of dynein protein are_____________________.
microtubules
86
Many cell organelles, most notably the nucleus, are anchored by _______________, which are assembled from a diverse class of proteins.
intermediate filaments
87
Centrosomes are sites where protein dimers assemble into _____________.
microtubules
88
The extension of pseudopodia in amoeba is due to the regulated assembly and destruction of ____________.
microfilaments
89
The only cytoskeletal fibers not associated with intracellular movement or whole cell locomotion are ______________.
intermediate filaments
90
During muscle contractions, myosin motor proteins move across tracks of _____________.
microfilamens
91
Which molecules do not normally cross the nuclear membrane?
Which molecules do not normally cross the nuclear membrane?
Nucleotide triphosphates
mRNA
DNA
Proteins
All processes involving DNA take place in the nucleus.
92
Which of the following statements about the nuclear envelope is false?
Which of the following statements about the nuclear envelope is false?
Molecules pass into and out of the nucleus through nuclear pores.
The nuclear envelope is composed of two lipid bilayers.
The nuclear envelope is continuous with the Golgi apparatus.
Nuclear pores are made up of a group of proteins that are collectively called the nuclear pore complex.
This statement is false; the nuclear envelope is continuous with the endoplasmic reticulum.
93
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.
94
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?
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
Active transport
Osmosis
Passive Transport. A 25,000-dalton protein is small enough to diffuse through nuclear pores without any expenditure of energy.
95
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 nucleus and the other in the cytoplasm. Which of the following conclusions can be drawn from these results?
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 nucleus and the other in the cytoplasm. Which of the following conclusions can be drawn from these results?
One of the fusion proteins entered the nucleus by passive transport.
Nucleoplasmin does not have a nuclear localization signal.
Only one of the two fusion proteins possesses a nuclear localization signal.
The cytoplasmic protein contains a nuclear localization signal.
Only one of the two fusion proteins possesses a nuclear localization signal.
.
The nuclear localization signal is only present in the fusion protein that enters the nucleus.
96
_______________ is the movement of materials into a cell via membranous vesicles.
Endocytosis
97
_________________ is the movement of materials out of a cell via membranous vesicles.
Exocytosis is the movement of materials out of a cell via membranous vesicles.
98
```
Endocytosis moves materials _____ a cell via _____.
into ... membranous vesicles
into ... a transport protein
out of ... diffusion
out of ... membranous vesicles
into ... facilitated diffusion
```
into ... membranous vesicles
The prefix "endo-" means "inward."
99
Which process do cells use to engulf large objects such as bacteria or debris?
Phagocyctosis
100
Which process is responsible for the up take of iron in human cells?
receptor- mediated endocytosis
101
Which process allows cells to engulf fluids and move them across the cell?
pincocytosis
"cell drinking"
102
Which process is associated with the secretion of cellular products from glands?
exocytosis
103
Which organelle plays a role in intracellular digestion?
Which organelle plays a role in intracellular digestion?
Golgi apparatus
ribosome
lysosome
chloroplast
plasmodesma
lysosome
The prefix "lyso-" means decomposition.
104
```
Which of the following proteins are synthesized by bound ribosomes?
Select all that apply.
Select all that apply.
DNA polymerase
ribosomal protein
lysosomal enzyme
insulin
actin
ER protein
```
lysosomal enzyme
insulin
ER Protein
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 secretion from the cell (such as insulin) are synthesized by bound ribosomes.
As a protein destined for the endomembrane system is being synthesized by a ribosome, the first amino acids in the growing polypeptide chain act as a signal sequence. That signal sequence ensures that the ribosome binds to the outer membrane of the ER and that the protein enters the ER lumen.
105
Name the functions of the smooth ER
calcium ion storage
lipid synthesis
poison detoxification
106
Name the function(s) of the rough ER
protein synthesis
107
Name the function of the Golgi apparatus
protein modification and sorting
| cisternal maturation
108
Name the functions of the lysosomes
macromolecule digestion
| autophagy
109
Which statements are true for chloroplasts? Select the three that apply.
They are the sites of reactions that convert chemical energy to ATP.
Their inner membrane has infoldings called cristae.
Their matrix contains enzymes that function in cellular respiration.
They contain the green pigment chlorophyll.
They are the sites of reactions that convert solar energy into chemical energy.
They have membranous sacs called thylakoids that are surrounded by a fluid called stroma.
They contain the green pigment chlorophyll.
They are the sites of reactions that convert solar energy into chemical energy.
They have membranous sacs called thylakoids that are surrounded by a fluid called stroma.
The chloroplast and the chemical reactions associated with it are extremely important for all living things. The photosynthetic reactions are responsible for converting solar energy into chemical energy that is used not only by the cells in which photosynthesis occurs but also by other organisms. For example, all of the foods you eat can be traced back to a plant or other photosynthetic organism. Furthermore, the chloroplast and its reactions have had a profound influence on the constitution of Earth’s atmosphere due to the fact that oxygen is a byproduct of photosynthesis.
110
What is the name of the structures that are surface appendages that allow a bacterium to stick to a surface?
Pili
111
In prokaryotic bacterial cells, where are protein synthesized?
The ribosomes
