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Anatomy of a Generalized Cell Flashcards

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1
Q

What are the three main regions all cells have?

A

A nucleus, cytoplasm, and a plasma membrane.

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2
Q

DNA

A

Deoxyribonucleic acid is genetic material much like a blueprint that contains instructions for building proteins and is also very necessary for cell reproduction.

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3
Q

The nucleus has three recognizable regions or structures:

A

the nuclear envelope, nucleoli, and chromatin

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4
Q

nuclear envelope or nuclear membrane

A

A double membrane barrier that bounds the nucleus; between the two membranes is a fluid-filled space. At various points the two membranes fuse, and nuclear pores penetrate through the fused regions (which allows substances to pass through it much more freely than elsewhere).

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5
Q

The nuclear envelope/membrane encloses ________

A

a jellylike fluid called nucleoplasm in which other nuclear elements are suspended.

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6
Q

nucleoli

A

small, dark-staining, essentially round bodies within the nucleus that are sites where ribosomes are assembled.

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7
Q

chromatin

A

a loose network of bumpy threads made up of DNA and protein scattered throughout the nucleus when the cell is not dividing.

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8
Q

What happens to chromatin when the cell is dividing to form two daughter cells?

A

The chromatin threads coil and condense to form dense, rod-like bodies called chromosomes (much like the way a stretched spring becomes shorter and thicker when allowed to relax).

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9
Q

plasma membrane (a.k.a. cell membrane)

A

flexible, fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment; plays a dynamic role in many cellular activities.

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10
Q

The fluid mosaic model of the plasma membrane

A

Twp lipid layers (composed mostly of phospholipids, but also contain much cholesterol) arranged “tail to tail” in which protein molecules float (some are free to move). The proteins form a constantly changing pattern or mosaic.

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11
Q

Describe the structure of phospholipid molecules in the plasma membrane.

A

lollipop-shaped, with polar heads that are hydrophilic and nonpolar tails that are hydrophobic.

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12
Q

What is beneficial about the self-orienting property of phospholipids?

A

It allows biological membranes to reseal themselves quickly when torn.

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13
Q

What is beneficial about the plasma membrane interior?

A

The hydrophobic makeup makes the membrane relatively impermeable to most water-soluble molecules.

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14
Q

How does cholesterol help the plasma membrane?

A

It helps keep the membrane fluid.

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15
Q

Many of the proteins protruding from the cell exterior are:

A

receptors for hormones (or other chemical messengers) OR are binding sites for anchoring the cell to fibers (or to other structures inside or outside the cell)

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16
Q

What could serve as anchoring structures for the proteins that are anchored in specific locations on the plasma membrane?

A

Filaments of the cytoskeleton attached to membrane proteins.

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17
Q

Most proteins that span the plasma membrane are involved in _________.

A

transport

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18
Q

Proteins that span the plasma membrane include those that:

A

cluster together to form protein channels (tiny pores); act as carriers that bind to a substance and move it through the membrane.

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19
Q

Attached to most proteins abutting the extracellular space are:

A

Branching sugar groups – the formed “sugar-proteins” are called glycoproteins, and because of their presence, the cell surface is a fuzzy, sticky, sugar-rich area called the glycocalyx

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20
Q

How are glycoproteins important?

A

They determine your blood type, act as receptors that certain bacteria, viruses, or toxins can bind to, and play a role in cell-to-cell recognition and interactions. Definite changes in glycoproteins occur in cells that are being transformed into cancer cells.

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21
Q

Typically, cells are bound together in 3 ways:

A
  • Glycoproteins in the glycocalyx act as an adhesive or cellular glue.
  • Wavy contours of the membranes of adjacent cells fit together in a tongue-and-groove fashion.
  • Special membrane junctions are formed (vary structurally depending on their roles).
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22
Q

Describe tight junctions.

A

impermeable junctions that bind cells together into leak-proof sheets that prevent substances from passing through the extracellular space between cells (basically, adjacent plasma membranes fuse together tightly like a zipper).
Ex: in small intestine, these junctions prevent digestive enzymes from seeping into the bloodstream.

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23
Q

What are desmosomes and what do they do?

A

They are anchoring junctions scattered like rivets along the sides of abutting cells. They prevent cells subjected to mechanical stress (like skin cells) from being torn.

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24
Q

Describe the structure of desmosomes.

A

They are button-like thickenings of adjacent plasma membranes (plaques), which are connected by fine protein filaments. Thicker protein filaments extend from the plaques inside the cell to those on the cells’ opposite sides (forming an internal system of strong “guy wires”).

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25
What do gap junctions do and where are they commonly found?
They are commonly seen in the heart and between embryonic cells, and function mainly to allow communication.
26
Describe gap junctions.
Neighboring cells are connected by hollow cylinders composed of proteins called connexons that span the entire width of the abutting membranes. Chemical molecules (like nutrients and ions) can pass directly through the water-filled connexon channels from one cell to another.
27
What is the cytoplasm?
the cellular material outside the nucleus and inside the plasma membrane.
28
What are the three major elements of cytoplasm?
cytosol, organelles, and inclusions
29
What is cytosol?
semitransparent fluid that suspends the other elements (mostly composed of water, nutrients and other solutes)
30
What are organelles (in general)?
the metabolic machinery of the cell - each type is specialized to carry out a specific function for the cell.
31
What are inclusions?
chemical substances that may or may not be present, depending on the cell type; most are stored nutrients or cell products.
32
What is the shape of mitochondria?
tiny, lozenge-like or sausage- shaped organelles, but in living cells they squirm, lengthen, and change shape almost continuously.
33
Describe the membrane(s) of mitochondria.
The mitochondrial wall consists of a double membrane. The outer one is smooth and featureless, but the inner one has shelf-like protrusions called cristae.
34
Describe the function of mitochondria.
Enzymes dissolved in the fluid within the mitochondria, as well as enzymes that form part of the cristae membranes, carry out the reactions in which oxygen is used to break down foods, releasing energy. Much of this energy escapes as heat, but some is captured and used to form ATP molecules. Mitochondria supply most of the ATP used in the cell, so they are the powerhouses of the cell.
35
What are ribosomes?
tiny, bi-lobed, dark bodies made of proteins and one variety of RNA called ribosomal RNA. They are the actual sites of protein synthesis in the cell.
36
What is the endoplasmic reticulum?
a system of fluid-filled cisterns (tubules, or canals) that coil and twist through the cytoplasm, accounting for half the cell's membranes.
37
What does the endoplasmic reticulum in general do?
It serves as a minicirculatory system for the cell because it provides a network of channels for carrying substances (primarily proteins) from one part of the cell to another.
38
What is the rough ER?
It is essentially the cell's membrane factory. It is studded with ribosomes.
39
What happens to the proteins made on the ribosomes of rough ER?
They migrate into the tubules of rough ER, where they fold into their functional 3D shapes and then are dispatched to other areas in transport vesicles.
40
Where would rough ER be especially abundant?
In cells that make and export proteins (e.g. pancreas cells)
41
What does the smooth ER do?
It functions in lipid metabolism and detoxification of drugs and pesticides. It communicates w/ the rough variety, but does nothing to contribute to protein synthesis.
42
What/where does the Golgi apparatus look like?
It is located near the nucleus and appears as a stack of flattened membranous sacs, associated with a swarm of vesicles.
43
What does the Golgi apparatus do?
It is the principal "traffic director" for the cellular proteins. Its major function is to modify & package proteins sent to it by the rough ER.
44
How does the Golgi apparatus package-for-release proteins?
The sacs in the apparatus swell as proteins accumulate, and then their swollen ends pinch off to form secretory vesicles, which travel the cell membrane.
45
What are lysosomes?
They are membranous bags containing powerful digestive enzymes, and appear in many different sizes.
46
What do lysosomes do?
They are capable of digesting worn-out or non-usable cell structures and most foreign substances that enter the cell; they are the cell's demolition sites.
47
Where are lysosomes especially abundant? How are they made?
They are especially abundant in phagocytes, cells that dispose of bacteria and cell debris. They are formed and packaged by ribosomes and the Golgi apparatus (respectively).
48
What are peroxisomes?
They are membranous sacs containing powerful oxidase enzymes that use molecular oxygen to detoxify a number of poisonous substances.
49
What are peroxisomes most important function?
Their most important function is to disarm dangerous free radicals.
50
What are free radicals?
Highly reactive chemicals with unpaired electrons that can scramble the structure of proteins and nucleic acids.
51
Where are peroxisomes especially abundant? How are they made?
Peroxisomes are especially numerous in liver and kidney cells; they appear to replicate themselves by simply pinching in half (like mitochondria).
52
What is the cytoskeleton?
An elaborate network of protein structures that extends throughout the cytoplasm.
53
What does the cytoskeleton essentially do?
acts as a cell's muscles and bones by furnishing an internal framework that: - determines cell shape - supports other organelles - provides the machinery for intracellular transport and various types of cellular movement
54
What are the 3 major components of the cytoskeleton?
microtubules, intermediate filaments, and microfilaments
55
What do the intermediate filaments do?
Their strong, stable, ropelike bodies help form desmosomes and provide internal guy wires to resist pulling forces on the cell.
56
What do the microfilaments do?
They (such as actin and myosin) are most involved in cell motility and in producing changes in cell shape.
57
What do the microtubules do?
Their tubelike bodies determine the overall shape of a cell and the distribution of organelles. They are very important during cell division.
58
What are centrioles?
A pair of rod-like bodies that lie close to the nucleus at right angles to each other; internally they are made up of a pinwheel array of fine microtubules.
59
What are the centrioles best known for doing?
They are best known for their role in generating micro- | tubules, and during cell division, the centrioles direct the formation of the mitotic spindle.
60
What are cilia?
whiplike cellular extensions that move substances along the cell surface (like those in the lungs that move mucus)
61
How do cells make cilia?
Centrioles multiply and line up beneath the plasma membrane at the free cell surface. Microtubules then sprout from the centrioles and put pressure on the membrane, forming projections.
62
What are the projections produced by centrioles called if they are substantially longer?
flagella
63
What are microvilli?
tiny, fingerlike extensions of the plasma membrane that project from an exposed cell surface; they increase surface area tremendously, and have a core of actin filaments that extend into the internal cytoskeleton of the cell and stiffen the microvillus.
64
Describe structure/function of a fibroblast.
It is a cell that connects body parts, and its elongated shape lies along the cable-like fibers that it secretes. It has a large rough ER and Golgi apparatus to make and secrete the protein building blocks of these fibers.
65
Describe structure/function of an erythrocyte.
A red blood cell (connects body parts), carries oxygen in the bloodstream; concave disc shape for extra surface are and streamlined flow; organelles have been shed to make room for oxygen-carrying pigment.
66
Describe structure/function of an epithelial cell.
hexagonal cell that lines and covers body organs; shape allows them to pack together into sheets; has abundant intermediate filaments that resist tearing when the epithelium is rubbed or pulled.
67
Describe structure/function of smooth and skeletal muscle cells.
elongated and filled with contractile filaments, so they can contract forcefully, move bones or change the size of organs.
68
Describe structure/function of a fat cell.
huge spherical shape of a fat | cell is produced by a large lipid droplet in its cytoplasm; stores nutrients.
69
Describe structure/function of a macrophage.
fights disease; extends long pseudopods to crawl through tissues to reach infection sites; contains many lysosomes.
70
Describe structure/function of a nerve cell.
gathers information and controls body functions; has long processes (extensions) for receiving and transmitting messages; covered with an extensive plasma membrane and a plentiful rough ER synthesizes membrane components.
71
Describe structure/function of an oocyte
female cell of reproduction; largest cell in the body; contains several copies of all organelles, for distribution to the daughter cells that arise when the fertilized egg divides to become an embryo.
72
Describe structure/function of a sperm cell
male cell of reproduction; long and streamlined, built for swimming to the egg for fertilization; flagellum acts as a motile whip to propel itself.
73
What is intracellular fluid?
a solution containing small amounts of gases (oxygen and carbon dioxide), nutrients, and salts, dissolved in water.
74
What is interstitial fluid?
Like intracellular fluid, except that it bathes the exterior of our cells and contains tons of nutrients, regulatory substances, wastes, etc.

Cells and Tissues (2 decks)

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