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Biology 240 > A Tour of the Cell > Flashcards

A Tour of the Cell Flashcards

1
Q

What occurs in a light microscope (LM)

A

Visible light is passed through a specimen and then through glass lenses

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2
Q

As a cell increases in size, what happens to its volume?

A

It grows proportionately more than its surface area

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3
Q

What are three important parameters of microscopy?

A

Magnification, Resolutions, and Contrast

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4
Q

What is scanning electron microscopes (SEMs)?

A

Focus a. beam of electrons onto the surface of a specimen, proving images that look 3-D

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5
Q

What are transmission electron microscopes (TEMs)?

A

Focus a beam of electrons through a specimen

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6
Q

What is cell fractionation?

A

Taking the cells apart and separates the major organelles from one another

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7
Q

What is differential centrifugation?

A

Fractionate cells into their component parts

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8
Q

What consists of prokaryotic cells?

A

bacteria and archaea

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9
Q

How are prokaryotic cells characterized?

A

No nucleus, DNA in an unbound region called the nucleoid, no membrane-bound organelles, cytoplasm bound by the plasma membrane

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10
Q

What are basic features of all cells?

A

Plasma membrane, semifluid substance called cytosol, chromosomes (carry genes), ribosomes (make proteins)

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11
Q

The basic structural and functional unit of every organism is one of two types of cells:

A

Prokaryotic or eukaryotic

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12
Q

What consists of eukaryotic cells?

A

Protists, fungi, animals, and plants

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13
Q

How are eukaryotic cells characterized?

A

By having DNA in a nucleus that is bounded by a double membrane, membrane-bound organelles, and cytoplasm in the region between the plasma membrane and nucleus

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14
Q

The eukaryotic cell’s genetic instructions are housed in the ____ and carried out by the ____

A

nucleus ; ribosomes

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15
Q

The nucleus contains most of what in a eukaryotic cell?

A

DNA

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16
Q

How is protein created?

A

Ribosomes use the information from the DNA in a eukaryotic cell to make proteins

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17
Q

What is the purpose of a nuclear envelope?

A

It encloses the nucleus, separating it from the cytoplasm

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18
Q

What is the nuclear envelope?

A

A double membrane; each membrane consists of a lipid bilayer

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19
Q

How is DNA organized in the nucleus?

A

Into discrete units called chromosomes

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20
Q

Each chromosome contains one DNA molecule associated with proteins called?

A

Chromatin

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21
Q

What is the nucleolus?

A

The site of ribosomal RNA (rRNA) synthesis, located within the nucleus

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22
Q

What are ribosomes?

A

Complexes made of ribosomal RNA and protein

23
Q

Where do ribosomes build proteins?

A

In the cytosol (free ribosomes) and on the outside of the endoplasmic reticulum or the nuclear envelope (bound ribosomes)

24
Q

What the two distinct regions of ER (Endoplasmic Reticulum):

A

Smooth ER, which lacks ribosomes, and Rough ER, whose surface is studded with ribosomes

25
Functions of Smooth ER include:
Synthesis lipids, detoxifies drugs and poisons, stores calcium ions
26
Functions of Rough ER include:
Has bound ribosomes, which secrete glycoproteins, distributes transport vesicles, is a membrane factory for the cell
27
What is a lysosome?
A membranous sac of hydrolytic enzymes that can digest macromolecules
28
When do lysosomal enzymes work best?
In the acidic environment inside the lysosome
29
What are hydrolytic enzymes and lysosomal membranes made by?
Rough ER and are then transferred to the Golgi apparatus for further processing
30
How can some types of cell engulf another cell?
By a process called phagocytosis, forming a food vacuole
31
What exactly is a phagocytosis?
When a lysosome fuses with the food vacuole and digests the contents
32
What is autophagy?
When lysosomes also use enzymes to recycle the cell's own organelles and macromolecules
33
What is the correct order of the exocytosis or secretion pathway?
Rough ER, Golgi, transport vesicle, plasma membrane
34
What is mitochondria the site of?
Cellular respiration, the metabolic process that uses oxygen to generate ATP
35
what is chloroplasts, found in plants and algae, the site of?
Photosynthesis
36
What do mitochondria and chloroplasts have in common with bacteria?
Enveloped by double membrane, contains free ribosomes and circular DNA molecules, and grows and reproduces somewhat independently in cells
37
What is cristae?
Folds in the inner membrane of the mitochondria
38
The inner membrane creates what two compartments?
Intermembrane space and mitochondrial matrix
39
What is the role of the cytoskeleton?
To help support the cell and maintain its shape
40
Three main types of fibers that make up the cytoskeleton include:
Microtubules, the thickest of the three components Microfilaments (actin filaments), the thinnest Intermediate filaments, middle range
41
Microtubules
- Hollow rods about 25 nm in diameters and about 200 nm to 25 microns long - Constructed of dimers of tubulin
42
What are the functions of microtubules?
Shaping the cell, guiding movement of organelles, separating chromosomes during cell
43
Microfilaments
-Solid rods about 7nm in diameter, built as a twisted double chain of actin subunits -A network of microfilaments helps support the cell's shape -Forms a cortex just inside plasma membrane to help support the cell's shape
44
Intermediate Filaments
-Range in diameter from 8 to 12 nanometers, longer than microfilaments but smaller than microtubules -More permanent cytoskeleton fixtures than other two -Support cell shape and fix organelles in place
45
What is the cell wall?
An extracellular structure that distinguishes plant cells from animals cells
46
What has cell walls?
Prokaryotes, fungi, and some protists
47
What is the purpose of the cell wall?
Protects the plant cell, maintains its shape, and prevents excessive uptake of water
48
Do animal cells lack walls?
Yes, but are covered by an elaborate extracellular matrix (ECM)
49
What is the extracellular matric (ECM) made up of?
glycoproteins such as collagen, proteoglycans, and fibronectin
50
Where can you find ECM proteins?
Binded to receptor proteins in the plasma membrane called integrins
51
What are plasmodesmata?
Channels that connect plant cells
52
What is the purpose of plasmodesmata?
To make water and small solutes (and sometimes proteins and RNA) able to pass from cell to cell
53
What happens at tight junctions?
Membranes of neighboring cells are pressed together to prevent leakage of extracellular fluid

Biology 240 (20 decks)

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