Chapter 6 - A Tour of the Cell

Question 1

larger organisms like plants and animals are…

Answer 1

multicellular

Question 2

when were microscopes invented?

Answer 2

1590 (and were further refined during 1600s)

Question 3

who was the first to see cell walls, when, and where?

Answer 3

Robert Hooke in 1665 - through a microscope while examining dead cells from the bark of an oak tree

Question 4

who was the first to visualize living cells?

Answer 4

Antoni van Leeuwenhoek roughly 1674

Question 5

what are light microscopes and how do they work?

Answer 5

light is passed through a specimen and through glass lenses -> lenses refract/bend the light in such a way that the specimen image is magnified as it’s projected into the eye or into a camera

Question 6

what are three important parameters in microscopy?

Answer 6

magnification
resolution
contrast

Question 7

what is magnification?

Answer 7

the ratio of an object’s image size to its real size

Question 8

how much can light microscopes magnify?

Answer 8

about 1,000x the actual size of a specimen

Question 9

what is resolution?

Answer 9

a measure of the clarity of the image; the minimum distance two points can be separated and still be distinguished as separate points

Question 10

a light microscope cannot resolve detail finer than…

Answer 10

0.2 micrometers, or 200 nanometers - regardless of the magnification

Question 11

a Paramecium is considered a…

Answer 11

single-celled organism

Question 12

define organelles

Answer 12

membrane-enclosed structures within eukaryotic cells

Question 13

when was the electron microscope introduced?

Answer 13

1950s

Question 14

how does an electron microscope work?

Answer 14

a beam of electrons passes through a specimen or onto its surface

resolution is inversely related to the wavelength of the light a microscope uses for imaging

Question 15

what resolution can electron microscopes achieve?

Answer 15

0.002 nm; cannot resolve structures smaller than 2 nm across

this is still a 100-fold improvement over the standard light microscope

Question 16

the cytoskeleton functions in…

Answer 16

structural support for the cell and in motility and signal transmission

Question 17

microtubules do what

Answer 17

shape the cell, guide organelle movement, and separate chromosomes in dividing cells

Question 18

cilia and flagella are

Answer 18

motile appendages containing microtubules; primary cilia also play sensory and signaling roles

Question 19

why isn’t the mitochondrion classified as part of the endomembrane system?

Answer 19

its structure is not derived from the ER or Golgi

Question 20

when biologists wish to study the internal ultrastructure of cells, they can achieve the finest resolution by using

Answer 20

a transmission electronic microscope

Question 21

the nuclear lamina is an array of filaments on the inner side of the nuclear membrane; if a method were found that could cause the lamina to fall into disarray, what would you expect to be the most likely consequence?

Answer 21

a change in the shape of the nucleus

Question 22

movement of vesicles within the cell depends on what cellular structures?

Answer 22

microtubules and motor proteins

Question 23

the smallest cell structure that would most likely be visible with a standard (not super-resolution) research-grade light microscope is

Answer 23

a mitochondrion

Question 24

in a plant cell, DNA may be found

Answer 24

in the nucleus, mitochondria, and chloroplasts

Question 25

motor proteins provide for molecular motion in cells by interacting with what types of cellular structures?

Answer 25

cytoskeletal structures

Question 26

which structure is the site of the synthesis of proteins that may be exported from the cell?

Answer 26

rough ER

Question 27

hydrolytic enzymes must be segregated and packaged to prevent general destruction of cellular components; which of the following organelles contains these hydrolytic enzymes in animal cells?

Answer 27

lysosome

Question 28

what produces and modifies polysaccharides that will be secreted?

Answer 28

Golgi apparatus

Question 29

a mycoplasma is an organism with a diameter between 0.1 and 1.0 micrometers; what does the organism’s size tell you about how it might be classified?

Answer 29

it could be a very small bacterium

Question 30

which plant cell organelle contains its own DNA and ribosomes?

Answer 30

mitochondrion

Question 31

which of the following correctly lists the order in which cellular components will be found in the pellet when homogenized cells are treated with increasingly rapid spins in a centrifuge?

Answer 31

nucleus, mitochondria, ribosomes

Question 32

when biologists wish to study the internal ultrastructure of cells, they can achieve the finest resolution by using

Answer 32

a transmission electronic microscope

Question 33

which organelle is the primary site of ATP synthesis in eukaryotic cells?

Answer 33

mitochondrion

Question 34

motor proteins provide for molecular motion in cells by interacting with what types of cellular structures?

Answer 34

cytoskeletal structures

Question 35

which structure is the site of the synthesis of proteins that may be exported from the cell?

Answer 35

rough ER

Question 36

the differences among the three categories of cytoskeletal elements outlined in the table above would suggest that each of the following has specialized roles; which of the following is a correct match? (all three elements are involved in the maintenance of cell shape)

Answer 36

microtubules and chromosome movement

Question 37

which type of organelle or structure is primarily involved in the synthesis of oils, phospholipids, and steroids?

Answer 37

smooth endoplasmic reticulum