2. Cell Structure and Varieties

Question 1

Cell

Answer 1

a small membrane bound unit filled with a
concentrated aqueous solution of chemicals with reproduction capacity

Question 2

How surface area-to-volume ratio constrains cell size

Answer 2

• cell surface area determines the amount of substances entering and exiting
  the cell
• To function, cells must maintain a large surface area to volume ratio

Question 3

Microscope

Answer 3

A tool which allows us to see details and objects too small to be seen with the naked eyes

Question 4

Robert Hooke

Answer 4

built the first compound microscope (two converging
lenses)

Question 5

Anton Van Leeuwenhoek
(1670)

Answer 5

• observed living
  microorganisms
• called them animalcules

Question 6

Matthias Shleiden (1838) and Theodor Schwann (1839)

Answer 6

Concluded all living things are made of cells

Question 7

Cell theory (1838)

Answer 7

• Cells are the fundamental units of life
• All living organisms are composed of cells
• All cells come from preexisting cells

Question 8

Modern cell theory

Answer 8

Modern cells evolved from a common ancestor

Question 9

Different types of light microscopy

Bright-field microscopy

Answer 9

light passes directly
through the cells, ittle contrast and details are not distinguished

Question 10

Different types of light microscopy

Phase-contrast microscopy

Answer 10

contrast is increased
by emphasizing differences in refractive index, enhances light and dark areas in the cell

Question 11

Different types of light microscopy

Differential interference-contrast microscopy

Answer 11

two beams of polarized light are used, the
combined images look as if the cell is casting a
shadow on one side.

Question 12

Different types of light microscopy

Stained bright-field microscopy

Answer 12

a stain enhances
contrast and reveals details not otherwise visible

Question 13

Different types of light microscopy

Fluorescence microscopy

Answer 13

a natural substance in the cell or a fluorescent dye that binds to a specific cell material is stimulated by a beam of light and the longer wavelength florescent light is observed coming directly from the dye

Question 14

Different types of light microscopy

Confocal microscopy

Answer 14

fluorescent materials are used
but adds a system of focusing both the stimulating and emitted light so that a single plane through the cell is seen

Question 15

Max Knoll and
Ernst Ruska (1931)

Answer 15

invented
electron microscope

Question 16

Transmission electron microscopy (TEM)

Answer 16

• a beam of electrons is focused on
  the object by magnets
• objects appear darker if they absorb the electrons
• If the electrons pass through they are detected on a fluorescent screen
• A region of a cell in a piece of testis

Question 17

Scanning Electron Microscopy (SEM)

Answer 17

• electrons are directed to the surface of the sample
• they cause other electrons to be emitted

Question 18

cytoplasm

Answer 18

Everything inside the cell (except nucleus if present)

Question 19

Cytosol

Answer 19

the fluid cytoplasm not
contained inside another compartment

Question 20

Prokaryotic Cell

Answer 20

does not have a nucleus or any other membrane-enclosed internal compartments

Question 21

Eukaryotic Cell

Answer 21

contain membrane-enclosed compartments called organelles

Question 22

Nucleus

Answer 22

most noticeable organelle in eukaryotes

Question 23

All prokaryotes

Answer 23

-A cell membrane
-A nucleoid
-A cytoplasm
-Ribosomes (25 nm in diameter)

Question 24

Specialized prokaryotes

Answer 24

-A cell wall and capsule
-Internal membranes
-Cytoskeleton
-Flagella, Pili and Fimbriae

Some prokaryotes swim using their flagella

Question 25

function

Cytosol

Answer 25

contains dissolved nutrients, helps break down waste products, and moves material around the cell

Question 26

function

Nucleus

Answer 26

the repository of genetic information and as the cell’s control center

Question 27

function

Endoplasmic reticulum (ER)

Answer 27

calcium storage, protein synthesis and lipid metabolism

Question 28

function

Golgi apparatus

Answer 28

transport, sorting and modification of both protein and lipid

Question 29

function

Lysosomes

Answer 29

the digestive system of the cell, serving both to degrade material taken up from outside the cell and to digest obsolete components of the cell itself

Question 30

function

Endosomes

Answer 30

sorting and delivery of internalized material from the cell surface and the transport of materials from the Golgi to the lysosome or vacuole

Question 31

function

Mitochondria

Answer 31

generate most of the chemical energy needed to power the cell’s biochemical reactions

Question 32

function

Chloroplast

Answer 32

to absorb light—usually sunlight

Question 33

function

Peroxisomes

Answer 33

sequester diverse oxidative reactions and play important roles in metabolism, reactive oxygen species detoxification, and signaling

Question 34

The endomembrane
system includes

Answer 34

-Cell membrane
-Nuclear envelope
-Endoplasmic reticulum
-Golgi apparatus
-Lysosomes

Question 35

Vesicles

Answer 35

transport substances between the various components of the endomembrane system

Question 36

Cytoskeleton

Answer 36

-Cell support and shape maintenance
-Positioning of cell organelles and other particles within the cell
-Organelles and other particles movement around in the cell
-Cytoplasm movements (cytoplasmic streaming)
-Anchoring the cell in place by interacting with extracellular structures

Question 37

Endosymbiosis

Answer 37

responsible for the appearance of mitochondria and chloroplasts