biology chapter 6

harvill

the _________ may also play a role in controlling cell division and the life span of a cell

nucleoli

at any given time ______ ribosomes are suspended in the cytosol, while ________ ribosomes are attached to the outside of the endoplasmic reticulum or nuclear envelope

free, bound

most proteins on ______ ribosomes function within the cytosol: examples are enzymes that catalyze the first steps of sugar breakdown

free

__________ ribosomes generally make proteins that are destined for insertion into membranes, for packaging within certain organelles such as lysosomes, or for export from the cell (secretion)

bound

what are sacs made of membrane called?

vesicles

the ER consists of a network of membraneous tubules and sacs called ________

cisternae

the ER membrane separates the internal compartment of the ER called the ER _______ from the cytosol

lumen (cavity) or cisternal space

among the steroids produced by the smooth ER in animal cells are the ______ hormones of vertebrates and the various steroid hormones secreted by the _______ glands

sex, adrenal

________ usually involves adding hydroxyl groups to drug molecules, making them more water-soluble and easier to flush from the body

detoxification

________ have carbohydrates covalently bonded to them

glycoproteins

what vesicles go from one part of the cell to another?

transport vesicles

inside the chloroplasts is another membranous system in the form of flattened, interconnected sacs called _________

thylakoids

each stack of a thylakoid is called a _______

granum

the fluid outside the thylakoid is the _______ which contain chloroplast DNA and ribosomes as well as , many enzymes

stroma

specialized peroxisomes called ________ are found in the fat-storing tissues of plant seeds

glyoxysomes

the large cell is a ________

macrophage

mitochondria supply what?

ATP

the cell is ________________________

a living unit greater than the sum of its parts

________ was invented in 1590, and refined during 1600’s

microscope

_________ was first seen on dead cells of oak bark by _____________ in 1665

cell walls, robert hooke

________ seen on living cells by ________- a few yeasr after hooke

cell walls, leeuwenhoek

th first microscopes used were __________

light microscopes

we use _________ microscopes in the lab

light

how does a light microscope work?

visible light is passed through the specimen and glass lens. the glass lens bends the light in such a way that the image is magnified as it is projected into the eye.

_______ ratio of an objects image size to its real size

magnification

________ can magnify effectively to about 1,000 times the actual size of the specimen (at greater magnifications, additional details cannot be seen clearly)

light microscopes

________ measure of the clarity of the image. it is the minimum distance 2 points can be separated and still distinguished as 2 points.

resolution

light microscopes cannot resolve detail finer than about _____________ (um) of _____________ (nm)

0.2 micrometer, 200 nanometer

___________ difference between brightness of light and dark areas of an image.

contrast

methods for enhancing contrast are :

staining cells

what can be seen by the unaided human height? (5 things)

human height, length of some nerve and muscle cells, chicken egg, and frog egg

what can be seen by the light microscope? (8 things)

frog egg, human egg, most plant and animal cells, nucleus, most bacteria, mitochondrion, and smallest bacteria

what can be seen by the electron microscope? (7 things)

smallest bacteria, viruses, ribosomes, proteins, lipids, small molecules and atoms

what are the base units? (5 units)

meter (m)

gram (g)

liter (l or L)

celsius ( c)

second (s)

centi

c

10 ^-2

mili

m

10^-3

micro

u

10^-6

nano

n

10^-9

pico

p

10^-12

kilo

k

10³

mega

M

10^6

giga

G

10^9

tera

T

10^12

peta

P

10^15

angstrom

A

10^-10

what can be seen by the super-resolution microscope? (3 things)

smallest bacteria, viruses, and ribosomes

___________ light passes directly through specimen. if they are stained, you can see better, but staining them ____________

brightfield, preserves (kills) them

what is phase contrast?

variations in density within the specimen are amplified to enhance contrast in unstained cells; especially useful for examining living, unstained cells

________________ as in phase contrast optical modifications are used to exaggerate differences in density; image appears almost 3-D

differential interference contrast

____________- locations of specific molecules are revealed by labeling the molecules with __________ dyes or antibodies, which absorb UV radiation and emit visible light

fluorescence, fluorescence

what is this is?

laser used to create a single plane of fluorescence; out of focus light from other planes. a 3-D reconstruction can be created, a standard fluoresence micrograph is blurry, out of focus light is not excluded.

confocal

what is deconvolution?

process that digitally removes out of focus light and reassigns it to its source, creating a much sharper 3-D image

____________ individual fluorescent molecules were excited by UV light and their position recorded. combining info from many molecules in different places “breaks” the resolution limit, resulting in a sharp image. each dot is well below 200 nanometer

super-resolution

what does EM stand for?

electron microscopy

what microscope shows a 3-D image of the surface of a specimen usually black and white but often artifically colorized to highlight particular structures?

scanning electron microscope (SEM)

what microscope profiles a thin section of a specimen?(while preparing a specimen the cilia were cut along the their lengths, creating longitudinal sections, while other cilia were cut straight and across, creating sections.

transmission electron microscope (TEM)

what microscope of proteins are frozen rapidly a temps less than -160c. locking the molecules into a rigid state.

cryo-electron microscope (cryo-EM)

how does a cryo-electro microscope work?

a beam of electrons is passed through the sample to visualize the molecules by electron microscopy and software is used to merge a series of such micrographs, creating a 3-D image.

__________ membrane enclosed structures wihtin eukaryotic cells

organelles

what happened in the 1950’s?

electron microscope was introduced

rather then focusing light the EM focuses ______________ through the specimen or onto its surface

a beam of electrons

____________ inversely related to the wavelength of the light (or electrons) a microscope uses for imaging, and electron beams have much more shorter wavelengths than visible light

resolution

what microscope can theoretically achieve a resolution of about 0.002 nm, though in practice they usually cannot resolve structures smaller than about 2nm. this is still a 100-fold improvement over the standard light microscope

modern electron microscope

what microscope is useful for the study of the topography of a specimen. with electron beams that scan the surface of the sample, usually coated with a thin film of gold. the beam excited electrons on the surface and secondary electrons are detected by a device that translates the pattern of electrons into an electrical signal sent to a video screen. the result is 3-D

scanning electron microscope (SEM)

what microscope is is used to study the internal structure of the specimen, much as a light microscope and aims light through a sample on a slide. the sample does have to be stained, with heavy metals it does make some parts of the cell more dense. the electrons that pass through are scattered due to the denser regions so fewer are transmitted. does not use glass lenses, uses electromagnets to bend the paths of the electrons ultimately focusing the image onto a monitor for viewing

transmission electron microscopy (TEM)

electron microscopes have revealed many _________ structures that were impossible to resolve with the light microscope

subcellular

what are two disadvantages of the electron microscope?

1) methods use to stain kill the cells, introduce artifacts

2) structural features seen in micrographs that don’t exist in living cells

both _______ and __________ microscopes have produced sharper images of 3-0 tissues and cells

confocal deconvolution

a group of new techniques and labeling molecules developed in recent years, called ____________ has allowed researchers to “break” the resolution barrier and distinguished subcellular structures as small as 10-20 nm across

super-resolution microscopy

a new type of TEM called ___________ allows specimens to be preserved at extremely low temps. it avoids the use preservatives, allowing visualizations of the structures in their cellular respirations

cryo-electron (cryo-EM)

what is used to compliment x-ray crystallography in revealing protein complexes and subcellular structures like ribosomes?

cryo-electron (cryo-em)

___________ are the most important in cytology

microscopes

cytology means _____________

the study of cell structure

understanding the function of each cell requires integrating ______ and _________

cytology biochemistry

biochemistry means __________

the study of the chemical processes (metabolism) of the cells

__________ a useful technique for studying cell structures and function. it takes cells apart and separates major organelles and other subcellular structures from one another

cell fractionation

what is used during cell fractionation?

centriuge

what is the definition of centrifuge?

spins test tubes holding mixtures of disrupted cells at a series of increasing speeds, a process called differinitial centrifugation

cell fractionation is used to separate cell components based on ________

size and density

what are the steps for cell fractionation?

1) cells are homogenized in a blender to break up them up.

2) the resulting mixture (homogenate) is centrifuged.

3) the liquid above the pellet (supernatant) is poured into another tube and centrifuged at a higher speed for a longer time, and this is repeated multiple times

4) this process is called differential centrifugation

5) results in series of pellets, each containing different cell components.

cell fractionation enables researchers to prepare specific components in bulk and identify their functions. a task _______________

not usually possible with intact cells

electron microscopes revealed large numbers of ___________

organelles called mitochondria

__________ basic structural and functional unit of every organism

cell

what are the two distinct types of cells?

prokaryotic cells, eukaryotic cells

prokaryotic cells- _______ is concentrated in a region that is ___ membrane enclosed called the _______

DNA, not, nucleoid

what does prokaryotic mean?

before nucleus

what are examples of prokaryotic cells?

domain bacteria and archaea

eukaryotic cells- most of the ____ is in an organelles called _________ which is bounded by a double membraane

DNA, nucleus

what does euakarytic mean?

true nucleus

what is an example of eukaryotic cells?

domain eukarya, protists, fungi, animals, and plants

what does protists mean?

informal term talking about a diverse group of mostly unicellular eukaryotes

all cells are bounded together by a selective barrier called_________

plasma membrane (cell membrane)

all cells have a jelly like fluid called ________

cytosol

all cells have _________ (which carry genes)

chromosomes

all cells have __________ (tiny complexes that make proteins according to instructions for genes)

ribosomes

the interior of either type of cell is called the _________

cytoplasm

in eukaryotic cells cytoplasm refers to only the region between the _______ and _______

nucleus, plasma membrane

within the cytoplasm are a variety of organelles of specialized form and function. these structures are ______ in prokaryotic cells

absent

in prokaryotes the cyotoplasm ________

have a job

eukaryotic cells are ______ that prokaryotic cells

larger