Cell Biology 1.2 Ultrastructure of Cells

Question 1

Define resolution

Answer 1

The shortest distance between 2 points that can be distinguished.

Question 2

Draw the table for light vs electron microscope

Answer 2

Light is limited to wavelengths visible by light (400-700nm)
Electrons have shorter wavelengths so higher visibility

human eye: 0.1mm, 100 micrometers, 100000 nanometers

light: 0.0002mm, 0.2 micrometers, 200 nanometers
electron: 0.000001mm, 0.001 micrometers, 1 nanometer

Question 3

Define ultrastructure of a cell

Answer 3

structures of a biologicial specimen that are at least 0.1 nm in their smallest dimension

Question 4

Describe how we see ultrastructure of cells

Answer 4

Since electron microscopes have a higher resolution, they can see the ultra structure of a cell.

Question 5

Describe binary fission

Answer 5

DNA replicated
2 DNA loops attach to membrane
cytokinesis forms to daughter cells
    membrane elongates and pinches off
daughter cells are genetically identicial

Happens in prokaryotes SOME eukaryotes

Question 6

Describe the advantages of compartamentalization

Answer 6

metabolism efficiency: enzymes & substrates can localize and be more concentrated
localized conditions: pH and other levels can be optimal for 1 part of 1 cell
toxic substances can be localized (lysosomes)
# and location of organelles can be changed depending on the needs of the cell

Question 7

Describe prokaryotes

Answer 7

smaller than eukaryotes came first, no compartmentalization, divide by binary fission

Question 8

Define what the various structures of the prokaryote do

Answer 8

Ribsome- protein synthesis
Cell wall- peptidogyran, protects cell shape
Nucleoid- region containing a single free DNA strand
Pili- protein filaments, cell adhesion/conjuction
Membrane- phospholipid w/ embedded proteins, controls entry/exit
Plasmid- independent small circles of DNA
Flagella- enlongated, inflexible corkcrew structures, rotate to move cell

Question 9

Describe the structures in a eukaryotic cell

Answer 9

Ribosome- 80s, protein synthesis
Golgi- membranous sacs, modifies proteins
Mitochondria- forms cristae to increase SA for cell respiration
Nucleus- double membrane structure w/ pores, DNA arranged in chromosomes
RER- cristae studded w/ ribosomes
Membrane- controls passage of materials in and out of the cell
Lysosome- vesicles containing enzymes

Question 10

Describe the nucleus

Answer 10

spherical w/ double membrane
pores/holes present
contains genetic info in the form of chromosomes (DNA + associated histone proteins)
uncoiled chromosomes are chromatin, darker color
mRNA is transcribed in nucleus before use in protein synthesis
mRNA leaves nucleus in pores (DNA to large to move through pores)

Question 11

Describe mitochondrion(ia)

Answer 11

double membrane
smooth other layer, folded inner
folds are cristae
variable in shape
site of ATP production by aerorespiration (if fat is used for energy it is also digested here)

Question 12

Describe ribosomes

Answer 12

80s/70s
no membrane
dark granules in cytoplasm
synthesize proteins to function in cytoplasm for use in cell (enzymes)
free in cytoplasm
bound to RER

Question 13

Describe the rER

Answer 13

flattened membrane sacs (cisternae)
near nucleus
80s ribosomes attached to outside cisternae
synthesizes proteins which are transported by vesicles to golgi

Question 14

Describe the Golgi Apparatus

Answer 14

cisternae (flattened membrane sacs)
no ribosomes
close to plasma membrane
cisternae short and more curved
modifies proteins from rER, repacked in vesicles for secretion from cell

Question 15

Describe vesicles

Answer 15

single membrane w/ fluid inside
very small
used to transport materials inside and outside the cell

Question 16

Describe lysosomes

Answer 16

sphereical w/ 1 membrane
formed from golgi vesicles
contains digestive enzymes 
     ingested food in vesicles
     unwanted/damaged organelles
     the cell itself (apoptosis)
high concentration of enzymes (a type of protein) make it stain darker and heavy on micrographs

Question 17

Describe vacuoles

Answer 17

single membrane w/ fluid inside
plant cells LARGE, occupy majority of cell volume
in animal cells, small/temporary

Question 18

Describe cilia

Answer 18

ANIMAL CELLS ONLY
thin projections from cell surface
contain microtubules
used to move cell or move fluid next to the cell

Question 19

Describe microtubules

Answer 19

small cylindrial fibers, plays a role in cell division and structure

Question 20

Describe centrioles

Answer 20

2 groups of 9 triple microtubules

mainly in animal cells, NOT in vascular plants or fungi

Question 21

Describe chloroplasts

Answer 21

PLANTS ONLY
doublem membrane
thylakoids (discs of flattened membranes)
site of photosynthesis: glucose
starch grains (if photosynthesis is too quick
components:
stroma, granum, lumen, lamelia

Question 22

Describe the cell wall

Answer 22

extracellular component
secreted by all plant cells
mainly cellulose (permeable, strong)
hard to digest (last a long time + durable)

Question 23

State the 2 types of prokaryote

Answer 23

Archaebacteria: found in extreme environments (extremophiles)
Eubacteria: traditional bacteria, E. Coli

Question 24

State the 4 types of eukaryotes & their descriptions

Answer 24

Protista: uni/multicellular w/o specialized tissue
Fungi: chitin of cell wall, heterotrophic absorption for nutrition
Plantae: cellulose cell wall, autotrophic (photosynthesis) for nutrition
Animalia: no cell wall, heterotrophic ingestion

Question 25

Outline the 2 advantages of an electron microscope

Answer 25

higher range of magnification

higher resolution

Question 26

Outline the disadvantages of an electron microscope

Answer 26

cannot display living specimens in natural colors