Inside the cell Flashcards
What is S?
Svedberg unit, sedimentation coefficient
What do the Svedberg unit measure?
the rate at which a particle sediments in a centrifuge
What is the Svedberg unit affected by?
mass, density and shape, particles that sediment faster have a larger number
What are the 2 subunits of ribosomes compose of?
rRNA and proteins
What is the smaller unit of ribosome called?
30S subunit
What is the larger subunit ribosome called?
50S subunit
What is the complete ribosome called?
70S subunit
Describe the 50S subunit
23S rRNA + 5S rRNA + more than 30 proteins
Describe the 30S subunit
16rRNA + more than 20 proteins
describe the ribosomes of eukaryotic cells
40S subunit + 60S subunit = 80S ribosome
What is the function of ribosomes?
protein synthesis
How many pairs of linear chromosomes do we have?
23 pairs
Describe the structure of chromosomes
one circular double stranded DNA chromosome. DNA is coiled and wrap around proteins (proteins are not histones)
What is the function of chromosomes
site of DNA and RNA synthesis
What is the structure of plasmids?
circular double stranded DNA
What is the function of plasmids
encode genes that give a cell selective advantage. eg antibiotic resistance
Describe the cytoskeleton
variety of types, made from protein, have roll in cell division and shape, similar to eukaryotic’s
Which bacteria have intracytoplasmic membranes
photosynthetic bacteria
What is the structure of intracytoplasmic membranes
varies, can be stacks of flattened vesicles
What is the function of intracytoplasmic membranes
to increase SA for photosynthesis
What is inclusion?
used to describe ganuelles or structures in the cytoplasm of bacteria
What is the structure and fn of inclusions?
varies
How are inclusions viewed?
light microscope, stained for ID purposes, not all bacteria have them
Name the three storage inclusions
glycogen, poly beta hydroxy butyrate (PHB), and polyphopshate
What is the structure of glycogen ?
polymers w/branching chains of glucose
What is the function of glycogen
source of nrg and carbon for biosynthesis
What is the structure of poly beta hydroxy butyrate
polymer synthesized from acetyl groups
What is the function of poly beta hydroxy butyrate
source of nrg and carbon for biosynthesis
What is the structure of polyphosphate?
bunch of phosphate linked together
What is the function of polyphsohate?
source of phoshphate for synthesis of nucleoside triphosphate and phospholipid
What is the stucture of microcompartments
a polyhedral shell made of proteins enclosing sequentially acting enzymes
What is an example of a microcompartment
carboxysomes
what is the structure of a carboxysome
polyhedral shell composed of 1000s of copies of 6 diff protein subunits, inside are 2 sequentially acting enzymes
What is the fn of carboxysomes
to make the fixation of CO2 more efficient
Which bacteria has carboxysomes
cyanobacteria and other CO2 fixing bacterial
What are gas vacuoles
composed of large numbers of gas vesicles
What is the structure of a gas vesicle
walls are made of multiple subunits of protein that self assemble to form hollow capped structure
What are the walls of gas vesicles permeable to
gases but not water
What is the fn of gas vacuoles
found in aquatic organisms, used to regulate buoyancy
How do gas vacuoles regulate buoyancy
cells collapse the vesicle to descend and synthesize new ones to ascend. cells can move to depth w/appropriate light, nutrients etc
What is the structure of magnetosomes
each contains crystals of magnetite (FeO4), from a chain inside the cell
What is the fn of magnetosomes
act like a magnet allowing bacteria to align w.earth’s magnetic field (north and down)
Why is it useful to have magnetosomes to aligh w/earth’s magnetic field
can be used to direct bacterial downwards towards nutrient rich sediments
