Cell structure and function Flashcards
what does the phrase morphology mean?
the outward appearance of cells
is a virus a living thing?
no
what is an example of a procaryotic cell?
cocci or bacilli
what are the main characteristics of prokaryotic cells?
they lack a nucleus or membrane bound organelles
what are the main characteristics of eukaryotic cells?
contains a nucleus enclosed in an envelope
has membrane bound organelles
how many layers does the nuclear envelope have?
2
how much space can the vacuole in a plant cell take up?
90%
what does a vacuole do for a plant cell?
gives it strength and rigidity
what do nucleus’ have that allow substances to enter/exit?
they have pores
what are ribosomes made up of?
1:2 protein: rRNA
what do the 2 sub-units of ribosomes do?
the smaller reads the mRNA
the larger produces the amino acid chain
where are ribosomes in prokaryotic cells?
they are free flowing
where are ribosomes in eukaryotic cells?
bound to the endoplasmic reiticulum (and some ff)
where do proteins end up after ribosomes?
the rough ER- very close to the nucleus, then the smooth ER,
Then they are transported, by vesicles to other areas of the cell
where do most proteins travel to first after the smooth ER?
the Golgi body
what is the Golgi body made of?
large, flat stacks known as cisternae
which area of the Golgi body do proteins arrive at?
the cis face
which area of the Golgi body do proteins leave from?
the trans-side
what happens at the Golgi body?
post-translational modifications of proteins by enzymes
what is protein thoughting?
where modified proteins are sorted and then transported to the correct area of the cell
what is constitutive secretion?
it is the pathway for proteins to be added to the cell membrane for growth and/or repair
what is regulated secretion?
the secretion of proteins at specific times e.g. a trigger signal, hormone etc
what is lysosomal secretion?
when vesicles containing lysosomes can digest/destroy misfolded proteins and remove them from the cell.
can lysosomes be sent outwith the cell?
yes - to destroy something outside
what are the different skeletal fibres within the cell?
microtubules
intermediate filaments
microfilaments
what are microtubules?
the largest skeletal fibre, essential to cell division e.g. tubulin
what are intermediate filaments?
a skeletal fibre that is adaptable and specific to different cell function
what are microfilaments?
the smallest skeletal fibre used for changing the shape of the cell e.g. actin
which cells have the contain the most actin?
muscle cells
where does movement occur with microtubules?
on the outside of the tubes
where is tubulin within the cell?
intracellular - works between organelles and vesicles
how do microtubules work?
motor molecules work to move the vesicles along the outside of the microtubule.
what is a kinesin?
a motor protein that moves vesicles the (+) way, away from the nucleus.
what is dynein?
a motor protein that moves vesicles the (-) way, towards the nucleus.
how is the microfilament actin made?
from monomers of globular actin (g-actin) which creates polymers of (f-actin)
what are mitochondira?
folded membrane on the inside where ATP is synthesised
what do mitochondria contain?
its own DNA and a double membrane
where is mitochondrial DNA inherited from?
the maternal line
how do mitochondria and chloroplasts divide?
binary fission
what do chloroplasts contain?
a double membrane and its own DNA
what are gap junctions?
a tunnel of 6 proteins used for chemical communicatin
what are adherence junctions ?
physically attached junctions that provide strong communication between adjacent cells
what are tight junctions or TJ’s ?
they are junctions that allow water/solutes between epithilial cells.
what do epiithelial cells do?
line the outer surfaces of organs and blood vessels
what are tight epithelia?
tight junctions between epithelial cells e.g. in the brain
what are leaky epithelial cells?
few tight junctions between epithelial cells e.g. the gut
