Cell biology - theme 1 Flashcards
cytosol environment
reducing environment
nuclear lamina
intermediate filaments which support the round shape of nucleus
pH of lysosomes compared to cytosol and why
lysosomes are more acidic pH 5.0 than cytosol pH 7.2
for hydrolases to break down bacteria and cell debris
autophagy
intracellular digestion of intracellular and extracellular matter
amphipathic
eg
hydrophobic and hydrophilic
e.g. phospholipid has hydrophobic tail and hydrophilic head
3 types of cell filaments and relative thickness
actin (thinnest)
intermediate filaments (intermediate thickness)
microtubles (thickest)
actin function and found in which cells
cell movement (macrophages), strength (microvilli), contraction (of muscle and contractile ring in cell division)
intermediate filaments function and found in which cells
mechanical strength (toughest filament) in cells prone to mechanical stress e.g. nerve axon, muscles, skin epithelia
2 types of intermediate filaments
general structure
an example of each
nuclear (meshwork) e.g. nuclear lamina
cytoplasmic (rope like) e.g. keratin filaments in epithelial cells, vimentin in connective tissue muscle and glial cells, neurofilaments in nerve cells
microtubules structure and function
hollow tubes, thickest filaments
internal cell organisation e.g. transporting, positioning organelles and vesicles, cell division
provide tracks along axon
function of fibroblasts
secrete ECM e.g. collagen around themselves by exocytosis
what does actin allow fibroblasts to do
move and weave collagen in different directions
collagen I
long fibrils
skin, bone, tendons, ligaments, dentine, interstitial tissues
collagen II
long fibrils
cartilage, vitreous humour
collagen III
long fibrils (I) skin, muscle, blood vessels
collagen IV
sheet forming collagen
connects basal lamina to basal surface of epithelial tissue
collagen V
long fibrils (similar to I) skin, bone, foetal membranes, placenta
elastin
interwoven protein with collagen
where is there lots of ECM
connective tissue
e.g. tendons, bone, soft jelly in eye
where are GAGs found
dentine (I), eyeball (II), gingiva and cartilage particularly in knee (II)
function of GAGs and how tho
fill space with fluid for resisting compression and impact of pressure
are negatively charged polysaccharides so attract Na+
[Na+] increases so osmosis of water into connective tissue
gene expression
acetylation
euchromatin
gene silencing
methylation
heterochromatin
heterochromatin
more tightly packed nucleosomes so silence genes
euchromatin
less condensed nucleosomes, more access to DNA so genes expressed
problem with helicase in DNA replication and how to resolve
helicase creates torisonal force causing supercoiling of double helix
topiosomerase creates breaks to relieve stress and open up for more supercoiling
okazaki fragment
lagging strand template of replication fork
polymerase unable to add bases to 5’ end
primase adds RNA primers along new strand so bases can be added onto the 3’ end of the primer
DNA ligase attaches fragments
function of DNA polymerase
add bases to 3’ end
proof reading of correct base pairing as it has a nuclease active site
bacteria cell shapes (4)
cocci (spherical) e.g. stretococcus
bacilli (straight rods) e.g. ecoli, salmonella
spirillum (curved rods) e.g. vibrio cholera
spirochetes (spirals) e.g. syphilis
all bacteria have (4)
peptidoglycan
cytoplasmic membrane
DNA
ribosomes
gram positive
thick peptidoglycan so stains purple
has lipoteichoic acid
no outer membrane
gram negative
thin peptidoglycan so stains pink
has periplasm between inner and outer membranes (enzymes)
outermembrane has porins to allow ions, sugar, aa to enter periplasm
outermembrane has endotoxin liposaccharides
molecular phylogeny
study of evolutionary relationships by comparing genetic information
growth factors
organic nutrients e.g. carbohydrates, amino acids, vitamins etc
bacteria can exchange DNA in three ways
transformation - DNA uptake from dead bacteria
transduction - virus injects DNA integrates into bacterial chromosome, virus leaves with bacterial genes and infects other cells
conjunction - direct transfer of DNA from one cell to another
where do bacteria live
biofilms
associated with ECM
test to quantify levels of protein in sample
ELISA test
test to identify specific nucleotide sequences
DNA hybridisation
melt to 95 oC to break H bonds
excess oligonucleotide probe (complementary base sequence to target) is labelled with flurophore/ enzyme
probes hybridise with DNA
