cell and tissue structure Flashcards
what are the two types of chromatin?
euchromatin
heterochromatin
what is euchromatin?
loosely packed DNA
what is heterochromatin?
densely-packed DNA
what happens in the nucleolus?
ribosomal RNA transcription
ribosome assembly
what is the function of the RER
makes proteins
transports them to the Golgi
what does the Golgi do?
synthesis, packing, transportation and modification of the proteins from the RER
breaks down any misfolded proteins
what are the main secretory pathways in a cell?
endocytosis
exocytosis
secretory vesicles
lysosomes
what is the constitutive secretory pathway?
not regulated
what is the regulated secretory pathway?
when the secretion of hormones and growth factors is controlled by signals
where are lysosomes made?
Golgi
what do lysosomes contain?
digestive enzymes
what are the roles of lysosomes?
defence against disease
autolysis
what is Tay Sachs disease?
failure of the lysosomes to break down lipids
cells become full of lipids and become dysfunctional
impacts tissue, then organ and then the health of the child
what do peroxisomes do?
metabolise fatty acids and lipids
play a role in detoxification
what is Zellwegers syndrome?
failure of peroxisomes to form so accumulate high levels of fatty acids
in what cells are there lots of peroxisomes?
liver cells to metabolise alcohol
what are cristae?
the folds of the inner membrane of the mitochondria
what is the cytoskeleton?
helps the cell maintain their shape and internal structure
what is the cytoskeleton made up of?
microfilaments/actin filaments
intermediate filaments
microtubules
name disease of the mitochondria
myopathies
what are the functions of actin microfilaments?
cell shape
organelle and vesicle transport
cell movement - cytokinesis
muscle movements
what are the functions of intermediate filaments?
tensile strength
structural integrity
what are the functions of microtubules?
cell scaffold organelle and vesicle transport mitotic spindle fibres form cilia and flagella drug targets
what is the structure of the plasma membrane?
phospholipid bilayer with transporters
what is immunocytochemistry?
science of using antibodies and chemical stains on individual cells.
what is immunohistochemistry?
process of detecting antigens in cells of a tissue section
what is chromatin?
DNA complexed with protein
what is an advantage of chromatin?
cell can package long strands of DNA tightly within a cell
what membrane does the nucleus have?
double membrane
what are nuclear pores?
holes in the double membrane which allow things to move in and out of the nucleus.
what is the function of the double membrane?
restricts substances coming in and out of the cell
what is the nucleolus?
site of ribosomal RNA transcription and ribosome assembly
where are ribosomes made then transported?
made in the nucleus then transported into the ER
how can you differentiate between heterochromatin and euchromatin?
heterochromatin is much darker on an EM
what are key proteins in the nuclear membrane?
laminin and emerin
name 2 laminopathies?
Emery-Dreifuss muscular dystrophy
Hutchinson-Gilford progeria syndrome
what is muscular dystrophy?
mutations in the skeletal and cardiac muscle which then affect function
what is hutchinson gilford progeria syndrome?
premature ageing
what does the RER do?
makes membranes + organelle proteins – basically all proteins secreted by cell
sorts proteins out and transports them to the Golgi apparatus
whats the difference between RER and SER?
RER has proteins on its surface
what do ribosomes do?
protein synthesis
translate nuclear mRNA –> proteins
what is the main modification of the ER?
glycosylation
after proteins are made in the RER where do they go?
Golgi
what are the 3 main roles of SER?
synthesis of carbohydrates and lipids
major storage site of calcium
needed in detoxifixation - contains enzymes needed to detoxify absorbed drugs and toxins
what structure is commonly found in the kidneys and liver?
SER - needed for detoxification
what is endocytosis?
process by which cells absorb molecules often recycles back to cell membrane e.g. growth factor receptors
what do lysosomes contain?
digestive enzymes
where are lysosomes made?
Golgi apparatus
what are lysosomes?
pieces of Golgi membrane which bud off and contain enzymes
what are the major roles of lysosomes?
o Defence against disease
o Autophagy - Clean-up of organelles
o Autolysis after cell death – destruction of cells or tissues by their own enzymes
what do peroxisomes detoxify?
o Free radicals from normal metabolic processes
o Hydrogen peroxide
o Alcohol
where are peroxisomes found?
liver and kidneys
describe the structure of mitochondri
double membrane
inner layer folded into cristae which increases their surface area
contains mitochondrial DNA
what are diseases of actin?
Genetic diseases e.g. gamma actin – congenital deafness
Muscle actins – cardiomyopathies, skeletal myopathies
what are diseases of the intermediate filaments?
keratin mutations in congenital epidermal blistering diseases e.g. epidermalysis bullosa, laminopathies
what are the functions of the plasma membrane?
o Anchors cytoskeleton
o Selective diffusion, transport, cell signalling, cell adhesion
o Interaction with extracellular membrane
o Separate internal from external environment
o Site of interaction with external environment
o Regulates entry and exit
