Cells and Tissues of the Body Flashcards
What is glycocalyx?
a covering made of glycoprotein and glycolipid that surrounds the cell membrane of the epithelial cell
What are functions of glycocalyx?
- cell recognition
- cell signalling
- cell adhesion
- protection
- permeability barrier
What are functions of the cell membrane?
- maintaining structure and functional integrity of the cell
- separating the intracellular space from the extracellular space
- allowing diffusion of some substances
- controlling passage of substates into and out of the cell
How does cholesterol maintain fluidity of the cell membrane when the body temperature is high and low respectively?
- high - reduces the fluidity of the cell membrane
- low - increases the fluidity of the cell membrane
What does TTX do?
prevent muscle contraction by blocking sodium channels in nerve cell membranes
What are the functions of the cytoplasm?
- cellular respiration, energy production
- synthesis of proteins
- waste handling
- growth and repair
- cell division (mitosis and meiosis)
What are the 4 levels of organisation within the cytosol?
- ion concentration gradients
- protein complexes
- protein compartments e.g. proteasome
- cytoskeleton
What do proteasomes do?
regulate the concentration of particular proteins and degrade misfolded proteins
What does ubiquitin do?
tag proteins for degradation catalysed by ubiquitin ligases
In an H&E stain, what does the H and E stain respectively?
- H - nucleus of the cell blue/purple
- E - cytoplasmic proteins red/pink
What are cytoplasmic inclusions?
metabolic products stored in the cytoplasm, typically in long-lived cells e.g. hepatocytes, neurons, and cardiac muscle cells
What are functions of the cytosol?
- protein synthesis
- metabolic pathways
- metabolite transport
- signal tranmission
- cell division
What are the 3 cytoskeletal fibres?
- MTs
- IFs
- microfilaments
What are microfilaments made up of?
G-actin monomers which form F-actin polymers which in turn form double helix microfilaments
What are functions of microfilaments?
- cell migration
- cell division
- cellular extensions
- cell junctions
- muscle contraction
- membrane transport
What are the 5 types of IF and where are they found?
- lamin found in the nucleus
- keratin found in epithelial cells
- vimentin found in fibroblasts
- desmin found in muscle cells
- neurofilaments found in neuronal cells
What do desmosomes do?
tether intermediate filaments to the plasma membrane in cardiac tissue and the epithelium
What do hemidesmosomes do?
anchor cells to the underlying basement membrane
What are MTs made up of?
alpha and beta tubulin
Where are MTs found?
centrioles, cilia and flagella
Where are the + and - ends of the MT respectively?
- plus - towards the periphery
- minus - towards the nucleus
What is anterograde transport?
movement from the negative to positive end of an MT via kinesin
What is retrograde transport?
movement from the positive to negative end of an MT via dynein
What happens if the cilia structure in the respiratory tract is defective?
it can lead to accumulation of mucus secretions
How can infertility arise in women?
defective cilia in the fallopian tube
Give examples of conditions that may arise in the case of defective cilia
- immotile-cilia syndrome
- situs inversus
- male sterility
What is the nucleus made up of?
- nuclear envelope
- nucleoplasm
- nucleoli
- chromatin/chromosomes
What are the 2 forms of chromatin?
- heterochromatin - compact form that does not facilitate gene activity
- euchromatin - open form that facilitates gene activity
What is the nucleolus?
production site of ribosomal subunits and rRNA
What are the 5 parts of the mitochondria?
- outer mitochondrial membrane
- inner mitochondrial membrane
- intermembrane space
- cristae (space formed by infoldings of the inner membrane)
- matrix (space within the inner membrane)
What do F1 particles do?
function in the synthesis of ATP from ADP + Pi comprising 15% of total inner membrane proteins
What are functions of the mitochondria?
- release of energy via TCA cycle or ETC
- heat production
- storage of cations
- regulate cell proliferation and programmed cell death
- some degradation functions e.g. fatty acid β-oxidation
- contains the mitochondrial genome (which is transmitted from mothers to offsprings)
What are functions of the ER?
- protein synthesis
- protein modification
- protein folding
- protein quality control
- protein sorting into those for transport to other organelles or those meant for export out of the cell
- limited proteolysis of newly synthesised proteins
What is the RER?
a tubular structure with a phospholipid bilayer continuous with the nuclear membrane (has ribosomes on surface)
What are the 3 fates of vesicles delivered to the Golgi body from the RER?
- incorporated into the cell membrane
- secretory protein
- lysosomal protein
Give examples of organs rich in RER
- exocrine pancreas
- goblet cells in GIT
- plasma cells
- nissil bodies in neurons
What are functions of the SER?
- lipid synthesis
- steroid synthesis
- breakdown of endogenous and exogenous compounds
Give examples of organs rich in SER
- testis
- ovaries
- adrenal cortex
Where is the Golgi apparatus?
between the ER and the cell membrane
What are functions of the Golgi apparatus?
- protein modification
- concentration, packaging and sorting of proteins
- delivery of proteins to correct destination
What is the Golgi body complex?
a disc-shaped membrane-defined cristae arranged like a stack
What are the 2 faces of the Golgi body?
- cis - near the RER, thinner forming face
- trans - near the cell membrane, maturing face
What do secretory vesicles contain?
protease enzymes that cut and modify secretory proteins at a specific amino acid position, resulting in their activation
What is the function of lysosomes?
intra-cytoplasmic digestion of waste
What is O-linked glycosylation?
when a glucose molecule is added to the oxygen molecule on a serine or threonine residue of the newly formed protein
Give examples of hydrolytic enzymes
- nucleases
- lipases
- proteases
- glycosidases
- acid phosphatases
What do proton ATPases do in the lysosomal membrane?
pump protons into the lysosomal lumen which lowers the pH to ~5 which is optimal for most enzymes
What are the 3 processes that bring molecules into the lysosomal cell?
- receptor mediated endocytosis
- phagocytosis
- autophagy
What are lipofuscin molecules?
a pigment left over from the breakdown and absorption of damaged blood cells
How do neutrophils release enzymes into the ECM?
by eating the bacteria and digesting it with lysosomal enzymes and later spitting out the bacterial antigens into the ECM to alert the immune/lymphatic system to take care of the infection
What is autolysis?
the cell eating itself when there is extensive cellular damage beyond repair
What is apoptosis?
programmed cell death
What is a peroxisome?
a membrane bound organelle that contains enzymes, proteins, and liquid
What are peroxisomes involved in?
- β-oxidation of very long chain fatty acids
- α- oxidation of branched-chain fatty acids
- catabolism of amino acids and alcohol
- synthesis of bile acids
- synthesis of plasmalogens which are important membrane phospholipids especially in white matter of brain
- conversion of reactive oxygen species e.g. hydrogen peroxide (H2O2) to safer molecules
