W3 - The Cell Flashcards
Discovery of the cell
Robert Hooke, 1665
Looked at a thin slice of cork through his 2-lens microscope.
= Discovered tiny, hollow structures + called them cells.
Who proposed the ‘cell theory’ and when?
Theodor Schwann
1839
What does the ‘cell theory’ state?
All organisms are made up of 1 or + cells
Cell is the basic unit of life, the smaller unit that shows all characteristics of life
All cells come from pre-existing cells.
Do prokaryotes have a distinct nucleus bounded by a membrane?
NO
Do prokaryotes have membrane bound organelles?
NO
What are plasmids?
Small circular extrachromosomal DNA mol
How many cells does the human body contain?
Around 37.2 trillion
Cytoplasm
Jelly like material in which organelles ‘float’
Cytosol
Soluble part left of the cytoplasm if all the organelles were removed.
What is the central dogma of molecular biology?
Flow of genetic info w/in a biological system.
What are the 3 processes of central dogma of molecular biology?
Replication
Transcription
Translation
Around how many genes do humans have?
25,000
Give examples of structural proteins
Collagen
Elastin
Keratin
Give examples of motility proteins
Actin
myosin
Tubulin
Give examples of storage proteins
Ovalbumin
Casein
Give examples of hormonal proteins
Insulin
Nerve growth factor (NGF)
What % of cellular ATP is made in the mitochondria by oxidative phosphorylation?
Just over 80%
Endosymbiotic theory
Mit were primitive bacterial cells.
Millions of years later… mit + eukaryotes became mutually beneficial.
NOW a permanent dependent relationship.
Mitochondria DNA
Circular
Comes only from the mother
How many genes roughly does mit DNA encode for?
37
Where are SER more prominent in?
Adrenal cortex (secreting steroid hormones)
Hepatocytes
Sarcoplasmic reticulum of muscle cells
Describe the Golgi apparatus
Stacks of membrane bound cistern between the ER + surface of cell.
Function of Golgi apparatus
Processing of proteins synthesised in the RER
What are ribosomes made of?
Protein
rRNA
What does the ribosome do to make new protein?
Clamps over tRNAs + mRNAs
What are the 3 main sites on a ribosome?
A
P
E
A site on a ribosome
Receives new tRNA
P site on ribosome
Receives peptide-bearing tRNA after peptide bond formation
E site on ribosome
Where tRNAs exit
What are the 4 major proteolytic systems?
Lysomomes - The ‘bulk’ protein breakdown
ATP dependent ubiquitin proteasome - protein breakdown
Calpains
Caspases
How are lysosomes created?
When early endoscopes from Golgi apparatus have hydrolytic enzymes added to them.
At what pH do lysosomes work best at?
Around 5
What are calpains?
Calcium activated degredated proteins.
What do calpains do?
Cleave + breakdown proteins in elevated levels of Ca2+
What are peroxisomes?
Membrane bound enzyme sacs
What do peroxisomes do?
Carry out oxidation reactions to prod H202. (Hydrogen peroxide)
+ oxidative reactions for uric acid, aa + FAs
What is the cytoskeleton?
Network of protein fibres
What are the functions of the cytoskeleton?
Mechanical strength
Locomotion
Remodelling
Chromosome separation in cell division
Intracellular transport of organelles
Cellular signalling
What are microfilaments in the cytoskeleton?
Linear polymers of actin subunits.
Characteristics of microfilaments in the cytoskeleton
Flexible
Strong
Resist buckling (compressive forces)
Resist filament fracture (tensile forces)
What are microtubules in the cytoskeleton?
Linear polymers of tubulin that act as conveyer belts in cells.
What do microtubules in the cytoskeleton do ?
Move vesicles, granules, organelles + chromosomes via special attachment proteins.
What do intermediate filaments in the cytoskeleton do?
W/stand mechanical stress.
What are focal adhesions?
Multi-protein structures forming mechanical links between intracellular actin bundles + extracellular substrate.
Large
Dynamic
Connects cytoskeleton of cell to ECM.
How many protein components do focal adhesions comprise of?
At least 150
What are signalling molecules (a.k.a ligands) ?
Mol that bind specifically to other mol i.e receptors.
Message carried by the ligands is relayed through a chain of chemical messengers in the cell.
Briefly lay out the signal transduction pathway
Ligand / extracellular signal mol
Receptor
Chemical messengers in cell to relay signal
Response
What is the result of a ligand binding to a cell-surface receptor?
Receptor’s intracellular domain changes shape.
= Sets off signalling events.
Is signalling nonlinear?
YES
