Lecture 1 and 2 Flashcards
How much of the bilayer do phospholipids make up?
50%
What type of layer do electron microscopes show of the plasma membrane?
Trilaminar layer
Describe the appearance of the trilaminar layer.
Outer: electron dense
Central: electron lucent
What three parts make up the polar head of a phospholipid
Nitrogenous compound
Phosphate bridge
glycerol
How much of the nucleus does DNA make up?
20%
What protein does the nucleus contain?
Nucleoprotein
RNA
What are the two types of nucleoprotein?
Histone proteins
Non-histone proteins
What are non-histone proteins found in the nucleus?
Enzymes for synthesis of DNA and RNA
The nucleus is ____-genous
Heterogenous
What name is given to the electron dense areas of the nucleus?
Heterochromatin (inactive coiled chromatin)
What name is given to the electron lucent areas of the nucleus?
Euchromatin (DNA involved in RNA synthesis)
Cells involved in highly active protein synthesis contain
Dense nucleoli
What does the nucleolus consist of?
RIbosomes and ribosomal RNA
Where is the nucleolus constructed? Where is it transported to?
Nucleolus
Cytoplasm
What happens in the RER?
Proteins fold into their tertiary structure, proteins exported
What is the RER?
System of flattened tubules covered with ribosomes
What is the SER?
Continous with and similar to RER but no ribosomes
What occurs in the SER?
Synthesis of lipids and membranes, membrane repair
Where is the SER prominent?
Cells which discrete lipid/steroids: liver, steroid-secreting cells of adrenals/gonads
What is the structure of the golgi?
4-6 saucer shaped stacked membrane bound cisternae
What is the function of the golgi?
Modification of proteins (glycolisation of proteins, package proteins into secretory granules)
What occurs in the mitochondria?
Energy production by oxidative phosphorylation
What are the four compartments of the mitochondria?
Outer membrane, inner membrane, matrix, intermembranous space
Why is the outermembrane of the mitochondria permeable?
Due to porin
What does the inner membrane of the mitochondria fold into?
Christae (increases surface area for reactions to take place on)
What does the mitochondrial matrix have?
Contains matrix granules
Binds Ca++
What does the intermembranous space of the mitochondria contain?
Enzymes
Why is the mitochondria unusual?
- Contains 1 or more strands of circular DNA
- Undergo self-replication
What is the name of the theory that mitochondria are derived from bacteria?
Endosymbiotic theory of mitochondria
How can the mitochondria be visualised under a microscope?
Cytochemical stain for cytochrome oxidase (involved in pathway)
Where are fatty acids and triglycerides made?
Cytosol
Where are cholesterol and phospholipids made?
sER
How can lipids be stained?
Frozen, stained with osmium tetroxide (stains black)
What is the diameter of microfilaments?
5-9nm
What is the most abundant protein in eukaryotic cells?
Actin (5%)
What is the structure of a microfilament?
Two-stranded helical polymer of G-actin protein
How many types of actin do mammals have?
6
What groups are mammals actin classified into?
Alpha (muscle cells/muscle differentiation)
Beta
Gamma
What is the diameter of a microtubule?
25nm
What is the shape of a microtubule?
Hollow cylinder
What is tubulin made of?
Alpha and beta tubulin (heterodimer)
Why do microtubules have a polar structure?
Each heterodimer is in the same orientation
Where do mictotubules extend from?
The centrosome
What motor proteins achieve movement along a microtubule?
Dynein and kinesin
What is the diameter of intermediate filaments?
10nm
What is the structure/shape of intermediate filaments?
Elongated rope-like fibrous molecules
What do intermediate filaments form?
Extensive netwoek around nucleus and out to cell periphery, spanning cytoplasm from one cell-cell junction to another
How many types of intermediate filaments are there?
More than 50
What are the three classes of intermediate filament?
Keratin filaments (cytokeratins)
Vimentin and vimentin related filaments
Neurofilamets
Where are cytokeratins found?
Epithelial cells
Where is vimentin and vimentin-related filaments found?
Cells of mesodermal origin
Where is the study of intermediate filament useful?
Diagnosis in histopathology
