Cell Ultrastructure Flashcards
(28 cards)
Why are electron microscopes capable of a higher limit of resolution than light microscopes?
Electron microscopes use the wavelength of electrons (0.004nm) which is much smaller than the wavelength of visible light used by light microscopes (0.7μm)
What is the average size of an animal cell?
10-20μm
What structure within the cell has the largest membrane area?
(Rough) endoplasmic reticulum
What composes the majority of the cell volume?
Cytosol
What is the cytoskeleton?
Complex network of interlinking fibres that extend throughout the cytoplasm
What is meant by the phospholipids within the plasma membrane being ‘amphipathic’?
Have both polar (hydrophilic) and non polar (hydrophobic) regions
What are the functions of the plasma membrane?
- Selective permeability
- Transport of materials along cell surface
- Endo/exocytosis
- Intercellular adhesion and recognition
- Cell signalling
What is the role of the smooth endoplasmic reticulum?
Lipid biosynthesis and steroidogenesis
Where would you find cells that contain smooth ER?
- Liver
- Mammary gland
- Adrenal glands
- Ovaries/testes
What is the role of the RER?
Protein synthesis and modification
Describe the structure of the Golgi apparatus
- Stacks of flattened membrane with surrounding vesicles
- cis and trans ends (cis end receives vesicles from the RER and trans end secretes vesicles either to plasma membrane, RER or lysosomes)
What is the role of the Golgi apparatus?
Modification, sorting, processing and packaging of proteins synthesised in RER
How do lysosomes appear when stained?
- Dark staining
- Contain many hydrolytic/digestive enzymes
What is a secondary lysosome?
Phagosome fused with a lysosome to form a PHAGOLYSOSOME
What is the main role of peroxisomes?
DETOXIFICATION of molecules such as alcohol, phenols, forming acid and formaldehyde
Where are peroxisomes found?
Cells of LIVER and KIDNEYS
What are cristae?
Folds in the inner mitochondrial membrane which increase surface area for electron transporter proteins
Which of the mitochondrial membranes are impermeable to small ions?
Inner mitochondrial membrane
Where does the intermembrane space lie?
Between the outer and inner mitochondrial membranes of mitochondria
Where does the mitochondrial DNA genome lie?
Within the mitochondrial matrix
What is unusual about mitochondrial inheritance?
Maternal lineage only
How is genetic information passed on through mitochondria?
Mitochondria contain their own genetic information within the matrix and can divide in a similar way to bacteria
Why do mitochondria possess their own set of DNA?
Descendant from prokaryotes that invaded ancestral eukaryotes so contain their own DNA
Describe the distribution of actin filaments within an animal cell
Arranged around the edge of the cell underlying the plasma membrane