Microscopy and Cell structure

Question 1

Define the limit of resolution

Answer 1

The minimum distance two objects can be distinguished at

Question 2

What is limit of resolution proportional to?

Answer 2

Wavelength

Question 3

What is the theoretical limit of resolution for a light microscope?

Answer 3

0.2 micrometres

Question 4

What is the theoretical limit of resolution for an electron microscope?

Answer 4

0.002nm

Question 5

What feature of the phospholipid bi layer structure makes it selective, and in what way?

Answer 5

Phospholipid molecules are ampipathic - Hydrophillic phosphate groups on outside, hydrophobic lipids on inside. This means they are relatively impermeable to most water soluble molecules.

Question 6

What feature of phospholipid bilayer allows it to mediate the majority of its functions?

Answer 6

Protein molecules dissolved within the membrane

Question 7

What is the structure of the golgi?

Answer 7

Saucer shaped stacks of cisternae

Question 8

How do vesicles get to golgi, and where do they fuse?

Answer 8

Bud off from Rough Endoplasmic reticulum and fuse with the convex cis face of the golgi body

Question 9

What feature of golgi bodies allows proteins to move through it?

Answer 9

Its polarity

Question 10

In which direction do protein migrate through golgi?

Answer 10

From convex cis phase to the the concave trans face of the stack

Question 11

What are the four function of the golgi?

Answer 11

Modify, sort, concentrate and package proteins synthesised on rough endoplasmic reticulum

Question 12

What two destinations do vesicles budding from the golgi have?

Answer 12

Either lysosome assembly or secretion

Question 13

What is the glycocalyx, and what is their function?

Answer 13

The cell “coat made up of oligosaccharide and polysaccharide side chains on the outiside of the plasma membrane Give the cell specificity

Question 14

What are the 7 functions of the plasma membrane of a cell?

Answer 14

Selective permeability Transport of materials along the cell surface Endocytosis Intracellular recognitio Exocytosis Signal transduction Intercellular adhesion

Question 15

What are the major functions of the nucleus?

Answer 15

1) Stores the cells DNA 2) It coordinates the cell’s activities, metaolism, growth, protein synthesis an mitosis

Question 16

What does most of the nuclear material consist of, and what does it form during mitosis?

Answer 16

Chromatin, the unstructured for of the cell’s DNA. Organises to form chromosomes during mitosis.

Question 17

What is the function of nuclear pores withing the nuclear envelope?

Answer 17

They allows specific types and sizes of molecules to pass back and forth between the nucleus and cytoplasm.

Question 18

What is the nuclear membrane attached to?

Answer 18

A series of tubules called the endoplasmic reticulum

Question 19

What is hte function of the nucleolus?

Answer 19

An organelle that synthesises protein producing macromolecular structure called ribosomes.

Question 20

What is the function of ribosomes?

Answer 20

Site of translation and also the unit used for protein synthesis.

Question 21

When does a ribosome bind to RER?

Answer 21

When it begins to synthesis a protein destined for the secretory pathway

Question 22

Give two major functions of the RER

Answer 22

Lsosomal enzymes with a mannose-6-phosphate marker added in the cis-golgi network Secreted proteins, either secreted constitutively or regulated Initial glycosylation - N linked

Question 23

What cells are smooth ER found in and what are their functions?

Answer 23

iver and mammary gland, and in the ovaries testes and adrenal glands Assist in lipid and steroid synthesis

Question 24

What do lysosomes contain, and how do they protect themselves against their contents?

Answer 24

They contain acid hydrolysases at pH 5. Lysosomal membrane proteins are highly glycosylated for protection from these enzymes.

Question 25

What do primary lysosomes fuse with?

Answer 25

Membrane bound vesicles, autophagosomes (defunct organelles) or with excess secretory product to form secondary lysosomes in which contents are degraded. 

Question 26

What do peroxisomes do?

Answer 26

Major site of oxygen utilisation and H202 production

Question 27

What utilises H202 produced from peroxisomes, and to what effect? 

Answer 27

Enzyme catalase utilises H202 to oxidise other substancs such as alcohol (half alcohol we drink oxidsed to acetaldehyde)

Question 28

What is interesting about peroxisome reproduction?

Answer 28

Self replicating, but no genome of their own

Question 29

Why are peroxisomes most present?

Answer 29

In kidney tubules and liver parenchymal cells, where they detoxify toxic molecules in blood stream

Question 30

What is the structure of a mitochondrion? 

Answer 30

Double membrane with innermembrane thrown into distincy folds called cistae which are usually lamellar

Question 31

What is the primary function of mitochondria?

Answer 31

Generation of energy rich ATP molecules by oxidative phosphorylatoion

Question 32

What are the main substrates of mitochondria?

Answer 32

Glucose and fatty acids

Question 33

What does the matrix of mitochondria contain? 

Answer 33

Enzymes involved in krebs and fatty acid cycles, DNA, RNA, ribosomes and calcium granules

Question 34

How can mitochondria divide?

Answer 34

Have their own genetic material

Question 35

Where do humans inherit mitochondria from?

Answer 35

Maternal line

Question 36

Give four functions of a cell cytoskeleton

Answer 36

Structural support or the plasma membrane and cell organelles Means of movement for organelles, plasma membrane and other cytosol constituents Locomotor mechanisms for amoeboid movements (e.g lymphocytes) and for cilia and flagella Contractability in cells of spcialised tissues (muscles) 

Question 37

Give four features of microfilaments

Answer 37

5nm diameter Two strings of actin twisted together Associated with ATP (contractile) Cann assemble and dissociate (dynamic)  

Question 38

Give four features of intermediate filaments

Answer 38

Not dynamic 10-12 nm diamete Common in nerve and neurological cells Also common in epithelial cells that are made of cytokeratin. Form tough suporting meshworks in cytoplasm.

Question 39

Give four features of microtubules

Answer 39

Thirteen alpha and beta subunits polymerise to form wall of the hollow microtubules They originate from the centrosome Found at sites where structures in cells are moved (mitotic spindle, for instance) Attachment proteins can attach to organelles and move them along the microtubule (movement of chromosomes along mitotic spindles - classic example)