Cell Biology 3

Question 1

Why is membrane transport important ?

Answer 1

• vital for life
• acts as a barrier to polar molecules
• allows distinct microenvironment to exist
• must allow selective transport of molecules/ions

Question 2

Passive Diffusion

Answer 2

• simplest
• no proteins involved
• occurs in protein free synthetic lipid bilayers
• molecules ions move in thermodynamically most favourable direction
• passive diffusion is often too slow to support life
• facilitated and active transport involves proteins
• facilitated occurs down conc gradient
• active can pump against conc gradient

Question 3

Carrier Proteins

Answer 3

• bind to specific nutrient’s and other solutes
• have moving parts
• proteins undergo shape changes
• solute transferred to other side of membrane

Question 4

channel proteins

Answer 4

• do not need to bind to solute
• for hydrophilic pores across bilayer
• pores often open and close
• pore is specific due to size and charge
• transport is faster compared to carrier proteins

Question 5

Protein transport

Answer 5

• genes to proteins
• transcription
• splicing
• translation

membrane and secretory proteins are manufactured on the rough ER

Question 6

Endoplasmic reticulum

Answer 6

• site of membrane and secretory protein synthesis
• large internal membrane network
• continuous with outer membrane of the nuclear envelope
• space inside = lumen
• two types of are er and rer

Question 6

Peroxisomes

Answer 6

• peroxisomes are used to carry out detoxifying reactions as well as other oxidation reactions such as beta oxidation of very long chain fatty acids.
• peroxisomes get their proteins by transmembrane transport.

Question 7

Golgi Apparatus

Answer 7

• collection of flattened discs
  -each eukaryotic cell has one golgi apparatus
• molecules travel through the golgi stack via transport molecules

Question 8

functions of the Golgi

Answer 8

• packaging and processing macromolecules for secretion or delivery to other sites in the cell but not nucleus, mitochondria and peroxisomes.

Question 9

Mitochondria

Answer 9

• obtaining energy from food
• oxidative phosphorylation
• cell biology in human disease
• power house of the cell
• contains its own circular DNA and ribosomes that resemble those of bacteria
• surrounded by a double membrane
• outer membrane is smooth and continuous
• inner membrane has numerous folds and projections called cristae

Question 10

Human diseases associated with organelles

Answer 10

• mitochondrial disorder
• lysosomal storage diseases
• peroxisomal disorders
• ER - PROTEIN folding disorder