Cell Ultrastructure

Question 0

Describe the structure and function of lysosomes

Answer 0

Contain acid hydrolases of a pH approx. 5. Membrane protein is highly glycosylated for protection. Generated by golgi apparatus and residual bodies.

Question 1

Describe the structure and function of golgi bodies

Answer 1

Saucer shaped stacks of cisternae. Polar proteins migrate from convex face to the concave face. Sort, concentrate, package and modify proteins into vesicles

Question 2

Describe the structure and function of mitochondria

Answer 2

Double membraned, cristae are usually lamellar, generate ATP by oxidative phosphorylation, maternal lineage.

Question 3

Describe the structure and function of nucleolus

Answer 3

Site of rRNA synthesis, ribosomal sub units exported from nucleus disappear during cell division

Question 4

Describe the structure and function of nuclear envelope

Answer 4

Double layer of membranes, perinuclear cisterna between inner and outer nuclear membranes

Question 5

Describe the structure and function of nucleus

Answer 5

Contains DNA, nucleoproteins and RNA. Not present in erythrocytes, stratum corneum cells and lens fibre cells

Question 6

Describe the structure and function of peroxisomes

Answer 6

Granular matrix, single membrane, no genome, self replicating, detoxify molecules

Question 7

Describe the function of the plasma membrane

Answer 7

Intercellular recognition, intercellular adhesion, signal transduction, compartmentalisation, selective permeability, transport, endocytosis, exocytosis

Question 8

Describe the structure and function of cytoskeleton

Answer 8

Microfilaments - two strings of actin, dynamic therefore needs ATP
Intermediate filaments - not dynamic
Microtubules - 13 alpha/beta sub units, hollow microtubules originate from centrosome, found where structures need to be moved

Question 9

What is the limit of resolution for scanning electron microscopes?

Answer 9

10nm, shows the surface of cells

Question 10

What is the limit of resolution for a transmission electron microscope?

Answer 10

2nm, shows the ultrastructure of a cell

Question 11

Describe a phospholipid

Answer 11

Amphipathic, relatively impermeable to water soluble molecules

Question 12

Describe the structure and function of rough endoplasmic reticulum

Answer 12

Active synthesis of proteins (ribosomes), destined for cell exterior, lysosomes and cell membrane incorporation

Question 13

Describe the structure and function of smooth endoplasmic reticulum

Answer 13

Cisternae not as flattened as RER, less extensive in liver/mammary glands/ovaries/testes/adrenal glands, more scattered in the cytoplasm, lipid biosynthesis and intracellular transport.