Cells

Question 1

What are the three types of cell junctions?

Answer 1

Tight junctions, desmosomes and gap junctions

Question 2

How do tight junctions work?

Answer 2

They fuse plasmalemma of adjacent cells to form a seal. In this way, they are a selective barrier. (found in intestinal epithelia)

Question 3

How do desmosomes work?

Answer 3

They strengthen connections between adjacent cells. They are resistant to twisting and bending. (found in skin epithelia).

Question 4

How do gap junctions work?

Answer 4

Allow cell to cell communication (connexions are channels).

Question 5

How does the basement membrane attach to cells?

Answer 5

Hemidesmosomes and focal adhesions

Question 6

What are integrins?

Answer 6

They are transmembrane proteins that attach cell cytoskeleton to extracellular matrix and sense whether adhesion has occurred. So they function as signal transducers as well as attachment.

Question 7

What are some problems with cell culturing?

Answer 7

Cells demonstrate contact inhibition, they behave and look differently, they demonstrate senescence.

Question 8

What is autocrine cell communication?

Answer 8

Cell releases substances that regulate it

Question 9

What is paracrine communication?

Answer 9

Cell releases substances that affect nearby cells.

Question 10

What is necrosis?

Answer 10

It is caused by cell injury and involves loss of functional control. Osmotic control lost, cell bursts. Tissue damage and inflammation is induced.

Question 11

What is apoptosis?

Answer 11

It is genetically programmed. Bcl-2 protein on mitochondria deactivated and induces caspase activation. They target specific proteins in nucleus to cause chromatin to be repackaged into apoptotic bodies that are phagocytosed.

Question 12

What is endocytosis?

Answer 12

Bulk transport into a cell. Vesicles formed once material is in the cell.

Question 13

What is exocytosis?

Answer 13

Secretion out of the cell

Question 14

What are some static cell types in the body?

Answer 14

• CNS
• Cardiac
• Skeletal Muscle

Question 15

What are some stable cell types in the body?

Answer 15

• Fibroblasts
• Endothelium
• Smooth Muscle

Question 16

What are some renewing cell types in the body?

Answer 16

• Blood
• Skin epithelium
• Gut epithelium

Question 17

Outline some differences in prokaryotes and eukaryotes?

Answer 17

No nucleus they have a plasmid, no mitochondria, they have specialisations e.g. flagella, pili, cell wall

Question 18

Describe mitochondrial DNA inheritance?

Answer 18

Circular, maternal lineage, no recombination (can be identical to siblings and mother).

Question 19

What are the four basic types of tissue?

Answer 19

Epithelial, muscle, nerve, connective tissue.

Question 20

Define epithelium and outline its functions

Answer 20

A tissue composed of cells that covers the external body surface and lines internal closed cavities and body tubes that communicate with the exterior. Epithelium also forms the secretory portions of glands and lines their ducts. In specialised epithelium functions as receptors for the special senses (smell, taste, hearing and vision).

Question 21

What are microvilli, stereovilli, cilia? Give examples of where they are found

Answer 21

Microvilli = intestine, kidney tubules

Stereovilli= particularly long microvilli- epididymis, sensory hair of ear

Cilia= motile cytoplasmic processes can beat in synchrony- tracheobronchial tract, oviducts

Question 22

What are the differences between rough and smooth ER?

Answer 22

Rough- ribosomes on flat cisternae

Smooth- no ribosomes and tubular shape (lipid biosynthesis and and steroid genesis function)

Question 23

What is the function of the golgi apparatus?

Answer 23

modify, sort, package proteins synthesised on the RER