Cell Structure

Question 1

Tight Junctions

Answer 1

Extracellular surfaces of two adjacent plasma membranes join together so that no extracellular space remains between them. Tight junctions occur in a band around the entire circumference of the cell.

Question 2

what are the two broad types of stem cells in mammals?

Answer 2

embryonic stem cells (isolated from inner cell mass of blastocytes)

adult stem cells (found in various tissues)

Question 3

what cells act as a repair system for adults?

Answer 3

stem cells
progenitor cells

Question 4

what stem cells can a developing embryo differentiate to?

Answer 4

germ layers which can then turn into all bodies, tissues and organs. can turn into all specialized cells.

Question 5

what is potency?

Answer 5

differentiation potential of the stem cell.

Question 6

characteristics of all cell types

Answer 6

surrounding membrane
protoplasm - cell contents in thick fluid
organelles - structure, for cell function.
control centre with DNA.

Question 7

prokaryotic cells

Answer 7

• lack a nucleus or membrane-bound organelles.
• the simplest types of cells
  -single circular chromosome
  -nucleoid region center, contains DNA.
  -surrounded by cell membrane + cell wall (peptidoglycan)
  -contains ribosomes (no membrane) in cytoplasm to make proteins
• one-celled organisms - bacteria.

Question 8

gram-positive

Answer 8

these bacteria have thick mesh-like cell walls made of peptidoglycan. stains purple e.g. gram positibe s.aures.

Question 9

gram-negative

Answer 9

these bacteria have thinner layer stains pink. e.g. gram-negative e.coli.

Question 10

eukaryotic cells

Answer 10

-membrane-bound nucleus
-divide cellular functions in organelles and the endomembrane system.
-cytoskeleton to support`