The Cell and its Organelles

Question 1

Cell definition

Answer 1

the basic structural and functional unit of all living things

Question 2

Functional characteristics of cells

Answer 2

1. cell metabolism and energy use
2. synthesis of molecules (lipids, phospolipids, DNA, RNA, proteins) for normal cell functioning
3. communication with other cells through chemical/electrical signals
4. reproduction and inheritance

Question 3

Plasma membrane

Answer 3

More a structure than an organelle

• encloses and supports cellular contents
• controls what goes in and out of cell
• involved in intercellular communication
• “security gate”

Question 4

Plasma membrane: structure

Answer 4

• lipid bilayer, phospholipids and cholesterol (45-50%); provides flexibility
• carbohydrates (4-8%)
• glycocalyx (outer surface of cell membrane)
  
  • glycoproteins (carbohydrates and proteins)
  • glycolipids (carbohydrates and lipids)
  • carbohydrates
    Cytoplasm - cellular fluid outside the nucleus but within the plasma membrane;
    contains organelles, cytosol (ions, molecules, proteins)

Question 5

Cytosol

Answer 5

Fluid portion of cytoplasm; water containing ions and proteins
- cytoplasmic inclusions - aggregates of chemicals (melanin, glycogen)
- cytoskeleton - support cell, gives shape, movement of organelles
Microtubules, microfilaments, intermediate filaments - provides structural support, mechanical strength

Question 6

Nucleus

Answer 6

“control centre” - most prominent structure when viewed
DNA is code fro structural and functional characteristics
Structure - nuclear envelope; bilayer membrane surrounding nucleus (porous)
> holds nucleus together; covered in nuclear pores - facilitates movement of molecules

Question 7

Nucleoplasm

Answer 7

cytoplasm in the nucleus

Question 8

Nucleolus

Answer 8

produces ribosomes

Question 9

Ribosomes

Answer 9

Site of protein synthesis

Found in nucleus, nucleolus, cytoplasm

Question 10

Ribosomes: structure

Answer 10

2 subunits - one large, one small

Can float freely, may be attached to endoplasmic reticulum (membrane bound)

Question 11

Endoplasmic reticulum

Answer 11

Rough ER - synthesises and modification of proteins
Smooth ER - site of lipid and steroid and carbohydrate synthesis; detoxification of harmful substances,; breakdown of glycogen to glucose

Question 12

Endoplasmic reticulum: structure

Answer 12

flattened interconnecting sacs and tubules
Rough ER - with ribosomes
Smooth ER - without ribosomes

Question 13

Golgi apparatus

Answer 13

Modifies, packages and distributes proteins and lipids made in rough ER

Question 14

Golgi apparatus: structure

Answer 14

Flattened membranous sacs with cisternae; secretory vesicles

Question 15

Lysosomes

Answer 15

Contains enzymes; digests unneeded molecules (nucleic acid, proteins, lipids, carbohydrates)

Question 16

Lysosomes: structure

Answer 16

Membrane-bound vesicles formed at the Golgi apparatus

Question 17

Mitochondria

Answer 17

Provides energy for “factory” to run; produces ATP

Question 18

Mitochondria: structure

Answer 18

Smooth outer membrane, intermembrane space, inner membrane, matrix (space between folds)

Question 19

Centrioles

Answer 19

Assists in mitosis - produces spindle fibres

Question 20

Centrioles: structure

Answer 20

Barrel-shaped organelles orientated at right angles to each other
Made of microtubule proteins (wall)
Two centrioles can be found in centrosome (cell’s centre)

Question 21

Cilia

Answer 21

Move substances across outer surface of cells

Question 22

Cilia: structure

Answer 22

Whip-like, motile cellular extensions which project from outer surface of certain cells

Question 23

Flagella

Answer 23

Move the cell independently

Question 24

Flagella: structure

Answer 24

Similar to cilia but longer; only found on sperm cells

Question 25

Microvilli

Answer 25

Increase the suface area

Absorptive cells of intestine, kidney tubules

Question 26

Microvilli (structure)

Answer 26

Extension of the plasma membrane
Each cell has many
Non-motile