THE CELL

Question 1

NUCLEUS

Answer 1

• where genetic info stored
• controls cellular structure + activities
• double membrane that forms the nuclear envelope
• holds codes for synthesis of 10,000 different proteins

Question 2

NUCLEOLUS

Answer 2

region where rRNA synthesis takes place

Question 3

NUCLEAR ENVELOPE

Answer 3

• 2 phospholipid bilayers

- nuclear pores to control passage in + out of nucleus

Question 4

RIBOSOMES

Answer 4

• protein synthesis machinery
• links amino acids together under instruction of mRNA
• non-membranous organelles
• found in ALL cell types
• protein synthesis requires all RNA types
• free in cytoplasm or associated with internal membranes
• consists of 2 subunits (small + large) which join together in cytoplasm to form functional unit

Question 5

ENDOPLASMIC RETICULUM

Answer 5

• extensive series of membrane bound channels (cisterns)

Question 6

ROUGH ENDOPLASMIC RETICULUM

Answer 6

• lies adjacent to nucleus
• attachment of ribosomes
• synthesis of proteins to be secreted, sent to lysosomes or plasma membrane

Question 7

SMOOTH ENDOPLASMIC RETICULUM

Answer 7

• extends from the rough ER
• synthesis of fatty acids + steroids
• stores calcium
• detoxification

Question 8

GOLGI APPARATUS

Answer 8

• flattened stacks of interconnected membranes
• packaging + distribution of molecules
• vesicles transport molecules to destination

Question 9

VACUOLE

Answer 9

• store nutrients for cell energy
• store waste products prior to expulsion
• membrane that surrounds fluid

Question 10

VESICLES

Answer 10

• fluid enclosed by lipid bilayer membrane
• can from during exocytosis, phagocytosis + endocytosis
• for transport of materials within cytoplasm
• involved in metabolism, transport + enzyme storage

Question 11

LYSOSOMES

Answer 11

• membrane bounded digestive vesicles
• arise from Golgi apparatus
• destroy cells or foreign matter that the cell has engulfed by phagocytosis
• involved in autophagy

Question 12

MITOCHONDRIA

Answer 12

• found in ALL types of eukaryotic cells
• cell’s powerhouse
• bounded by membranes (outer, intermembrane space, inner, matrix)
• metabolise sugars to make ATP
• have their own DNA + ribosomes

Question 13

CYTOSKELETON

Answer 13

• network of protein fibres found in all eukaryotic cells
• supports shape of cell
• keeps organelles in fixed locations

Question 14

CELL FIBRES

Answer 14

• MICROFILAMENTS
• MICROTUBULES (largest)
• INTERMEDIATE FILAMENTS

Question 15

CENTROSOME

Answer 15

• region surrounding nucleus in most animal cells
• specialised units are centrioles
• microtubule organising centre

Question 16

CELL MEMBRANE FUNCTIONS

Answer 16

• defines cell boundary
• regulates what moves in + out of the cell
• supports cell
• allows cell signalling + cell recognition

Question 17

MEMBRANE STRUCTURE

Answer 17

1. PHOSPHOLIPIDS
   - arranged in bilayer (~50%)
2. proteins
   - inserted in bilayer (~50%)
3. cholesterol
   - makes membrane less permeable to hydrophilic molecules

hydrogen bonding of water holds the 2 layers together, fluid structure

Question 18

DESCRIBE MEMBRANE

Answer 18

• not static
• active
• move against each other
• proteins move in + out constantly
• phospholipids mostly move laterally

Question 19

WHAT ALLOWS PHOSPHOLIPIDS TO FORM MEMBRANES?

Answer 19

• polar hydrophilic heads
• non-polar hydrophobic tails

the charges allow phospholipids to form membranes

Question 20

MEMBRANE PROTEIN FUNCTIONS

Answer 20

• transporters
• enzymes
• cell surface receptors
• cell surface identity markers
• cell-to-cell adhesion proteins
• attachments to cytoskeleton

Question 21

MEMBRANE PORES

Answer 21

• extensive non-polar regions within transmembrane protein can create a pore in membrane
• interior is polar to allow water + small polar molecules to pass through

Question 22

3 MAIN PARTS OF A CELL

Answer 22

• plasma membrane
• nucleus
• cytoplasm

Question 23

WHY IS NUCLEUS KNOWN AS CONTROL CENTRE?

Answer 23

• stores all genetic info needed to control protein synthesis
• proteins essential to structure + function of cells
• controlling their synthesis means nucleus controls cellular operations

Question 24

WHY ARE PROTEINS SYNTHESISED BY RIBOSOMES ATTACHED TO ER DIFFERENT FROM UNATTACHED RIBOSOMES?

Answer 24

• attached synthesise proteins for use in specific organelles, plasma membrane or exportation
• unattached/ ‘free’ synthesise proteins for use within cytosol

Question 25

WHERE IS TESTOSTERONE SYNTHESISED?

Answer 25

steroid synthesised in the smooth ENDOPLASMIC reticulum

Question 26

3 DESTINATIONS OF PROTEIN PACKED BY GOLGI APPARATUS

Answer 26

1. insertion into plasma membrane 2. insertion into organelle member 3. removal (by exocytosis) from cell for use elsewhere in body

Question 27

WHAT DOES IT MEAN IF CELL HAS MANY MITOCHONDRIA?

Answer 27

- high energy requirement - high work load - e.g. skeletal muscles or light receptor cells

Question 28

WHY IS IT ESSENTIAL FOR LYSOSOMES TO HAVE MEMBRANES?

Answer 28

so powerful they could destroy the cell

Question 29

SECRETORY VESICLES

Answer 29

transports protein out of cell via exocytosis

Question 30

MEMBRANE VESICLES

Answer 30

carries new molecules to the plasma membrane

Question 31

TRANSPORT VESICLE

Answer 31

carries molecules to other intercellular destinations e.g. lysosomes

Question 32

MAIN COMPONENTS OF PLASMA MEMBRANE

Answer 32

- phospholipid - cholesterol - glycolipid - protein