chapter 2 - sub cellular structures brain dumps

Question 1

list everything you know about the Nucleus

Answer 1

• surrounded by a nuclear envelope, double membrane
• perforated with nuclear pores
• nucleolus = densely stained structure where ribosomal RNA is produced
• chromatin- when a cell is not dividing, chromosomes form chromatin (long entangled structures)

Question 2

list everything you know about lysosomes

Answer 2

-single membrane, glycoslated membrane transport proteins attached
- apparent in ALL cells
- lipid layer inside
- filled with a hydrolytic enzyme mixture (digestive, low pH)
- function = break down foreign particles, old/damaged cells and excess organelles
- abundant in white blood cells
- 1um

Question 3

list everything you know about chloroplasts

Answer 3

• 6-10 um long
• double membrane
• “stroma” liquid fills the chloroplast
• contains stacks of “thylakoid membranes” called “grana”
• Thylakoid membranes are the site of photosynthesis stage 1

Question 4

list everything you know about ribosomes

Answer 4

-2 units combine in cytoplasm (small and large sub-unit)
- 22 nm long in eukaryotic, 18nm long in prokaryotic
made in nucleus - from ribosomal RNA and proteins
- RER attached - synthesize proteins for outside the cell
- FREE - synthesize proteins for inside the cell

Question 5

list everything you know about the vacuole

Answer 5

• single membrane called “tonoplast”
• function = water storage & hold food for later use or waste removal
• “cell sap” watery solution of sugars, enzymes and pigments
• permanent only in PLANT cells
• when full of “cell sap” vacuole is “turgid”

Question 6

list everything you know about the cell wall

Answer 6

• made of - plants = cellulose
  fungi = chitin
  bacteria = peptidoglycan
• pores are “plasmodesmata”
  (connect 2 cells by their cytoplasm)
• pores speed up exchange of substanes by avoiding passing through walls
• functions= maintain cell structure
  = carbohydrate store

Question 7

list everything you know about the endoplasmic reticulum

Answer 7

• double membrane
• forms an extensive system of membranes
• smooth ER - contains enzymes for the production of lipids
• rough ER - continuous with nuclear envelope, encrusted with ribosomes for protein synthesis
• contains cavities made of cisternae

Question 8

list everything you know about the Golgi apparatus

Answer 8

• double membrane
• stack of flattened (double membrane) cisternae
• one end forms new vesicles
• other end modifies, sorts and packages molecules for transport
• some Golgi vesicles are “lysosomes”

Question 9

list everything you know about mitochondria

Answer 9

• double membrane
• 2-5um long
• inner membrane is coated in enzymes which catalyse reactions of aerobic respiration to produce ATP (an organic compound that captures energy to release it to fuel other cellular processes)
• inner membrane folds inwards forming “CRISTAE”
• the “MATRIX” is the liquid projected by the cristae (contains enzymes, proteins, mitochondrial DNA and other molecules to catalyse reactions)

Question 10

what properties would a solution need to have to prevent damage to organelles? (3)

Answer 10

ice cold - prevent enzyme activity

buffered to prevent denaturing of enzyme/protein

same water potential to prevent lysis/ bursting of organelle.

Question 11

list everything you know about the cytoskeleton

Answer 11

function- holds organelles in place, controls movement of the cell and movement of organelles within the cell.
3 components
1. microfilaments - contractile fibres formed from the protein ACTIN

2. microtubules - globular tubulin proteins polymerise to form a scaffold-like structure that determines the shape of a cell.
3. intermediate fibres - give mechanical strength to cells

also contains centrioles - present in eukaryotes (apart from flowering plants and most fungi) composed of microtubules