Tushar 1.2 - Organelles

Question 1

Nucleus

Answer 1

• nucleolus: where ribosomes are made
• nuclear pores for transport of molecules
• nucleus contains genetic material
• has double membrane
• chromosomes present during cell division, orelse chromatin
• DNA wrapped around histone proteins

Question 2

Rough endoplasmic reticulum

Answer 2

• flattened membrane sacs called cisternae that have ribosomes (80s) to make proteins
• proteins made here are for the membrane or other cells
• proteins made eventually bud off in a vesicle to leave the rER
• ER is continuous with the nuclear envelope (membrane)
• summary: produces and transports proteins

Question 3

What do vesicles do

Answer 3

Move material within cell

Question 4

Golgi apparatus

Answer 4

Made of cisternae (flattened membrane sacs)

• collects, modifies, processes the protein from rER and then protein is released in another vesicle
• these vesicle with protein are carried to the membrane for secretion (exocytosis)

Question 5

Smooth endoplasmic reticulum

Answer 5

• has many enzymes on surface
• produces lipids and phospholipids (for cell membrane)
• in liver cells, toxins broken down here

Question 6

Lysosomes

Answer 6

Have hydrolytic enzymes that break down proteins, carbs, lipids and old organelles
- can digest pathogens engulfed by phagocytosis

Question 7

Free ribosomes

Answer 7

• not membrane bound
• made in nucleus
• site of protein synthesis
• prokaryotes: 70s, eukaryotes: 80s

Question 8

Mitochondria

Answer 8

• site of aerobic respiration
• have double membrane, own DNA and ribosomes
• inner membrane is folded to increases SA, these folds are called cristae
• fluid inside called matrix
• fat also digested here if being used as an energy source in cell

Question 9

Chloroplast

Answer 9

• site of photosynthesis
• double membrane, own DNA and ribosomes
• stacks of thylakoid disks inside which contain chlorophyll (absorb light).
• thylakoid made out of flattened membrane
• stroma is fluid portion
• starch grain present in high rates of photosynthesis
• 1 stack of thylakoids is granum

Question 10

Vacuole

Answer 10

Single membrane with fluid, water, salt, proteins,…
- plant vacuoles = large, helps make cell turgid
vesicle = small vacuole used for transport within cell

Question 11

Microtubules and centrosome

Answer 11

• found near nucleus
• centrioles inside centrosomes (there are 2 centrioles)
• centrioles made of 9 microtubules
• microtubules move chromosomes during division and centrioles form an anchor point for the microtubules
• plants dont have centrosome, they can also divide without centrioles

Question 12

Cilia and flagella

Answer 12

• flagella larger
• both used for locomotion
• cilia can create current and move fluid