Lesson 28 - Organelles and their functions

Question 1

what are the main parts of a eukaryotic cell?

Answer 1

Nucleus
Mitochondria
Chloroplast
Endoplasmic Reticulum
Golgi Apparatus
Lysosomes
Ribosomes
Vacuole
Cell Wall

Question 2

what is the function of the nucleus?

Answer 2

• Contains the organism’s genetic material (in the form of DNA - chromosomes)
• Acts as the control centre of the cell - controls the cell’s activities (through controlling proteins synthesis)

Question 3

what is the function of the mitochondria?

Answer 3

• Site of aerobic respiration
• Produce ATP as a product of respiration (used by cells as an immediate source of energy)
• Therefore, cells with a high level of metabolic activity that require a lot of ATP (muscle cells) have lots of large mitochondria

Question 4

what is the function of the chloroplasts?

Answer 4

Contains chlorophyll for absorption of light for photosynthesis (converts light energy to chemical energy - photophosphorylation - produces ATP)

Question 5

what is the function of the Endoplasmic Reticulum?

Answer 5

There are two types of ER:
- Rough ER (RER) - synthesis & transport of proteins
- SmoothER (SER) - synthesis & transport of lipids and carbohydrates

Question 6

what is the function of the Golgi Apparatus?

Answer 6

• A stack of membranes that form flattened sacs, called cisternae, which collect, modify and transport proteins (often adding non-protein components)
• Proteins, lipids and carbohydrates produced in the ER enter and are passed through the golgi apparatus
• The proteins are then ‘labelled’, to be sent to their correct destination
• The modified proteins are transported in golgi vesicles (which are regularly pinched off from the ends of the cisternae) to their destination

Question 7

what is the function of the Lysosomes?

Answer 7

• Hydrolyse material taken up by cells (phagocytic cells)
• Release enzymes to the outside of the cell in order to destroy external material
• Digest old, worn out organelles for recycling
• Break down of cells that have died

Question 8

what is the function of the nucleus?

Question 9

what is the function of the nucleus?

Question 10

what is the function of the ribosomes?

Answer 10

The site of protein synthesis

Question 11

What are some parts of a mitochondria?

Answer 11

70S ribosomes (ribosomes in eukaryotic cells are 80S)
matrix (similar to a cytoplasm)
DNA
Cristae (inner folds of the matrix)
Granules
inner and outer membrane
intermembrane space

Question 12

Description of the nucleus?

Answer 12

• Largest most prominent organelle
• Usually spherical and about 10-20 micrometers in diameter

Question 13

Description of the mitochondria?

Answer 13

Usually rod-shaped and around 1-10 micrometers long

Question 14

Description of the chloroplast?

Answer 14

• Typically disc shaped
• Usually 2-10 micrometers long and 1 micrometer wide
• Contains DNA and ribosomes so they can easily manufacture some of the proteins needed for photosynthesis

Question 15

Description of the endoplasmic reticulum?

Answer 15

• A 3D system of membranes that spreads throughout the cytoplasm of a cell
• The membranes form a network of tubules and flattened sacs called cisternae
• It is continuous (attached to) the outer nuclear membrane

Question 16

Description of the lysosome?

Answer 16

Form when vesicles that bud off the golgi apparatus contain hydrolytic enzymes (eg. lysozymes) for breaking down/hydrolysing old/unwanted material

Question 17

Description of the ribosome?

Answer 17

• Small granules found in all cells
• Occur in large numbers (can be almost 25% of the dry mass of the cell)
• They may either be found in the cytoplasm or be attached to the rough ER
• They have 2 subunits - a large and small
• Made of ribosomal RNA and protein
• 2 types:
  80S (found in Eukaryotic cells) - larger
  70S (found in Prokaryotic cells, mitochondria & chloroplasts) - smaller

Question 18

Description of the vacuole?

Answer 18

• A fluid-filled sac with a single membrane
• Usually a single large vacuole in plant cells
• Storage bubbles

Question 19

Function of the vacuole?

Answer 19

• They support herbaceous plants (non-woody/soft) or herbaceous parts of woody plants by making cells turgid/rigid
• Storage of useful substances for the plant cells
• Also storage of waste products (isolates materials that could be harmful to the cell)

Question 20

Description of cell wall?

Answer 20

• Found in plant cells
• Made of cellulose fibers, very strong so supports the functions
• Fungi also have cell walls (chitin)
• Algae also have cell walls (cellulose or Glycoproteins or both)

Question 21

function of cell wall

Answer 21

• Providing the cell with strength to prevent it bursting due to osmosis
• Providing strength and support to the whole plant

Question 22

description of a centriole?

Answer 22

• Small hollow cylinders
• A centrosome = 2 centrioles (orientated at right-angles to each other)
• Form a network of fine fibres in the cytoplasm called the cytoskeleton made out of microtubules and filaments

Question 23

function of a centriole?

Answer 23

• Supports the cell’s shape
• Organises and moves organelles
• During cell division the pair separate to opposite ends of the cell and form the spindle