5: Prokaryotic and Eukaryotic Cells pt.2

Question 1

What is the meaning of organelles?

Answer 1

Tiny organs of the cell, which is one of the distinctive features of a eukaryotic cell

Question 2

What are ribosomes?

Answer 2

• A minute organelle and are not membrane bound.
• Composed of 40% protein and 60% RNA
• Manufactured in the nucleolus of the nucleus
• 2 types: 70S and 80S (Svedberg unit)

Question 3

What are the functions of ribosomes?

Answer 3

• Synthesizes proteins, in which it is the site of translation from the messenger RNA to protein
• Synthesizes enzymes

Question 4

What is the endoplasmic reticulum?

Answer 4

A network of membranous tubules and flattened sac called cisternae

Question 5

What are the functions of endoplasmic reticulum?

Answer 5

• Provides structural skeleton to maintain cellular shape
• Provides pathway for protein synthesis

Question 6

What is the difference between smooth and rough endoplasmic reticulum?

Answer 6

Smooth ER: has a continuous membrane network that consists of tubular vesicles that lack ribosomes on the outer surface
- Function: Detoxifies drugs, alcohol and poison
- Produces lipids and carbohydrate metabolism

Rough ER: network of continuous flattened sacs studded with ribosomes
-Function: Helps make proteins due to presence of ribosome
- Manufactures, modifies and transports proteins for export from cell

Question 7

What is golgi apparatus?

Answer 7

• Consists of stacked, parallel flattened membrane sacs
• Cis face Golgi: receives material by fusing with vesicles
• Trans face Golgi: buds off vesicles that travel to plasma membrane

Question 8

What are the functions of golgi apparatus?

Answer 8

• Modifies raw material from ER
• Produces secretory vesicles and routes products from ER to the plasma membrane

Question 9

What are lysosomes?

Answer 9

• Vesicles produced by the golgi apparatus
• Appear as dark, spherical bodies containing various digestive enzymes
• Circular but bigger than ribosomes

Question 10

Give 3 functions of lysosomes

Answer 10

• Digest extracellular particles
• Digest food contents like proteins, fats and glycogen
• Supply the necessary amount of energy to the cell

Question 11

What is a vacuole?

Answer 11

• Huge water-filled sac for cellular storage
• 3 types: Food vacuole, contractile vacuole, central vacuole

Question 12

What are the functions of a vacuole?

Answer 12

• Stores water and nutrient
• controls homeostasis by pumping excess water out of the cell
• supports the shape of the cell

Question 13

What is a mitochondrion?

Answer 13

• Double membrane surrounding fluid-filled matrix with a smooth outer and inner to increase surface area for chemical reaction
• If a cell needs more energy, then it has more mitochondria

Question 14

What is the function of mitochondria?

Answer 14

Site for cellular respiration to release energy and produce ATP

Question 15

What is a chloroplast?

Answer 15

• Belongs to a group of structures called plastids
• Similar to structure to a mitochondrion
• Green in colour because of chlorophyll

Question 16

What are chloroplasts for?

Answer 16

Photosynthetic pigment chlorophyll captures energy from the sun to produce food for the plant cell

Question 17

What is a cytoskeleton and what is it for?

Answer 17

• A network of fibers that extend throughout the cytoplasm
• Composed of three components: Intermediate filaments, microtubules and microfilaments
• Function: Aids in cellular support and movement
• Gives shape to the cell

Question 18

What are centrioles?

Answer 18

• Found only in animal cells
• Self-replicates

-Helps organise microtubules assembly duringcell division

Question 19

What is the extracellular matrix?

Answer 19

• Main ingredients of ECM are glycoproteins secreted by the cells
• Most abundant glycoprotein in ECM: collagen (forms strong fibers outside the cells)
• Fibronectins and other ECM proteins bind to cell surface receptor proteins called integrins that are built into the plasma membrane

Question 20

What are cell walls?

Answer 20

• Found in prokaryotes, fungi and some protists
• In plants: protects the cell, maintains shape and prevents excessive uptake of water
• Function: provides support and protection to the cell membrane

Question 21

What are plant cell walls composed of?

Answer 21

Formed from fibrils of cellulose molecules in a matrix of polysaccharides and glycoproteins

Question 22

What is a cell membrane?

Answer 22

• Consists of continuous bilayer of phospholipid molecules and proteins
• selectively permeable in which some substances can pass readily from one side but others do so with great difficulty

Question 23

What is the function of a cell membrane?

Answer 23

• Controls movement of substance in and out of cells
• Serves as a boundary between the cytoplasm and its external environment

Question 24

Who created the fluid mosaic model?

Answer 24

Singer and Nicholson (1972)

Question 25

What is the difference between cell wall and plasma membrane?

Answer 25

Cell wall is to give shape and support to plant cell while the plasma membrane is to control the movement of substance in and out of the cells. The cell wall is highly permeable while plasma membrane is semi-permeable

Question 26

What is a glycocalyx?

Answer 26

• A loose carbohydrate coat on the entire surface of the cell
• Composed of a mixture of glycoprotein and glycolipid macromolecules
• Functions to stabilise and protect, allows attachment to other cells and allows the cell to interact with the environment