3.4 - Cytoplasm

Question 1

What is the Cytosol?

Answer 1

• Liquid portion of the cytoplasm

Question 2

What is the composition of the cytoplasm?

Answer 2

• 75-90% water
• Ions
• Glucose
• Amino acids
• Fatty acids
• Lipids
• Proteins

Question 3

What are the three filaments that make up the cytoskeleton?

Answer 3

• Microfilaments (smallest)
• Intermediate filaments (middle)
• Microtubules (biggest)

Question 4

What is the function of the cytoskeleton?

Answer 4

• Maintains shape of the cell (microfilaments)
• Organises cellular contents (Intermediate)
• Responsible for cell movements (Microtubules)

Question 5

What is the structure of a centrosome?

Answer 5

• 9 clusters of 3 microtubules make up a centriole
• 2 centrioles per centrosome
• Pericentriolar material surrounds centrioles

Question 6

What is the function of a centrosome?

Answer 6

• Organising centre for microtubules
• Forms the mitotic spindle

Question 7

Describe Cilia and Flagella

Answer 7

• Motile cell surface projections
• Inner core of microtubules
• Cilia: small and hair-like
• Flagella: larger and tail-like

Question 8

What are the functions of cilia and flagella?

Answer 8

• Cilia: Move fluids over a cell surface
• Flagella: Responsible for cell movement

Question 9

Describe the structure of ribosomes

Answer 9

• Composed of two subunits (large and small)
• Contain rRNA and proteins
• subunits leave the nucleus separately and come together in the cytosol

Question 10

What is the function of a ribosome?

Answer 10

• Protein synthesis during mRNA translation

Question 11

Describe the structure of the RER

Answer 11

• Membranous network of folded membranes
• studded with ribosomes
• continuous with the nuclear envelope
• very extensive

Question 12

Describe the structure of the SER

Answer 12

• Membranous network of folded membranes
• NOT studded with ribosomes
• continuous with the RER
• very extensive

Question 13

What is the function of the RER?

Answer 13

• Site of synthesis of glycoproteins and phospholipids

Question 14

What are the functions of the SER?

Answer 14

• Site of fatty acid and steroid synthesis
• Release glucose into the blood stream
• Metabolism of drugs and toxic substances
• storage of Ca2+ for muscle contraction (sarcoplasmic reticulum)

Question 15

Describe the structure of the golgi apparatus

Answer 15

• Sac of 3-20 flattened membranous sacs
• Sacs are called cisterns
• More extensive in cells that secrete proteins

Question 16

What are the functions of the golgi apparatus?

Answer 16

• Accepts proteins from RER
• Forms glycolipids and glycoproteins
• Store, packages and exports proteins

Question 17

Describe the function of a lysosome

Answer 17

• Vesicle formed from the golgi
• contains digestive enzymes

Question 18

What are the functions of lysosomes?

Answer 18

• Fuses to and digests contents of vesicles
• Autophagy: digests worn-out organelles
• Autolysis: digests whole cells
• Digests extracellular materials

Question 19

Describe the structure of peroxisomes

Answer 19

• Vesicles containing oxidative enzymes

Question 20

What is the function of peroxisomes?

Answer 20

• Detoxify harmful substances
• H2O2, free radicals

Question 21

Describe the structure of proteasomes

Answer 21

• Barrel shaped structure
• contains protease enzymes

Question 22

What is the function of proteosomes?

Answer 22

• Degrade proteins by cutting them into smaller peptides

Question 23

Describe the structure of a mitochondrion

Answer 23

• Two membranes (inner and outer)
• Inner membrane is folded (cristae)
• Inner membrane is studded with enzymes
• Fluid filled cavity inside is called the mitochondrial matrix
• Ribosomes present inside the matrix

Question 24

What is the function of a mitochondrion

Answer 24

• Powerhouse of the cell
• Production site for ATP