Cells

Question 1

Describe the structure and function of the bilipid membrane

Answer 1

• Amphipathic phosholipid bilayer
• impermeable to water soluble molecules
• protein molecules dissolved within bilayer mediate most other functions of cell membrane

Question 2

What are the main functions of the plasma membrane?

Answer 2

• selective permeability
• transport of materials
• endocytosis and exocytosis
• intercellular recognition
• signal transduction
• intercellular adhesion

Question 3

What is the glycocalyx? What is the function?

Answer 3

• Cell coat made up of polysaccharides and oligosaccharides

- Side chains give cell specificity

Question 4

What is the function of the nucleolus?

Answer 4

Synthesising ribosomes

Question 5

What is the function of the ribosomes?

Answer 5

Protein synthesis

Question 6

What is the function of the nucleus?

Answer 6

• Storing cell DNA

- Co-ordinating cell activity

Question 7

What is chromatin?

Answer 7

condensed form of cells DNA that organises to form chromosomes in mitosis

Question 8

What is the nuclear envelope and what does it do?

Answer 8

• double layered membrane
• separates nucleus contents from rest of cellular cytoplasm
• attached to endoplasmic reticulum

Question 9

What is the function of nuclear pores?

Answer 9

they allow specific types and sizes of molecules to pass

Question 10

What is the function of lysosomes?

Answer 10

• they contain acid hydrolases at pH 5 that digest cellular material
• primary lysosomes bind with endocytosed material, membrane bound vesicles, autophagosomes or with excess secretory product to form secondary lysosomes

Question 11

What is the function of mitochondria?

Answer 11

-ATP production

Question 12

What is the lineage of mitochondria?

Answer 12

Maternal only

Question 13

What is the function of the golgi apparatus?

Answer 13

Sorting, modifying, packaging and processing proteins

Question 14

How does the golgi apparatus work?

Answer 14

• Vesicles bud off RER
• They bind to convex cis face of golgi body
• Vesicles leave trans face

Question 15

What is the structure and function of peroxisomes?

Answer 15

Roughly spherical with granular matrix

They are the sites of oxygen utilisation and hydrogen peroxide production

RH2 + 02 –> R + H202

Question 16

Which enzyme uses the hydrogen peroxide to oxidise other substances?

Answer 16

Catalase

Question 17

What are microfilaments?

Answer 17

• 5nm diameter
• Two actin strings twisted together
• Contractile
• Can associate and disassociate

Question 18

What are intermediate filaments?

Answer 18

• Not dynamic
• 10-12nm diameter
• common in neurological and nerve cells and epithelial cells
• made up of cytokeratin
• they form a tough supporting mesh in cytoplasm
• anchored to the membrane by desmosomes

Question 19

What are microtubules?

Answer 19

• 13 alpha and beta subunits that originate from centrosomes

- attach to organelles via attachment of dynein and kinesin to move them

Question 20

What is the function of the RER?

Answer 20

• Synthesis of lysosomal enzymes and proteins

- Site of glycosylation

Question 21

What is the function smooth ER?

Answer 21

-Lipid synthesis and steroid genesis

Question 22

Where is smooth ER found?

Answer 22

• Liver
• Mammary Gland
• Ovaries
• Testes
• Adrenal glands

Question 23

What are the main differences between eukaryotic and prokaryotic cells?

Answer 23

Prokaryotic cells are found only in bacteria. They have a cell wall, no nucleus (only a plasmid), may have flagella

Question 24

What is the difference between heterochromatin and euchromatin?

Answer 24

• Light-staining areas of the nucleus are called “euchromatin”. Abundant euchromatin denotes an active cell.
• Dark-staining areas of the nucleus are called “heterochromatin”. There is always a rim of heterochromatin under the real nuclear membrane. Abundant heterochromatin with only scanty euchromatin denotes an inactive cell.