cell structure

Question 1

What stains can be used for the nucleus?

Answer 1

The nucleus can be stained using acetic orcein, methylene blue, or toluidine blue.

Question 2

How do images from confocal microscopes differ from those from electron microscopes?

Answer 2

Images from confocal microscopes have lower resolution, can have fluorescent tags, show movement in living cells, and reveal different layers within the sample.

Question 3

What is the maximum magnification of a light microscope?

Answer 3

The maximum magnification of a light microscope is up to 1500x.

Question 4

What is magnification?

Answer 4

Magnification is the number of times larger the image is compared to the object.

Question 5

What is resolution in microscopy?

Answer 5

Resolution is the ability to distinguish between two separate points and the level of detail that can be seen.

Question 6

What is the function of mitochondria?

Answer 6

Mitochondria are the site of aerobic respiration, producing ATP.

Question 7

What is the role of the smooth endoplasmic reticulum?

Answer 7

The smooth endoplasmic reticulum is involved in the transport, production, and processing of lipids and carbohydrates.

Question 8

Why can’t organelles be seen with a light microscope?

Answer 8

Light microscope resolution is not great enough to allow organelles to be seen.

Question 9

What are the main components of prokaryotic and plant cell walls?

Answer 9

Prokaryotic cell walls are made of peptidoglycan, whereas plant cell walls are made of cellulose.

Question 10

How are bacteria adapted to adhere to gut cells?

Answer 10

Bacteria have pilli (extenstion of the plasma membrane) for attachment and glycoproteins in their cell membranes with a specific complmentary shape so thay can bind to receptor on human cells of gut lining

Question 11

Do prokaryotes have contractile vacuoles?

Answer 11

No, prokaryotes do not have contractile vacuoles; this feature is found in some single-celled eukaryotes like amoeba.

Question 12

What is the resolution and magnification of light microscopes?

Answer 12

Light microscopes have a resolution of 50 - 200 nm and a magnification of x1500.

Question 13

What is the resolution of transmission electron microscopes (TEM)?

Answer 13

TEM have a resolution of 0.05 - 1.0 nm.

Question 14

What are the differences between plant and animal cells?

Answer 14

Plant cells have a permanent vacuole, cellulose cell wall, chloroplasts, starch grains, tonoplast, and plasmodesmata. Animal cells have centrioles and glycogen granules.

Question 15

What distinguishes prokaryotic cells from eukaryotic cells?

Answer 15

Prokaryotic cells have free naked circular DNA and smaller ribosomes.

Question 16

What distinguishes eukaryotic cells from prokaryotic cells?

Answer 16

Eukaryotic cells have a nucleus, nuclear envelope, nucleolus, membrane-bound organelles, larger ribosomes, and generally larger cell size.

Question 17

What is the function of the cytoskeleton?

Answer 17

The cytoskeleton supports the cell, can change its shape, facilitates movement for exocytosis, endocytosis, and moves organelles, RNA, proteins, and chromosomes and hold organelles in place , alllows movment of cilia

Question 18

How does the cytoskeleton move organelles?

Answer 18

The cytoskeleton moves organelles around the cell using microtubules.
(+ cytoskeleton also makes up cilia)

Question 19

What does viral RNA do?

Answer 19

Viral RNA carries the code for viral proteins to the host cell ribosomes.

Question 20

What are the steps of polypeptide synthesis?

Answer 20

• transcription and translation.
• In transcription the DNA transcribed into mRNA and free RNA nucleotides line up by complementary base-pairing to template DNA strand catalysed by RNA polymerase to make a single strand of mRNA.
• In translation the mRNA moves to the ribosomes and tRNA molecules bind to mRNA, with anticodons binding to codons.
• A specific amino acid is attached to each tRNA molecule, and as the amino acids bond together they form peptide bonds between them

Question 21

What is the role of the Golgi apparatus?

Answer 21

• The Golgi apparatus processes proteins from the RER, makes glycoproteins + repackages them into vesicles
• make lysosomes, replenishes plasma membrane, and is involved in lipid synthesis.

Question 22

What is the function of the nuclear envelope?

Answer 22

The nuclear envelope has nuclear pores for communication between the nucleus and cytoplasm.

Question 23

What do lysosomes contain and what is their function?

Answer 23

• Lysosomes contain hydrolytic enzymes to break down worn-out organelles, foreign objects, toxins, and pathogens.
• destroy the cell in apoptosis

Question 24

Where does protein synthesis occur?

Answer 24

Ribosomes are the site of protein synthesis.

Question 25

What is the function of chloroplasts?

Answer 25

Chloroplasts are the site of photosynthesis.

Question 26

Why do mitochondria vary in shape and size?

Answer 26

Mitochondria vary in shape and size due to division, different planes of sectioning, and potential artefact formation.

Question 27

What is the process of extracellular protein production and secretion?

Answer 27

- the nucleus contains a gene for the desired protein and is the site of transcription and produces mRNA via transcription. - Ribosomes on the RER are the site of protein synthesis (translation). - The protein is then transported in a transport vesicle to the Golgi apparatus, which modifies and repackages the protein into a secretory vesicle. - The vesicle moves along the cytoskeleton and fuses with the cell surface membrane, so secretion occurs by exocytosis.

Question 28

What are suitable stains for cell nuclei?

Answer 28

Suitable stains for cell nuclei include acetic orcein, methylene blue, and toluidine blue.

Question 29

Why do animals store glucose as glycogen?

Answer 29

Glycogen is insoluble, compact, highly branched for quick glucose release, and metabolically inactive.

Question 30

What happens when a cell is placed in a medium with lower water potential?

Answer 30

Water moves out of the cell by osmosis as it has a higher water potential than the surrounding solution.

Question 31

How do small, non-polar substances enter cells?

Answer 31

Small, non-polar substances enter cells by diffusing through the phospholipid bilayer.

Question 32

How do large substances enter cells?

Answer 32

Large substances enter cells using transport proteins or by endocytosis.

Question 33

How do polar substances enter cells?

Answer 33

Polar substances enter cells through pore/channel proteins or transport proteins, often via active transport.

Question 34

What structures are associated with the cytoskeleton?

Answer 34

Flagellum, cilium, microtubules, microfilaments, and undulipodium are associated with the cytoskeleton.

Question 35

What processes rely on the cytoskeleton for movement?

Answer 35

Processes include movement of chromosomes in cell division, cytoplasm in cytokinesis, and RNA in protein synthesis.

Question 36

What is the mesosome's function in prokaryotes?

Answer 36

The mesosome is the site of aerobic respiration in prokaryotes.

Question 37

Why do we stain specimens for microscopy?

Answer 37

Staining increases contrast, making it easier to see details and recognize different cell types and molecules.

Question 38

What is a limitation of staining dead cells?

Answer 38

Dead cells may not take up stains that require active transport.

Question 39

What can scanning electron microscopes show?

Answer 39

Scanning electron microscopes allow visualization of the 3D shape of a specimen with great depth of field, focusing on surface features.

Question 40

What can transmission electron microscopes reveal?

Answer 40

Transmission electron microscopes allow visualization of shapes and details of small organelles.

Question 41

What can a medium power light microscope not reveal?

Answer 41

A medium power light microscope cannot reveal the phospholipid bilayer, ribosomes, Golgi, RER, SER, cytoskeleton, centrioles, lysosomes, or mitochondria.

Question 42

How are vesicles moved between organelles?

Answer 42

Vesicles are moved along microtubules in the cytoskeleton, which provide tracks for movement using ATP.

Question 43

How are cilia moved?

Answer 43

Cilia are moved by the cytoskeleton.

Question 44

What is a partially permeable membrane?

Answer 44

A partially permeable membrane allows free movement of some substances while preventing movement of others.