Cells

Question 1

What does crystal violet stain?

Answer 1

It stains cell walls purple

Question 2

What does methylene blue stain?

Answer 2

It stains the nucleus

Question 3

What does congo red stain?

Answer 3

It is a negative stain, providing a contrast between the cell and the background

Question 4

What are some properties of light microscopes?

Answer 4

They are the first and most common type of microscope. Light is sent from a source through a specimen. The image is magnified by glass lenses. They are easier to use. Mostly used to study living cells, and they show a 2D image. The resolution is limited at 200nm, magnification is limited at x2000

Question 5

What is the nucleolus?

Answer 5

An area inside the nucleus which contains RNA, where chromosomes unwind

Question 6

What is a cytoskeleton?

Answer 6

A network of protein filaments (actin or microtubules) within the cytoplasms that move organelles from place to place within the cell, allows some cells to move and allow the contraction of muscle cells

Question 7

What are ribosomes?

Answer 7

Organelles without membranes where protein synthesis takes place : proteins are assembled there

Question 8

What is the structure of the RER?

Answer 8

A system of membranes, containing fluid filled cavities (cisternae). It is coated with ribosomes.

Question 9

What is the function of the RER?

Answer 9

It is an intracellular transport system- the cisternae form channels for transporting substances from one area of a cell to another.

Provides a large surface area for ribosomes. Transport proteins through the membrane and into the cisternae to be transported to the golgi apparatus for packaging.

Question 10

What is the function of lysosomes?

Answer 10

They keep the powerful hydrolytic enzymes separate from the rest of the cell.
They can digest foreign matter and return the digested components to be reused within the cell.

Question 11

What role does the nucleus play in the making and secretion of proteins?

Answer 11

mRNA copy of the gene is made in the nucleus. This mRNA leaves the nucleus through a nuclear pore.

Question 12

What role do the ribosomes/REM play in the making and secretion of proteins?

Answer 12

The mRNA attaches to a ribosome which is attached to the REM. The ribosome reads the instruction required to assemble the required protein. The protein is assembled. It passes into the REM through the cisternae - where the molecules are ‘pinched off’ within vesicles and travels via microtubules towards the golgi apparatus

Question 13

What role does the golgi apparatus play in the making and secretion of proteins?

Answer 13

The vesicles form with the golgi apparatus, where the protein molecules are modified and packaged. These vesicles are then pinched off again from the golgi apparatus, and move towards the plasma membrane.

Question 14

What role does the plasma membrane play in the making and secretion of proteins?

Answer 14

The vesicle and plasma membrane fuse together, and the protein molecules pass through and is then released to the outside of the cell.

Question 15

What are the similarities between eukaryotic and prokaryotic cells?

Answer 15

They both contain a plasma membrane, cytoplasm, and ribosomes for the synthesis of proteins, as well as DNA and RNA.

Question 16

What are the differences between eukaryotic and prokaryotic cells?

Answer 16

Prokaryotic cells are much smaller(1-5 micrometres), they have a less well developed cytoskeleton with no centrioles, they don’t have a nucleus, they do not contain membrane bound organelles, and their cell wall is made out of peptidoglycan (not cellulose), they have smaller ribosomes, and have naked DNA floating freely around the cytoplasm.

Question 17

What are some extra features of prokaryotes?

Answer 17

They have a protective waxy capsule surrounding their cell wall, small loops of plasmids as well as the main loop of DNA, flagella, and pili.
These cells divide by binary fission instead of mitosis. This is because they do not have linear chromosomes to carry out the process of mitosis.

Question 18

What is magnification?

Answer 18

Magnification is the measure of how many times an item appears in comparison to the original object.

Question 19

What is resolution?

Answer 19

Resolution is the clarity of the picture under the microscope - the ability to produce an image which shows fine detail clearly.

Question 20

Summary of optical microscopes

Answer 20

Used to study whole living specimens, magnification is limited at x2000 since the resolution is also limited to the wavelength of visible light. Uses photomicrographs which is the name of the image portrayed.

Question 21

Summary of laser scanning microscopes

Answer 21

Use laser light to scan a object point by point, and assemble the pixels to create an image. These images have a high resolution as well as a high contrast. They have depth selectivity and can focus on structures at different depths. This can therefore be used to observe whole living specimens as well as the cells.