Cell structure

Question 1

Function of nucleus?

Answer 1

Houses all of the cell’s genetic material in the form of DNA, which contains the instructions for protein synthesis.

Question 2

Function of nucleolus?

Answer 2

Makes ribosomes and RNA which pass into the cytoplasm and are used in protein synthesis

Question 3

Function of nuclear envelope?

Answer 3

A double membrane with nuclear pores to allow mRNA out to go to the ribosomes for use in protein synthesis

Question 4

Function of rough endoplasmic reticulum?

Answer 4

Transports proteins made by the attached ribosomes

Question 5

Function of smooth endoplasmic reticulum?

Answer 5

Involved in the making of lipids.

Question 6

Function of golgi apparatus?

Answer 6

Modifies proteins received from the Rough ER and then packages them into vesicles so they can be transported.

Produces lysosomes

Question 7

Function of ribsomes?

Answer 7

Site of protein synthesis.

Question 8

Function of mitochondria?

Answer 8

Site of respiration and production of ATP.

Question 9

Function of lysosomes?

Answer 9

Contain lysins which are digestive enzymes which break down organelles, pathogens and cells. When a cells dies it undergoes autolysis under the direction of lysosomes

Question 10

Function of chloroplasts?

Answer 10

Site of photosynthesis in plant cells.

Question 11

Function of cell surface membrane?

Answer 11

Controls the entry and exit of substances into and out of the cell.

Question 12

Function of centrioles?

Answer 12

Form the spindle which moves chromosomes during cell division.

Question 13

Function of flagella?

Answer 13

locomotion.

Question 14

Role of organelles in production of proteins:

Answer 14

1. The gene containing the instructions for the production of the hormones is copied onto a piece of mRNA
2. mRNA leaves the nucleus through the nuclear pore.
3. mRNA attaches to a ribosome sometimes part of the RER
4. Ribosome reads the instruction to assemble the protein
5. Molecules are ‘pinched off’ in vesicles and travel towards the golgi apparatus
6. Vesicle fuses with golgi apparatus
7. Golgi apparatus processes and packages the molecules, ready for release
8. The molecules are ‘pinched off’ in vesicles from the golgi apparatus and move towards the cell surface membrane
9. Vesicles fuse with the cell surface membrane
10. Cell surface membrane opens to release molecules outside this is exocytosis

Question 15

Properties and function of cytoskeleton:

Answer 15

-Strengthening and maintaining the structure of the cell
-Providing support to cellular organelles and maintaining their position
-Involved in movements of cellular material e.g. moving chromosomes during cell division
-Mobilising the cell

Question 16

Properties and functions of centrioles:

Answer 16

Centrioles are made up of microtubules. Centrioles consist of small, hollow cylindrical proteins called microtubules.
Centrioles are mainly present in animal cells. They are found in most animal cells but are only present in certain plants.
Centrioles help chromosomes separate during cell division. During cell division, it is vital that chromosomes are equally separated so that each of the daughter cells will have the same number of chromosomes. Centrioles ensure this happens by pulling the chromosomes apart equally to each end of the dividing cell.

Question 17

Advantages of Transmission electron microscopes:

Answer 17

They give high-resolution images (more detail)
This allows the internal structures within cells (or even within organelles) to be seen

Question 18

Disadvantages of Transmission electron microscopes:

Answer 18

They can only be used with very thin specimens or thin sections of the object being observed
They cannot be used to observe live specimens
The lengthy treatment required to prepare specimens means that artefacts can be introduced
They do not produce a colour image (unlike optical microscopes that produce a colour image)

Question 19

Advantages of Scanning electron microscopes:

Answer 19

They can be used on thick or 3-D specimens
They allow the external, 3-D structure of specimens to be observed

Question 20

Disadvantages of Scanning electron microscopes:

Answer 20

They give lower resolution images (less detail) than TEMs
They cannot be used to observe live specimens (unlike optical microscopes that can be used to observe live specimens)
They do not produce a colour image (unlike optical microscopes that produce a colour image)

Question 21

Advantages of lasar scanning confocal microscopes:

Answer 21

They can be used on thick or 3-D specimens
They allow the external, 3-D structure of specimens to be observed
Very clear images are produced. The high resolution is due to the fact that the laser beam can be focused at a very specific depth
You can even see the structure of the cytoskeleton in cells

Question 22

Disadvantages of lasar scanning confocal microscopes:

Answer 22

It is a slow process and takes a long time to obtain an image
The laser has the potential to cause photodamage to the cells