cell structure

Question 1

what is the structure of the mitochondria and its function?

Answer 1

The mitochondria consists of a double membrane which has a fluid centre called the matrix. Its function is to produce ATP in aerobic respiration

Question 2

What is the structure of the nucleus and its function?

Answer 2

it is surrounded by a double membrane called the nuclear envelope which separates the nucleus components from the rest of the cell. it contains pores which allows substances to enter and leave the nucleus. in addition it is the site of ribosomal production

Question 3

What are cilia?

Answer 3

These are hair like projections which are involved in cell signalling or moving substances.

Question 4

what is the structure and function of the golgi apparatus

Answer 4

Stacks of membranes called cisternae , here proteins and lipids are modified then packaged into vesicles and then transported around the cellw

Question 5

what are centrioles

Answer 5

These are made of microtubules which as a pair form centrosomes which are involved in the production of spindle fibres.

Question 6

what are lysosomes?

Answer 6

They are vesicles formed by the golgi apparatus and contain hydrolytic enzymes

Question 7

What are the structure and functions of ribosomes?

Answer 7

Small spherical molecules made of proteins and ribosomal RNA. Found in cytoplasm for protein assembly or attached to the red for synthesis

Question 8

function and structure of the rough endoplasmic reticulum?

Answer 8

Coated with ribosomes on the outer surface. it is the intracellular transport system through cisternae. Site of protein synthesis.

Question 9

function and structure of the smooth endoplasmic reticulum?

Answer 9

No ribosomes, involved with lipid metabolism, synthesis of cholesterol and lipids

Question 10

What is the function and structure of chloroplasts?

Answer 10

Surrounded by a double membrane which contains thylakoids which have chlorophyll pigments. Site of photosynthesis.

Question 11

What is the function and structure of the cell wall?

Answer 11

In plants, algae and fungi: polysaccharides - cellulose in plants and chitin in fungi

Question 12

What is the function and structure of the cytoskeleton?

Answer 12

The cytoskeleton is a network of protein structures which enable movement and provide structural integrity within a cell

Question 13

diameter of actin microfilaments?

Answer 13

7nm

Question 14

diameter and function of intermediate filaments?

Answer 14

10nm and keep the nucleus in a stable position in the cell cytoplasm and involved in signalling between cells.

Question 15

diameter and function of microtubules?

Answer 15

18 - 30 nm, form a track along which proteins move organelles, form spindle fibres, centrioles, cilia and undulopodia

Question 16

What are they cytoskeletal motor proteins?

Answer 16

myosin, kinesis, dyenins
Bind to ATP for energy

Question 17

What is the process of producing and secreting a protein?

Answer 17

1. gene transcribed to mRNA
2. mRNA leave the nucleus and goes to ribosome on RER
3. mRNA is translated and the protein is assembled from amino acids
4. Protein enters the cisternae
5. Packaged into vesicles
6. transported to golgi
7. modified
8. travels to plasma membrane
9. fuses with membrane
10. secreted

Question 18

What are optical microscopes?

Answer 18

these microscopes focus a beam of light on a specimen. The magnification is up to x2000, has a limited resolution

Question 19

What are laser scanning microscopes?

Answer 19

Laser light is used to scan an object and assemble an image on the computer. Have a high resolution and high contrast

Question 20

What are electron microscopes?

Answer 20

These use a beam of fast travelling electrons at a wavelength of 0.004nm
This has good resolution and the image is focused by magnets onto a screen.

Question 21

What are transmission electron microscopes?

Answer 21

These electrons pass through a sample and are then focused on a screen, the specimen needs to be dehydrates and stained with metal salts.
m = x2000000

Question 22

What are scanning electron microscopes?

Answer 22

Where electrons are fired at a sample which causes secondary electrons to bounce off and are then focused on a screen to produce a 3D image
The specimen needs to be placed in a vacuum and coated in metal
m = x 200000