Cell Structure

Question 1

What it the definition for resolution?

Answer 1

Resolution is the ability to distinguish between two points on an image

Question 2

What is the definition for magnification?

Answer 2

Magnification is the number of times larger an image appears compared to its actual size

Question 3

How do you calculate magnification?

Answer 3

Magnification = Image / Actual

Question 4

What are the advantages of a scanning electron microscope?

Answer 4

-They produce a 3D image
- Have higher surface detail

Question 5

What are the advantages of a transmission electron microscope?

Answer 5

• They have higher magnification and resolution

Question 6

What are the disadvantages of all electron microscopes? (state 4)

Answer 6

• High specialist training required for use
• Electron beam can damage the image
• Complex slide preparation is required meaning an artefact may be produced (distorts image)
• Cannot observe live processes as organism must be dead as viewed in a vacuum

Question 7

What are the advantages and disadvantages of laser scanning confocal microscopes?

Answer 7

Advantages:
- can be used on live organisms
- produce a 3D image
Disadvantages:
- lower magnification and resolution than electron microscopes

Question 8

What is the structure and function of the nucleolus?

Answer 8

-contains rRNA
-ribosome synthesis

Question 9

What is the structure and function of nuclear pores?

Answer 9

-they are at regular intervals around the nuclear envelope
-they allow mRNA, tRNA and rRNA out of the nucleus

Question 10

What is the structure and function of the nuclear envelope?

Answer 10

-it is a double membrane that compartmentalises the nucleus

Question 11

What is the structure and function of the chromatin?

Answer 11

-stored inside nucleus, contains chromosomes
-loosely packed DNA

Question 12

What is the structure and function of the rough endoplasmic reticulum?

Answer 12

-intracellular membrane system that is covered in ribosomes.
- it is continuous with the nuclear envelope
-contains cisternae
-synthesis and folding of proteins for export

Question 13

What is the structure and function of the Golgi apparatus?

Answer 13

• made up of membranous sacs called cisternae
  -packaging and modification of protein into vesicles
  synthesis of glycoproteins, hormones, etc.

Question 14

What is the structure and function of the phospholipid bilayer?

Answer 14

-compartmentalises the cell
-controls what enters and leaves the cell
-made of a phospholipid bilayer

Question 15

What is the structure and function of lysosomes?

Answer 15

-they are membrane bound sacs of enzymes
-contain hydrolytic enzymes needed for intracellular digestion

Question 16

What is the structure and function of the centriole?

Answer 16

-consist of bundles of microtubules
-produce spindle fibres in mitosis and meiosis

Question 17

What is the structure and function of the microvilli?

Answer 17

-out foldings of the plasma membrane
-increase surface area for movement of molecules

Question 18

What is the structure and function of the mitochondria?

Answer 18

-made of a double membrane, inner membrane is folded into cristae
-site of aerobic respiration (production of ATP)

Question 19

What is the structure and function of the smooth endoplasmic reticulum?

Answer 19

-intracellular membrane system without ribosomes
-lipid synthesis, phospholipid synthesis, steroid hormone synthesis

Question 20

What is the structure and function of the cellulose cell wall?

Answer 20

-cellulose is made up of beta glucose monomers (alternate beta glucose monomers are rotated 180* to produce a straight chain)
-provides mechanical strength
-permeable

Question 21

What is the structure and function of the tonoplast?

Answer 21

-single membrane surrounding vacuole
-exerts turgor pressure on the cellulose cell wall

Question 22

What is the structure and function of the cell sap?

Answer 22

-acts as a store
-contains sugars and water

Question 23

What is the structure and function of starch grains?

Answer 23

-found in plant cells only, contain starch
-compact and insoluble
-storage of carbohydrates

Question 24

What is the structure and function of the chloroplasts?

Answer 24

-absorb light in the form of photons for photosynthesis
-contain a double membrane, stroma and stacks of thylakoids called grana

Question 25

What is the structure and function of the plasmodesma?

Answer 25

-pores linking plant cells
-allow exchange of water and minerals between cells

Question 26

What are the three parts of the cytoskeleton and what are they made up of and what is their function?

Answer 26

Microfilaments- Actin. cell movement, cell division.
Microtubules- Tubulin. movement of organelles and vesicles around cell
-Intermediate fibres- Elastin and Collagen. provides mechanical strength, holds organelles in place

Question 27

How is a protein made within the cell?

Answer 27

1. gene transcribed in nucleus and binds to mRNA
2. mRNA moves out of nucleus through nuclear pore and attaches to a ribosome in the RER
3. translation of mRNA produces a polypeptide chain
4. as polypeptide chain moves through cisternae of RER, it is folded into a 3D shape
5. polypeptide buds off into a vesicle and moves towards golgi apparatus via microtubules using motor proteins.
6. vesicle fuses with cis face of golgi and the gene is released
7. as the gene moves through the golgi it is modified and packaged into another vesicle and leaves the golgi from the trans face.
8. gene moves towards plasma membrane in another vesicle and fuses to plasma membrane .
9. protein released by exocytosis