Cell Structure

Question 1

Define Magnification

Answer 1

The number of times larger an image appears compared to its actual size.

Question 2

Define Resolution

Answer 2

The ability to distinguish between 2 separate points in an image.

Question 3

Describe a Laser Confocal Light Microscope

Answer 3

You can use a live specimen.
Has colour and 3D image.
High Depth Selectivity.
Lower magnification and resolution than SEM/TEM [but still quite high]
Disadvantages could be that it is a slow process.

Question 4

Describe a Scanning Electron Microscope.

Answer 4

100x-100,000x MAG and 3-10nm RES
Electrons are fired at specimens and bounce off the surface. It is then detected by a computer and the image is built up.
Produces a 3D image.
High, but lower mag and res than TEM.
Cant use live specimens.
No colour.

Question 5

Describe a Transmission Electron Microscope

Answer 5

100x-2,000,000x MAG and 0.2-1.0nm RES
Electrons are fired through the specimen and detected by a computer.
Produces a 2D image.
High mag and res.
Cant use live specimens, or thin ones.
Long process.
No colour produced.

Question 6

Nucleus

Answer 6

Contains chromatins. [DNA]
Controls the reactions of the cell.
Has a nuclear envelope and nuclear pores.

Question 7

Nucleolus

Answer 7

Contains ribosomal RNA
Ribosome synthesis.

Question 8

Ribosomes

Answer 8

Protein Synthesis

Question 9

Rough Endoplasmic Reticulum

Answer 9

Transports and packages proteins [processes proteins].
Has ribosomes attached to it.
Proteins are produced are used for activities outside that cell.

Question 10

Smooth Endoplasmic Reticulum

Answer 10

Lipid, phospholipid, steroids synthesis. [cholesterol]

Question 11

Golgi Apparatus

Answer 11

Modifies and repackages protein into vesicles for them to leave the cell.

Question 12

Mitochondria

Answer 12

Has a inner membrane fold called cristae.
Matrix formed by cristae contains enzymes needed for respiration.
Has some smaller pieces of DNA.
Produces ATP, involved in aerobic respiration.

Question 13

Microvilli

Answer 13

Out folding of the plasma membrane.
Increases the surface area for movement of molecules.

Question 14

Centrioles

Answer 14

Bundles of microtubules.
Produces spindle fibres for cell division

Question 15

Lysosome

Answer 15

Membrane-bound sac of enzymes.
Hydrolytic enzymes.

Question 16

Cellulose Cell Wall

Answer 16

Structural support for plant cell.

Question 17

Vacuoles

Answer 17

Has a membrane called tonoplast.
Helps keep cell turgid.

Question 18

Chloroplast

Answer 18

Contains chlorophyll which is used for photosynthesis.
Has stack of thylakoids called grana.
Thylakoids contains the chlorophyll.

Question 19

Plasmodesma [ta]

Answer 19

Allows exchange of water and miracle between cells.
Pores linking plant cells.

Question 20

Middle Lamella

Answer 20

Contains pectin [glue].
Sandwhiched between cellulose.

Question 21

Microfilament

Answer 21

Long, thin, flexible threads.
5nm
Made from actin.
Used in cell movement, division and for muscle contraction.

Question 22

Microtubules

Answer 22

Thick, cylindrical tubes.
25nm
Made from tubulin.
Movement of organelles around cell, requires molar protein and ATP.
9+3 arrangement in centrioles.

Question 23

Intermediate fibres

Answer 23

“rope-like” proteins that span the cell.
Variable diameter.
Made from Elastin collagen.
Cell scaffolding and mechanical strength.
Prevents cell from collapsing and hold organelles in place.

Question 24

How are proteins produced?

Answer 24

mRNA [copy of the DNA code] made in the nucleus. mRNA then leaves the nucleus through the nuclear pore, and goes to the ribosomes that are attached to the RER.
Proteins are produced and are then folded and packaged as it moves along the RER. The proteins then leave the RER via vesicles and fuses to the cis-face of the Golgi apparatus, it is then repackaged and modified into vesicles. It then leaves the Golgi via the trans-face, and fuses to the plasma membrane. The materials of the proteins are then released out of the cell. [exocytosis]