A2.2 Cell Structure

Question 1

Formula for calculating magnification

Answer 1

measured size of image/actual size of specimen

Question 2

millimeter—> micrometer= ?

Answer 2

x1000

Question 3

Resolution

Answer 3

The minimum difference between two points or objects at which they are still distinguishable as two points/objects.

Question 4

Magnification

Answer 4

The increase in an objects image size compared to its actual size. It is shown on magnified pictures.

Question 5

Light microscope features

Answer 5

• Inexpensive
• Simple specimen prep
• Magnifies up to 2000x
• Specimens can be living or dead

Question 6

Electron microscope features

Answer 6

• Expensive
• Complex specimen prep
• Magnifies over 500,000x
• Specimens must be dead

Question 7

What property of electrons allows the electron microscope to have such greater magnification and resolution.

Answer 7

Electrons have a shorter wavelength than light

Question 8

Freeze fracture specimen prep

Answer 8

The specimen is rapidly frozen and then physically broken apart. This reveals a plane throughout the specimen that can then be examined.

Question 9

Cryogenic electron microscopy

Answer 9

Allows a 3d image of proteins within cells to be formed on a computer.

Question 10

Artefacts

Answer 10

Structural features seen in pictures produced by an EM that are not a part of the cell rather, they are produced during the preparation of the samples for EM.

Question 11

Fluorescent stains

Answer 11

Substances/dyes that combine with specific cellular components. They can be irradiated with UV light so the parts of the cell that combined with the dye will fluorescence. This produces assorted colours, increasing visibility of the highlighted components.

Question 12

Immunofluorescence

Answer 12

Allows greater visibility of living tissue. Uses antibodies combined with dye. Specific antibodies coloured with specific dye combine with specific molecules. This allows the target to be detected (usually viral proteins that have infected cells).

Question 13

Brightfield Microscope

Answer 13

Visible light is used. Specimen appears light on a light background.

Question 14

Darkfield Microscope

Answer 14

Opaque lens is used in the condenser, blocks direct light from entering the specimen. Specimen appears light on a dark background.

Question 15

Phase-contrast

Answer 15

Special lens used to reveal detailed images of specimens without staining.

Question 16

Structures common across all cells

Answer 16

-DNA
- A cytoplasm
- A plasma membrane surrounding the cytoplasm

Question 17

Cytosol

Answer 17

The liquid component of the cytoplasm (the cytoplasm without organelles etc)

Question 18

Prokaryote vs Eukaryote cells

Answer 18

Prokaryote have no internal membranes creating specialised areas whereas Eukaryotes do (organelles)

Question 19

What type of cells are bacteria and archea

Answer 19

prokaryote

Question 20

Cell wall

Answer 20

Protects and maintains the shape of the cell, stops it from rupturing when the water pressure is greater inside that outside.

Question 21

Peptidoglycan

Answer 21

a carbohydrate-protein complex that cell walls are made of

Question 22

Capsule

Answer 22

an additional layer of polysaccharide outside the cell wall that lets them adhere to things

Question 23

Plasma membrane

Answer 23

Inside the cell wall. Controls the movement of materials into and out of the cell

Question 24

Gram positive vs negative bacteria staining

Answer 24

Gram-positive’s cell walls retain the crystal violet stain whereas gram negative’s don’t

Question 25

Are Bacillius and Staphylococcus gram positive or negative?

Answer 25

Positive

Question 26

Pili

Answer 26

Hair like structures on the outside of the cell wall. Used for attachment and joining bacterial cells for the transfer of DNA from one cell to another.

Question 27

Flagella

Answer 27

Long tail-like structures that enable bacteria to move

Question 28

Cytoplasm of a prokaryote

Answer 28

The complete interior of the cell. There are no specialised areas because internal membranes don’t exist in prokaryotic cells.

Question 29

Downside to prokaryotic cells

Answer 29

The reactions all taking place in one spot can limit the cells efficiency due to the possible interaction between reactions.

Question 30

DNA in prokaryotes

Answer 30

The bacterial chromosome is a single long, continuous and circular thread of DNA. It is not associated with histones

Question 31

Plasmids

Answer 31

Small circular DNA molecules which are not connected to the main chromosome. Not required under normal conditions but helps them adapt to unusual circumstances

Question 32

Ribosomes

Answer 32

sites of protein synthesis

Question 33

Binary fission

Answer 33

The process by which prokaryotic cells divide.