A2.2

Question 1

Microscopy

What is Cytology?

Answer 1

• Specific branch of biology that is focused on study of the cell and all aspects related to cellular structure and function.
• Relies on microscopes to provide understanding.

Question 1

Microscopy

What is Magnification?

Answer 1

Magnification:
- The increase in an object’s image size compared to its actual size. (how many times larger is the viewed image that the object itself.
- Can be calculated by dividing size of the image by actual size of the object.

Actual Image: Image size/ mag
Mag: image size/ actual image
Image Size: Actual x Mag

Question 2

Microscopy

What is meant by resolution

Answer 2

Minimal distance between two points/ objects at which they can still be distinguished as two.
— INDICATOR OR CLARITY (high res, higher clarity)
- Relationship between resolution and mag = inverse, as mag gets higher, resolution gets lower.

Question 3

Microscopy

What is a micrograph?

Answer 3

A photo taken through a microscope to reveal the view of the microscope.
- Can be done from a light microscope but the ones of organelles are from an electron microscope.
- Often black and white

Question 4

Microscopy

What does it mean to freeze fracture?

Answer 4

A technique that aids in viewing internal structures with an electron microscope.
1) specimen is rapidly frozen, then broken apart (fractured) creating a plane through the cell that can be observed.
2) Ice can be vaporized off and then a carbon/ patinum vapor is used to etch the surface and examine that etching under microscope.

Question 5

Microscopy

What is a fluorescent stain?

Answer 5

• Dyes that combine only with specific cellular components.
• When samples are irritated with UV/ violet blue light, those parts that it combines with will fluoresce and product visable colours to highlight those cellular components.

Question 6

Microscopy

What is immunofluorescence?

Answer 6

• Makes use of antibodies that have dyes combined with them.
• Antibiodies are matched to identify/ bind to certain target molecules, often protiens.
• Antibiody binds to the target molecule —> creates a coloured glow.
• Used to detect viral proteins inside of cells.

Question 7

Microscopy

Micrometre vs Centimetre

Answer 7

Micro –> 10^6 metres, would be 10^4 centimetres or 10^3 mm.
1 Micrometre = 0.001 mm.

Question 8

Microscopy

Benefits of a Light Microscope

Answer 8

• Can pass light through organisms and are able to be used with both living/dead specimens.
• Affordable, safe, provide quality images at lower magnifications + visable colour

Question 9

Microscopy

Benefits of an Electron Microscope

Answer 9

• Use beams of electrons
• Short wavelength of electrons preserves resolution at higher magnifications
• can magnify up to 1,000,000 times.
• can not be used with living species/ always black and white

Question 10

Microscopy

Coarse Focus vs Fine Focus

Answer 10

COARSE - makes larger adjustments bring objects into focus. Used first.

FINE - Adds sharpness and clarity.

Question 11

Microscopy

To calculate actual size

Answer 11

Magnification=image size/actual size.

• Use scale bar to find the first determine the magnification.

Question 12

Microscopy

Scanning Electron Mciroscpoe vs Transmission

Answer 12

SEM - (scanning electron microscope): uses a beam of electrons to scan the outer surface of the specimen –> provides detailed images of the exteriors.

TEM - (transmission electron microscope): beams electrons through a thin section of the specimen to allow internal structures to be viewed.

Question 13

Microscopy

Cryogenic Electron Mircosopy

(Cryo-EM), used for researching protein structure.

Answer 13

• Protein solution is applied to a grid, this layer is flash frozen (like with liquid ethane)
• Frozen protein gird is placed in an electron microscope, the pattern the electrons are transmitted by the protein is recorded, the computer uses the pattern to create a theorised 3D protein structure image.

Question 14

Microscopy

Benefits of Flurorescent Stains

Answer 14

• stains bind to specific structures, help them to stand out from surrounding structures.
• special fluroescent microscopes are useful at creating imgaes that clearly show the placement of key cellular structures.

Question 15

Prokaryotes and Eukaryotes

What is a prokaryotic cell?

Answer 15

• Simple unicellular organisms, primarily bacteria.
• Prokayotic cells are small and simple, lacking in complex organelles.
• Term means “before nucleus”, they’re ancesteral organisms, before evolution of nucelus.

Question 16

What is a Eukaryotic Cell?

Answer 16

• Eukaryotic cells are larger, more complex, make up plans and animals and fungi and protists
• Term means “true nucelus”, the DNA of their cells contain nucelus.
• also contain other membrane bound (structurall complex) specialised organelles carrying out unique functions.

Question 17

Prokaryotes and Eukaryotes

What is peptidoglycan?

Answer 17

• The make up of fungi, plants, and prokaryotic cell’s cell walls unique from other organisms and is usually comprised of a carbohydrate and protein polymer called peptidoglycan.
• Can be found in the cell membranes of all bacteria.
• another type of prokaryotes called archae, and they don’t usually have peptidoglycan.

Question 18

Prokaryotes and Eukaryotes

Features common to all cells

Answer 18

• A cell membrane (phospholipid bilayer) to allow transport into and out of cells.
• DNA to provide the isntructions for the production of protiens.
• Ribosomes to make proteins
• Cytoplasm as the inside component of the cell.

Question 19

Prokaryotes and Eukaryotes

(some) Bacterial Cell Structure: Capsule

Answer 19

An additional thick layer outside of the cell wall.
- Made up of polysaccharides and is used to help the bacteria adhere to structures in other organisms (teeth, skin - fruits/ vegtables.)

Question 20

Prokaryotes and Eukaryotes

(some) Bacterial Cell Structure: Pili

Answer 20

Small hair structures on the outside of the cell wall.
- Can be used to attatch onto other organisms but also have a uniqe function in reproduction.
- Have two bateria cells to join together and exchange DNA to facilitate a form of sexual reproduction.

Question 21

Prokaryotes and Eukaryotes

(some) Baterial Cell Structure: Flagella

Answer 21

A Whip-like tail called a flagellum (singular) or multiple flagella.
- Longer than pili, help the cell to move.

Question 22

Prokaryotes and Eukaryotes

(some) Bacterial Cell Structure: Plasmids

In prokaryotes.

Answer 22

• A small long continuous circular double-stranded thread of DNA
• Separate from a cell’s main chromosomal DNA and can replicate independently
• These are not connected to the main chromosome
• Often have helpful adaptive genes, like antibiotic resistance.
• Bacteria can transfer plasmids to one another and share adaptive genes.

Question 23

Prokaryotes and Eukaryotes

Gram Positive vs Gram Negative Bacteria

Answer 23

Divided into Pos or Neg based of their cell membrane.

GRAM-POS: they have a thick layer of peptidoglycan as their cell wall.

GRAM-NEG: also have a peptidoglycan, but a thin layer underneath an additional outer membrane.

Question 24

# Prokaryotes and Eukaryotes Eukaryotic Cellular Organelles: Cytoplasm

Answer 24

Cytoplasm is the interior of both prokaryotic and eukaryotic cells. - Contains the fluid substance called: CYTOSOL, that other cellular structures can exist in. Prokaryotes: The cytoplasm has no specialised areas and performs many chemical reactions. Eukaryotes: The cytoplasm contains a cytoskeleton to help it maintian shape and structure.

Question 25

# Prokaryotes and Eukaryotes Eurkaryotic Cellular Organelles: Nucelus | The region of eukaryotic cells where DNA resides.

Answer 25

* Contains its **own double membrane**: Nuclea **envelope, that contains pores** in it (crucial for mRNA to leave the nucelus). * DNA is organised into linear chromosomes. * Chromosomes are **condensed chromatin which contains DNA wrapped around histones**. *The nuclus also has a **nucleolus, that manfucatures ribosome subunits**.*

Question 26

# Prokaryotes and Eukaryotes Eukaryotic Cellular Orgnaelles: Cysoskeleton

Answer 26

* A network of fibres that **maintain cell shape**, anchor some organelles, aid in cell movement and organelle movement. * Contains actin filaments/microfilaments intermediate filaments and microtubules.

Question 27

# Prokaryotes and Eukaryotes Eukaryotic Cellular Organelles: Rough Enplasmic Reticulum

Answer 27

* After ribosomes make a protein, the rough ER helps in **developing the protien and transporting** it around the cell to the **golgi apparatus**. * The endoplasmic reticulum is an interconnected network of tubules or channels that **extend from the nucleus out throughout the cell**. --> functions in **transporting materials** throughout cell.

Question 28

# Prokaryotes and Eukaryotes Eukaryotic Cellular Organelles: Smooth ER

Answer 28

* SER **synthesizes and transports lipids, phospholipids, and steroids**, storing and releasing calcium ions, and detoxifying harmful substances * **Doesn't contain ribosomes**.