Cell Biology

Question 1

What is classification?

Answer 1

The grouping of organisms based on structural similarities.

🔺NB: enables tracking of particular organism & whether something is a new species or forms part of existing species.

Question 2

Hierarchical system of classification

“King Phillip Came Over From Great Spain”

Answer 2

• kingdom
• phylum
• class
• order
• family
• genus
• species

Question 3

What are the 4 types of microscopes

Answer 3

1. Light microscope
2. Dissecting microscope
3. Scanning electron microscope(SEM)
4. Transmission electron microscope (TEM)

Question 4

What are TEM and SEM used for?

Answer 4

TEM: highly detailed cross section

SEM: topography & surface of specimen in 3-D.

Question 5

3 basic principles of cells confirmed by microscope study

Answer 5

1) all living things are composed of cells
2) a single cell is the smallest unit that exhibits characteristics of life
3) all cells come only from pre-existing cells

Question 6

Prokaryotes

Answer 6

-single cells organism with neither a distinct nucleus with a membrane/ specialized organelle.

General characteristics:
•Fall under monera
•First life form that assisted changers that allowed for more complex forms of life to occur
•Can adapt to live in any environment hence most abundant

Question 7

Structural and functional adaptations of prokaryotes

Answer 7

Unicellular
Small (0.8-8 micrometer)
3 main shapes

Question 8

3 main shapes of prokaryotes

Answer 8

Spherical(Cocci)
Rod(Baciili)
Spiral(Spirilla)

Question 9

Gram stain technique

Answer 9

• Hans Christian Gram

- categorizes bacterial species according to differences in cell wall composition.

Question 10

Technique of Gram stain

Answer 10

1. Culture bacteria
2. Wet mount—> sample onto a slide
3. Stain with crystal violet +iodine
4. Alcohol rinse
5. Counter stain with red Safranin dye.

***structure of bacterium’s cell wall determines staining response

Question 11

Gram +ve bacteria

Answer 11

• simple cell wall
• thick peptidoglycan wall

🔺

• 1.Violet stains thick peptidoglycan wall
• 2.Alcohol cannot remove stain
• 3.Safranin counter dye is applied
• 4.Blue stain masks red dye
• Only produces exotoxins
• Antibiotic=Penicillin(prevents cross linking therefore cell loses functionality)

Question 12

Gram -ve

Answer 12

Complex cell wall
Thin layer of peptidoglycan + outer membrane with lipopolysaccharides

🔺

1. violet stains thin peptidoglycan layer
2. Alcohol rinse
3. Safranin applied membrane = pink

• lipids of lipopolysaccharides=toxic therefor causing fever or shock.
• outer membrane of bacteria helps protect again body’s defenses.
• membrane brands make hard to detect
• more resistant than Gram +ve as membrane slows down entry of drugs.
• produces endo and exotoxins
• enters body through wound
• antibiotic=streptomycin