Introduction And Cell Biology

Question 1

What are the seven characteristics of life?

Answer 1

1. Display order
2. Harness and utilize energy
3. Reproduce
4. Respond to stimuli
5. Exhibit homeostasis
6. Grow and develop
7. Evolve and adapt to the environment

Question 2

What is Cell Theory?

Answer 2

1. All organisms are composed of one or more cells - unicellular vs multicellular
2. The cell is the basic unit of life
3. Cells are not created, but come from existing cells (ended spontaneous generation)

Question 3

What is microscopy?

Answer 3

The technical field that use microscopes to view objects that cannot be seen with the naked eye

Question 4

What is magnification?

Answer 4

Ability to make smaller objects appear larger. Dependent on the type of lens used

Ex. 10x, 40x, 100x = numerical value of how many times you can make a specimen look larger

Question 5

What is resolution?

Answer 5

Ability to detect or distinguish two structures that are very close together. Essentially, you’re able to tell two super close things apart from each other. Dependent on the wavelength of light used.

Shorter wavelength = better resolution
Longer wavelength = poorer resolution

Question 6

What is contrast?

Answer 6

Ability to distinguish an object of interest from the background; dyes enhance contrast

Question 7

What are the types of microscopy?

Answer 7

Light microscopy
1. Fluorescent microscopy

2. Election microscopy
   A) transmission electron microscope
   B) scanning electron microscope

Question 8

What is light microscopy?

Answer 8

• uses visible light for illumination
• magnification of about 1000x - 1500x
• resolution of about 200nm
• living cells can be examined in natural state without being killed, fixed, or stained

Question 9

What is fluorescent microscopy?

Answer 9

• similar to light microscopy, but added features
• fluorescent dye, or UV light causes organisms to fluorescence
• allows us to see particular parts in higher levels of contrast

Question 10

What is electron microscopy?

Answer 10

• image produced by a beam of high velocity electrons
• higher resolution compared to light microscopes because wavelength of electrons/X-rays are shorter
• higher magnification and contrast as well

Question 11

What is transmission electron microscope?

Answer 11

• thin slices are stained with heavy metals and fixed
• electrons pass through the sample and create an image (portions that appear darker are portions in which the electrons can’t pass through
• offer valuable information on the inner structure of the sample

Question 12

What is scanning electron microscope?

Answer 12

• sample coated with heavy metal
• creates a 3D image by detecting reflected electrons
• provides information on the samples surface and composition

Question 13

Why are cells so small?

Answer 13

1. speed of diffusion - diffusion relates to substances moving from the outside of the cell towards the inside. When cells are larger, it takes a longer time for these substances to diffuse
2. surface area to volume ratio - when we increase the internal volume, much less surface area is available to exchange materials needed by the cell
3. easier to replace damaged/old/dying cells
4. wont disrupt function if they are damaged

Question 14

What are the two major groups of cells?

Answer 14

Prokaryotes and eukaryotes

Question 15

What are prokaryotes?

Answer 15

• no nucleus, but have a central area called the nucleolid that contains DNA
• no membrane bound organelles
• have cell walls
• one circular DNA
• kingdoms include bacteria and archaea

Question 16

What are eukaryotes?

Answer 16

• have membrane bound nucleus
• have membrane bound organelles ‘
• some may have cell walls, some may not (plant cells vs animal cells)
• kingdoms include plantae, animalia, fungi, Protista
• several linear chromosomes