Cell Theory 2.1 U2

Question 1

What does a light microscope do?

Answer 1

Uses lenses to magnify the image of an object by focusing light after it passes through the specimen

Question 2

What are the pros of a light microscope?

Answer 2

Great for viewing living organisms
Easy to use, common in schools
Cheaper, smaller, and simpler than other types of microscopes
No need for other special machinery or techniques (ie. vacuum, radiation) to operate
Object being viewed retains its natural/authentic color

Question 3

What are the cons of a light microscope?

Answer 3

Components may not be visible (most cells are transparent) unless using special stains (usually kills the cell)
Lower resolution than other types
A microscope can only show an image of something that is smaller than the wavelength of light used. Since visible light has a (relatively) long wavelength, and the light is diffracted/scattered as it passes through the matter and lenses, this makes the image blurry at higher magnifications.
Maximum useful magnification - 1000x
Only shows a 2D image at higher magnifications

Question 4

What are the two types of light microscopes?

Answer 4

Compound Microscope
Dissecting (or Stereo) Microscope

Question 5

What is a compound microscope?

Answer 5

Typically 40x-400x, can view individual cells, 2-D image

Question 6

What is a dissecting(stereo) microscope?

Answer 6

Typically 7-20x, can only view larger objects, 3-D image

Question 7

What does an electron microscope do?

Answer 7

Uses a beam of electrons, instead of light, which are focused using magnetic fields

Question 8

What are the pros of an electron microscope?

Answer 8

Higher resolution images (due to shorter wavelength of electrons vs. visible light)
Good for viewing whole cells or individual components
Can be used at higher magnifications, up to 1,000,000x

Question 9

What are the cons of an electron microscope?

Answer 9

Requires sample to go through a special chemical fixation process and then viewed in a vacuum
Cannot view living cells
Much more expensive, complicated, larger, and difficult to operate
Requires a lot of specialized equipment to work properly and is very sensitive/easy to damage

Question 10

What are the two types of electron microscopes?

Answer 10

Transmission Electron Microscopy (TEM)
Scanning Electron Microscopy (SEM)

Question 11

What is a TEM microscope?

Answer 11

Transmission Electron Microscopy (TEM)
Beams pass through thin samples, creates flat/2D images
Good for viewing cellular structures and larger proteins

Question 12

What is a SEM microscope?

Answer 12

Scanning Electron Microscopy (SEM)
Beam scans the surface, producing high resolution 3D images
Good for viewing surfaces of cells

Question 13

What main thing did Robert Hooke discover?

Answer 13

He described the cork as having box-shaped, pore-like structures, which he called “cells”

In 1665, Robert Hooke published observations he made using a microscope, in the book Micrographia.

Question 14

What did Antonie van Leeuwenhoek discover?

Answer 14

He developed hundreds of simple single lens microscopes with an increased magnification! This allowed him to view organisms in more detail
Observed many biological specimens using his single lens microscopes, and sent his findings to the Royal Society
Saw tiny creatures he called them animalcules(Micromolecules)

Question 15

What did theodor schwann and schleiden discover?

Answer 15

Studied cells along with Matthias Schleiden, compared their studies of animal and plant cells
In 1839, proposed classical cell theory:
All living organisms are made of cells
Cells are the basic unit of life

Both Schwann and Schleiden were mistaken about the origins of those cells, though, which was correctly identified by another scientist…

Question 16

What did Rudolf Virchow add to the cell theory?

Answer 16

In 1855, he added a third conclusion to classical cell theory:
All cells come from preexisting cells

Question 17

What is the classical cell theory and what does the modern cell theory add to that?

Answer 17

Classical Cell Theory:
- All living things are made up of cells
- Cells are the basic units of structure and function in living things
- All cells are produced from existing cells
Modern Cell Theory adds:
- DNA contains hereditary information that is passed from cell to cell during division
- All cells are basically the same in chemical composition and metabolic activities
- Energy flow occurs within cells

Question 18

What do all cells(most) have?

Answer 18

Contain DNA (molecule that carries genetic information)
Are surrounded by a cell membrane (plasma membrane)
Have cytoplasm
Have ribosomes
On average range from 5 to 50 micrometers in diameter

Question 19

What are traits of prokaryotes?

Answer 19

NO nucleus
NO membrane-bound organelles
They are simple & unicellular

Question 20

What are the two types of prokaryotes?

Answer 20

Bacteria vs. Archaea

Question 21

What is bacteria?

Answer 21

Domain of prokaryotes that contain peptidoglycan in their cell walls
Live almost everywhere (fresh/salt water, land, within and on human bodies, etc)
Some a “good” some are “bad” (ie. some “help” other organisms and some cause disease, etc)

Question 22

What is archaea?

Answer 22

Domain of prokaryotes without peptidoglycan in their cell walls
Most live in extremely harsh environments (acidic, hot, salty, etc.)

Question 23

What is peptidoglycan?

Answer 23

Polymer of sugars and amino acids that can surround the cell membrane

Question 24

How do prokaryotes reproduce?

Answer 24

Binary fission
Conjugation

Question 25

What is Binary fission?

Answer 25

type of asexual reproduction in which an organism replicates its DNA and divides in half, producing 2 identical daughter cells.

Question 26

What is Conjugation?

Answer 26

Process in which some prokaryotes exchange genetic information by moving a cell through a hollow bridge from one cell to another

Question 27

How do favorable conditions affect asexual reproduction?

Answer 27

In favorable conditions, can grow and divide quickly! As fast as once every 20 minutes!
In unfavorable conditions, many form an endospore (a thick internal wall that encloses DNA and a portion of the cytoplasm) that can remain dormant for months or years!

Question 28

What is an endospore?

Answer 28

a thick internal wall that encloses DNA and a portion of the cytoplasm

Question 29

What are prokaryotes two categories of their modes of nutrition?

Answer 29

Autotrophs
Heterotrophs

Question 30

How can you further split up auto trophs and heterotrophs?

Answer 30

Photo-Autotroph
Chemo-Autotroph
Photo-Heterotroph
Chemo-Heterotroph

Question 31

What does a Photo-Autotroph do?

Answer 31

-Light as energy source
-CO2 as C source

Question 32

What does a Chemo-Autotroph do?

Answer 32

-Chemicals as energy source
-CO2 as C source

Question 33

What does a Photo-Heterotroph do?

Answer 33

-Light as energy source
-Organic compounds as C source

Question 34

What does a Chemo-Heterotroph do?

Answer 34

-Chemicals as energy source
-Organic compounds as C source

Question 35

Explain good prokaryotes?

Answer 35

Essential in maintaining ecological balance of the living world!
Decomposers, Producers, Nitrogen fixers, Human uses

Question 36

Explain bad prokaryotes?

Answer 36

Bacteria can be pathogens
Can damage host tissues and cells, or cause tissue damage when they provoke an immune response (ex. tuberculosis)
Can release toxins that act as poison, interfering or killing the host (ex. diptheria)

Question 37

What are decomposers?

Answer 37

break down dead organisms, supply raw materials

Question 38

What are producers?

Answer 38

conduct photosynthesis

Question 39

What are nitrogen fixers?

Answer 39

provide 90% of nitrogen used by other organisms

Question 40

What are Human uses?

Answer 40

used in wide variety of foods and other commercial products

Question 41

What are Pathogens?

Answer 41

agents that cause diseases (bacteria and virus can be pathogenic, there are currently no known pathogenic archaea)

Question 42

What are characteristics of eukaryotes?

Answer 42

Generally larger and more complex than prokaryotes, can be unicellular or multicellular
DNA found in nucleus, have dozens of internal structures (organelles)
Includes Animals, Plants, Protists, and Fungi

Question 43

What is the Endosymbiotic theory?

Answer 43

The endosymbiotic theory states that some of the organelles in today’s eukaryotic cells were once prokaryotic microbes

Question 44

What is some evidence for the endosymbiotic theory?

Answer 44

Mitochondria and chloroplasts are both similar in size to bacteria and contain their own DNA, ribosomes, and double membrane. This single stranded DNA is found exclusively in prokaryotes.
Chloroplast membranes closely resemble the membranes of photosynthetic prokaryotes
Some cells today contain bacteria and algae living in an endosymbiotic relationship

Question 45

What is Asexual Reproduction?

Answer 45

a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes.

Question 46

What is Mitosis?

Answer 46

Eukaryotes reproduce asexually in the process of mitosis.
A part of the cell cycle in which replicated chromosomes are seperated into two new nuclei.

Question 47

What is the microscope term resolution?

Answer 47

Shortest distance btwn two places on one specimen that can be identified as different

Question 48

What is the microscope term field of view?

Answer 48

what you can see through the microscope lens

Question 49

What is the microscope term Depth of field?

Answer 49

the range in which the object can still be clearly seen

Question 50

What is the microscope term magnification?

Answer 50

when a microscope creates an image a differnt size to the actual object it is looking at.