Lecture 3 and 4 Cell Theory

Question 1

Who was Robert Hooke?

Answer 1

invented the microscope, first to publish a picture of a cell, geological studies, first people to prove that seabed could become a mountain top

Question 2

Who was Anton Moonhawks?

Answer 2

Anton Moonhawks: identified first microorganisms, stem cells, animal cells

Question 3

What are the three generalizations of Cell theory?

Answer 3

1. All organisms are composed of one or
more cells.
2. The cell is the basic structural and
functional unit of all living organisms.
3. Cells arise only from the division of
preexisting cells.

Question 4

Which of the following are eukarya?

Bacterium
Archaean
Protist
Algae
Fungal Cells
Animal Cells
Plant Cells

Answer 4

Protist
Algae
Fungal Cells
Animal Cells
Plant Cells

Question 5

What is the Universal Phylogenetic Tree

The Tree of Life

Answer 5

• Three domain system,
based on a comparison
of ribosomal RNA genes,
divides microorganisms
into:
• Bacteria (true bacteria).
• Archaea.
• Eukarya (eukaryotes).

Question 6

In the tree of life diagram, why are mitochondria and chloroplasts divergent from Bacteria?

Answer 6

Chloroplast and mitochondria were bacteria, we have bacterial dna, different organisms can merge together, share metabolism, theory that they originated from an endosymbiotic relationship with bacteria

Question 7

What are the three basic Basic Features of Cell Structure and Function?

Answer 7

• As the basic structural and functional
units of all living organisms, cells carry
out the essential processes of life
• Cells contain DNA and RNA, which
carry hereditary information and
direct the manufacture of cellular
molecules
• Cells use energy, respond to changes
in their environment, reproduce, and
pass on hereditary information

Question 8

What is the largest cell?

Answer 8

Egg yolk

Question 9

Light microscopes?

Answer 9

Light microscopes - use dyes
that stain particular
structures in the cell based
on their chemical structure.
Resolution down to 0.2 m

Question 10

Magnification?

Answer 10

Magnification – the ratio of
the object viewed (e.g.
400:1)

Question 11

Resolution?

Answer 11

Resolution – Minimum
distance two points can be
separated

Question 12

Different Types of light
microscopes are used to
reveal different
structures/functions
within cells. Name some types of light microscopes

Answer 12

• Bright Field/Dark Field
• Phase-constrast
• Differential interference
contrast
• Confocal laser
scanning…

Question 13

Electron Microscopes

Answer 13

Electron Microscopes - use

electrons rather than light

Question 14

Transmission E.M.

Answer 14

Transmission E.M. - specimen
thin sectioned. Electrons
passed through structure.
practical resolution down to
2 nm

Question 15

Scanning E.M.

Answer 15

Scanning E.M. - specimen
coated in gold. Electrons
scanned over specimen,
emitted electrons captured.

Question 16

Scanning Tunnelling

Microscope

Answer 16

Scanning Tunnelling
Microscope - highest clarity.
resolution to atomic level (0.1-
0.2 nm)

Question 17

Why are cells so small?

Answer 17

Cell size is limited by surface area-tovolume ratio
Surface area determines the amount
of substances that can be exchanged
between a cell and the outside
environment
Doubling the diameter of a cell
increases
its surface area by four times but
increases its volume by eight times
The bigger the cell the harder it is to take in
nutrients and remove waste products

Question 18

What is the plasma membrane?

What is the lipid bilayer?

Answer 18

• plasma membrane, a bilayer made of lipids
  with embedded protein molecules
• surrounds cell
• hydrophobic barrier to water-soluble substances
  –Selected substances can penetrate cell
  membranes through transport protein
  channels
  –Selective transport of ions and watersoluble molecules maintains the specialized
  internal environments required for cellular
  life

Question 19

What’s the difference between eukaryotic and prokaryotic cells?

Answer 19

Prokaryotes (domains Bacteria
and Archaea) –The nucleoid region has no boundary
membrane. –Many species of bacteria have few
internal membranes.
- lack nuclear enveloppe

Eukaryotes (domain Eukarya)
 –The true nucleus is separated from the
surrounding cytoplasm by membranes. 
–Cytoplasm typically contains extensive
membrane systems that form organelles.
- eukaryotic cells have a membrane-bound nucleus and prokaryotic cells do not.

Question 20

why are prokaryotes no longer a group?

Answer 20

Both bacteria and archaea were, until recently, grouped together as prokaryotes

The term “prokaryotic cell” is still used and refers to a
particular cell architecture, i.e., one lacking a nucleus

More advanced biochemical and genetic techniques
revealed that they are evolutionarily distinct and the term
“prokaryote” has fallen out of use by microbiologists

Question 21

Name the parts of Bacteria and Archeae

Answer 21

pili, plasma membrane, cell wall, capsule, nucleoid, cytoplasm ribosomes