5: Prokaryotic and Eukaryotic Cells pt.1

Question 1

Give three meaning of the modern cell theory.

Answer 1

1. The cell is the structural unit of life for all organisms.
2. All organisms are composed of one or more cells.
3. All living cells must come from a living cell

Question 2

Who discovered cells?

Answer 2

Robert Hooke discovered cells in 1665 by examining very thin slices of cork under a compound microscope

Question 3

Who was the first person to witness a live cell under a microscope in 1674?

Answer 3

Antony van Leeuwenhoek

Question 4

Who developed the cell theory?

Answer 4

Theodor Schwann Matthias Jakob Schleiden, Rudolf Virchow

Question 5

Give the names of the cell types.

Answer 5

Prokaryote (unicellular)
Eukaryote (multicellular)

Question 6

What are the characteristics of prokaryotes?

Answer 6

1. Has no nuclei or membrane-bound nuclei
2. Size ranges from 0.1-5 micrometer
3. Has a variety of shapes

Question 7

What is a capsule in regards to prokaryotic cells?

Answer 7

It is the outermost layer which is sticky to adheres to substrate and as protection.

Question 8

What is the cell wall made out of and why?

Answer 8

A prokaryote’s cell wall is made from peptidoglycan and is for the shape, protection and support from burst

Question 9

Why are there cell plasma membrane underneath the cell wall?

Answer 9

To cover the inner part of the cell.

Question 10

What is the semisolid that contains enzyme and other solution is called?

Answer 10

Cytoplasm

Question 11

Where is the genetic material stored in a prokaryote?

Answer 11

In the nucleoid, with no membrane separating it from the rest of the cell.

Question 12

What size is the ribosome and for what?

Answer 12

70S and to synthesize protein

Question 13

What are pili for?

Answer 13

To attach to the surface.

Question 14

What are flagella for?

Answer 14

To move around

Question 15

What are plasmids in regards to the prokaryotic cell?

Answer 15

Small, circular, double-stranded DNA molecules that carries genes for antibiotic resistance

Question 16

What are the characteristics of a eukaryotic cell?

Answer 16

1. Has a true nucleus that is contained in a membrane-bound structure.
2. Size ranges from 10-100 micrometer
3. Has a more advanced structural composition and performs more complex functions.
4. Has double membrane-bound organelles

Question 17

What are the members of the membrane system in a eukaryote?

Answer 17

The nuclear envelope, endoplasmic reticulum, Golgi apparatus

Question 18

What are the organelles and membrane derived structures in the cytoplasm of a eukaryote?

Answer 18

Ribosomes, mitochondria, chloroplasts, lysosomes

Question 19

What is the meaning of magnification in microscopy?

Answer 19

The ratio of an object’s image to its real size

Question 20

What is the meaning of resolving power?

Answer 20

A measure of image clarity, where the smallest/minimum distance two points can be separated and still be viewed as two separate points

Question 21

What is the meaning of resolution?

Answer 21

The level of details actually observed in the specimen and is limited by the wavelength of the source

Question 22

Explain compound/light microscope.

Answer 22

• Has visible light rays which passes through specimens and uses glass lenses to view objects
• Has different times of magnification ranging from 4X, 10X, 40X and 100X
• Magnification power = objective lens x ocular lens
• At higher magnification, image blurs and need to adjust the fine course knob/put oil on the lens
• Can only resolve individual cells, not the internal anatomy like the organelles

Question 23

Explain stereo/dissecting microscope

Answer 23

• Allows user to see 3D structure which is useful for surgery or dissection
• To study the largest cellular structures only

Question 24

Explain electron microscope

Answer 24

• focuses a beam of electrons through the specimen or onto its surface
• Resolution is inversely related to wavelength, therefore electron microscopes with shorter wavelength than visible light have finer resolution
• Resolution of a modern EM could reach 0.1 n,. but the practical limit is closer to about 2 nm
• Two types of EM: Transmission Electron Microscope & Scanning Electron Microscope

Question 25

Explain Transmission Electron Microscope

Answer 25

• Has a same design as light microscope, but the lenses are electromagnets
• Passes electrons through a specimen, focuses with a magnetic lens and projects images onto a fluorescent screen/photographic film
• Produces a detailed-image in static, 2D, and highly processed

Question 26

Explain Scanning Electron Microscope

Answer 26

• Passes a beam of electron over the surface of a metal-coated specimen
• Produces a television type 3D picture on a screen
• Provides topographical info on the surfaces of cells and tissues

Question 27

Explain the nucleus of a eukaryotic cell

Answer 27

• Centrally located
• The largest organelle in the cell

-Bounded by a nuclear envelope

Question 28

Give the functions of a nucleus?

Answer 28

• Contains hereditary material and can transmit all genetic information to the new generation
• Acts as the control center for all the cellular activities of the cells

Question 29

Give four structure of the nucleus

Answer 29

Nucleosome - The fundamental unit of chromatin, the material of which eukaryotic chromosomes are made

Chromatin - Thin, thread-like unwound material consisting of DNA and protein

Chromosome - Tightly packed DNA and visible as individual chromosomes during cell division

Nuclear envelope - Double membrane enclosing the nucleus; perforated by pores and continuous with ER