Cell Structure

Question 1

What is the basis structural unit of all living organisms?

Answer 1

Cells are the basic structural unit of all living organisms

Question 2

What is the cell theory?

Answer 2

-All organisms are made of cells.
-All existing cells come from pre-existing cells.
-The cell is the most basic unit of life.

Question 3

What are the exceptions to the theory?

Answer 3

• Striated muscle fibres
  -Aseptate fungal hyphae
  Giant algae.

Question 4

Why are optical light microscopes an invaluable tool?

Answer 4

Optical (light) microscopes are an invaluable tool for scientists as they allow for tissues, cells and organelles to be seen and studied

Question 5

How do optical light microscopes work?

Answer 5

-Light is directed through the thin layer of biological material that is supported on a glass slide
-This light is focused through several lenses so that an image is visible through the eyepiece
-The magnifying power of the microscope can be increased by rotating the higher power objective lens into place

Question 6

What are the key components of an optical light microscope?

Answer 6

The eyepiece lens
The objective lenses
The stage
The light source
The coarse and fine focus

Question 7

What is the formula for magnification?

Answer 7

magnification: image/drawing size : actual size.

Question 8

What are the common unifying features of ALL cells?

Answer 8

-DNA as genetic material
-cytoplasm
-Plasma membrane

Question 9

How does the DNA differ between eukaryotes and prokaryotes?

Answer 9

All living cells contain some sort of DNA, this varies between eukaryotic cells and prokaryotic cells

Question 10

What does the presence of DNA mean in a cell?

Answer 10

The presence of DNA means that a new cell can be formed from an old cell, as genetic material is able to be stored and transferred

Question 11

What else does DNA control in the cell?

Answer 11

DNA also controls the production of enzymes and other vital proteins within the cell

Question 12

What is the cytoplasm composed of?

Answer 12

It is composed of mainly water with dissolved substances, such as ions
The fluid is known as cytosol

Question 13

What occurs in the cytoplasm?

Answer 13

Important chemical reactions occur in the cytoplasm.

Question 14

Where is the cytoplasm found?

Answer 14

Cytoplasm is found within the boundary of a cell.
It is enclosed by a plasma membrane composed of lipids.

Question 15

Where is the plasma membrane found in a cell?

Answer 15

The plasma membrane surrounds the cell and encloses all the cell contents.

Question 16

How is the plasma membrane composed?

Answer 16

In all cell types, the plasma membrane has two layers and this is called a bilayer

Question 17

What does the bilayer consist of?

Answer 17

The bilayer consists of lipids; these vary depending on the type of organism

Question 18

What is the membrane responsible for?

Answer 18

For controlling the interactions of the cell’s interior with the exterior
-Needed materials are transported into the cell interior
-Waste substances are exported out of the cell to the surrounding environment

Question 19

What functions do the proteins have that are studded on the membrane?

Answer 19

Cell recognition
Cell communication
Transport into and out of the cell

Question 20

What are prokaryotes?

Answer 20

Prokaryotes have the simplest cell structure, being the first organisms to evolve on Earth and have been classified into two domains.

Question 21

What structure do prokaryotes not have?

Answer 21

Prokaryotes do not have a nucleus.

Question 22

What does the structure of a prokaryote lack?

Answer 22

Prokaryotes have a simple cell structure and lack compartmentalisation (not divided into compartments). it lacks membrane-bound organelles

Question 23

What structures are common to prokaryotes?

Answer 23

70S ribosomes
DNA in a loop
Cytoplasm
Plasma membrane
Cell wall

Question 24

What is the difference between the ribosomes in prokaryotes and eukaryotes?

Answer 24

Ribosomes in prokaryotes are 70S because they are much smaller. Ribosomes in eukaryotes are much larger and knows as 80S.

Question 25

What two domains have prokaryotes been classified in:

Answer 25

-Bacteria includes commonly known bacteria such as E.coli and Helicobacter. -Archaebacteria or Archaea - typically found in extreme environments such as high temperatures and salt concentrations and include methanogens (organisms that exist in anaerobic conditions and produce methane gas)

Question 26

What is the function of prokaryotic ribosomes (70S)?

Answer 26

The binding and reading of MRNA during translation to produce proteins.

Question 27

Where is the genetic material of a prokaryote located?

Answer 27

Although prokaryotes do not have a nucleus, they do have genetic material in the form of a singular circular DNA molecule located in the nucleoid and in smaller loops called plasmids.

Question 28

What are plasmids in prokaryotes?

Answer 28

Plasmids are small loops of DNA that are separate from the main circular DNA molecule.

Question 29

What do plasmids in prokaryotes contain?

Answer 29

Plasmids contain genes that can be passed between prokaryotes.

Question 30

What is found in the cytoplasm of a prokaryote?

Answer 30

The cytoplasm is the site where the 70S ribosomes are found in a prokaryote.

Question 31

What occurs in the cytoplasm of a prokaryote?

Answer 31

It is the site of many cellular reactions.

Question 32

What is a major component of the cytoplasm of a prokaryote?

Answer 32

A major component is a gel-like cytosol, a water-based solution that contains ions, small molecules and macromolecules.

Question 33

What is the cell membrane of prokaryotes composed of?

Answer 33

A lipid bilayer.

Question 34

What do a group of prokaryotes (archaea) have their plasma membrane formed as?

Answer 34

An archaea have their plasma membrane formed as a monolayer as opposed to a bilayer.

Question 35

What is the role of the plasma membrane?

Answer 35

To control substances entering and exiting the cell.

Question 36

What does the cell wall of most prokaryotes contain?

Answer 36

a cell wall containing murein/ peptidoglycan (glycoprotein).

Question 37

What does the cell wall do in a prokaryote?

Answer 37

It acts as protection, maintaining the shape of the cell and preventing it from bursting.

Question 38

How does the cell wall of prokaryotes (bacteria) allow us to classify them?

Answer 38

-ability to retain a dye called crystal violet classifies a group of bacteria as gran positive, they appear blue/violet after exposure to the dye. -bacteria that does not react with the dye are Gran negative bacteria.

Question 39

What are examples of gran positive bacteria?

Answer 39

Examples of gram positive bacteria are Bacillus and Staphylococcus.

Question 40

What are the structures that only some prokaryotic cells have that differentiate the species and act as a selective advantage?

Answer 40

-Plasmids -Capsules -Flagellum -Pili

Question 41

What is a capsule?

Answer 41

Some prokaryotes are surrounded by a final outer later known as a capsule. -Helps to protect bacteria from drying out and from attack by cells of the immune system fo the host organism.

Question 42

What is a flagellum?

Answer 42

Long, tail-like structures that rotate, enabling the prokaryote to move.

Question 43

What are pili?

Answer 43

Shorter and thinner structures than flagella. They assist with movement, avoidance of attack by white blood cells, conjugation and are commonly used to allow bacteria to adhere to surfaces.