Chapter 2- Basic Components of Living Systems

Question 1

Name the three components of cell theory

Answer 1

All living tissue is composed of cells
Cells are the most basic unit of all life
Cells can only develop from existing cells

Question 2

What are the two lenses in a light microscope and their roles?

Answer 2

An objective lens magnifies the image
The eyepiece lens further magnifies it

Question 3

Describe the four types of slide preparation

Answer 3

Dry Mount
Smear
Squash
Wet mount

Question 4

Define diffraction

Answer 4

Diffraction is the bending of light as it passes through the sample

Question 5

Give two examples of negatively charged dyes

Answer 5

Nigrosin and congo red

Question 6

Give two examples of positively charged dyes

Answer 6

Crystal violet and methylene blue

Question 7

What is the role of iodine in staining?

Answer 7

Fixes the stains

Question 8

Describe Gram staining technique

Answer 8

1. Apply Crystal Violet and iodine
2. Wash slide with alcohol- gram negative bacteria have thinner walls and lose the stain
3. Use safranin (counter-stain)

Question 9

Give another example of a differential staining technique

Answer 9

Acid fast technique- used to differentiate different species of mycobacterium. A lipid solvent carries carbofuchsin dye into the cells, and then the slide is washed with dilute alcohol

Question 10

Define resolution

Answer 10

The ability to see individual objects as separate entities

Question 11

What is resolution limited by in microscopy?

Answer 11

Diffraction- as structures are close together the light rays reflecting off them overlap and detail is lost

Question 12

What is the formula for magnification?

Answer 12

Magnification- size of image/actual size of object

Question 13

Define an artefact in microscopy

Answer 13

Structures created during the preparation process

Question 14

What are the two different types of electron microscope?

Answer 14

Transmission- electrons are transmitted through a specimen and focused to produce an image
Scanning- a beam of electrons is sent across a surface and returning electrons collected

Question 15

Which form of microscopy has the best resolution?

Answer 15

Transmission electron microscopy (about 0.5nm)

Question 16

Why must specimens in electron microscopes be dead?

Answer 16

The inside of an electron microscope is a vacuum

Question 17

What is AFM?

Answer 17

Atomic Force Microscopy- a sharp tip on a cantilever used to scan the surface of a specimen

Question 18

Define the ultrastructure of a cell

Answer 18

The features visible with an electron microscope

Question 19

What is the function of organelles

Answer 19

To separate the environments of the cell interior and provide distinct conditions for cellular reactions

Question 20

Define metabolism

Answer 20

Involving all the chemical reactions in a cell, including synthesis and breaking down

Question 21

What is the function of the nucleolus?

Answer 21

The area within the ribosome responsible for producing ribosomes, composed of proteins and RNA

Question 22

What are the three components of the cytoskeleton?

Answer 22

Microfilaments
Micro tubules
Intermediate fibres

Question 23

Describe the function of microtubules

Answer 23

Made of tubulin proteins
Form tubes that determine the shape of scaffold and act as tracks for movement of organelles
Form spindle fibres

Question 24

Describe the function of microfilaments

Answer 24

Formed from actin
Responsible for cell movement and contraction during cytokinesis

Question 25

Describe the role of intermediate fibres

Answer 25

Give mechanical strength to cells

Question 26

Describe how microfibrils help cell movement

Answer 26

Filaments change length with the addition and subtraction of monomers Subunits have to change shape to join the minus end but not the plus end They join at a faster rate at the plus end, increasing in length in one direction

Question 27

What are centrioles formed of?

Answer 27

Microtubules

Question 28

What is the 9+2 arrangement?

Answer 28

The internal structure of a cilia- 2 microtubules surrounded by nine pairs of microtubules arranged as a wheel

Question 29

What is the difference between the smooth and rough end plastic reticulum?

Answer 29

Smooth- responsible for lipid and carbohydrate synthesis and storage Rough- covered with ribosomes, responsible for synthesis of proteins

Question 30

What is the role of the Golgi apparatus?

Answer 30

Modifies the proteins and packages them into vesicles

Question 31

What are plant cell walls composed of?

Answer 31

Cellulose

Question 32

What is the purpose and structure of the vacuole?

Answer 32

Membrane lined sacs containing cell sap, involved in the maintenance of turgor

Question 33

What is the name of the fluid enclosed in chloroplasts?

Answer 33

Stroma

Question 34

What are the two evolutionary domains of prokaryotic cells?

Answer 34

Archaea and Bacteria

Question 35

Describe the structure of DNA in prokaryotes

Answer 35

Prokaryotes only have one super compact molecule of DNA, with genes grouped into operons

Question 36

What kind of ribosomes do prokaryotes and eukaryotes have respectively?

Answer 36

80s - eukaryotes, larger 70s - prokaryotes

Question 37

What are prokaryotic cell walls composed of?

Answer 37

Murein (aka peptidoglycan)

Question 38

What is the theory of endosymbiosis?

Answer 38

The theory that mitochondria and chloroplasts were originally free living organisms, leading to the evolution of eukaryotes