2.1.1 Basic Components of Living Systems

Question 1

Cell theory states that:

Answer 1

• both plant and animal tissue composed of cells
• cells are the basic unit of all life
• cells only develop from existing cells

Question 2

Compound light microscope

Answer 2

Mag = 2000X

Res = 200nm

Objective and eyepiece lenses
Dead/alive specimens
Inexpensive

Can’t see ultrastructure of cell

Question 3

Why is staining used?

Answer 3

To observe specific organelles

To differentiate between different types of cell

To distinguish between diff tissues

Question 4

Positive staining

Answer 4

e.g. methylene blue

+ve charged stain attracted to -ve components

Question 5

Negative staining

Answer 5

e.g. nigrosin

Contrast between anything and water

Question 6

Units of measurement

Answer 6

mm ➗ 1000 = micrometer

micrometer ➗ 1000 = nanometer

Question 7

definition of MAGNIFICATION

Answer 7

How many times larger the image is than the actual size of the object viewed

Question 8

Calculating magnification

Answer 8

Mag=image➗actual

I
A M

Question 9

definition of RESOLUTION

Answer 9

The ability to distinguish individual objects as separate entities

Question 10

TEM

Answer 10

Mag = 500,000X
Res = 0.5 nm

Beam of electrons
Travel through specimen
Create a b&w 2D image
Ultrastructure can be seen

Question 11

SEM

Answer 11

Mag = 100,000X
Res = 3-10 nm

Beam of electrons
Across surface of specimen
Reflected atoms collected
3D images of surface

Question 12

Laser scanning confocal microscope

Answer 12

Res = higher than light

Single spot of focused light across specimen (point illumination)
Causes fluorescence from components labelled w dye
2D image

Question 13

Light vs Electron

Answer 13

Light =
inexpensive,portable,simple prep, natural colour,X2000 mag,living and dead,200nm res

Electron =
expensive,large,complex sample prep,b&w images,X500,000 mag,dead specimens only,0.5/3-10nm res

Question 14

Light mag/res

Answer 14

Mag X2000

Res 200nm

Question 15

TEM mag/res

Answer 15

Mag X500,000

Res 0.5nm

Question 16

SEM mag/res

Answer 16

Mag X100,000

Res 3-10mm

Question 17

Nucleus

Answer 17

DNA
Synthesis of proteins 
Nuclear envelope=double membrane
Nuclear pores
Chromatin coils into chromasomes

Question 18

Nucleolus

Answer 18

In nucleus

Produces ribosomes

Question 19

Mitochondria

Answer 19

Sire of final stages of cellular respiration
Energy stored in bonds
Production of ATP
Double membrane

Question 20

Vesicles

Answer 20

Sacs for storage and transport

Transport materials inside the cell

Question 21

Centrioles

Answer 21

Made of microtubules, two form centrosome

Flagella and cilia

Question 22

Endoplasmic reticulum

Answer 22

Network of membranes with flattened sacs / cisternae

Question 23

Rough ER

Answer 23

Ribosomes on surface

Synthesis and transport of proteins

Question 24

Smooth ER

Answer 24

Lipid and carbohydrate synthesis

Storage

Question 25

Ribosomes

Answer 25

Made of RNA Made in nucleolus Site of protein synthesis

Question 26

Golgi apparatus

Answer 26

Cisternae No ribosomes Modify proteins Packages proteins into vesicles

Question 27

Protein production

Answer 27

i) synthesised on ribosomes on ER ii) pass into cisternae, packaged into transport vesicles iii) move to golgi via cytoskeleton iv) vesicle fuses w cis face of golgi, proteins enter. Proteins modified then leave on trans face v) secretory vesicles carry to surface membrane = exocytosis

Question 28

Cellulose cell wall

Answer 28

``` Plants Carbohydrate Freely permeable Shape Defence mechanism ```

Question 29

Vacuoles

Answer 29

``` Plants Contain cell sap Maintain turgor Membrane=tonoplast Selectively permeable ```

Question 30

Chloroplasts

Answer 30

``` Plants Photosynthesis Green Double membrane Fluid=stroma Internal membranes=thylakoids Several thylakoids=granum Grana joined to membrane called lamellae ```

Question 31

Lysosomes

Answer 31

Specialised vesicles Hydrolytic enzymes Break down waste material Immune system

Question 32

Cytoskeleton

Answer 32

i) microfilaments Actin, contractile, cell movement/contraction ii) microtubules Globular tubulin, proteins, shape, tracts for movement iii) intermediate fibres Strength, shape

Question 33

Prokaryotes

Answer 33

``` No nucleus Circular DNA Non-membrane-bound organelles Peptidoglycan cell wall 70s smaller ribosomes Reproduce: binery fission Unicellular ```

Question 34

Eukaryotes

Answer 34

``` Nucleus Linear DNA Membrane-bound organelles Chitin cell wall (fungi) Cellulose cell wall (plants) 80s larger ribosomes Reproduce: asexual/sexual Uni/multicellular ```