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Biology > Chapter 2 - Basic Components Of Living Systems > Flashcards

Chapter 2 - Basic Components Of Living Systems Flashcards

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1
Q

Definition of a light microscope

A

an instrument that uses visible light and glass lenses to see objects magnified many times

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2
Q

Definition compound light microscope

A

Microscope which uses 2 lenses: the objective lens + eyepiece lens

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3
Q

What can you see through a light microscope?

A

Whole cells and tissues

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4
Q

Define magnification

A

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

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5
Q

Define resolution

A

The ability to see individual objects as separate entities

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6
Q

How can you increase the resolution?

A

Using beams of electrons (which have shorter wavelength) therefore the beam can be closer before the light is diffracted

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7
Q

What is the formula for magnification

A

Size of image/actual size

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8
Q

1SM=….

A

10 micrometres (0.01mm)

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9
Q

What is an electron microscope

A

Where a beam of electron (with a wlgth less than 1mm) is used to illuminate the specimen

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10
Q

What is the max magnification of electron and light microscope?

A

X500 000

X 2 000

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11
Q

Describe the advantages of an electron microscope

A
  • High resolution
  • High magnification
  • 3D image
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12
Q

Suggest disadvantages of using an electron microscope

A
  • Expensive
  • Needs to be carefully managed
  • Complex specimen preparation
  • Specimens can be easily damaged by the electron beam
  • Artifacts produced
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13
Q

What is a transmission electron microscope?

A

Where a beam of electrons is transmitted through a specimen + 2D

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14
Q

What can you see with a transmission electron microscope?

A

Organelles

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15
Q

What is a scanning electron microscope?

A

Where a beam of electrons is sent across the surface of a specimen and the reflected electrons are collected.

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16
Q

What is the resolving power of the TEM and is is a high or low resolution?

A

0.5nm & high resolution

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17
Q

What is the resolving power of the SEM and is is a high or low resolution?

A

3-10nm & low resolution

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18
Q

Definition of an artefact

A

A visible structural detail caused by processing the specimen.

Not a feature of the specimen

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19
Q

How does a laser scanning confocal microscope work?

A

Moves a single spot of light across a specimen (point illumination) causing fluorescence from the components that have been dyed.

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20
Q

What is a conventional optical microscope?

A

Uses visible light to illuminate specimens and produce magn. images

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21
Q

Do laser scanning confocal microscopes produce 2D or 3D images?

A

Both

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22
Q

Metabolism involves…

A

The build up (anabolic) and break down (catabolic) of molecules

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23
Q

Describe the nucleus in a eukaryotic cell

A

It contains the coded genetic information in form of DNA molecules

It controls the metabolic activities of the cell bc DNA directs all the synthesis of proteins

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24
Q

Where is the nucleus contained in?

A

The nuclear envelop to protect it from damage

Also contains nuclear pores to allow molecules to go in and out of nucleus.

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25
Q

How is DNA stored in eukaryotes?

A
  1. DNA is associated with histones to form chromatin

2. Chromatin coils and condenses to form chromosomes

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26
Q

What is the function of a membrane in prokaryotes?

A

They are selectively permeable

Control the movement of substances into and out of the cell and organelles

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27
Q

What is the nucleolus?

A

An area within the nucleus responsible for producing ribosomes

Composed of proteins and RNA, used to make ribosomal RNA then combine with proteins to form the ribosomes

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28
Q

What is the mitochondria responsible for?

A

The site of the final stages of cellular respiration

It takes in complex organic molecules, breaks them down, and creates energy rich molecules for the cell.

29
Q

Describe the structure of the mitochondria

A

Double membrane

Inner membrane = highly folded to form cristae

Fluid interior = matrix

Membrane forming the cristae contains enzymes used in aerobic resp.

30
Q

Do mitochondria have their own DNA?

A

Yes, mtDNA they can produce their own enzymes and reproduce themselves

31
Q

What are vesicles?

A

They are membranous sacs with fluid

Used for transportation and storage

Consist of single membrane with fluid inside

32
Q

What are lysosomes?

Responsible for..

A

Specialised forms of vesicles which contain hydrolytic enzymes

Role:

Break down waste materials in c. (including old organelles)

Breakdown of pathogens ingested by phagocytes

Cell death (apoptosis)

33
Q

What is the cytoskeleton?

A

A network of fibres necessary for the shape and stability of the cell, and movement of organelles.

34
Q

What are the three components of the cytoskeleton?

A
  1. Microfilaments
  2. Microtubules
  3. Intermediate fibres
35
Q

What are microfilaments?

A

Contractile fibres formed from protein actin

Responsible for cell movement and contraction during cytokinesis (when the cytoplasm of cell divides)

36
Q

What are microtubules?

A

Tubes formed from globular tubulin

Form scaffold like structures that determine the structure of the cell

Act as tracks for the movement of organelles (e.g. vesicles)
(e.g. spindle fibres in c divi)

37
Q

What are intermediate fibres?

A

Give mechanical strength to cells and help maintain their integrity

38
Q

What are centrioles?

A

A component of the cytoskeleton present in most euk.

Made of microtubules

Two associated centrioles form the centrosome

Centrosome involved in assembly and organisation of spindle fibres in CD

39
Q

What is the function of flagella?

A

To enable cell motility,

Or as sensory organelle detecting chemical changes in envirn

40
Q

Describe the two types of cilia

A
  1. Stationary
    present on surface of many c. (e.g. nose)
  2. Mobile
    Beat in rhythmic manner, create a current and causes fluids or objects to move
    (e.g. trachea, fallopian tube)
41
Q

Describe the arrangement in cilia cells

A

Each cilium has 2 central microtubules surrounded by 9 pairs of microtubules

9+2 arrangement (like a wheel)

Pairs of parallel microtubules slide over each other causing movement

42
Q

What is the endoplasmic reticulum?

A

A network of membranes enclosing flattened sacs (cisternae)

Connected to the outer membrane of the nucleus

43
Q

Describe the roles of the two endoplasmic reticulums

A

Smooth endoplasmic reticulum = lipid and carbohydrate synthesis and storage (don’t have ribosomes and formed of cisternae)

Rough endoplasmic reticulum= has ribosomes bound to the surface, responsible for the synthesis and transport of proteins (have ribosomes)

44
Q

Describe ribosomes in the cytoplasm

A

Can be free floating in the cytoplasm or attached to endoplasmic reticulum

Constructed of RNA molecules made in the nucleolus of the cell

Site of protein synthesis

45
Q

Describe the structure and role of the golgi apparatus

A

Similar structure to the smooth endo. ret.

Formed of cisternae

Doesn’t have ribosomes

Modifies proteins and packages them into vesicles (e.g. secretory vesicles)

46
Q

Light microscope specimen is (alive/dead or both)

Electron (alive/dead or both)

A

both

dead

47
Q

What are prokaryotes

A
  • No nucleus or membrane bound organelles
  • Single celled
  • Cytoplasm (water, cytosol and salts)
48
Q

Examples of prokaryotic and eukaryotic

A

Algae
Bacteria

Animal
Plant

49
Q

Why do we have compartments?

A

To allow different conditions for reactions to take place

50
Q

Describe the production of proteins

A
  1. Proteins are synthesised on the ribosomes bound to the Rough endoplasmic reticulum
  2. The proteins are passed into its cisternae and are packaged into transport vesicles
  3. The vesicles containing the newly synthesised proteins move towards the Golgi apparatus via the cytoskeleton
  4. Vesicles fuse with the cis face of the Golgi apparatus and proteins enter and leave via the trans face
  5. Secretory vesicles carry proteins to the cell surface membrane and fuse releasing their contents by exocytosis.
51
Q

Describe plant cell walls

A

Made of cellulose, freely permeable

Gives cell its shape

Contents of cells press against the cell making it rigid

Acts as a defence mechanism

52
Q

What are vacuoles?

A

Membrane lined sacs in the cytoplasm containing cell sap (permanent in plants)

Important to maintain the turgidity of the cell

53
Q

What is the cell membrane of the vacuole called?

A

Tonoplast

  • Selectively permeable
  • Can appear in animal c. but not permanent
54
Q

What is chloroplast?

A

Organelles responsible for photosynthesis

55
Q

Describe the structure of chloroplast

A

Double membrane structure

Fluid enclosed is called the stroma

Internal network of membranes, which form flattened sacs called thylakoids (provides a large surface area needed for enzymes, proteins and pigment molecules for photo.)

Have chloroplast DNA

56
Q

What are several thylakoids called? and what do they contain?

A

Granum

-Contain chlorophyll pigments, where light dependent reactions occur during photosyn.

57
Q

Grana join together to form …

A

Membranes called lamellae

58
Q

Prokaryotic cells are (unicellular/multicellular)

A

Unicellular

59
Q

How many molecules of DNA do prokaryotes have?

A

1 - a chromosome, which supercoiled to make it more compact

Often grouped into operons (meaning a n. of genes are switched on or off at the same time)

60
Q

The ribosomes in prokaryotic cells are (smaller/larger) than those in eukaryotic

A

Smaller

61
Q

How big are the ribosomes in eukaryotic cells

A

Large ones are 80S and smaller ones are 70S

62
Q

What is the cell wall in prokaryotic cells made of?

A

peptidoglycan (formed from amino acids and sugars)

63
Q

How does the flagella in a prokaryotic cell move?

A

They DONT have a 9 + 2 arrangement

Energy supplied by the process of chemiosmosis, not from ATP (like euk.)

Basal body attaches to the filament of the flagellum to the cell surface membrane of the bacterium

A molecular motor causes the hook to rotate giving the filament a whip like movement

64
Q

Describe the similarities and differences between the structures of prokaryotic and eukaryotic cells (11 marks)

A
  1. Prokaryote
  2. Eukaryote

Nucleus: not present, present

DNA : Circular , linear

DNA organisation: Proteins fold and condense DNA, associated w histones

Extra chromosomal DNA: circular DNA (plasmids) , only present in certain organelles (e.g. chloroplasts and mitochondria)

Organelles: non membrane bound, both membrane and non

Cell wall: peptidoglycan, chitin fungi, cellulose plant and not in animals

Ribosomes: smaller 70S , larger 80S

Cytoskeleton: present , present but more complex

Reproduction: binary fission, (as)sexual

Cell type: unicellular, both

Cell surface membrane: both

65
Q

What is the diameter of a eukaryotic and prokaryotic cell?

A

Euk. 20-40 micrometers

Prok. 0.5-5 micrometers

66
Q

What is the diameter of the ribosomes on prok. and euk.?

A

Prok. =18nm

Euk = 22nm

67
Q

Why can lungs be considered as organs?

A

Because an organ is a collection of tissues, the tissues in the lungs work together to enable gas exchange

68
Q

State three roles of membranes inside cells

A
  1. Form compartments within a cell (e.g. mitochondria / nucleus)
  2. The isolation of contents of organelles (e.g. hydrolytic enzymes)
  3. Can be the site for attachment of enzymes or receptors
  4. Provide selective permeability, controls what leaves and enters
  5. Creates concentration gradients for specific environments (e.g. pH)

Biology (15 decks)

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