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Biology a level - ocr a > Chapter 2 Basic Components Of living systems > Flashcards

Chapter 2 Basic Components Of living systems Flashcards

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1
Q

What is an organelle

A

A membrane bound compartment with varying functions

By providing distinct environments and conditions for different cellular reactions

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2
Q

Uses of membranes

A

Serve as barriers
Allow molecules to diffuse across lipid bilayer
Cell signaling

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3
Q

Nucleus

A

Contains genetic material - which directs the synthesis of all proteins
Controls metabolic activities of cells

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4
Q

Nuclear envelope

A

Surrounds the nucleus

Contains nuclear pores - movement in and out

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5
Q

Nucleolus

A

Produces ribosomes
Composed of proteins and RNA

RNA used to make rRNA which combines with proteins to form ribosomes for protein synthesis

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6
Q

Cell wall

A

Supports the plant
Made of cellulose
Gives shape
Protects from pathogens

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7
Q

Mitochondria

Structure (matrix crista)

A

The site of aerobic respiration
Where atp is produced

Double membrane
Inner membrane folds to form crista
Inside crista is matrix
Matrix has enzymes for respiration

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8
Q

Vesicles

A

Storage
Transport materials inside cell

Fluid filled, membrane bound sacs

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9
Q

Lysosomes

A

Membrane bound
Contain hydrolytic enzymes (digestive)

Break down waste material in cells
Break down pathogens, dead organelles

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10
Q

Cytoskeleton

A

Network of fibres necessary for the shape and stability of a cell

Controls movement of organelles

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11
Q

What are the three main components of cytoskeleton

A

Micro filaments
Microtubules
Intermediate fibres
Centrioles

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12
Q

Microfilaments

A

Contractile filaments formed by actin

Responsible for cell movement and cell contractions
During cytokinesis

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13
Q

Microtubules

A

Globular tubular proteins polymerise to form tubes to form structure that determines the shape of the cell

Act as tracks for the organelles go follow (spindle fibres)

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14
Q

Intermediate fibres

A

Provide mechanical strength to cells

Help maintain integrity

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15
Q

Centrioles

A

Involved in the separation of chromosomes

Hollow cylinders of microtubules
Star shape
2 make centrosome

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16
Q

Flagellum

A

Microtubules contract to make flagellum move
Help swim
Detect chemical changes

2 microtubules in middle
9 pairs outside in circle

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17
Q

Cilia

A

Beat to cause fluid or objects to move

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18
Q

Smooth endoplasmic reticulum

A

Produces and stores
Lipids and carbohydrates

No ribosomes
Fluid filled, membrane bound, flattened sacs

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19
Q

Rough endoplasmic reticulum

A

Transfers, synthesises, folds and processes proteins made from attached ribosomes

Fluid filled, membrane bound, flattened sacs
Membrane enclosing fluid filled space - cisternae
Surface has ribosomes

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20
Q

Ribosomes

A

Site of protein synthesis

No membrane
2 sub units
Made from RNA

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21
Q

Golgi apparatus

A

Processes and packages new lipids and proteins
Makes lysosomes
Modifying proteins and packages them into vesicles

Fluid filled, membrane bound, flattened sacs

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22
Q

Protein production

A
  • proteins formed on ribosomes on ER
  • transported into ER cisternae and are packaged into transport vesicles
  • vesicles move to Golgi apparatus via the cytoskeleton transport system
  • vesicles fuse with cis face of Golgi apparatus and the protein enters
  • proteins are structurally modified before leaving Golgi in vesicles from trans face
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23
Q

Different types of vesicles that secretory vesicles make

A

Secretory vesicles fuse with cell surface membrane - exocytosis

Lysosomes - stay in cell

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24
Q

Vacuoles

A

Maintain turgid and maintain rigid framework

Membrane lined sacs filled with sap

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25
Q

Chloroplasts

A

Responsible for photosynthesis
Reactions driven by daylight

Double membrane 
Stroma = fluid in chloroplast 
Thylakoids = flattened sacs 
Granum = stacked thylakoids - contain chlorophyll pigment 
Lamelle = joins stacks of granum / grana
Has starch grains
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26
Q

Similarities between plant and animal cells

A
  • eukaryotic
  • have organelles : Golgi, nucleus, ER, mitochondria, ribosomes, membranes
  • obtain energy from cellular respiration
27
Q

Differences between plant and animal cells

A
  • Plant cells are larger
  • organelles: chloroplast, vacuole, cell wall, animal = centrioles
  • different shape: animal= round irregular, plant = rectangular
  • store energy: animal = glycogen, plant = starch
28
Q

Similarities between eukaryotic and prokaryotic

A
  • have: membranes, cytoplasm, ribosomes, DNA
  • cellular respiration
  • undergo cell division
  • require energy
29
Q

Differences between eukaryotic and prokaryotic

A
  • eukaryotic are membrane bound
  • eukaryotic is bigger
  • prokaryotic cells undergo cell division by binary fission
  • prokaryotic has one large coiled chromosome
  • prokaryotic no nucleus
  • cell walls: p= peptigoglycan, e = chitin, cellulose
  • ribosomes : p= 70s, e= 80s
  • flagella does not have 9+2 arrangement, motor causes hook to rotate
30
Q

Magnification

A

How much bigger the image is than the specimen

31
Q

Magnification equation

A

Magnification = image size/ actual size

32
Q

Resolution

A

Smallest distance between two points on a specimen that can be distinguished as two separate entities

33
Q

Dry mount

A

Cut into thin slices - sectioning
Place on slide
Cover slip

Used to view pollen, dust,hair, plant

34
Q

Wet mount

A

Suspended in liquid

Coverslip placed on at angle

35
Q

Squash slide

A

Wet mount
Lens tissue used to press down on cover slip

For soft samples
Root tip

36
Q

Smear slide

A

Smear sample onto slide using another slide
Cover slip

Used for blood cells

37
Q

What is resolution in a light microscope limited by

A

Wavelength of light

De fraction of light

38
Q

What does staining do

A

Increases contrast to see better

As different components take up different stains

39
Q

How to prepare for staining

A

Sample is air dried
Heat fixed - passed through flame
Specimen will adhere to microscope and take up stain

40
Q

Positively charged dyes

Crystal violet
Eosin
Methylene blue

A

Bacteria
Cytoplasm
DNA

Attracted to negatively charged cytosol
Stains cell components

41
Q

Negatively charged dyes

Nigrosin
Congored

A

Repelled by negatively charge cytosol

Stain background
Stay outside cell

42
Q

Electron microscope stain

A

Specimen dipped in solution or heavy metals

Metal ions scatter electrons
Creates contrast
Places turn darker than others

43
Q

What is differential staining

A

Can distinguish between 2 types of organisms

And different organelles

44
Q

Gram staining technique

Separates bacteria into gram positive and negative

A

Crystal violet applied
Then iodine - fixes stain
Slide washed with alcohol

Gram positive stay BLUE - retain the dye
Gram negative have thinner cell walls - lose the dye

Stained with safranin
Gram negative - RED

45
Q

Why is gram negative bacteria not susceptible to penicillin

A

Has protein layer around cell wall that prevents penicillin from attacking

46
Q

What is acid fast technique used to separate

A

Different species of mycobacterium from other bacteria

47
Q

How does acid fast technique work

A

Lipid solvent carries carbolfuchsin dye into cells
Washed with dilute acid alcohol
Mycobacterium is not affected by alcohol and stays RED
Other bacterium turned BLUE

48
Q

What are artefacts

A

Visible structural detail caused by processing the specimen and not a feature of the specimen

49
Q

Artefacts of light microscope

A

Air bubbles

50
Q

Artefact of electron microscope

A

Loss of continuity of membrane

Empty spaces in cytoplasm

Distortion of organelle

Mesosomes - membrane folds - produced by chemicals used in fixing

51
Q

How is resolution limited by diffraction of light

A

Tendency of light waves to spread as they pass close to physical structures

Light waves overlap - not seen as separate entities

52
Q

How to increase resolution

A

Using beams of electrons
With shorter wavelengths
Less overlapping

53
Q

1000 nanometres nm =

1000 micrometres um =

1000 mm =

A

1 um

1mm

1m

54
Q

How to calibrate an epg and sm

1000sm divisions = 1mm

1 sm d = 10um

A
  • put stage micrometre in place
  • focus
  • align sm and EPG
  • find magnification factor
55
Q

Light microscope

A

Uses light to magnify
Wavelengths are filtered to produce an image

Whole cells/ tissues

56
Q

TEM electron microscope

Transmission

A

Uses electromagnets to focus a beam of electrons and transmit them through specimen

Denser parts absorb more = darker

Ultrastructure / organelles

Resolving power = 0.5

57
Q

SEM

Scanning electron microscope

A

Scan a beam of electrons across specimen
Reflected electrons gathered in cathode ray tube to produce 3D image

Only see surface
Resolving power of 3-10nm

58
Q

Factors of light microscope

A 
Lower resolution 
Cheaper 
No vacuum needed 
Colour 
Living specimens 
Small
59
Q

Laser confocal microscopes

A

Uses laser beams to scan specimen - tagged with fluorescent dye

Fluorescent light in focused through pinhole onto détecter is hooked to computer
Only light focused close to pinhole is detected

60
Q

Uses of laser confocal microscopes

A

Look at different depths of thick specimens
Diagnosis of eye disease
Distribution of molecules within cells
Development of drugs

61
Q

Maximum resolution

Light
TEM
SEM

A
  1. 2 um
  2. 0002um
  3. 002um
62
Q

Maximum magnification of

Light
TEM
SEM

A

1500 x

1,000,000 x

500,000 x

63
Q

How to use a light microscope

A

Selected lowest powered magnification
Use coarse adjustment knob to bring stage up
Looked down
Use coarse adjustment until focused
Use fine adjustment to get better focused

Use higher magnification

64
Q

How to find uncertainty

A

Uncertainty = ( percentage error / 100 ) x reading

Biology a level - ocr a (11 decks)

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