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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

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
Chloroplasts
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 ```
26
Similarities between plant and animal cells
- eukaryotic - have organelles : Golgi, nucleus, ER, mitochondria, ribosomes, membranes - obtain energy from cellular respiration
27
Differences between plant and animal cells
- 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
Similarities between eukaryotic and prokaryotic
- have: membranes, cytoplasm, ribosomes, DNA - cellular respiration - undergo cell division - require energy
29
Differences between eukaryotic and prokaryotic
- 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
Magnification
How much bigger the image is than the specimen
31
Magnification equation
Magnification = image size/ actual size
32
Resolution
Smallest distance between two points on a specimen that can be distinguished as two separate entities
33
Dry mount
Cut into thin slices - sectioning Place on slide Cover slip Used to view pollen, dust,hair, plant
34
Wet mount
Suspended in liquid | Coverslip placed on at angle
35
Squash slide
Wet mount Lens tissue used to press down on cover slip For soft samples Root tip
36
Smear slide
Smear sample onto slide using another slide Cover slip Used for blood cells
37
What is resolution in a light microscope limited by
Wavelength of light | De fraction of light
38
What does staining do
Increases contrast to see better | As different components take up different stains
39
How to prepare for staining
Sample is air dried Heat fixed - passed through flame Specimen will adhere to microscope and take up stain
40
Positively charged dyes Crystal violet Eosin Methylene blue
Bacteria Cytoplasm DNA Attracted to negatively charged cytosol Stains cell components
41
Negatively charged dyes Nigrosin Congored
Repelled by negatively charge cytosol Stain background Stay outside cell
42
Electron microscope stain
Specimen dipped in solution or heavy metals Metal ions scatter electrons Creates contrast Places turn darker than others
43
What is differential staining
Can distinguish between 2 types of organisms | And different organelles
44
Gram staining technique Separates bacteria into gram positive and negative
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
Why is gram negative bacteria not susceptible to penicillin
Has protein layer around cell wall that prevents penicillin from attacking
46
What is acid fast technique used to separate
Different species of mycobacterium from other bacteria
47
How does acid fast technique work
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
What are artefacts
Visible structural detail caused by processing the specimen and not a feature of the specimen
49
Artefacts of light microscope
Air bubbles
50
Artefact of electron microscope
Loss of continuity of membrane Empty spaces in cytoplasm Distortion of organelle Mesosomes - membrane folds - produced by chemicals used in fixing
51
How is resolution limited by diffraction of light
Tendency of light waves to spread as they pass close to physical structures Light waves overlap - not seen as separate entities
52
How to increase resolution
Using beams of electrons With shorter wavelengths Less overlapping
53
1000 nanometres nm = 1000 micrometres um = 1000 mm =
1 um 1mm 1m
54
How to calibrate an epg and sm 1000sm divisions = 1mm 1 sm d = 10um
- put stage micrometre in place - focus - align sm and EPG - find magnification factor
55
Light microscope
Uses light to magnify Wavelengths are filtered to produce an image Whole cells/ tissues
56
TEM electron microscope | Transmission
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
SEM | Scanning electron microscope
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
Factors of light microscope
``` Lower resolution Cheaper No vacuum needed Colour Living specimens Small ```
59
Laser confocal microscopes
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
Uses of laser confocal microscopes
Look at different depths of thick specimens Diagnosis of eye disease Distribution of molecules within cells Development of drugs
61
Maximum resolution Light TEM SEM
0. 2 um 0. 0002um 0. 002um
62
Maximum magnification of Light TEM SEM
1500 x 1,000,000 x 500,000 x
63
How to use a light microscope
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
How to find uncertainty
Uncertainty = ( percentage error / 100 ) x reading

Biology a level - ocr a (11 decks)

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