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Biology > Cells Part 1- Cell Structure And Microscopy > Flashcards

Cells Part 1- Cell Structure And Microscopy Flashcards

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1
Q

Describe how a light microscopes work

A

Beams of light are condensed to form an image
Focused with a glass lense

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2
Q

What are the advantages and disadvantages of light microscope

A

Lower mag and reso
Alive, coloured, seen with eye

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3
Q

What is resolution

A

Minimum distance between 2 points at which can be distinguished from each other

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4
Q

What is magnification

A

How much bigger than image is than the specimen

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5
Q

What is the wavelength of an electron

A

0.01 to 0.001 nm

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6
Q

How to transmission electron microscopes work

A

Beams of electrons pass through the specimen
Parts absorb electrons appear dark
Produces a photo micrograph

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7
Q

What are the advantages and disadvantages of TEM

A

Smaller objects seen, higher resolution
In vacuum, no living, complex staining technique, extremely thin specimen, artefact, not coloured

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8
Q

How to scanning electron microscopes work

A

Beams of electrons directed on surface of specimen in a regular pattern
Builds 3D image after analysing pattern scattered electrons that gather in cathode ray tube

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9
Q

How to scanning electron microscopes work

A

Beams of electrons directed on surface of specimen in a regular pattern
Builds 3D image after analysing pattern scattered electrons that gather in cathode ray tube

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10
Q

What are the advantages and disadvantages of SEM

A

3D, high resolution, thicker
Vacuum, lower reso then TEM, complex staining, no internal structures seen

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11
Q

What conditions are needed for cell fractionation

A

Cold- reduce enzyme activity
Isotonic - Same water potential - prevent osmotic damage to organelle
Buffered- prevent denaturing

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12
Q

What are the stages of cell fractionation

A

1.) Homogenisation- cells are homogenised in a blender to beak them open. The resulting mixture is called cell homogenate (resultant fluid after homogenisation that contains the broken open cells and their components
2.) The homogenate is filtered through a gauze to separate any large cell debris, like connective tissue, from the organelle
3.) Ultracentrifugation- it is centrifuged at various speeds and durations to fractionate the cell components, forming a series of pellets. The heaviest organelles form pellet at the bottom. The supernatant is drained off and spun in a centrifuge at a high speed and the process is repeated

1.Break open cells/tissue and filter
OR
Grind/blend cells/tissue/leaves and filter;
Accept homogenise and filter
2. In cold, same water potential/concentration, pH controlled solution;
Accept for ‘same water potential/ concentration’, isotonic
Accept for ‘pH controlled’, buffered
3. Centrifuge/spin and remove nuclei/cell debris;
4. (Centrifuge/spin) at high(er) speed, chloroplasts settle out;

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13
Q

Why can the same organelle appear differently within the same cell

A

Cells are a cut/ cross section
Mitochondria are orientated differently

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14
Q

What is an artefact and why should they be minimised

A

Visible entity that resembles structural detail of specimen
Not a legitimate feature of the specimen

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15
Q

What are the functions of the nucleus

A

Ribosomal rna- assemble ribosomes
mRNA - protein synthesis
Protect dna and genetic information
Replicate dna for cell division

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16
Q

What is the nuclear membrane for

A

Outer and inner membrane
Protect and enclose dna
Pores

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17
Q

What is the nucleoplasm for

A

Controls cell activities
Contains chromatin

18
Q

What are nuclear pores

A

Allow sentry of substances
Nucleotides for dna
Exit of mRNA for protein synthesis

19
Q

What is the nucleolus

A

Small spherical
Makes rna- ribosomes

20
Q

Describe and give the function of mitochondria

A

Repsiration for Krebs cycle
Production of atp

Double membrane
Cristae - folds, increase sa (attachment of enzymes)
Matrix- semi rigid. Site of Krebs cycle

21
Q

Adaptations of rough Endoplasmic respiration

A

Ribosome sof surface
Large sa
Pathway to transport proteins throughout cell
Protein synthesis

22
Q

Adaptations of smooth Endoplasmic reticulum

A

Synthesises, stores and transports lipids and carbohydrates
No ribosomes
Extension of nuclear membrane (more tubular)

23
Q

Ribosomes

A

2 subunits - rna, protein
80s- larger
70s- prokaryotic

24
Q

Adaptations and function of Golgi body

A

Made from lipids and proteins
Receives vesicles from ER
Modifies by adding
Produces transport vesicles to move or membrane
Exocytosis- vesicle fuses with cell surface membranes to release contents out of cell

25
Q

Adaption and functions of lysosomes

A

Breakdown material ingested by phagocytosis cells- engulf and destroy
Release enzyme
Formed in Golgi body
(Lysosome fusion eight vesicle sand release hydrolytic enzymes)

26
Q

Adaptation and functions of chloroplast

A

Site of photosynthesis
Double plasma membrane - isolate reactions
Stoma- fluid filled matrix. Synthesis of sugars
Starch grains
Grana- contains chlorophyll and stacks of thylakoids - light absorption

27
Q

Adaptation and functions of chloroplast

A

Site of photosynthesis
Double plasma membrane - isolate reactions
Stoma- fluid filled matrix. Synthesis of sugars
Starch grains
Grana- contains chlorophyll and stacks of thylakoids - light absorption

28
Q

Function of vacuole

A

Fluid filled sack
Loneplast- single membrane
Solution of : water, minerals, sugar, salt, amino acids, wastes, pigments
Storage vesicle, waste disposal, protection, growth
Makes the cell turgid

29
Q

What is in the cell wall of algae

A

Cellulose
Glycoproteins

30
Q

What is in the cell wall of fungi

A

Chitin
Glycon
Glycoproteins

31
Q

What is a capsule

A

Late rof slime
Protects cells form other cells
Groups of bacteria to stick together

32
Q

Give structures that are found in both prokaryotic and eukaryotic cells

A

Cell membrane
Ribosomes
Cytoplasm
DNA

33
Q

Compare and contrast a prokaryotic and eukaryotic cell

A
  1. Magnification (figures) show A is bigger than B;
  2. A has a nucleus whereas B has free DNA;
  3. A has mitochondria whereas & does not;
  4. A has Golgi body/endoplasmic reticulum whereas B does not;
    5.-
    A has no cell wall whereas B has a murein/glycoprotein cell wall;
    Accept peptidoglycan
  5. A has no capsule whereas B has a capsule;
    A has DNA is bound to histones/proteins whereas B has
    DNA not associated with histones/proteins
    OR
    A has linear DNA whereas B has circular DNA:
  6. A has larger ribosomes;
34
Q

Outline the organelles in the production, transport and release of proteins form eukaryotic cells

A
  1. DNA in nucleus is code (for protein);
  2. Ribosomes/rough endoplasmic reticulum produce (protein);
    Accept rER for ‘rough endoplasmic reticulum’
  3. Mitochondria produce ATP (for protein synthesis);
  4. Golgi apparatus package/modify:
    OR
    Carbohydrate added/glycoprotein produced by Golgi apparatus;
    Accept body for ‘apparatus
  5. Vesicles transport
    OR
    Rough endoplasmic reticulum transports;
  6. (Vesicles) fuse with cell(-surface) membrane:
    Accept exocytosis at cell membrane
35
Q

Contrast how optical and TEM work and contrast limitations of use while studying cells

A

TEM use electrons and optical use light;

TEM allows a greater resolution;
(So with TEM) smaller organelles / named cell structure can be observed
OR
greater detail in organelles / named cell structure can be observed:

TEM view only dead / dehydrated specimens and optical (can) view live specimens;

TEM does not show colour and optical (can):

TEM requires thinner specimens;

TEM requires a more complex/time consuming preparation;

TEM focuses using magnets and optical uses (glass) lenses;
‘clearer’ is not equivalent to ‘detail”
Accept ‘Only optical can view live specimens”
5. Accept ‘Only optical can show colour
Accept ‘TEM requires a more difficult preparation
Ignore references to artefacts

36
Q

Desire how you count make a temporary mount of a piece of plant tissue to observe the position of starch grains

A

Add drop of water to (glass) slide;
Obtain thin section (of plant tissue) and place on slide / float on drop of water;
Stain with / add iodine in potassium iodide.
- Allow any appropriate method that avoids trapping air bubbles
Lower cover slip using mounted needle.

37
Q

What structures do viruses consist of

A

Lipid envelope, matrix, capsid, Nucleic acid, reverse transcriptase, attachment proteins, mesosomes

38
Q

What are the similarities and differences between mitosis and binary fission

A

Both replicate dna, identical daughter cells produce

No nucelus, no nuclear membrane breaks down, no chromosomes, plasmids replicate, no membrane-bound organelles, no spindle fibres

39
Q

What are kinetochores

A

Protein complex on centromere, attachment point for spindle microtubules

40
Q

What are chromatids

A

Replicate chromosomes / identical copies of chirmsomes
Joined at their centromeres
Following dna replication

Biology (13 decks)

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