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A- Level Biology > C2- Cell biology > Flashcards

C2- Cell biology Flashcards

1
Q

What are the 4 main types of slide preparation?

A

Wet mount- Specimen submerged in water and cover slip added
Dry mount- Specimen placed onto slide directly and cover slip placed on top
Squash slides- Wet mount prepared and cover slip is used to squash the cells
Smear slides- Edge of a slide is used to create a smooth thin layer of cells over a slide.

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2
Q

What is magnification

A

the number of times larger an
image is compared with the real size of the object.

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3
Q

What is resolution

A

the ability to distinguish between
two separate points. If two points cannot be resolved
they will be seen as one point, eg. like car headlights

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4
Q

Light Microscope advantages (5)

A

Can be used to look at cells and large organelles within cells

Staining cells makes organelles clearer

Preparation quick and simple

Natural colour of material observed

Living tissues can be observed

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5
Q

TEM vs SEM

A

TEM passes a beam of electrons through the specimen

SEM fires a beam of electrons across the surface, which
are reflected, and then collected

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6
Q

Transition electron microscopy

A

2D image

Max Magnification = x 500,000

Better resolving power– 0.5nm

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7
Q

Scanning electron microscopy

A

3D image

Max Magnification =x 100, 000

Less resolving power = 3-10nm

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8
Q

Methylene Blue stain

A

Positively charged dye attracted to negatively charged molecules

Stains DNA

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9
Q

Differential staining

A

Used to distinguish between 2 types of organisms, or organelles within an organism

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10
Q

Positively charged stains

A

Crystal violet

Methylene Blue

Attracted to negatively charged materials in the cytoplasm

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11
Q

Dry mount

A

used with whole or sectioned specimens

Can see living organisms

Mounts are temporary unless you seal the coverslip

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12
Q

Wet Mount

A

Specimens suspended in liquids such as oil or water

Cover slip placed at an angle

Greater refraction due to the liquid
-> Greater magnification and resolution

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13
Q

Squash slide

A

Wet mount first prepared

Gently press down on cover slip

Good for softer samples such as roots

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14
Q

Smear slide

A

Edge of a slide is used to smear a sample creating a thin even coating

Cover slip then placed

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15
Q

Negatively Charged Dyes

A

Congo Red

Nigrosin

Repelled by negatively charged cytosol
-> Stays outside cells, makes them stand out

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16
Q

Differential staining

A

Aids distinguishing between organisms or organelles

Gram stain technique

Acid fast technique

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17
Q

Prepared slide types (4)

A

1- Fixing= formaldehyde used to preserve
2- Sectioning= Dehydrate, wax and then slice with a microtome
3- Staining
4- permanent mounting

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18
Q

Cytoplasm- Structure

A

Contains Enzymes

Fluid = Cytosol

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19
Q

Cytoplasm- Function (3)

A

Where chemical reactions for cells take place

Holds membrane bound compartments (organelles)

Metabolism
-> Catabolism+ Anabolism. Break down and building of molecules

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20
Q

Nucleus- Structure (4)

A

Dark patches= Chromatin

Double membrane= nuclear envelope

Nuclear pores -> RNA can leave though as DNA too large

Nucleolus inside

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21
Q

Nucleus- Function (4)

A

Contains genetic material

Chromatin= histones (proteins) forms complex with DNA. Coils and then condenses into chromosomes

Contains instructions to make proteins

When cells divide chromatin condenses to visible chromosomes

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22
Q

Nucleolus (4)

A
  • Inside Nucleus

-Composed of proteins + RNA

-Produces ribosomes

  • RNA used to produce ribosomal DNA (rRNA) combined with proteins to make ribosomes
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23
Q

Mitochondria- Structure (4)

A
  • 2 membranes separated by a fluid filled space
  • Inner membrane folded to cristae. The inner fluid is the Matrix
  • Membrane holds respiration energy

-Own DNA (mtDNA) and own enzymes

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24
Q

Mitochondria- Function

A

Where ATP is produced during respiration

25
Q

Vesicles

A

Single membrane with fluid inside

used to transport materials inside cells

26
Q

Lyosomes

A

Specialised vesicles that contain hydrolytic enzymes

Break down waste material in cells such as old organelles

Play a role in apoptosis

Break down pathogens ingested by phagocytotic cells

27
Q

Flagella

A

whiplike

longer (than cilia)

For cell movement

Extensions form cell surface

28
Q

cillia

A

Hair like

Numerous

Extensions form cell surface

Present in sensory organs

Involved in creating currents

29
Q

Endoplasmic rectilium

structure

A

flattened membrane bound sacs (cisternae) which are continuous with outer membrane

30
Q

Endoplasmic rectilium

Function

A

smooth= involved in making lipids

rough= transport proteins made on attached ribosomes

31
Q

Ribosomes

Structure

A

Very small organelles in cytoplasm and on RER

2 Subunits- large and small

Manufactured in the nucleolus from RNA and proteins

32
Q

Ribosome

Function

A

Site of protein synthesis
–> Acts as an assembly line to use MRNA to make proteins

33
Q

Golgi apparatus

Structure

A

Stack of membrane bound flattened sacs

Similar structure to the Smooth ER

34
Q

Golgi apparatus

Function

A

Receives proteins from ER

Modifies them (post office)
–> e.g. adds sugar

35
Q

Protein production

5 key steps

A

1- Proteins are synthesised on ribosomes on RER

2- Pass into cisternae and are packaged into transport vesicles

3- vesicles move to golgi apparatus via function of the cytoskeleton

4-Vesicles fuse with Cis face of golgi apparatus. Proteins then enter. Proteins are structurally modified. Then leave in vesicles from the trans face

5- Secretory vesicles carry proteins to membrane and then fuse. Released via exocytosis. Some vesicles form lysosomes

36
Q

Centrioles

A

small protein tubes of microtubules

Form fibres in cell division called spindles which go on to separate chromosomes

37
Q

Cytoskeleton

A

Present throughout cytoplasm

responsible for the shape and stability of a cell

holds organelles in place and controls movement

38
Q

Cytoskeleton

Microfilaments

A

Contractile fibres
–> contain actin

Responsible for cell movement

39
Q

Cytoskeleton

Microtubules

A

scaffolding proteins for the shape of the cell

spindle fibres
–> pull apart chromosomes in cell division

40
Q

cytoskeleton

intermediate fibres

A

mechanical strength

41
Q

How to calibrate eyepiece graticule

A

SMU/ EMU x100

SMU=, stage micrometer

EMU= Eyepiece micrometer

42
Q

Graticule

stage vs eyepeice

A

Stage= true lengths

eyepiece= regular divisions that must be calibrated

43
Q

Biological drawing

low power lens

A

No individual cells should be drawn

44
Q

Biological drawing

5 key points

A

pencil only

scale bar

magnification

title

no shading

45
Q

Exocytosis

A

Process by which materials are removed from or transported out of cells

( vesicles fuse with cell membrane and release proteins)

46
Q

Vesicle vs Pernament Vacuole

A

Both are membrane bound sacs that function in storage and transport

Permanent vacuole doesn’t fuse with membranes

Plant vacuoles have enzymes that break down macromolecules
–> like lysosomes

47
Q

Compartmentalisation

A

The separation of the cell interior in distinct compartments with specific local conditions that allow simultaneous occurrence of diverse metabolic reactions and processes

48
Q

Endosymbiosis

A

An organism that lives within the body or cells of another organism

(opposite of parasitosis)

Theory for ribosomes and mitochondria

49
Q

Prokaryotes

A

plasmids replicate independent of main chromosomes

cell wall made of peptidoglycan

mesosome= inner extensions of cell membrane, site of respiration

smaller ribosomes
–> 70s not 80s

50
Q

Prokaryotic ribosomes

A

70s not 80s

s= where they settle in a centrifugal tube

51
Q

Prokaryotic flagella

A

Do not have a 9+2 arrangement

Smaller

Movement from chemiosmosis not ATP

“watermill”

52
Q

Chloroplasts

structure

A

2 membranes separated by a fluid filled space

stack of thylakoids is a granum

chlorophyll molecules present on the membranes

53
Q

Chloroplasts

Function

A

Site of photosynthesis

Light energy is used to derive carbohydrate molecules form carbon dioxide

54
Q

Permanent vacuole

Structure

A

Bound by a membrane called the tonoplast

Vacuole contains cell sap
–> solution of sugars, amino acids, salts, waste chemicals

55
Q

Permanent Vacuole

function

A

Food stores

accumulate waste products

maintains turgidity

56
Q

Cell wall (plants)

Structure

A

Cellulose cell walls

57
Q

Cell wall (plants)

Function

A

!!!Different in bacteria and fungi

protects cell from mechanical damage

maintains rigidity under turgor
–> water diffusion in/out of cell

Freely permeable

Barrier to pathogens

58
Q

Organelles not membrane bound

A

Cytoskeleton

villi/ flagellum

ribosomes

A- Level Biology (7 decks)

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