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biology OCR > 2.1.1- cell structure > Flashcards

2.1.1- cell structure Flashcards

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1
Q

What is the magnification and resolution of a light microscope?

A

magnification x1500-x2000
resolution 200nm

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2
Q

what is the magnification and resolution of a TEM (transmission electron microscope)

A

magnification x500,000
resolution 0.5nm (highest)

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3
Q

what is the magnification and resolution of a SEM (scanning electron microscope)

A

magnification x500,000
resolution 3-10nm

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4
Q

what are the pros and cons of a light microscope?

A

pros: live samples, cheaper, less expertise, colour
cons: lower resolution, lower magnification

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5
Q

what are the pros and cons of a TEM?

A

pros: highest resolution, viewing ultrastructures
cons: black and white, dead samples, expensive, 2d

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6
Q

what are the pros and cons of SEM?

A

pros: 3D images, can view surfaces
cons: black and white, dead samples, expensive, specimens must be coated in metal.

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7
Q

what does an eyepiece graticule do?

A

is calibrated to measure specimens

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8
Q

what does a stage micrometer do?

A

calibrates the eyepiece graticule at different magnifications

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9
Q

what is the equation for the calculation of one EPG division?

A

size of one stage micrometer division / number of EPG divisions covered

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10
Q

explain four different slide preparation techniques

A

dry mount: solid specimens viewed whole or sectioned. sample placed on slide and cover slip on top e.g. pollen
wet mount: specimens suspended in liquid, cover slip placed on at an angle to avoid air bubbles, e.g. aquatic samples
squash slide: wet mount prepared, lend is gently pressed to squash cells e.g. root tips
smear slides: edge of slide is used to smear sample creating a thin layer e.g. blood smear

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11
Q

what is positive staining?

A

positive stains are attracted to negative parts of a cell, including the cell components. these pick up the stain and stand out. examples include methylene blue and crystal violet.

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12
Q

what is negative staining?

A

negative stains are repelled by negative parts of the cell, so stay outside of cell components. this makes cells stand out against a stained background.

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13
Q

what is differential staining?

A

staining with multiple dyes to differentiate between different types of structures in a specimen. For example the gram-stain technique or the acid fast technique.

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14
Q

what is the gram-stain technique?

A

used to differentiate between gram positive and gram negative bacteria. crystal violet dye is added, iodine fixes the stain, slide washed with alcohol. gram positive bacteria retain the dye so appear blue/violet. a counter stain is added to highlight the gram negative bacteria, such as red safranin

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15
Q

what is the acid-fast technique?

A

used to distinguish between mycobacterium and other bacterium. Carbolfuchsin is added, cells are washed with an acid/alcohol solution. mycobacterium not affected by wash and retain the stain and show up as blue. second stain is added to highlight other bacteria, such a methylene blue.

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16
Q

how do you convert from millimetres to micrometres, for example 7 millimetres to micrometers

A

multiply by 1000. 7mm is 7000 micrometers

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17
Q

define magnification

A

how many times greater the image size is compared to the actual size

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18
Q

define resolution

A

the ability to distinguish between two separate points.

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19
Q

what organelles are involved in protein synthesis?

A

nucleus, nucleolus, RER, ribosomes, golgi body, cell surface membrane

20
Q

describe process of protein synthesis at each organelle involved

A

nucleus: stores cell’s genetic info as DNA, transcription occurs to get mRNA
nucleous: manufactures ribosomes from RNA and protein
RER: site of ribosomes
ribosome: translation of protein. polypeptides folded and processed into proteins.
golgi: vesicles for secretion, modified and packaged.
cell surface membrane: fused with in exocytosis to release vesicle contents.

21
Q

what are 3 functions of the cytoskeleton?

A

mechanical strength, aiding transport, enabling cell movement

22
Q

what is the function of the nucleus?

A
  • stores the genetic information of a eukaryotic organism in DNA.
  • It organises the protein synthesis.
  • controls the metabolic rate of the cell
23
Q

what is the function of the nucleolus?

A

responsible for protein synthesis since the nucleolus produces ribosomes. It is made of RNA and proteins which combine to form ribosomes. Ribosomes then undergo translation to form polypeptide chains

24
Q

what is the function of the nuclear envelope?

A

a protective double membrane that contains the DNA, separating it from the cytoplasm’s reactions to prevent damage.

25
Q

what is the function of the RER?

A

manages the synthesis and transport of proteins

26
Q

what is the function of the SER?

A

responsible for the production and storage of carbohydrates and lipids

27
Q

what is the function of the golgi apparatus?

A

modifies and packages proteins into vesicles.

28
Q

what is the function of ribosomes?

A

the site of protein sythesis, located in the cytoplasm or on the RER.

29
Q

what is the function of mitochondria?

A

the site of the conversion of stored energy into ATP for cellular respiration

30
Q

what is the function of lysosomes?

A

a form of vesicle for inside the cell, containing hydrolyctic enzymes which break down a cell’s waste materials. Important for the immune system as they break down pathogens ingested by phagocytes.

31
Q

what is the function of chloroplasts?

A

responsible for photosynthesis. contains the green pigment chlorphyll which allows light-dependent reactions to occur.

32
Q

what is the function of the plasma membrane?

A

protects the cell from it’s surroundings, stabilises he cytoskeleton to provide shape to the cell. cell signalling, containing receptors that can detect signals

33
Q

what is the function of centrioles?

A

construction of microtubules, essential to the production and organisation of spindle fibres in cell division.

34
Q

function and structure of the cell wall

A

made of cellulose for structure and rigidity, fully permeable so substances can pass freely. A defence mechanism against pathogens.
made of cellulose for structure and rigidity, fully permeable so substances pass through freely.

35
Q

flagella function

A

tail-like extensions of prokaryotic cell walls, used to improve cell mobility

36
Q

cilia function

A

hair-like extensions of cells, common in sensory organs like the nose, but also as a medium to aid the transfer of fluids, such as in the lungs to trachea to waft mucus away

37
Q

what are microtubules and what is their function?

A

globular tubulin proteins that form ling tubes. involved in cell mobility, transport in the cell, and shape. Apply compression forces to the cell.

38
Q

what are microfilaments and what do they do?

A

contractile proteins like actin, responsible for cell movement and contraction during cytokinesis. they determine cell shape, motion of cell surface. movement of subcellular components.

39
Q

what are intermediate filaments?

A

protrude from a ring around the nucleus towards the plasma membrane. They aid mechanical stength, and anchor subcellular components in place.

40
Q

what is endosymbiotic theory?

A

chloroplasts and mitochondria have evolved from prokaryotic cells and that the DNA and ribosomes they retain are derived from this evolution

41
Q

do prokaryotic cells have mitochondria?

A

no

42
Q

do prokaryotic cells have a cell membrane?

A

yes

43
Q

do bacterial cells have ribosomes?

A

yes

44
Q

what does a capsule do in bacterial cells?

A

protective layer that stops dehydration and the attack of white blood cells

45
Q
A

biology OCR (4 decks)

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