A2.2 - cell structure Flashcards

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1
Q

magnification

A

increase in an object’s image size compared to its actual size

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2
Q

multicellularity

A

having more than one cell in an organism

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3
Q

resolution

A

minimal distance between two points at which they have be distinguished as two points

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4
Q

cells

A

basic structural unit of all living organisms

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5
Q

deductive reasoning

A

used to generate predictions from theories
- based on cell theory, a newly discovered organism can be predicted to consist of one or more cells

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6
Q

how do you prepare a sample to be used in a microscope?

A
  1. a thin sample is taken and placed on a slide
  2. stains may be used to improve visibility of structures
  3. a cover slip is lowered gently over the sample, avoiding air bubbles and blotting excess stain
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7
Q

how do you use a microscope?

A
  1. lamp is switched on and the lowest power objective lens is selected, with the stage being moved to the lowest position
  2. place slide in middle of stage so light is shining through it
  3. move stage to the highest position until the lens doesn’t touch the sample
  4. look through eyepiece leans and use coarse focus and fine focus knob to focus the image
  5. move sample if needed and use a higher magnification
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8
Q

eyepiece graticule

A

located in the eyepiece and engraved with 100 equal arbitary units and doesn’t alter magnification

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9
Q

arbitary units

A

size they measure depends on the microscope, total magnification and objective lens

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10
Q

micrometer

A

slide with a ruler 1mm long divided into 0.1mm divisions used to determine graticule divisions

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11
Q

how do you calculate a graticule unit?

A

comparing the units of the graticule to the known unit size of the stage micrometer allows you to determine the size of the object being examined

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12
Q

scale bars

A

drawn proportionally to a structure of known size determined using a graticule and stage micrometer

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13
Q

how do you calculate magnification?

A

magnification = eyepiece lens x objective lens

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14
Q

how do you calculate image size?

A

image size = actual size x magnification

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15
Q

how do you measure the actual size and image size?

A

actual size - scale bar
image size - ruler

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16
Q

how do you convert between units?

A

1cm = 10mm = 10000µm = 10000000nm

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17
Q

light microscopy

A

uses light to form an image with dead or living specimens to a maximum of 2000x magnification

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18
Q

fluorescent stains

A

bind to specific cellular components, based on the combinations of dye, and light up when irradiated with UV

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19
Q

immunofluorescence

A

uses antibodies attached with fluorescent dyes to bind to a particular molecule
- different wavelengths given off can be used to fund out locations of proteins within a cell
- allows components to be targeted more precisely e.g) a specific protein or RNA molecules

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20
Q

electron microscopy

A

uses interactions with electrons to produce an image
- higher resolution and magnification
- specimen mys be dead and fixed in plastic
- structural features are produced during preparation which can hinder image accuracy

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21
Q

what are the 2 types of electron microscopy?

A

SEM - scanning electron microscope - produces image of the surface of the object
TEM - transmission electron microscopy - uses electrons passing through a thin section

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22
Q

freeze fracture

A

rapidly freezing a biological specimen before breaking it down to reveal a plane through the sample which can be examined (membranes)

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23
Q

cyrogenic electron miscroscopy

A

allows imaging of single protein molecules and interactions with other molecules

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24
Q

what 3 structures are common to cells in all living organisms?

A

DNA, cytoplasm, plasma membrane

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25
Q

what is the function of DNA?

A

stores genetic code (sequence of nucleotides) and allows this to transfer during protein synthesis and cell division

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26
Q

what is the function of the cytoplasm?

A

made of matrix and water where metabolic reactions occur

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27
Q

what is the function of the plasma membrane?

A

lipid bilayer with embedded proteins to enclose cytoplasm, control movement of substances in and out of cells and supporting cell recognition and communication

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28
Q

prokaryotic cells

A

bacterial cells (Gram positive eubacteria such as Bacillus or Staphylococcus)

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29
Q

what are the components of prokaryotic cells?

A

cell wall, plasma membrane, cytoplasm, naked DNA, 70S ribosome

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30
Q

what are extra 3 components prokaryotic cells may contain?

A

plasmid, flagellum, pili

31
Q

eukaryotic cells

A

plant or animal cells (exocrine gland or palisade mesophyll cell)

32
Q

what are the components of eukaryotic cells?

A

plasma membrane, compartmentalized cytoplasm, 80S ribosomes, nucleus, double membrane

33
Q

what do membrane-bound cytoplasmic organelles include?

A

mitochondria, rough endoplasmic reticulum, smooth enoplasmic reticulum, Golgi apparatus, vesicles, vacoules, cytoskeleton

34
Q

what are the 7 life function processes of life?

A

Metabolism - chemical reactions within an organism
Reproduction - producing similar cells or organisms from existing ones
Sensitivity - responsiveness to stimuli
Homeostasis - regulating and maintaining a stable interior environment
Excretion - eliminating metabolic waste
Nutrition - organisms make use of nutrients/food
Growth - increase in size or number of cells

35
Q

how do plant, animal and fungal cells differ in terms of composition of cell walls?

A

plant - cellulose
animal - no cell wall
fungal - chitin

36
Q

how do plant, animal and fungal cells differ in terms of size and function of vacuoles?

A

plant - large vacuole to store carbs and nutrition and maintaining turgor pressure and rigidity from water
animal - small numerous vacuoles with unique functions
fungal - small numerous vacuoles with unique functions

37
Q

how do plant, animal and fungal cells differ in terms of presence of plastids?

A

plant - chloroplast to make carbs from photosynthesis and amyloplasts to store starch
animal - none
fungal - none

38
Q

how do plant, animal and fungal cells differ in terms of structures involved in cell division?

A

plant - centrosomes
animal - centrosomes and centrioles
fungal - centrosomes

39
Q

how do plant, animal and fungal cells differ in terms of presence of cilia and flagella?

A

plant - none
animal - cilia or flagella to direct nasal body
fungal - cilia or flagella but no nasal body

40
Q

plastids

A

small structures found in plant cells that store and produce substances essential for the cell’s function, such as pigments, starch, and lipids.

41
Q

what are atypical cells?

A

cells with no or more than 1 nucleus

42
Q

what are 2 examples of multi-nucleus cells?

A

aseptae fungal hyphae - has a continuous filament that contains multiple nuclei
skeletal muscle fibres - multiple nuclei on elongated cells to allow for larger contraction

43
Q

what are 2 examples of no nucleus cells?

A

erythrocytes (red blood cells) - no nucleus to carry more oxygen and biconcave shape increases sa:v ratio to maximise exchange
phloem sieve tubes - cells connected end-on-end with pores that rely on companion cells to supply nutrients and ATP

44
Q

how can you identify bacterial cells in a light micrograph?

A
  • rod-shaped
  • stain purple with crystal violet
  • small (1-10micrometres)
45
Q

how can you identify animal cells in a light micrograph?

A
  • nucleus
  • irregular shape and position
  • larger (10-50micrometres)
46
Q

how can you identify plant cells in a light micrograph?

A
  • nucleus and cell wall
  • cells are closely packed
  • chloroplasts
  • larger (10-100micrometres)
47
Q

what is the function of the cell wall?

A

protects and maintains the shape of the cell
- made of peptidoglycan

48
Q

what is the function of the plasmid?

A

small loops of DNA containing genes that are not essential but can aid survival in unusual conditions

49
Q

naked DNA

A

DNA found in a loop called a nucleoid

50
Q

what is the function of the pili?

A

attachment to surfaces, transfer of genes and movement

51
Q

what is the function of the flagellum?

A

allows movement of the bacterial cell (longer than pili)

52
Q

what is the function of the compartmentalized cytoplasm?

A

fills the space between the membrane and nucleus

53
Q

what is the function of the 80S and 70S ribosome?

A

70S - protein synthesis
80S - protein synthesis ( in cytoplasm or attached to rough endoplasmic reticulum)

54
Q

what is the function of the double membrane?

A

allows communication between the nucleus and the rest of the cell

55
Q

what is the function of the cytoskeleton?

A

forms long fibres which maintain cell shape, anchor organelles, facilitate cell movement and move chromosomes during cell division (ac)

56
Q

what is the function of the nucleus?

A

linear chromosomes of DNA bound to histones that store genetic material

57
Q

what is the function of the mitochondria?

A

site of aerobic respiration to release energy and produce ATP

58
Q

what is the function of the cristae in the mitochondria?

A

foldings of the inner membrane where ATP is produced

59
Q

what is the function of the matrix in the mitochondria?

A

found within inner membrane and contains enzymes for respiration

60
Q

what is the function of the chloroplast?

A

specialised plastic that undergoes photosynthesis

61
Q

what is the function of the outer membrane in mitochondria?

A

compartmentalise the mitochondrial processes from those in the cytoplasm

62
Q

what is the function of the granum in chloroplasts?

A

stacks of thylakoid membranes providing a large surface area

63
Q

what is the function of the stroma in a chloroplast?

A

contains enzymes for photosynthesis

64
Q

what is the function of the sap vacuole?

A

large sac containing water to provide rigidity and sugars to allow storage of nutrients in plants

65
Q

what is the function of the rough endoplasmic reticulum?

A

network of interconnected membranes attached with ribosomes to produce proteins from 80S ribosomes

66
Q

what is the function of the Golgi apparatus?

A

produces lyosomes and processes protein from rough endoplasmic reticulum to the vesicles for secretion

67
Q

what is the function of the secretory vesicles?

A

carry proteins to the plasma membrane and secrete them by exocytosis

68
Q

what is the function of the smooth endoplasmic reticulum?

A

network of interconnected membranes with no ribosomes that produces lipids and hormones

69
Q

what is the function of the microvilli?

A

provide increased surface area to facilitate absorption

70
Q

what are the organelles?

A

discrete sub-uits of cells adapted to form a certain function

71
Q

what are other cell structures?

A

cell wall, plasma membrane, microvilli

72
Q

what is found in the mitochondria?

A

crista, matrix, inner membrane, outer membrane, DNA, 70S ribosome, intermembrane space

73
Q

what is found in the chloroplasts?

A

granum, inner membrane, outer membrane, stroma, 70S ribosome, starch granules, lumen, lamella, thylakoid membrane, DNA