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Biology > M2 chapter 2: basic components of living systems > Flashcards

M2 chapter 2: basic components of living systems Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is an impact of microscopes?

A

we can see things in more detail than the eye as they are magnified, for example cell structures

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2
Q

who developed the first microscope?

A

Robert Hooke

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3
Q

what is cell theory?

A
  1. cells are the basic unit of life
  2. cells only develop from existing cells
  3. plant and animal tissue is composed of cells
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4
Q

what is resolution?

A

measures detail obtained by a microscope
smallest difference between 2 points that can still be seen as 2 points

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5
Q

how do you use a microscope?

A

switch on there light source and place the slide on the stage. love the smallest objective lens over the whole in the stage. turn the coarse do using wheel to make the objective lens as close to the stage as possible. look into the eyepiece lens. turn the coarse focussing wheel until what you see is clear. turn the fine focusing wheel to sharpen the image. repeat steps 3-6 for the remaining two lenses.

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6
Q

tips for microscope drawings?

A

title
magnification
sharp pencil
white unlined paper
draw smooth continuous lines
no shading
clearly defined structures
proportions are correct
labels don’t cross/ no arrowheads
lines are parallel

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7
Q

what are cells?

A

the basic unit of life

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8
Q

what is a dry mount sample prep?

A

Solid specimen viewed with a cover slip on top. No water needed.

Specimen can be viewed whole or cut into very thin slices (‘sectioning’).

Used to view small, inanimate objects/living tissue that doesn’t require water to live.

Examples: hair, pollen, dust, insect parts…

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9
Q

what is a wet mount sample prep?

A

Specimens suspended in liquid (i.e.// water or oil).

Cover slips added at an angle.- no air

Allows small aquatic organisms to be viewed in this way.

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10
Q

what is a squash sample prep?

A

A wet mount is first prepared.

Pressure then applied to the cover slip to squash the sample, ensuring it is thin enough to transmit the light.

Example: observing mitosis in root meristems (root tip squashes).

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11
Q

what is a smear sample prep?

A

Edge of a slide is used to smear a sample, creating a thin, even coat on another slide.

A cover slip is then added to the sample.

Example: observing cells within blood.

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12
Q

why do we use staining in microscopy?

A

makes images have a higher contrast as different cellular components take up stains to different degrees

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13
Q

how are positively charged stains used?

A

positive dyes are attracted to negative materials in cellular cytoplasm, staining the components. Making them more visible as they’re stained

Examples: crystal violet, methylene blue

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14
Q

how are negatively charged stains used?

A

negative dyes are repelled by negative cytosol (aqueous interior of cells).

Dyes stay outside of cells. Cells remain unstained and stand out against the stained background.

Examples: nigrosin, Congo red

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15
Q

how is differential staining used?

A

Used to distinguish between two types of organism that would otherwise be hard to identify.

Also differentiates between different organelles of a single organism within a tissue sample.

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16
Q

gram positive and negative bacteria

what is the gram staining technique?

A

1.Crystal violet is applied to a bacterial specimen slide.
2. Iodine is then added, fixing the dye.
3. The slide is washed with alcohol.
4. Gram-positive bacteria retain the crystal violet stain and appear blue/purple.
5.Gram-negative bacteria have thinner cell walls and lose the stain. They are then stained with safranin dye (a counterstain), making them appear red.

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17
Q

what are gram positive bacteria?

A

they have a thick cell wall which retains dye

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18
Q

what are gram negative bacteria?

A

they have a thin cell wall which loses dye

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19
Q

what is the acid fast technique?

A

It distinguishes between mycobacterium (a genus of bacteria) and other bacteria.
1. Lipid solvent is used to carry the carbolfuchsin dye into the cells being studied.
2. Cells are then washed with dilute acid-alcohol solution. Mycobacterium are not affected by this and retain the stain which is bright red.
3. Other bacteria lose the stain and are exposed to methylene blue stain, which is blue.

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20
Q

what are the five units of measurements?

A

metre
millimetre
micrometre
nanometre
picometre

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21
Q

what is the equation for magnification?

A

magnification = size of image/ actual size of object​

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22
Q

what is the eyepiece graticule?

A

ruler in the lens

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23
Q

what is the stage micrometer?

A

a ruler on a coverlip used in calibration

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24
Q

what is an advantage of using a electron microscope?

A

-higher resolution due to shorter wavelength
- higher magnification so you can see cell ultrastructure

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25
Q

what is a disadvantage of using an electron microscope?

A

-very expensive
-complex prep which can lead to artefacts(air bubbles)
-training required to use them

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26
Q

how is a TEM microscope used?

A

Beam of electrons transmitted through specimen. Focussed to produce an image.​
Similar to light microscopy​
Resolving power of 0.5nm

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27
Q

how is a SEM microsope used?

A

Beam of electrons sent across surface of specimen. Reflected electrons collected.​
Produced 3D images
​Resolving power of 3-10nm.

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28
Q

what type of microscopy can only view dead specimens/

A

TEM and SEM

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29
Q

how does laser scanning confocal microscopy work?

A

-Single spot of focussed light moved across a specimen, previously marked with fluorescent dye.​
-Fluorescence: absorption and re-radiation of light.​
-Components marked with the dye fluoresce.​
-Re-radiated light: longer wavelength & lower energy. Filtered through a pinhole aperture.(Unwanted radiation doesn’t pass through – would reduce resolution)​
-Produces very high resolution images​

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30
Q

how is laser scanning confocal microscopy used in real life?

A

currently used to diagnose eye diseases and in the development of new drugs.​

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31
Q

what is an eukaryote?

A

A eukaryote is any organism consisting of one or more cells that contain DNA in a membrane-bound nucleus, separate from the cytoplasm.​

32
Q

what is a membrane known as at a level?

A

These are known as plasma or cell surface membranes.​

​

33
Q

why are membranes important?

A

-keeping all cellular components inside the cell​
-allowing selected molecules to move in and out of the cell​
-isolating organelles from the rest of the cytoplasm, allowing cellular processes to occur separately.
-membranes are important in cell signalling
-allowing a cell to change shape.

34
Q

what is in the nucleus?

A

contains chromatin (dna and histone proteins)
nucleolus
nuclear membrane
nuclear pores

35
Q

what does the nucleolus do?

A

makes ribosomes and ribosomal rna (RRNA)

36
Q

what does nuclear pores do?

A

they are a hole in the membrane which allows Mrna to leave the nucleus for protein synthesis

37
Q

how are ribosomes made and what do they do?

A

made by rrna which fold up into sub units which join together to make ribosomes.
they are involved in protein synthesis

38
Q

what is the rough endoplasmic reticulum (RER)?

A

ribosomes attach to this where they translate the Mrna into proteins which are then transported by the cisterne

39
Q

what is the smooth endoplasmic reticulum?

A

involved in lipid and carbohydrate synthesis

40
Q

what is a transport vesicle?

A

the membrane of the ER continually buds off to form vesicles.
these are packages (bubbles) of molecules which are formed in the ER to transport to the golgi apparatus

40
Q

what is the golgi apparatus?

A

it modifies the packages sent to it from the er and packages them for destinations inside or outside of cell.
these then leave through cisterne at the opposite end of the golgi and bud off into vesicles.

41
Q

what is the golgi vesicles?

A

they bud off the golgi transporting the packaged molecules around the cell or by exocytosis (leaves via membrane)

42
Q

what is the mitochondria structure?

A

they generate energy.
the structure is surrounded by 2 membranes, the inner layer folds forward to form the cristae which projects into a liquid called the matrix
the inner membrane is coated in enzymes which catalyses aerobic respiration to produce ATP

43
Q

what are microtubules?

A

they are the main component of cytoskeleton. these connect to the cells organelles to each other to keep them in place and transport materials around the cell

44
Q

what are centrioles?

A

they coordinate the growth of microtubules in eukaryotic cells. they are a microtubule organising centre

45
Q

what is the cytoskeleton?

A

it is a network of fine actin elements. they maintain and change the cells shape

46
Q

what are cilia?

A

they are 5-10 micro metres long, they are hair like outgrowths from the surface of a cell which best to power cell movement

47
Q

what is the flagellum and what is it used for?

A

they stick out of a cell and are surrounded by a plasma membrane.
the inside structure has 2 microtubules in the centre and 9 pairs of microtubules around the edge.
these microtubules contract to move the flagellum

48
Q

what is the cell wall in plant cells made up of?

A

cellulose which is a polysaccharide and a complex carbohydrate - can also function as a carbohydrate store

49
Q

what are the gaps in the cell wall called?

A

plasmodesmata, enables transport of cytoplasm between cells,

50
Q

what is the structure of chloroplasts?

A

have a double membrane
filled with liquid called stroma
contains stacks of thylakoid membranes which make up grana

51
Q

what does the grana do in photosynthesis?

A

use carbon dioxide, water and light to build sugars

52
Q

what is the role of the vacuole?

A

they create turgou pressure to keep cell form and turgid. ( maintains cell shape)

53
Q

what is the structure of the vacuole in a plant cell?

A

has a membrane called tonoplast
is filled with a watery substance consisting of cell sap, sugars, enzymes and pigments

54
Q

what is the tonoplast?

A

the partially permeable membrane of the permanent vacuole in a plant cell

55
Q

what is the amyloplast?

A

is a double membrane bound sac with contains starch granules

56
Q

are plant cells eukaryotic?

A

yes because they have a nucleus and other membrane-bound organelles.

57
Q

what is in a plant cell which isn’t in a animal cell?

A

cell wall and chloroplasts

58
Q

what connect grana (stacks of thylakoid membranes) together?

A

stromal lamellae

59
Q

what do lysosomes do?

A

contain digestive enzymes and break down and recycle cellular waste and unwanted material
digest the large molecules of nutrients in the cell and change them into simpler substances so the cell to benefit from them
white blood cells use the digestive enzymes in the lysosomes to digest and destroy the pathogens which invade the cell.

60
Q

where are lysosomes made?

A

they are small vesicles formed from the golgi body containing digestive enzymes

61
Q

what is a prokaryote?

A

a cell in which dna is loose in the cytoplasm has no nucelus or membrane bound organelles

62
Q

what are the 2 domains of prokaryotes?

A

bacteria and archaea

63
Q

what are the cell wall of prokaryotes made of?

A

petidoglycan

64
Q

how small is bacteria?

A

1-5 micro metres

65
Q

what is the mass of dna in the cytoplasm called?

A

nucleoid

66
Q

what is different about the ribosomes in a prokaryote than a eukaryote?

A

they are smaller, have 70s ribosomes

67
Q

where do prokaryotes make ATP?

A

mesosomes

68
Q

what is the mesosomes?

A

a invagination of the cell membrane

69
Q

what does the nucleiod do?

A

controls cell including reproduction. it contains most genetic material of the cell and is where transcription and replication of dna takes place

70
Q

what are bacterial capsules?

A

mucous like protective layer so it hides the antigens on its surface making it harder to detect in the immune system. the capsule is made of polysaccharides

71
Q

what are flagella powered by?

A

protein motors

72
Q

what are pilli?

A

hollow protein structures used during bacterial conjugation ( transferring genetic material from one bacterium to another)

73
Q

what are plasmids?

A

small loops of dna

74
Q

what is an advantage of plasmids being replicated independently in bacterial conjunction?

A

they can transfer an advantage such as antibiotic resistance or desirable characteristics

Biology (15 decks)

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