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biology > topic 2: cell structure > Flashcards

topic 2: cell structure Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

eukaryotic organisms and examples

A

complex and larger structures e.g. animals, plants and fungi

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2
Q

name the 12 organelles in a eukaryotic organisms

A
  1. nucleus
  2. cell surface (plasma) membrane
  3. cell wall
  4. vacuole
  5. rough endoplasmic reticulum (RER)
  6. smooth endoplasmic reticulum (SER)
  7. golgi apparatus
  8. golgi vesicles
  9. chloroplasts
  10. ribosomes
  11. mitochondria
    12.lysosomes
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3
Q

structure of nucleus

A

-NUCLEAR ENVELOPE(double membrane) contain NUCLEAR PORES which allows large molecules like RNA to move between the nucleus and cytoplasm
-CHROMOSOMES (which are made from protein bound linear DNA)
-has one or more NUCLEOLUS

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4
Q

function of a nucleus

A

-the nucleus contains genetic material and CONTROLS CELL ACTIVITIES by controlling the transcription of DNA

  • DNA contains genetic code for making proteins

-nucleolus is the site of RNA production and manufactures ribosomes

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5
Q

structure of cell surface (plasma) membrane

A

-surrounds animal cells and is inside cell wall of bacteria and plant cells

-contains a phospholipid bilayer (made up of lipids and proteins) with molecules embedded (e.g. proteins, carbohydrates and cholesterol)

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6
Q

function of cell surface (plasma) membrane

A

-regulates the movement of substances into and out of the cell
-has receptor molecules which respond to chemicals like hormones

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7
Q

structure of RER (rough endoplasmic reticulum)

A

-system of membranes enclosing a fluid filled space
the surface is covered with ribosomes attached to membranes which makes it appear ROUGH

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8
Q

function of RER (rough endoplasmic reticulum)

A

-PROTEIN SYNTHESIS on ribosomes
-TRANSPORTS processed materials (e.g. proteins made on attached ribosomes)

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9
Q

structure of SER (smooth endoplasmic reticulum)

A

-system of membranes enclosing a fluid filled space without ribosomes attached to membranes

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10
Q

function of SER (smooth endoplasmic reticulum)

A

-synthesizes and transports lipids

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11
Q

structure of golgi apparatus

A

-a group of fluid filled, membrane-bound flattened sacs, with vesicles at the edges of the sacs

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12
Q

function of the golgi apparatus

A

-modifies and processes proteins that are made in the cell
-packages them into vesicles to be transported out of the cell
-forms lysosomes

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13
Q

structure of golgi vesicles

A

-small fluid-filled membrane bound sacs
-found at the edges of golgi apparatus

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14
Q

function of the golgi vesicles

A

-stores lipids and proteins made by the golgi apparatus, and transports them to the cell surface membrane where it fuses with the membrane, which releases contents out of the cell

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15
Q

structure of the lysosomes

A

-a round membrane-bound organelle, contains digestive lysosomal enzymes (hydrolytic enzymes)
-type of golgi vesicle

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16
Q

function lysosomes

A

-digests invading cells and old/worn out organelles in the cell
-break down material - digest large molecules into smaller/ soluble molecules

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17
Q

structure of ribosomes

A

-made up of two subunits: RNA and protein
- small organelle
-not surrounded by a membrane

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18
Q

function of ribosomes

A

-site of protein synthesis
-RER transports proteins made on attached ribosomes (to the cell surface membrane and fuses with the membrane, which release contents out of the cell)

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19
Q

structure of mitochondria

A

-oval shaped organelle surrounded by a double membrane - the inner membrane folded to form cristae and maximise surface area
-matrix (central part) is inside the inner membrane with enzymes (proteins and lipids) and DNA

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20
Q

function of mitochondria

A

-the site of aerobic respiration, to produce ATP (energy store)

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21
Q

structure of chloroplasts (5 structures)

A

-a small, flattened organelle in photosynthesizing cells
-ENVELOPE - surrounded by a double membrane
-contains THYKALOIDS which are flat disks with pigment/chlorophyll in
- GRANA is stacked thylakoids which are linked together by lamellae
-LAMELLAE are flattened membranes which link grana together, to transport chemicals
-STROMA is a fluid which contains enzymes for photosynthesis and stores starch grains

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22
Q

function of chloroplasts

A

-site of photosynthesis

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23
Q

structure of cell wall

A

-a rigid structure that surrounds cells in plants, algae and fungi

-plant and algae - cellulose
-fungi - chitin

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24
Q

function of cell wall

A

-supports and strengthens cell
-keeps shape of cell and prevents change of shape

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25
Q

structure of vacuole

A

-a membrane-bound organelle found in the cytoplasm of plant cells
-contains cell sap (a weak solution of sugars and salts) which gives rigidity

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26
Q

function of vacuole

A

-maintains pressure inside the cell
-keeps cell rigid
-isolation of unwanted chemicals

27
Q

prokaryotic cells and examples

A

prokaryotic cells are smaller and simpler e.g. bacteria

28
Q

prokaryotic and eukaryotic cells differences

A

-the cytoplasm in P lacks membrane bound organelles
-P has smaller ribosomes
-P has no nucleus, they have a single circular DNA molecule that is free in the cytoplasm

29
Q

many prokaryotic cells have…

A

-plasmids
-a slime capsule surrounding the cell
-flagella

30
Q

flagellum

A

-a long hair like structure that rotates, which is responsible for the movement of cells

31
Q

plasmids

A

-small circular loops of DNA, which passes on genetic information to other bacteria

32
Q

slime capsule

A

-the capsule is made up of secreted slime made of protein, which protects the cell from the attack by cells of the immune system (E.g. white blood cells/ phagocytosis)
-protects from pathogens and phagocytosis

33
Q

ribosomes

A

-small ribosomes which are made up of proteins and rRNA, this is the site of protein synthesis

34
Q

nucleoid

A

-DNA- protein assemblies which contain the genomes (entire set of DNA genetic material) of prokaryotic organisms

35
Q

pili

A

-a hollow/ hair like structure made of protein, allows bacteria to attach to other cells

36
Q

cell plasma membrane

A

-a phospholipid layer(proteins and lipids) with molecules embedded in it, it controls the movement of substances into and out of the cell

37
Q

virus + purpose + structure

A

-ACELLULAR and NON LIVING, which are NOT CELLS
-viruses invade and replicate inside of cells of other organisms, known as host cells and attach to them

-the structure of a virus particle consist of genetic material, capsid and attachment protein

38
Q

virus - genetic material

A

-consists of nucleic acids (either DNA or RNA)

39
Q

virus - capsid

A

a protective protein coat which encloses the virus

40
Q

virus - attachment protein

A

sticks out from the edge of the capsid, allows the virus to attach to a host cell

41
Q

cell fractionation

A

used to separate and isolate the different organelles, so they can be studied easily under an electron microscope

42
Q

3 steps of cell fractionation

A
  1. homogenisation: breaking up the cell
  2. filtration: getting rid of large cell debris
  3. ultracentrifugation: separating the organelles
43
Q

homogenisation

A

-this breaks up cells by vibrating the cells or grinding the cells up in a blender
-this breaks up the plasma membrane and releases the organelles into the solution

44
Q

3 characteristics the solution must have

A

-ice cold - to reduce enzyme activity, when the cell is broken open, the enzymes are release and if denatured this could damage the organelles (and change the shape of the protein)
-isotonic (same concentration of chemicals as the cells being broken down), to prevent damage to organelles by osmosis
-buffered (maintain pH) - to maintain the pH and prevent damage to the organelles (enzymes could denature and change shape of the protein)

45
Q
  1. filtration
A

the homogenised (broken up) solution if filtered through a gauze to remove any large cell debris, the organelles are small and will pass through the gauze

46
Q
  1. ultracentrifugation
A

-the solution is poured into a test tube, then put into a centrifuge (a machine that seperates material by spinning) and is spun at a low speed
-the heaviest organelles (e.g. nuclei) go to the bottom of the tube by the centrifuge and form a pellet (thick sediment at the bottom)
- the rest of the lighter organelles stay suspended (split) in the fluid above the sediment - the supernatant
-the supernatant is drained and poured into another test tube, and respun in the centrifuge at a higher speed, with the next heaviest organelles (e.g. mitochondria) forming a pellet at the bottom of the tube
-the process is repeated at higher and higher speeds, until all the organelles are separated out
-each time, the pellet at the bottom of the tube is made up of lighter and lighter organelles

47
Q

organelles are separated in order of mass

A

-nucleus, chloroplasts, mitochondria, lysosomes, ER (endoplasmic reticulum), ribosomes

48
Q

magnification

A

-how much bigger the image is than the specimen (actual size)

49
Q

resolution

A

(how detailed the image is)
-the able to distinguish between 2 points that are close together on an image

50
Q

2 types of microscopes

A

-optical (light) microscope
-electron microscopes (2 types: SEM (Scanning electronic microscope) and TEM (transmission electron microscopes))

51
Q

how does a optical microscope work?

A

-uses light to form an image by illuminating the specimen
-specimens must be thin enough to transmit the light

52
Q

Why is the resolution of an optical microscope low?

A

Light has a relatively long wavelength, so the resolution is low

53
Q

advantage of optical light microscope

A

-colour image
-living specimens can be used
-cheap and easy to use

54
Q

disadvantages of optical microscope

A

-lower magnification and resolution (due to the long wavelength of light)
-can only be used on thin specimens
-cant view smaller organelles (e.g. ribosomes, lysosomes, ER)

55
Q

2 types of electron microscopes

A

-transmission electron microscope (TEM)
-scanning electron microscope (SEM)

56
Q

how does a scanning electron microscope work?

A

-scans a beam of electrons across the specimen, knocks electrons off the specimen and gathered in a cathode ray tube to form an image

57
Q

advantages of scanning electronic microscope

A

-colour image
-3D images
-shows the surface of the specimen

58
Q

disadvantages of scanning electron microscope

A

-lower resolution image than TEM

59
Q

how does a transmission electron microscope work?

A

-the beam of electrons are transmitted through the specimen - denser parts absorb more electron, so look darker

60
Q

advantages of transmission electron microscope

A

-highest magnification and resolution than SEM
-can see internal details of organelles

61
Q

disadvantages of transmission electron microscope

A

-used only on thin specimens
-black and white image
-2D

62
Q

How can an eyepiece graticule be used to measure magnification?

A

The eyepiece graticule is CALIBRATED against a STAGE MICROMETER SCALE (known length) - works out the length that each eyepiece graticule division represents

63
Q

artefact

A

-Something that results from the way a specimen is prepared
-Artefacts are anything seen in the image that are not part of the specimen

biology (9 decks)

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