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OCR Biology A level New Spec > 2.1.1 Cell structure > Flashcards

2.1.1 Cell structure Flashcards

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1
Q

What are the two types of organism + describe them

A

Eukaryotes - made up of eukaryotic cells + more complex and make up plants + animals
Prokaryotes - usually single celled organisms and simpler - e.g bacteria is a prokaryotic cell

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2
Q

Draw and label an animal cell

A

pic here

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3
Q

Draw and label a plant cell

A

pic here

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4
Q

Name 3 differences between plant and animal cells

A

Plant cells have
- a cell wall w plasmodesmata (channels for exchanging subs from cell to cell)
- a vacuole (contains cell sap)
- chloroplasts (involved w photosynthesis)
WHICH animal cells DONT have

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5
Q

Describe + name functions of the plasma membrane

A
  • Also known as the cell surface membrane; is found on animal cell surfaces and beneath cell walls on plant + prokaryotic cells
  • made up of lipids and proteins
  • regulates the movement of subs into and out of the cell
  • contains receptor molecules; allowing it to respond to chemicals like hormones
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6
Q

Describe + name functions of the cell wall

A
  • rigid structure surrounding plant cells
  • made up of cellulose fibres
  • supports plant cells by preventing them from bursting when cell is turgid
  • maintain shape
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7
Q

Describe + name functions of the nucleus

A
  • large organelle
  • surrounded by nuclear envelope (doub membrane) - there r nuclear pores
  • nucleus contains chromatin and a nucleolus (contains RNA)
  • controls cells activities (by controlling transcription of dna)
  • contains instructions for protein synthesis
  • pores allow subs to move between cyto and nucleus
  • nucleolus makes ribosomes
  • stores the organisms genome
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8
Q

Describe + name functions of the lysosome

A
  • round membrane-bound organelle
  • contains digestive/hydrolytic enzymes that digests invading cells and breaks down the old cell components
  • membrane prevents the enzymes from leaking into the cyto
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9
Q

Describe + name functions of the ribosome

A
  • small organelle found in cyto and rough endoplasmic reticulum (RER) made of rRNA
  • has two subunits (large and small) which pass thru cell envelope and then combine in cyto
  • made of rRNA
  • it is the site of protein synthesis
  • made in nucleolus
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10
Q

Describe + name functions of the rough endoplasmic reticulum (RER)

A
  • system of membranes enclosing fluid filled cavities (cisternae)
  • surface covered w ribosomes
  • fold + processes proteins made at the ribos
  • provides large SA for ribos
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11
Q

Describe + name functions of the smooth endoplasmic reticulum (SER)

A
  • system of membranes enclosing fluids (cisternae) w no ribos on surface
  • contains enzymes that synthesise cholesterol/lipids/phospholipids/steroid hormones
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12
Q

Describe + name functions of the vesicle

A
  • a small membrane -bound fluid filled sac in the cyto
  • transports subs in/out of the cell via plasma membrane (exocytosis) + between organelles
  • formed by golgi appratus/ endoplasmic reticulum/ cell surface
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13
Q

Describe + name functions of the golgi appratus

A
  • group of fluid filled membrane-bound flattened sacs
  • vesicles surround it
  • processes and packages new lipids and proteins
    e. g. modify by add sugar chains/add lipid molecules/fold into 3D shape
  • makes lysosomes
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14
Q

Describe + name functions of the mitochondrion/mitochondria

A
  • has double membrane
    -inner membrane folded to form structures called cristae
  • inside is the matrix; contains enzymes involved in respiration
  • site of aerobic respiration/ where ATP is produced
    abundant in cells that need a lot of energy e.g liver cells
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15
Q

Describe + name functions of the chloroplast

A
  • found in plant cells
  • double membrane
  • contains thylakoids (flattened membranes sacs that contain chlorophyll) that stack up to form granum/grana
  • connected by lamallae
  • contains starch grains and loops of DNA
  • stroma is the inner fluid
  • site of photosynthesis; some happen in grana some in stroma
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16
Q

Describe + name functions of the centriole

A
  • small hollow cylinders
  • made up of two bundles of microtubules (protein cylinders) at right angles to each other
  • found in animal and plant cells
  • involved in the separation of chromosomes during cell division (forms the spindle)
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17
Q

Describe + name functions of the cilia/cilium

A
  • hair like structures found on surface membrane of animal cells
  • cross section: have outer membrane + ring of 9 pairs of protein microtubules inside, with a single pair of microtubules in the middle (9+2 formation)
  • microtubules allow cilia to move
  • movement is used by cell to move subs along the cell surface e.g. cilia in trachea sweep dust and mucus out of lungs
  • can act as antenna (contains receptors to detect changes in environment)
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18
Q

Describe + name functions of the flagellum/flagella (in eukaryotes)

A
  • same structure as cilia - ring of 9 pairs of microtubules surrounding the centre pair (9+2 formation)
  • the microtubules contract to make the flagellum move
  • used to propel cell forwards e.g. sperm cells
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19
Q

what is this + what microscope took this

A

plant cell

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20
Q

what is this + what microscope took this

A

nucleus

21
Q

what is this + what microscope took this

A

SER/RER

22
Q

what is this + what microscope took this

A

golgi

23
Q

what is this + what microscope took this

A

mitochondia

24
Q

what is this + what microscope took this

A

chloroplast

25
Q

what is this + what microscope took this

A

centriole

26
Q

describe the process of protein production

A
  1. mRNA of gene for protein is made in nucleus
  2. mRNA leaves nucleus thru nuclear pore
  3. mRNA attaches to ribosome/RER + ribosomes read instructions to assemble protein
  4. proteins made at RER are processed and folded at the RER
  5. protein is placed into vesicles and travel to golgi
  6. at golgi proteins undergo further processing e.g sugar chains trimmed/added
  7. proteins enter more vesicles + transported around the cell
  8. some vesicles fuse w plasma membrane
  9. plasma membrane opens to release protein (exocytosis)
27
Q

how is the cytoskeleton arranged

A

a network of protein structures made up of:

  1. microfilaments (made of actin)
  2. intermediate fibres
  3. cylindrical microtubules (made of tubulin)
  4. cytoskeletal motor proteins (myosins/kinesins/dyneins) - r enzymes and can use ATP as energy source
28
Q

what r the main functions of the cytoskeleton

A
  1. microfilaments;
    - give support/mechanical strength
    - keep cells shape stable
    - allow cell movement
  2. microtubules;
    - provide shape/support to cells
    - they make up the track which motor proteins use to transport organelles
    - form the spindle before cell division to move chromosomes
  3. Intermediate fibres;
    - anchor nucleus within cyto
    - enable cell signalling
    - stablises tissues
29
Q

Name 5 differences between eukaryotes and prokaryotes

A
  1. Pcells DNA is circular vs Ecells DNA is linear
  2. Pcells no nucleus DNA free in cyto vs Ecells DNA in nucleus + its present
  3. Pcells cell wall made of peptidoglycan vc Ecells no cell wall in animals, in plants made of cellulose + in fungi made of chitin
  4. Pcells no membrane bound organelles e.g RER/chloroplasts vs Ecells membrane bound organelles
  5. small ribosomes (<20nm) vs big ribosomes (>20nm)
30
Q

Draw and label a bacteria cell

A

pic here

31
Q

how do P cells divide

A

binary fission

32
Q

define magnification + how do u calculate it

A

how much bigger the image is compared to the specimen

mag =image size/object size

33
Q

define resolution

A

how detailed the image is - how well a microscope can distinguish between two points that r close together - higher res clearer image

34
Q

convert 1 mm to micrometres and nanometres

A

1mm = 1000µm = 10,00,000nm

35
Q

name the 4 microscopes used in microscopy

A
  • light microscope
  • laser scanning confocal micro
  • transmission electron micro (TEM)
  • scanning electron micro (SEM)
36
Q

advantage/disadvantages to light microscope and what r the magnification and resolutions

A 
adv:
- cheap 
- easy to use
- can study living specimens 
-colour image
dis: 
- limited resolution and magnification compared to others 
- cant see small organelles e.g ribos
max res: 0.2microm
max mag: x1500
37
Q

advantage/disadvantages to scanning electron microscope and what r the magnification and resolutions

A 
adv:
-much higher mag and res than light (wavelength of e is shorter than light)
-forms 3D image 
- no need for thin section of specimen
dis:
- lower mag and res than TEM 
-cant see internal structures
- expensive and hard to use
max res: 0.002microm
max mag:
38
Q

advantage/disadvantages to transmission electron micro and what r the magnification and resolutions

A 
adv:
- better mag and res than light and SEM
- shorter wavelength (e than light)
- allows internal structures to be seen 
dis:
- cant look at living specimens 
- specimens need to b in vacuum 
- use thin slice of specimen (create artefacts)
-expensive and hard to use
- no colour image
max res: 0.0002 
max mag: >x1.000.000
39
Q

how does a laser scanning confocal microscope work

A
  • they use laser beams to scan a specimen tagged w fluorescent dyes
  • the beam is focused thru a lens and aimed a a beam splitter which splits the beam+ some light is directed at specimen
  • when the laser hits dyes specimen fluoresces
  • light is then focused thru a pinhole in onto a detector and hooked to a comp to generate image
40
Q

adv and dis of lscm

A 
adv:
- higher res than light m
- can view objects inside cells and has depth selectivity 
- can observe living specimens 
dis:
- more expensive than light
- lower res than SEM/TEM

res low-high
light - lscm - sem - tem

41
Q

explain how electron microscopes work

A

SEM:
- scans beam of electrons across specimen
- knocks off electrons on specimen which r collected at a cathode ray tube to form a 3D image
TEM:
- use electromagnets to focus a beam of electrons transmitted thru the specimen to produce 2d images
- denser parts of specimen make image darker as they absorb more electrons

42
Q

how do u use a light microscope

A
  1. clip slide containing specimen onto stage
  2. select lowest power objective lens
  3. use coarse adjustment knob to bring stage to just below the lens
  4. look down eyepiece and adjust fine focus and light intensity for clearest image
  5. repeat with higher power lens if needed
43
Q

what is a eyepiece graticule and a stage micrometer + how do u use it

A

eyepiece g:
- fitted onto eyepiece and is like a ruler w no units
stage micrometer:
- is placed on the stage and has 1 micrometer markings on it

  1. set magnification
  2. record how many eyepiece graticule units is equal to 1 micrometer
  3. work out how large specimen is
44
Q

how do u do slide prep

A
  • add few drops of water to blank microscope slide
  • use forceps to pick up sample (must be thin)
  • put onto the slide
  • use a pipette to add stain (if needed)
  • place cover slip on top
  • put slide on microscope stage and adjust mag
45
Q

what stains is used for nuclei

A 
methylene blue (dyes blue)
OR
acetic orcein (stains chromosomes red)
46
Q

what stain is used for cytoplasm

A

eosin (dyes it pink)

47
Q

what stain is used for cell membranes(lipids)

A

sudan red

48
Q

diagram of relative sizes os strcutures

A

diagram of relative sizes os strcutures

49
Q

cell theory is ..

A

that all living organisms r made up of cells

OCR Biology A level New Spec (28 decks)

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