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SNAB biology hoe > 2A & 3A Cells and Transport > Flashcards

2A & 3A Cells and Transport Flashcards

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1
Q

name 3 similarities and 3 differences between prokaryotic and eukaryotic cells

A

similarities:

  • both have ribosomes
  • both have cell surface (plasma) membranes
  • both have cytoplasm

differences:

  • prokaryotic DNA in plasmids and cytoplasm whereas eukaryotic DNA in nucleus
  • eukaryotes have membrane-bound organelles whereas prokaryotes do not
  • eukaryotes are larger
  • prokaryotes have plasmids
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2
Q

magnification

A

size of image / size of real object

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3
Q

tissue

A
  • group of similar cells
  • that are specially adapted
  • to work together to carry out particular function
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4
Q

what kind of cell does MITOSIS produce

A

genetically identical daughter cells

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5
Q

what is mitosis needed for?

A
  • growth
  • repairing damaged tissues
  • asexual reproduction
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6
Q

what does the cell cycle consist of?

A
  1. INTERPHASE -> period of cell growth and DNA replication (G1 -> SYNTHESIS ->G2)
  2. MITOSIS
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7
Q

what happens during INTERPHASE?

A
  1. G1 -> cell grows and new proteins made
  2. SYNTHESIS -> cell unravels and replicates its DNA ready to divide by mitosis
  3. G2 -> cell keeps growing and proteins needed for cell division are made
    -> ATP content increased

cell’s organelles also replicated so to has spares

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8
Q

order of stages in mitosis

A

P ussy like BMAT but for pussies
M edical
A dmissions
T est

  1. PROPHASE
  2. METAPHASE
  3. ANAPHASE
  4. TELOPHASE
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9
Q

what happens in PROPHASE?

A
  1. chromosomes condense -> get shorter and fatter
  2. centrioles (bundles of proteins) moving to opposite ends of cell -> makes network of protein fibres = SPINDLE
  3. nuclear envelope breaks down and chromosomes lie free in cytoplasm
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10
Q

what happens in METAPHASE?

A
  1. chromosomes (each with 2 chromatids) line up along middle of cell
  2. and become attached to spindle by centromere
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11
Q

what happens in ANAPHASE?

A
  1. centromeres divide -> separating each pair of sister chromatids
  2. spindles contract -> pulling sister chromatids to opposite ends of spindle
  3. makes chromatids appear v-shaped
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12
Q

what happens in TELOPHASE?

A
  1. chromatids reach opposite ends on spindle
  2. uncoil and become long and thin (chromosomes again!)
  3. nuclear envelope forms around each group of chromosomes so there are 2 nuclei
  4. cytoplasm divides -> now 2 genetically identical daughter cells!
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13
Q

what is cholesterol?

A

component of cell membrane that allows whole thing to be fluid / rigid depending on temp

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14
Q

diffusion (passive)

A

net movement of particles from area of high conc.->low. conc.

passive process -> no ATP needed

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15
Q

active transport

A

movement of molecules / ions across SEMI-PERMEABLE MEMBRANE from low->high conc. using ATP and carrier proteins

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16
Q

receptors

A

molecules (could be proteins) in cell membrane that recognise other molecules that can enter cell

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17
Q

glycoproteins

A

act as cell receptor on surface membrane

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18
Q

functions of proteins in cell membrane?

A

transport
communication

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19
Q

intrinsic proteins

A

= integral

  • embedded in MEMBRANE
  • with PRECISE ARRANGEMENT DETERMINED by …
  • their HYDROPHILIC and HYDROPHOBIC regions
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20
Q

extrinsic proteins

A

= peripheral

found on the outer or inner surface of the membrane

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21
Q

why is cholesterol important in cell surface membrane?

A

increases fluidity of membrane at low temp. stops it becoming too RIGID
-> as cholesterol stops phospholipid tails packing too closely together

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22
Q

how does relationship between cholesterol and phospholipid tails affect cell membrane?

A

interactions stabilise cell membrane at higher temp. by stopping membrane from becoming too FLUID

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23
Q

state 2 factors that affect permeability of cell membranes

A
  • temp
  • alcohol conc (ethanol)
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24
Q

how is beetroot used to measure permeability of cell membranes?

(3 marks)

A

high permeability = more red (betalains) pigment leaks out into surrounding sol in given amount of time

colorimeter used to determine absorbance hence conc of pigment

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25
Q

outline procedure to investigate effect of temp on permeability of cell membrane

A
  1. cut beetroot into 8 identical cubes with scalpel (no skin) -> put in distilled water overnight to remove any dye released when cut
  2. wash and blot dry with filter paper
  3. place each cube in 8 diff test tubes with 10cm³ distilled water
  4. place each test tube into 8 diff water baths ranging from 0-70 ℃. leave for 30 mins
  5. filter each sol out into cuvette and read absorbance using colorimeter
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26
Q

what are the safety hazards in testing effect of ethanol on membrane permeability?

A
  • ethanol is an IRRITANT and FLAMMABLE
    -> keep away from naked flames and wear goggles
  • keep sharp scalpel away from fingers
  • handle hot water with care
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27
Q

explain effect of temp on membrane permeabilty

(3 marks)

A
  • increasing temp = increase in membrane permeability
    -> high temp DENATURE some membrane proteins
    -> creates gaps in membrane for molecules to pass through
  • decreasing temp = decreases Eᵏ of phospholipids -> so they pack tighter together
    -> restricts movement of molecules across membrane
28
Q

what is the effect of increasing ethanol conc on membrane permeability?

A

increasing ethanol conc = increased membrane permeability

-> as ethanol ruptures membrane to form gaps for molecules to pass through

29
Q

how does low s.a : vol ratio affect transport of molecules?

A

low s.a : vol ratio = further distance molecules need to travel to reach all parts of organism

  • diffusion alone isnt sufficient so SPECIALISED GAS EXCH. SURFACES required
30
Q

name 3 features of efficient gas exchange surface

A
  • large s.a -> eg folded membranes in mitochondria
  • short distance -> walls of capillaries
  • steep conc grad maintained by BLOOD SUPPLY / VENTILATION eg alveoli
31
Q

what is Ficks Law?

A

large s.a = larger diff in conc

shorter diffusion distance = faster rate of diffusion

rate of diffusion ∝ ( s.a x conc diff ) ÷ membrane thickness

32
Q

where in plants can cells undergoing mitosis be found?

A

meristem tissue at shoot and root tips

33
Q

what is the mitotic index?

A

ratio of
cells undergoing mitosis : total no. of cells in sample

34
Q

outline procedure to prepare root tip slide

(abbrieviated version)

A
  1. warm 2 cm³ 1M HCl to 60℃ in water bath
  2. cut 1-2 cm root tip of garlic and add to HCl -> leave for 5 mins
  3. remove from HCl and wash with cold distilled water
  4. dry and place on slide
  5. macarate with mounted needle to spread out cells
  6. add 1 drop stain to make chromosomes visible and observe
35
Q

mitotic index calculation

do q’s on this

A

no. cells with visible chromosomes
÷
no. cells in sample

36
Q

state hazards and precautions for reagents in observing stages of mitosis practical

A

HCl -> corrosive, avoid contact with skin

Toluidine Blue O stain -> irritant, avoid contact with skin

scalpel -> cut away from fingers

37
Q

why is the root tip placed in hot HCl?
(stages of mitosis practical)

A

HCl dissolves MIDDLE LAMELLAE in order to break up cellulose cell wall

this allows STAIN to PERMEATE and TIP to be SQUASHED more easily

38
Q

describe how the lungs are adapted for rapid gas exchange

A
  • lots of alveoli = larger s.a for diffusion to occur across
  • alveolar epithelium and capillary epithelium are one cell thick -> short diffusion pathway
  • all alveoli have good blood supply from capillaries
    -> constantly take away O₂ and bring more CO₂
    = maintains conc gradient
  • breathing in and out refreshes air in alveoli -> keeps conc grad high
39
Q

organ system

A

group of different organs that work together to carry out a particular function

40
Q

osmosis

A

net movement of free water molecules across partially permeable membrane from area of high to low conc

41
Q

facilitated diffusion

A
  • diffusion of larger molecules (eg glucose, a.a) and charged particles (ions) via carrier / channel proteins in cell membrane

as these molecules / ions cannot diffuse directly through bilayer

42
Q

endocytosis

A

cells taking in substances that are too large to be taken into cell via carrier proteins

  • cell surrounds substance with section of its cell membrane
  • membrane pinches off to form vesicle inside cell containing ingested substance
43
Q

exocytosis

A

movement of substances leaving cell

as some substances (eg. dig enzyme, hormones, lipids) made by cell

  • vesicles containing substances pinch off from sacs of golgi apparatus and move towards cell membrane
  • vesicles fuse with cell membrane and release contents outside cell
44
Q

describe how a carrier protein operates

A

move larger molecules in / out of cell

diff carrier proteins facilitate diffusion of diff molecules

  1. large molecule attaches to carrier protein in membrane
  2. protein changes shape …
  3. … releasing molecule on opposite side of membrabne
45
Q

describe how a channel protein operates

A

channel proteins form pores in membrane for charged particles to diffuse through (down conc grad)

46
Q

which organelles in eukaryotes have double membranes?

A
  • mitochondria
  • nucleus (nuclear envelope)
  • (chloroplasts) for plants only
47
Q

describe the nucleus and its function in eukaryotic cells

A
  • large organelle surrounded by nuclear envelope (double membrane) …
  • … with pores (gaps) -> allow substances eg RNA to move from nucleus->cytoplasm
  • contains chromatin (made from DNA and proteins)
  • contains nucleolus -> makes ribosomes
48
Q

describe the lysosome and its function in eukaryotic cells

A

round organelle surrounded by membrane

-> contains dig enzymes which can …

  • eat invading cells
  • eat worn out bits of cell
49
Q

where are ribosomes in eukaryotic cells and what are they made of?

A
  • cytoplasm
  • attached to rER

made of proteins and RNA

NO MEMBRANE

50
Q

describe the rER and its function in eukaryotic cells

A
  • system of membranes enclosing fluid-filled space
  • surface covered in ribosomes
  • folds and processes proteins that have been made at ribosomes
51
Q

describe the sER and its function in eukaryotic cells

A
  • system of membranes enclosing fluid-filled space
  • but NO RIBOSOMES
  • synthesises and processes lipids
52
Q

describe the Golgi apparatus and its function in eukaryotic cells

A
  • group of fluid-filled membrane-bound, flattened sacs
  • has vesicles at edges of sacs
  • processes and packages new lipids and proteins
  • makes lysosomes
53
Q

describe the mitochondria and their function in eukaryotic cells

A
  • double membrane with inner one folded to form cristae
  • inside is matrix -> contains enzymes involved in respiration
  • site of aerobic respiration -> where ATP produced
54
Q

describe the centrioles and their function is eukaryotic cells

A
  • small hollow cyclinders made of mictrotubules (tiny protein cyclinders)
  • in all animal cells but also some plant cells
  • involved in separation of chromosomes during cell division
55
Q

describe how organelles in eukaryotic cells allow protein transport within cells

A
  1. proteins made in ribosomes
  2. ribosomes on rER make proteins that are excreted / attached to cell membrane
  3. free ribosomes in cytoplasm make proteins that stay in cytoplasm
  4. new proteins made at rER are folded and processed (eg. sugar chains added) in rER
  5. rER packages proteins in vesicles
  6. then transported to golgi in vesicles
  7. at golgi: proteins undergo further processing (eg. sugar chains trimmed / more added AND prosthetic groups added eg. iron in haemoglobin)
  8. proteins enter more vesicles to be transported around cell

-> eg. extracellular enzymes (eg. dig enzymes) move to cell surface to be secreted

56
Q

describe the DNA in prokaryotic cells

A

- circular DNA:

->one long coiled up strand (bacterial chromosome in bacteria cell)

-> not attached to any histone proteins

-> floats free in cytoplasm

- plasmids:

-> small loops of DNA

-> contains genes for eg. antibiotic resistance

-> can be passed between prokaryotes

57
Q

describe mesosomes in prokaryotic cells

A

inwards folds in plasma membrane

could be used in cellular processes or just artifact in cells

58
Q

some prokaryotes have pili. describe their function in these cells

A

help prokaryote stick to other cells

-> used in transfer of genetic material between cells

59
Q

describe the function of cell wall in prokaryotic cells

A

supports cell and prevents it changing shape

made from polymer murein (glycoprotein: protein with carb attached)

60
Q

describe the function of the capsule in prokaryotic (eg. bacterial) cells

A

made of secreted slime

helps protect bacteria from attack by cells of immune system

61
Q

organ

A

group of different tissues that work together to perform a particular function

62
Q

give one diff between a tissue and an organ

A

tissues made of one type of cell

organ made of diff tissues

63
Q

active transport

A
  • uses ATP to move molecules / ions from low->high conc (against conc grad) …
  • across plasma membranes
  • using carrier proteins
64
Q

active transport requires ATP.

Describe where this ATP comes from in animals

A
  • ATP produced from respiration
  • acts as immediate source of energy in cell
  • when ATP is hydrolysed: broken down into ADP + Pi …
  • releasing energy …
  • which is used to move molecule against conc gradient
65
Q

suggest what would happen if phospholipid bilayer had no cholesterol

A

cholesterol controls rigidy/fluidity

too fluid = unstable, cell would burst under osmotic Pa

too rigid = brittle

66
Q

rate of diffusion

using Ficks Law

A

Permeability constant x s.a
x (conc difference ÷ thickness of membrane)

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