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SEMESTER 1 > BIO cells and cell transport > Flashcards

BIO cells and cell transport Flashcards

1
Q

what do prokaryotes consist of?

A

eg bacteria, very small single celled organisms no nucleus and no membrane bound organelles in their cytoplasm
always have:
- cell wall (made of murein-glycoprotein)
-cell surface membrane
-circular DNA free in cytoplasm not associated with proteins
- ribosomes
-cytoplasm

may be present:
capsule surround cell wall
one or more plasmids
flagella

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2
Q

compare eukaryotes and prokaryotes

A

eukaryotes
- nucleus present
-membrane-bound organelles
- eg mitochondria, SER,RER
- larger 80s ribosomes
-DNA linear
- Cell wall if present doesn’t have murein

prokaryotes
-no nucleus
-no membrane bound organelles
-smalle 70s ribosomes
-DNA circular
-murein cell wall

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3
Q

what are the cell organelles inside a eukaryote?

A

nucleus
ribosomes
RER SER
Golgi apparatus
lysosomes
mitochondria
chloroplasts

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4
Q

what does nucleus contain and bound by what does it control ?

A

contains genetic material DNA determining development, structure+function of cell

bound by a double membrane NUCLEAR ENVELOPE which has nuclear pores allowing communication with cytoplasm

-nucleus contains protein bound linear DNA + one or more nucleoli (RNA)

  • in dividing cell DNA + protein found in chromosomes
  • nucleus controls protein synthesis + so development+function of cell
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5
Q

what are ribosomes and what is their use?

A

-very small organelles made uo of protein and rRNA
- can be present in cytoplasm singly or attached to RER
- used in protein synthesis joining amino acids together

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6
Q

what is RER, what does it consists of and what is its use ?

A

-consist flattened membrane sacs which form internal transport system

-surface of RER has ribosomes that make secretory proteins (proteins released out of cell
- proteins sent to Golgi apparatus for modification and packaging

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7
Q

what does SER consist of what is its role?

A

-consists of flattened membrane sacs which form internal transport system in cell

-SER lacks ribosomes and involved in production + transport of lipids

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8
Q

what does Golgi apparatus and vesicles consist of and what the roles? and what is Golgi apparatus abundant in and where?

A

-conist of flattened membrane sacs

  • adds carbohydrates to proteins received from RER to make glycoproteins
  • packages proteins/glycoproteins into Golgi vesicles for SECRETION
  • makes lysosomes-type of Golgi vesicles that releases LYSOZYMES(hydrophilic enzyme)

-golgi apparatus abundant in secretory cells eg in pancreas

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9
Q

what are lysosomes, what do they contain and do and where are they found?

A

-simple sacs containing hydrolytic enzymes eg lysozyme surrounded by single membrane
-enzymes have to be kept apart from rest of cell or would Destroy it
-lysosomes formed by Golgi apparatus

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10
Q

what are the 3 functions for lysosomes?

A
  1. digestion of material taken in by phagocytosis- lysosomes fuse with vesicle formed during phagocytosis releasing hydrolytic enzyme which digest material inside
  2. non-functioning organelles within cell are engulfed + digested within lysosomes
  3. release of enzymes outside cell-sometimes enzymes of lysosomes released from cell
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11
Q

what are centrioles and what is their role and what are they made up of(including spindle)?

A
  • centrioles small hallow cylinders each containing 9 triplets of microtubles
  • in animal cells nuclear division beginning centrioles replicate themselves + 2 pairs migrate to opposite poles of cell + form spindle structure on which chromosomes line up
  • spindle itself is made up of microtubules (spindle fibres) which control separation of chromosomes/chromatids
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12
Q

what are mitochondria involved in?

A

-aerobic respiration making ATP
-variable shape and size mostly rod shaped

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13
Q

describe structure of mitochondria and what does matrix consist of?

A

-bound by 2 membranes forming envelope around matrix

  • between outer smooth membrane + inner folded membrane is the inter-membrane space
  • folds of inner membrane called cristae
  • matrix contains enzymes for respiration + also DNA + ribosomes
  • cells need lots of ATP so have lots of mitochondria
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14
Q

where are chloroplasts found and consist of, how does the structure provide large surface area and what is the membrane system surrounded by(what does that contain?

A

found in photosynthetic plant cell+ algae varying in number 1-100

-consist of flattened biconvex discs surrounded by an envelope consisting of 2 membranes

-envelope encloses a membrane consisting of many flattened sacs called thylakoids which in place form stacks called grana

  • they provide large surface area for chlorophyll molecules which absorb light for photosynthesis

-membrane system surrounded by stroma which has enzymes, sugars + starch granules

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15
Q

what do plant cells contain that animal cells do not and where is cellulose embedded into?

A

-cell wall providing support, strength + shape to cell. consist of cellulose microfibrils(provides strength) embedded in matrix lining containing other polysaccharides eg hemicellulose

-chloroplasts (in photosynthetic cells) containing pigment chlorophyll

  • large vacuole/tonoplast- contianing soluble sugars,salts + sometimes pigment
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16
Q

what does cell wall of algae consist of + fungi?

A

-algae consist of cellulose or glycoproteins or mix

  • fungi doesn’t contain cellulose has nitrogen-containing polysaccharide chitin (glycan + glycoprotein)
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17
Q

what is the process by which cells become specialised to perform specific functions?

A

-cell differentiation

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18
Q

define a tissue in multicellular organisms?

A

tissue group of similar cells perform specific function and have common origin

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19
Q

give an example of plant tissue and its function

A

xylem transports water + nutrients while phloem transports sugars and other organic substances

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20
Q

what is an organ and how is it composed?

A

organ group of different tissues working together to perform specific function

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21
Q

name an organ in digestive system and its role

A

stomach plays a role in digestion of food

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22
Q

what is main function of epithelial cells in small intestine?

A

to absorb digested food products such as glucose and amino acids

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23
Q

how are the cell surface membranes of epithelial cells in small intestine adapted for absorption?

A

they folded into microvilli increasing surface area for nutrient absorption

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24
Q

what role do mitochondria play in epithelia cells of small intestine?

A

provide ATP for active uptake of digested food molecules

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25
describe what is meant by a system in multicellular organisms
system consists of 2 or more organs that work together to perform complex function such as digestive system
26
what is the process used to separate cellular components based on density?
centrifugation
27
what type of solution used to prevent organelle damage during centrifugation?
isotonic buffer solution
28
why is a low temp used during homogenisation?
prevent enzyme activity that could cause organelle self digestion
29
what happens to organelles when an isotonic solution used?
osmotic movement of water is prevented ensuring organelles do not burst.shrival
30
after centrifugation at low speed which organelles forms pellet at bottom of tube?
nuclei
31
how does differential centrifugation progress in terms of organelle density?
centrifugation starts low speeds to isolate denser organelles eg nuclei then increase speed to isolate lighter organelles
32
which organelle is isolated after nuclei during centrifugation?
chloroplasts (in plant cells)
33
what is the role of buffer solution in centrifugation?
maintain pH preventing protein denaturation
34
why os filtering used after homogenisation?
to remove debris scubas cell walls or unbroken whole cells
35
which organelle is isolated last during differential centrifugation?
ribosomes
36
describe process of centrifugation
1. cells broken by homogenising in ice cold,isotonic buffer solution + resulting suspension may be filtered to remove debris that haven't burst in homogenisation 2. homogenate centrifuged at low speed so densest organelles form pellet at bottom 3. supernatant liquid above contains rest organelles + spun at higher speed for longer time period 4. procedure repeated increasing speed+ duration of centrifugation in order to obtain series of pellets containing organelles of decrease density 5. organelles usually isolates on order nuclei, chloroplasts, mitochondria, ER + riobososomes
37
what type of light source used in light microscopy?
visible light
38
what is needed for specimens to be viewed under light microscope + why?
thin + stained to make structures visible to allow light to pass through and for single or few layers of cells to be visible
39
what is major limitation of light microscopy?
poor resolution so very small structures can't be seen.
40
what is stained to enhance visibility in light microscopy?
cellular structures
41
what replaces lenses in electron microscopy in focusing?
electromagnets
42
how does wavelength of electrons compare to light?
electrons have shorter wave length than light providing greater resolution
43
what structural detail can electron microscopes reveal that light microscopy can't?
the fine (ultrastructure) details of a cell
44
what happens to images at high mag when using light microscopy?
images become blurred due to poor resolution
45
what is a major advantage of electron microscopy over light?
greater resolution, allowing for detailed visualisation of close objects
46
compare electron and light microscopes
electron -uses beam of electrons -much greater resolution -focused using magnets -much greater detail - specimens dead + dehydrates -image not in colour -prep of specimen complex + time consuming light -uses beam of light -low resolution -focused using glass lenses -much lower detail -specimen can be living -image in colour prep of specimen easy + quick
47
compare TEM + SEM
TEM - higher resolution than SEM - makes image of internal structure -gives 2D image -sections must be very thin SEM -lower resolution than TEM - makes image of external/surface structures -gives 3D image -sections can be thicker than with TEM
48
what are units for measurement ?
mm -um-nm x1000
49
50
how is a cell membrane described, and why?
fluid mosaic model because phospholipids move within bilayer creating fluid structure+ proteins unevenly distributed forming a mosaic
51
describe orientation of phospholipid bilayer?
hydrophilic heads face inwards toward cytoplasm and outwards toward the extracellular fluid while hydrophobic tails face each other
52
how do small non polar molecules like CO2 + O2 cross membrane?
by diffusing through gaps between phospholipids
53
how does water pass through cell membrane?
passes through water protein channels called aquaporins by osmosis
54
what restricts passage of water-soluble ions + polar molecules across cell membrane?
hydrophobic interior of phospholipid layer restricts passage of water-soluble ions + polar molecule
55
why do charged substances need transport proteins to cross membrane?
charged substances can't pass through hydrophobic bilayer by simple diffusion + need transport proteins
56
what enables lipid-soluble molecules to pass through quickly through cell membrane?
due to its hydrophobic interior
57
what role do transpire proteins play in membrane permeability?
transport proteins assist in movement of charged + larger polar molecules across membrane
58
what is the significance of fluid-mosaic model in cell membrane function?
describes dynamic movement of phospholipids + proteins creates a semi permeable flexible membrane that regulates passage of substances
59
what role does cholesterol play on cell membrane?
provides strength to membrane + restricts movement of phospholipids making membrane less fluid + reducing ion loss from cell
60
how do protein molecules spanning the membrane assist in transport?
they act as carriers or channels, aiding passage of water-soluble ions + polar molecules across membrane
61
what is role of carrier proteins?
have specific tertiary structure complementary to polar molecule helping transport them by facilities diffusion + active transport
62
how do channel protein facilitate diffusion?
channel proteins have specific tertiary structure along with size + charge which determine which molecules can be transported by facilitated diffusion
63
what is the function of receptor proteins in membrane?
act as specific binding sites for hormones allowing cell to respond by detecting signals. they have specific tertiary structure complementary to hormone
64
how are glycoproteins + glycolipids involved in cell signalling + immune response?
glycoproteins + glycolipids have branched carbohydrate chains act as receptors or antigens for cell=cell recognition. allow cells to detect foreign antigens eg those invading bacteria + coordinate immune responses
65
what is the role of glycoproteins in cell recognition?
act as antigen enabling cells to recognise + communicate with one another playing key role in cell-cell recognition
66
how do specific tertiary structures of proteins impact their function in the membrane?
specific tertiary structure of proteins ensures that they are complementary to their target molecules allowing selective transport + signalling
67
describe process of diffusion is it passive and give an example
-net movement of molecules from high concentration to low until molecules equally distributed -passive process so doesn't need energy from respiration -gaseous exchange occurs by diffusion
68
what is rate of diffusion proportional to?
surface area x concentration difference / diffusion distance
69
describe process of facilitated diffusion is it passive?
- allows transport of polar molecules eg glucose + amino acids across membrane down conc gradient through a membrane - uses channel proteins + carrier proteins -passive process (doesn't need energy from respiration) - not inhibited by respiratory inhibitors eg cyanide
70
describe process of active transport is it passive
- movement of molecules or ions through partial permeable membrane by carrier proteins against a concentration gradient - Active transport needs energy from HYDROLYSIS of ATP made during respiration so not passive - molecules attaches to carrier protein which has specific tertiary structure complementary to p[olar molecule eg glucose - binding causes the carrier proteins to change shape and transport molecules across membrane
71
what are factors which decrease rate of respiration and so will decrease active transport?
- lowering temperature - lack of O2 - metabolic +respiratory inhibitors eg cyanide
72
what do cells in active transport possess large amount of?
cells involved in active transport have large number of mitochondria to give ATP needed by respiration
73
what is the process of osmosis?
net movement of water particles from dilute conc(high water potential) to concentrated solution (low water potential). - diffusion of water molecules across partially permeable membrane
74
describe osmosis through solute concentration?
movement of water from low concentration of solute molecules to high conc of solute molecules
75
what is water potential defined as?
potential of water molecules to leave a solution by osmosis so in osmosis water moves from high (less negative) water potential to low (more neg) water potential through partially permeable membrane
76
what potential does pure water have?
(distilled) highest water potential zero. any solution will have neg water potential and more concentrated solution the lower its water potential it will be (more neg)
77
in which direction does water move during osmosis?
water moves down water potential gradient
78
how do ions in a cell affect its water potential?
presence of ions lowers cells water potential, allowing water to enter by osmosis
79
what happens to vacuole as water enters a plant cell?
vacuole enlarges as water enters
80
what pressure is exerted as vacuole + cytoplasm expand?
vacuole, cytoplasm + cell membrane can't outward turgor pressure on cell wall
81
why is turgor pressure important for plants?
turgor pressure provides essential support for many plants
82
what happens to a red blood cell in an isotonic solution?
osmosis doesn't occur as there is no net movement of water, water potential inside + outside cell is equal
83
what happens ton a red blood cell in a solution with low solute concentration (High water potential)?
water moves into cell by osmosis, causing cell to swell. if pressure becomes too great, cell surface membrane ,may rupture causing cell to burst
84
what happens to a red blood cell in a solution with high solute concentration( low water potential)?
water moves out of cell by osmosis, causing cell to shrink as its volume decreases
85
why does a red blood cell burst when placed in a solution with high water potential?
water entering cell increases its volume causing pressure to rise until cell surface membrane ruptures
86
what is the effect of water moving out of a red blood cell during osmosis?
cell shrinks as its volume decreases
87

SEMESTER 1 (8 decks)

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