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biology paper 1 > 3.2.1 cell structure > Flashcards

3.2.1 cell structure Flashcards

1
Q

what is the structure and function of vacoles?

A

fluid filled sac with a single membrane = tonoplast

contains solution of mineral salts, sugars, amino acids, wastes and sometimes pigments such as anthocyanins

support plants by making them turgid

sugars and amino acids = temporary food store

pigments = colour petals to attract pollinating insects

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2
Q

what is the structure and function of a cell wall?

A

cell wall consists of microfibrilis of the polysaccharide cellulose, embedded in a matrix

constists of many polysaccharides

middle lamella = marks the boundary between adjcent cell walls and cements adjacent cell walls together

provides mechanical strength

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3
Q

Plant cells are also eukaryotic. Outline the fucntions of each part of a plant cell. 10 marks

A

nucleus = controls activities of the cell, contains genetic information that can be transmitted to the next generation, produces ribosomes

smooth ER = makes and transports lipids and hormones

rough ER = has ribosomes and takes part in protein synthesis and the transport of proteins around the cell

golgi body = processes molecules and proteins, used in secretion

lysosome = hydrolytic, and has digestive enzymes, breakdown of organelles

mitochondria = formation of ATP and provides energy

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4
Q

what is thestructureand thefunctionof the centrioles?

A

structure = small protein tubes of microtubules
not surrounded by membranes

function = form fibres in cell division known as spindles which separate chromosomes

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5
Q

what is thestructureand thefunctionof the ribosome?

A

80S = found in eukaryotic cells

70S = found in prokaryotic cells, mitochondria and chloroplasts

contain ribosomal RNA and proteins

where protein syntheisis occurs

structure = very small organelles in cytoplasm, bound to rough ER
consists of 2 subunits
not surrounded by membranes

function = site of protein synthesis which acts as an assembly line to use mRNA to assemble proteins

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6
Q

what is thestructureand thefunctionof the lysosome?

A

formed by golgi appartus with the vesicles containing protease and lipases
contain lysozymes = which hydrolyse the cells walls of a certain bacterias

hydrolyses material when ingested by phagocytic cells

releases enzymes to the outside world in order to destroy material around the cell

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7
Q

what is thestructureand thefunctionof the chloroplasts?

A

chloroplast envelope = double plasma membrane which is highly selective about what it lets in and out the cell

grana = stacks of thylakoids
first stage of photosynthesis takes place

thylakoids = contains photosynthesis pigment of chlorophyll
granual membranes = large SA for chlorophyll to attach in a ordered fashion
may have tubular extensions which join other thylakoids in a grana

stroma = fluid filled matrix
second stage of photosynthesis, uses enzymes from stroma fluid
contains starch grains

contains both DNA and ribosomes to make proteins needed for photosynthesis

function = site of photosynthesis
light energy is used to derive carbohydrate molecules from CO2

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8
Q

what is thestructureand thefunctionof the Mitochondria?

A

double membrane = controls what goes in and out of cell
inner membrane = folded to form cristae

cristae = allows a large SA for attachment of enzymes and proteins for respiration

matrix = contains proteins, lipids, ribosomes and DNA
many enzymes involved in respiration are in the matrix

function = site where ATP is produced during respiration

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9
Q

what is thestructureand thefunctionof the Golgi Apparatus?

A

cisternae = flatterned stacked sacs of membranes

recieves proteins from ER

modifies proteins often adding non protein components eg adding carbohydrates to proteinsb = glycoproteins

transported in golgi vesicles

form lysosomes

transport, modify, store lipids

secretes carbohydrates

structure = stack of membrane bound flattened sacs

function = receives proteins from ER
modifies them eg adds sugar
packages proteins into vesicles to be transported inside cell to the outside

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10
Q

what is thestructureand thefunctionof the Endoplasmic Reticulum?

A

RER = ribosomes present on outer surface of membrane
provides large SA for synthesis of proteins and glycoproteins
provides a pathway for transport of materials especially proteins

SER = does not have ribosomes present on surface of membrane
tubular apperance
synthesises, stores and transports lipids
synthesises, stores and transports carbohydrates

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11
Q

what is the structure and the function of the nucleus?

A

nuclear envolope = double membrane.
outer membrane is continunous with endoplasmic reticulum with ribosomes on its surface
controls what enters and leaves

nuclear pores = allows large molecules to pass through eg mRNA

nucleoplasm = makes up the bulk of the nucleus and is a jelly like substance

chromosomes = protein bound, linear dna

nucleolus = manufactures ribosomal RNA and assembles ribosomes

structure = largest organelle
spherical and dark patches = chromatin
surrounded by nuclear envelope
nucleus inside

function = contains genetic material
chromatin consists of dna and proteins
nucleous makes rna and ribosomes

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12
Q

what does a root hair cell do?

A

very large number due to them being long and having hair like projections which allows more active transport of mineral ions = increases rate of water by osmosis

mitrochondria = energy in form of ATP, then used to drive the active transport up it’s concentration gradient

thinner walls = water can move out easily

permanent vacole = contains cell sap which is more concentrated than soil water

no chloroplasts

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13
Q

what does a guard cell do?

A

allow gas exchnage and control water loss within the leaf

thick cell walls = facing outside the cell or leaf and stomata

thin cell walls = facing adjacent epidermal cells

several small vacoles instead of one big vacole

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14
Q

what does a ciliated epithelium?

A

cilia (hair like structures) on top of the surface of a cell

move substances in one direction = mainly mucus

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15
Q

what does a palisade cell do?

A

mainly focus on photosynthesis process

contains large number of chloroplasts on their SA that absorb a large amount of sunlight and undergo photosynthesis effectvely

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16
Q

what does a sperm cell do?

A

tail = able to move through energy generated by mitochondria which propels the cell

head = contains acrosome (specialised lysosome that releases energy so that the sperm cell can penetrate the ovum coat of the egg

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17
Q

what does a root hair cell do?

A

large number, allows more active transport
mitochondria = energy in form of ATP, used to drive active transport up the concentration gradient
permeant vacuole = contains cell sap which is more concentrated than soil water
no chloroplasts found

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18
Q

what does a guard cell do?

A

allow gas exchange and control water loss
thick cell walls = facing outside the cell towards stomata
thin cell walls = facing adjacent epidermal cells

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19
Q

what does a ciliated epithelium?

A

cilia (hair like structures) on the top of the surface
move substances, mainly mucus

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20
Q

what does a neutrophil do?

A

flexible shape that allows them to squeeze through cell junctions in the cell capillaries wall
engulf microorganisms
large number present in lysosomes

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21
Q

what does a erythrocyte do?

A

contains haemoglobin that combines with oxygen
no nucleus so they can contain more haemoglobin
small and flexible
biconcave shape to maximises there SA for oxygen absorption

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22
Q

what is the process of cell specialisation

A

young cell
cell division
cell growth
cell specialisation
mature cell

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23
Q

What is an organ system?

A

A group of organs organised into organ systems that work well together

24
Q

what is an organ?

A

Aggregations of tissues performing similar functions

25
Q

What is a tissue?

A

A tissue is a group of cells that work together to perform a particular function

eg epithelial tissues = consists of a sheet of skin cells

eg zylem = used to tansport water and mineral ions throughout the plant and provides mechanical support

26
Q

what do multi celled organisms have in common?

A

smaller s/a: volume
not all cells in contact with external environment
specialised cells to perform different functions

27
Q

what do single celled organisms have in common?

A

large s/a: volume
all cells exposed to environment
effective exchange surface
all cells perform all functions

28
Q

what is a prokaryote?

A

bacteria
no membrane bound organelles

29
Q

what is a eukaryote?

A

plants, animals, fungi and protoctists cells
membrane bound organelles

30
Q

how to viruses attach as attachment proteins?

A

present on the lipid envelope, if not present, present on the lipsid

allows virus to identify and attach to host

attachment is achieved when receptors on the capsid become connected to complimentary receptors proteins on the cell membrane of the target cell

virus must enter the cell which is covered by phospholipid bilayer, a cells natural barrier to outside world

usually the two membranes fuse and the capsid enters the genome

31
Q

what are the four virus shapes?

A

shape:
1. rod
2. polyhedral
3. envelope covered in spikes
4. t-phages (head and tail)

32
Q

what is the role of capsids in viruses?

A

protectice protein coat/shell surrounding the nucleic acid

shape dependant on the virus (rod/more complex)

built from a large number of protein subunits called capometres

most complex capsids are found among viruses that infect bacteria categories

shape:
1. rod
2. polyhedral

33
Q

what genetic material is in genomes?

A

genomes may consist of
1. double stranded DNA, single stranded RNA
2. double stranded RNA, single strandes RNA
3. single stranded RNA, single stranded RNA

virus of DNA or RNA depends on it’s nucleic acid making up the genome

usually organised in a linear or circular molecule of nucleic acid

smaller viruses only have 4 genes while the largest have hundreds

34
Q

describe the virus structure

A
  1. core = viral nucleic acid (DNA or RNA)
  2. capsid = protein shell
  3. core + capsid = nucleocapsid
35
Q

what are viruses?

A

acellular non living particles

contain nucleic acids such as DNA or RNA as genetic material but can only multiply inside living host cells

nucleid acid is protected by the capsid

capsid = attachment proteins allow the virus to attach to host cell

may have a tail section

36
Q

what does prokaryotic cells consist of?

A

bacterial cell wall = made up of a tough protein called mylein (not cellulose like plant cells)

plasma membrane = has the same structure in eukaryotic and proeukaryotic and is the main boundary between cells and environment

genetic material = singular circular piece of DNA carrying only a few genes which occur throughout the cytoplasm

ribosomes = site of protein synthesis, does not attach to membranes

flagellum = rotates allowing bacteria to move

capsule = slime layer is a protein which can stop the cell drying out and protects cell from digestive enzymes

37
Q

give a comparison of prokaryotic and eukaryotic cells

A

prokaryotic cells do not contain any membrane organelles = they do not have mitochondria
they have mesosomes which are foldings in the cell membrane that provide a large SA for the attachment of enzymes for respiration

38
Q

what is the structure of a bacterial cell?

A

versatile, adaptable and very successful = small size cell wall made of murein

polymer of polysaccharides and peptides capsule = mucilaginous slime around cell wall

cell surface membrane = 70S ribosomes

circular strand of DNA = genetic material

plasmids = smaller circular pieces of DNA (smaller then large circular strand of DNA)

39
Q

what do prokaryotic cells not have?

A

smaller and have no nucleus or nuclear envelope found in bacteria and cyanobacteria kingdom: prokaryotae

40
Q

what do eukaryotic cells have?

A

larger and have a nucleus bounded by nuclear membranes kingdoms : protoctisa, fungi, plantae and animalia

41
Q

what are the 8 kingdoms?

A

domain
kingdom
physium
class
order
family
genus
species

42
Q

what is a limitation of using a light microscope (gsce)?

A

poor resolution so we use electron microscopes to achieve a better resolution

43
Q

how does a scanning electron microscope work?

A

directs a beam of electrons on to the surface from above

scanned over the surface of a sample

trajectory of secondary electrons and scattered electrons depends on the contours + topography of a specimen

resolving power = 20nm

can build up a 3D image by computer analysis of the pattern of scatterned electrons and secondary electrons produced

44
Q

list some limitations of transmission electron microscopes

A
  1. whole system must be in a vaccum and living specimens cannot be observed = only non-living specimens and must be extremely thin
  2. complex staining process is required
  3. specimen must be extremely thin
  4. image may contain artefacts = may appear in the finished photomicrograph but are not part of the actual specimen
    therefore not easy to be sure that what we seen on a photomicrograph really exsists in that form
45
Q

how does a transmission electron microscopework?

A

consists of an electric gun that produces a beam of eletrons that is focused onto the specimen by a condenser electromagnet

electrons are transmitted through a sample

parts of specimen absorb electrons becoming dark, other parts let electrons pass through so appear bright

produced image = photomicrograph

resolving power = 0.1nm = may not always be achieved as difficulties preparing the specimen limit resolution and a higher resolution can damage and destroy the specimen

46
Q

what are the two types of microscopes?

A
  1. transmission = electrons are transmitted through the sample
  2. scanning = electrons are scanned over sample of the surface
47
Q

describe resolution in terms of magnification

A

resolution or resolving power = minimum distance apart that two objects can be in order for them to appear as seperate objects

resolving power depends on wavelength or form of radiation used

increasing magnification of an image increases size of an image (doesnt always increase resolution)

every microscope has a limit of resolution

48
Q

what is the magnification equation?

A

magnification = size of object / size of real object

in practice: (more commonly used)

size of real object = size of image / magnification

49
Q

what is the object in magnification?

A

object is the material is put under a microscope

50
Q

what is the process of cell fractionation?

A
  1. tissue is cut into pieces in a cold, buffered isotonic solution
  2. tissue is homogenised eg in a blender
  3. homogenised suspension is filtered
  4. filter is centrifuged at a low speed
  5. supernatent is decanted and re-centrifuged at a higher speeds until desired organelle is seperated
  6. supernatent is analysed for content
51
Q

describe the process of ultracentrifugation

A

process by which the frgaments in the filtered homogenate are seperated in a machiene called a centrifuge

this spins tubes of homogenate at a very high speed in order to create a centrifugal force

  1. tube of filtrate is placed in centrifuge and sped at a low speed
  2. heaviest organelles (nuclei) are forced to the bottom of the tube, where they form a thin sediment or pellet
  3. fluid at the top of the tube (supernatant) is removed
  4. supernatent is transfereed to another tube and spun in the centrifuge at a faster speed than before
  5. next heaviest organelles, the mitrochondria, are forced to the bottom of the tube
  6. the process is continued in this way so that at each increase in speed, the next heaviest organelle is sedimented and seperated out
52
Q

what is homogenation? and why is it used?

A

homogenized = blended

cells are broken up by a blender which releases the organelles from the cell

resultant fluid (homogenate) = is then filtered to remove any complete cells and larger pieces of debris

53
Q

what are the two stages to cell fractionation?

A
  1. homogenation
  2. ultracentrifugation
54
Q

why is tissue placed in solution?

A

tissue is placed in a cold buffered solution with the same water potential as the tissue

cold = to reduce enzyme activity that might break down the organelles

same water potential = prevents organelles bursting or shrinking as a result of osmotic gain or loss of water

buffered = so PH does not fluctuate, any changes in PH could alter the structure of the organelles or affect the functioning of enzymes

55
Q

what is cell fractionation?

A

process where cells are broken up and different organelles they contain are isolated and seperated out

used to help study structure and function of the various organelles that make up cells

biology paper 1 (23 decks)

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