2.1 cell structure Flashcards

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1
Q

name all the organelles you could find in an eukaryotic cell

A

nucleus, nucleolus, nuclear envelope, RER, SER, golgi apparatus, ribosomes, mitochondria, lysosomes, cellsurface/plamic membrane, centrioles, cell wall, chloroplats, permenant/non p vacuole, flagella, cilia

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2
Q

describe the organelles in the nucleus and all their functions

A

nucleus- contains cell activity by controlling the transcription of DNA which contains instructions to make proteins, contains organisms genome
nucleolus- makes ribosomes by making RNA
chromatin- consists of DNA and proteins
nuclear envelope- a double membrane which has nuclear pores to allow substance to move between the cell and nucleus

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3
Q

describe the function and structure of the RER

A

rough endoplasmic reticulum - folds processes proteins made by the ribosomes (adds a carbohydrate group), has ribosomes attached to it

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4
Q

describe the function and structure of the SER

A

smooth endoplasmic reticulum - synthesises and processes lipids, phospholipids and steroids, has no ribosomes attached

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5
Q

describe the function and structure of the golgi apparatus

A

processes and packages new proteins and lipids into vesicles, made of membrane bound flattened sacs

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6
Q

what is the function of ribosomes and whats the difference between free ribosomes?

A

site of protein synthesis
free - float free and are not attached to the RER

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7
Q

describe the role of mitochondria and their structure

A

site of aerobic respiration where ATP is produced
smooth outer membrane
folded inner membrane that form cristae
matrix which contains enzymes

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8
Q

what is the role of lysosomes

A

contains digestive enzymes (lysozyme)

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9
Q

describe the function and structure of centrioles

A

involved with the seperation of chromosomes during cell division
small hollow cylinders, made of microtubules (9 pairs) held by supporting proteins

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10
Q

describe the flagella’s structure, function and where it’s found

A

made of 9 pairs of microtubules with 2 in the middle, basal body
outside the cell on the cell surface membrane
movement/locomotion of the cell

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11
Q

describe the cilia’s structure, function and where its found

A

made of 9 microtubules with 2 in the middle, basal body
outside surface of cell surface membrane
moves substances along cell surface

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12
Q

how does the cilia and flagella move

A

motor proteins move across generating a force which makes it beat

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13
Q

describe the function of a cell wall and what its made from

A

provides rigid structure and has a defense mechanism to protect against pathogens and is fully permeable
cellulose

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14
Q

are vacuoles permanent or non permanent in plant cells

A

permanent vacuoles in plant cells
non permanent vacuoles in animal cells

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15
Q

describe the structure of the vacuole and what it contains and stores

A

membrane (tonoplast) lined sacs that contain cell sap
stores water

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16
Q

are vacuoles fully permeable

A

no, selectively permeable

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17
Q

what type of membrane does a chloroplast have
describe the internal features of a chloroplast

A

double membrane
internal membrane = thylakoid
grana = stacked up thylakoid
grana joined by lamallae
inside fluid = stoma

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18
Q

what is the role of chloroplasts and what else do they contain thats different to other organelles

A

site of photosynthesis
contain DNA and ribosomes

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19
Q

what is the cytoskeleton

A

an extensive network of protein fibres

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20
Q

what is the function of the cytoskelton

A

structural support and strengthening
intracellular movement/ transport organelles within a cell
cellular movement

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21
Q

name the three protein fibres in cytoskeleton

A

microfilaments
microtubules
intermediate filaments

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22
Q

desribe the structure of microfilaments

A

narrowest 7nm
made of many linked monomers of protein actin in a double helix structure
actin filaments assemble and dissassemble quickly allowing movement

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23
Q

describe the structure of microtubules

A

largest 25nm
made of tubulin proteins in a hollow tube like structure consiting of 2 subunits
grows and shrinks quickly due to addition and removal of tubulin proteins

24
Q

describe the structure of intermediate filaments and their role

A

8-10nm
made of multiple strands of fibrous proteins wound together permanent, structural role by bearing tension and maintain the shape of the cell

25
Q

describe the role the nucleus plays in creating proteins

A

contains DNA which codes for the production of proteins and contains the nucleolus which manufactures ribosomes

26
Q

describe the stages of protein synthesis

A

1.DNA is copied into a molecule of mRNA via transcription
2.mRNA strand leaves the nucleus through a nuclear pore and attaches to a ribosome on the RER
3.ribosome ‘reads’ the genetic instructions on mRNA and uses this code to synthesise a protein via translation
4.protein then passes into the lumen (the inside space) of the rough endoplasmic reticulum to be folded and processed
5.proteins transported by vesicles from the RER to the golgi apparatus and fuses to release the protein
6.golgi modifies the protein
7.protein leaves the golgi by secretory vesicles by pinching it off and fuse with cell surface membrane and undergo exocytosis

27
Q

what is a prokaryote

A

a single celled organism that does not contain membrane bound organelles

28
Q

name the structures always present in a prokaryotic cell

A

cell wall, plasma membrane, cytoplasm, circular DNA/nucleoid, ribosomes

29
Q

name the additional structures found in a prokaryotic cell

A

flagellum, capsule, plasmids, pilli, mesosome, infolding of plasma membrane

30
Q

what is the function of a capsule

A

final outer layer helps to protect bacteria from drying out as made from slime and protects from attacks from immune systems

31
Q

what are plasmids

A

small loops of DNA contains genes that can be passed between prokaryotes

32
Q

what is the function of pilli

A

attachment to other cells/surfaces and involved in sexual reproduction

33
Q

what are mesosome

A

the infolding of plasma membrane, helps the formation of cell walls and associated with DNA during cell division

34
Q

what is the infolding of plasma membrane used for in prokaryotic cells

A

may form a photosynthetic membrane and carry out nitrogen fixation

35
Q

compare the size of a eukaryotic to a prokaryotic cell and the size of their ribosomes

A

prokaryotic cells are smaller and have smaller ribosomes to (70s) eukaryotic (80s)

36
Q

what do cell walls contain in eukaryotic cells(plant), fungi and prokaryotic cells

A

plant - cellulose
fungi - chitin
pro- peptidogylcan and murien

37
Q

compare how DNA is in euakrytotic cells to prokaryotic

A

eukaryotic - linear, seperate strands of DNA in chromosomes , wrapped around protein histones
prokaryotic - circular strand of DNA, no histone, proteins fold and condense, small loops (plasmids)

38
Q

describe the endosymbiont theory

A

mitochondria and chloroplasts (and other organelles) were formally prokaryotes

39
Q

what evidence in cells supports the endosymbiont theory

A

mitochondria and chloroplasts contain their own DNA and ribosomes

40
Q

what is the magnification equation

A

magnification = image size/ actual size

41
Q

what is magnification

A

the number of times larger an image is compared to the object

42
Q

what is resolution

A

the ability to see two points separately as two points
to see detail

43
Q

name 4 types of microscopes

A

light/ optical
laser scanning confocal
transmission electron (TEM)
scanning electron (SEM)

44
Q

name the advantages and disadvantages of a light microscope

A

portable, easy to use, can see living or dead specimen, cheap
specimen need to be thin/transparent, max mag. of x1500 and res. of 200nm

45
Q

what is observed with a laser scanning conofocal microscope and how does it observe

A

whole living specimen and their structures at different depths
uses laser light to scan and produce a computer image

46
Q

what is observed how is it observed with a TEM

A

a thin sample of a dead specimen
eectrons pass through specimen, denser parts they pass less easily providing contrast

47
Q

name the advantages and disadvantages of electron microscopes (TEM and SEM)

A

much higher magnification/resolution, produces detailed images of structures, SEM produces a 3D image and detailed surface view
very expensive, need trained staff, have to have dead samples as placed in vacuum

48
Q

what is the maximum magnification and resolution of light, laser scanning conofocal, TEM, SEM microscopes

A

light = x1500, 200nm
LSC= x
TEM= x500000, 0.02nm
SEM=x100000, 0.5nm-1nm

49
Q

how do you prepare a specimen

A

staining - helps to see cell by increasing contrast of structures to identify certain parts of a cell eg. methylene blue = nucleic acid turns blue
sectioning - embed specimen in wax, then cut thin

50
Q

what is a stage micrometer and how many divisions and what size are they

A

a scale thats fitted on a cover slip and its divisions are a known size (10nm and there are 1000 divisions)

51
Q

what is an eyepiece graticule

A

a scale that is in the eyepiece lens (units are aribitary)

52
Q

how do you calibrate an eyepiece graticule

A

align the e.g and s.m
count how many divisions of the e.g correspond to a set number of s.m ddivisions
calculate how big one e.g is

53
Q

what image does a laser scanning confocal microscope show

A

2D or 3D
coloured or back and white

54
Q

what image does a TEM show

A

2D
black and white

55
Q

what image does a SEM show

A

3D
black and white