Cells Flashcards
1
Q
gWhat does nucleus have
A
Nuclear envelope
Nucleurnpores
Nuecluoplasm
Chromosomes
Nucleolus
2
Q
Nuclear ENVELOPE
A
3
Q
Nuclear pores
A
4
Q
Nucleoplasm
A
5
Q
Chromosomes
A
6
Q
Nucleolus
A
7
Q
Functions of nucleus
A
8
Q
Mitochondria structures
A
Inner membrane folds to form Cristae
Holds the protein in place required for aerobic respiration
9
Q
Double membrane
A
10
Q
Cristae
A
11
Q
Matrix
A
12
Q
What chloroplasts contain
A
13
Q
Grana
A
14
Q
Stroma
A
15
Q
How chloroplast adapted
A
16
Q
Rough endoplasmid reticulum
A
To hold ribosomes in place
Form vesicles to seperste proteins products from the cytoplasm
17
Q
Smooth endoplasmid reticulum
A
18
Q
Function of Golgi apparatus
A
19
Q
Function of lysosomes esicles
A
Vesicles contsintjng hydrolysis enzymes
Seperste hydroylytic enzymes from the cytoplasm
20
Q
Ribosomes
A
21
Q
Cell wall
A
22
Q
Vacuoles
A
23
Q
Why is tissue placed in buffer
A
Keeps the ph constant
Enzymes are protein which would be affected by the ph so if ph changes they would denature
24
Q
Why would specimens be held in vacuum chamber
A
To hold it still
25
Largest to smallest chloroplast nucleus ribosome mitochondria
Nucleus
Chloroplast
Mitochondria
Ribosomes
26
Why is tissue placed in cold
Stop harmful bacteria down
Slow enzymes down
Stops breaking down the organelles for digestion
27
Why do some parts of a specimen see, bright
Allows electrons to pass through
28
Electron beam characteristics
Short wavelength
Resolve objects well
High revolving power
Negatively charged
Beam focused using electromagnets
29
Cell fractionation
Separates organelles according to their density
30
Centrifuge process
1)filtrate placed In centrifuge and spun at low speed
2)heaviest organelle forced to bottom of tube forming thin sediment or pellet
3)fluid at top is supernatant is removed leaving nucleui sediment
4)supernatant transferred to another tube and spun even faster
31
What are the two stages of cell fractionation
1)homogenation
2)ultracentrifugation
32
What does transmission microscope consider
Electron gun that produces a beam of electrons that is focused onto the specimen by a condenser electromagnet
33
How electron microscopes works
1)Use an electron beam of light which is focused using electromagnets as electrons are neg charged
2)Specimen has to be spec prepared and held inside vacuum chamber
3)Beam passes through this section of specimen .heavy metal stain absorbs electrons but electron passes through other parts of specimen
4)These areas appear brighter
5)the image formed as photograph (electron micrograph)or as image on tv
34
Homogenised
Cells are broken up
35
Resolution definition
The minimum distance apart that two objects can be in order for them to appear as separate items
36
Why tissue in same water potential
Isotonic
It would burst
Prevents osmosis so no lysis shrinkage of organelles
37
Light microscope characteristics
Light
Longer wavelengths
Cannot see objects more than 200nm
Glass lens focuses
38
What actually is ultracentrifugation
Process when the drag,ente are filtered and homogenate are separated from in centrifuge sounnng the tubes at high speed
39
What does resolving power depend on
The wavelength or form of radiation used
Greater resolution greater Clarity clearer image and more precise
40
How has fractionation and ultrafugation has helped
Allow detailed study of structure and function of organelles by showing what isolated components do
41
Tem characteristics
Electrons
Very short wavelength
0.1 nm resolving power
Prices by electromagnets
Vacuum needed
Complex staining process
2d image
Extremely thin specimen
Electrons from below
42
What actually happens in homogenation
Cells broken in blender releasing organelles fro, cell. Resultant Fukui (homogenate) filtered to remove complete cells or large pieces of debris
43
How to obtain large numbers of isolated organelle
Cells are broken up and then different organelles separated out
Tissue is placed in cold buffered solution of same water potential
44
Scanning electron microscope
Also beam of electron onto surface pf specimen from above rather than below
Beam passed backcknand forfth
3d
Lower resolving power
45
How cell fractionation is carried out
1)cells in specific solutions
2)tissue placed in isotonic solution
3)tissue placed in a ph buffer
4)placed in ice cold solution /water
5)the cells are then homogenised in a blender
6)removing debris
7)filtered homogenate spun at a low speed
8)increasing speed removing suoernatant at each stage
8)nucleui are the densest organelle form the first pellet
10)mitochondria form the next pellet
11)keep spinnning until you form the fractions that you want eg.depending on what you want to isolate like ribosomes or mitochondria
12)supernatant is spun at even higher speeds to pellet ribosomes
46
Cristae
Site of electron transport chain
47
Transmission electron microscope limitations
in a vacuum so living specimens can’t be observed
#complex staining process required
-extremely thin specimen
-2d
48
Sem chacarteristics
Electrons
Short wavelength
20nm resolving power
Focused using electromagnets
Vacuum needed
Dead specimens
Electrons directed from above
49
Why electron microscopes have a higher resolution than an optical
Electron beam has shorter wavelength and light rays
50
What have we learnt from electron microscopes
Cells contain organelles to carry out different functions
Internal structure of organelles and how they function
Structure of bacteria and viruses
Causes of medical conditions
51
Cell specialisation
-cells of multicellular organisms are each specialised in different ways to perform a particular role
-stem cells in embryo are identical but then as it matures they become specialised
-to do this some genes are switched on and off
52
Tissue
A collection kf similar cells that preform a specific function
53
Organ
A combination of tissues that are coordinated to preform a variety of functions
54
Tissue types
Epithelial
Connective
Muscle
Nervous
55
Epithelial
Covers the outside of your body as well as your internal organs
56
Muscle tissue
Cells that shorten due to the chemical and physical interaction between myofilsmrntd actin and myosin
57
Nervous tissue
58
Virus structure - hiv
Acellular (not cells)
59
When are chromosomes visible
During cell divisions
You would see chromatins
60
What do chromosomes consist of
Each chromosome consists of two chrimsrids joined somehweee along its length at the centromere
Genetic info (genes/alleles)carried on each chromatic is identical
61
Two main parts of cell cycle
Interphase
Cell division
62
Cell cycle
G1)growth if duaghger cells. Rep or organelles
S)replication of dna
G2)cell checks dna and makes any repairs. Cell prepared fir division
3)nuclear division
4)cytoplasmic division
63
G1 stage
Variable duration
Eg. Some cells do not divide like nervous cells
Formation of cellular proteins
64
S stage
Constant duration
Formation of cellular proteins
65
G2 duration
Constant
Formation of cellular proteins
66
Interphase in embryo
There is no interphase for the first few division
As the zygote contains materials to form the first 16 cells
Cells decrease in size as cells divide
67
What stage does dna unravel
S
Interphase
68
What holds chromatids together
Centromere
69
Protein associated with dna in the chromosomes
Histone
70
What produces spindle fibres
Centriole
71
Prokaryotic characteristics
1)no nucleus
2)dna not associated with
3)plasmids
4)no chloroplasts only bacterial chlorophyll
5)smaller ribosomes
6)Muerin cell wall
7)capsule
72
Eukaryotic characteristics
1)distinct nucleus
2)dna associated with histone
3)no plasmids
4)membrane bound
5)chloroplast
6)ribosomes cellulose cell wal
7)no capsule
73
Viruses(more)
Acellular
Smaller than bacteria
Nucleui acids enclosed in protein coat capsid
dna or rna as genetic material
Multiply inside host cells
74
What mitosis does
Produces two daughter cells that have the same number of chromosomes as the parent cells and each other
75
Meiosis does
Produces four daughter cells
Each with half number chromosomes
76
Interphase
Cell is not dividing
Replication of dna
Then joined at centromere
77
Prophase
When chromosomes become visible
Long thin threads
Centrioles opposite poles form spindle fibres
Nuclear envelope breaks down
Chromosomes at equator
78
Metaphase
Chromosomes made of two chromatids
Joined by centromere
Chromosomes pulled along the spindle apparatus
79
Anaphase
Centromeres divide into two
Fibres pull chromatids
Opposite poles now chromosomes
80
Telophase and cytokinesis
Chromosomes thinner again
Spindle fibres disintegrate
Nucleus envelope and nucleolus reform
Cytoplasm divides
81
Replication of viruses
Cannot undergo cell division
Replicate attach to host cells with proteins on their surface
Inject nucleuc acid into host cell
Provides instructions for hosts metabolic processes
Stewart producing new viral components
Then assembled into a new virus
82
The role of the cell surface membrane is.
To control the movement of substances into and out of the cell / exchange of substances with the cell’s external environment; [1 mark]
Contains molecules on its outer surface that enable cell to cell communication / display hormone receptors / present antigens ; [1 mark]
83
Lysosomes
Sacs/compartments surrounded by membrane OR sacs/compartments containing digestive enzymes; [1 mark]
84
stage micrometer is needed in addition to the eyepiece graticule because...
The size of the units of the eyepiece graticule change depending on the magnification being used; [1 mark]
The micrometer can be used to calibrate the graticule; [1 mark]
85
1)chromosomes shorten due to super coiling
2)chromosomes become identical chromatids
86
causes of cancer
occurs when the rate of cell multiplication is faster than the rate of cell death which causes growth of tumour. often in a tissue with a high rate or mitosis such as the lung or bowel.
87
malignant tumour
destroy the surrounding tissue and their cells can break away and spread through the food or lymph into other sites where the form secondary tumours
88
benign
can compress tissues preventing normal blood flow or nerve function
89
factors to do with cancer
infection
gender
occupation
sun and radiation
alcohol
pollution
diet
tobacco
90
preventing cancer with diet
-food containing antioxidants fruits and veg that destroy radicals (chemicals from the diet and uv etc that contribute to ageing and dna damage.
91
preventing cancer -viruses
they can trigger some cancers
eg.hep trigger liver and cervical cancer
preventing viruses by vaccines may prevent cancer
92
inherited cancer
-through genes
-BRCA1 gene synthesis a protein to repair dna
-mutation in the brca1 gene predispose a person to breast cancer later in life if the other allele in great tissue becomes damaged.
-other gene predispose people to other cancers
93
how cancer can be treated
-surgery- remove cancerous tissue
-chemotherapy- chemical used to destroy cancer cells
-radiotheraoy- x rays to destroy cancer cells
94
problems with radiotherapy and chemotherapy
-damage to healthy ceklls
-infertility
-hair loss
95
binary fission
1)circular dna replicates and both copies attach to cell membrane
2)plasmids also replicate
3)cell membrane begins to grow between 2 dna molecules and pinch inwards dividing cytoplasm
4)new cell wall forms between 2 molecules of dna dividing original cell into 2 daughter cells
96
What cell looks like in interphase
Growth of daughter cells
Organelles replicate
Dna replicates
Dna repairs
97
How cell looks like during prophase
Chromosomes more visible in nucleus
Chromosomes thicken
Spindle fibres form
Nuclear envelope disappear
98
How cell looks like in metaphase
Chromosomes line up at the equator
Spindle fibres from centrioles attatch
99
Anaphase how cell looks
Chromatids at opposite poles
Spindle fibres contract and pull chromatids opposite poles
100
Telophase how cell looks
Uncoiled chromosomes and nucleur envelope
Chromosomes uncoil do spindle fibres disintegrated and envelope reappears
101
fluid mosaic membrane
102
phospholipid bilayer
the most stable arrangement
fatty acid face inwards
103
liposome
water inside the structure and outside.spherical bilayer that forms with hydrophilic heads facing outwards and hydrophobic tails to the inner potion
104
micelle
phospholipids in water
hydrophilic head attcrated but tails are hydrophobic
105
bilayer sheets
cytoplasm contains lots of holes tissue fluid surrounds the cell because hydrophilic heads are facing outwards so bilayer forms
106
intrinsic
span the membrane
channel protein has water filled pores to allow water soluble ions to diffuse across or carrier proteins binds to ion then changes shape to move across membrane
107
extrinsic
give mechanical support or act as cell receptor with glycolipids
108
cholesterol
reduces lateral movement of the phospholipids and hence reaches membrane fluidity at high temperatures
prevents leakage of water and dissolved ions from the cell
adds strength to membrane
109
the more unsaturated fatty acids ...
the less tightly packed and more fluid the membrane
110
glycolipid
-used for cell attachment
-form receptors
111
glycoprotein
-form receptors for hormones and neurotransmitters
-used for cell attachment for tissue formation
112
membrane permeability
high temps it becomes more permeability
