2.1.1 cell structure Flashcards
1
Q
what is the magnification of a light microscope
2.1.1(a)
A
2000x
2
Q
what is the resolution of a light microscope
2.1.1(a)
A
200nm
3
Q
how do light microscopes work
2.1.1(a)
A
they use visible light to illuminate the specimen
4
Q
what is the resolution of a light microscope limited by
2.1.1(a)
A
the wavelength of visible light
5
Q
what is the magnification of a laser scanning confocal microscope
2.1.1(a)
A
1000x
6
Q
what is the resolution of a laser scanning confocal microscope
2.1.1(a)
A
120nm
7
Q
how does laser scanning confocal microscopy produce an image/what colour
2.1.1(a)
A
it uses a laser and a concentrated beam of light to scan an object point by point
the information is assembled by a computer into one image and displayed on a computer screen
the colour of fluorescent tag which glow a certain colour under the UV laser light
8
Q
what cells can laser scanning confocal microscopy be used on and what does it show
2.1.1(a)
A
used on live cells
so an image can be taken every few seconds to show the movement of substances inside cells
9
Q
what is the magnification of TEM
2.1.1(a)
A
2 000 000x
10
Q
what is the resolution of TEM
2.1.1(a)
A
1nm
11
Q
how do TEM produce an image and what is that image called
2.1.1(a)
A
they use a beam of electrons to illuminate the specimen
the image is then interpreted by a computer
it is called an electron micrograph
12
Q
what cells are TEM used on and why
2.1.1(a)
A
dead cells
the specimen has to be sliced thinly then fixed using a highly toxic stain
AND
the sample must be placed in a vacuum so that electrons in the beam aren’t scattered by air particles
13
Q
what colour is the image produced by TEM 2.1.1(a)
A
black and white until artificial false colour is added
14
Q
what is the magnification of a SEN
2.1.1(a)
A
200 000x
15
Q
what is the resolution of a SEN
2.1.1(a)
A
20nm
16
Q
How is an image assembled by a computer using a SEN
2.1.1(a)
A
the sample is sprayed with a fine film of metal atoms
electrons are scattered from the metal atom layer and detected by an electron detector
the image is assembled by a computer
17
Q
What colour is the image assembled by an SEN
2.1.1(a)
A
black and white until artificial false colour is added
18
Q
is the image produced by a laser scanning confocal microscope 2D or 3D
2.1.1(a)
A
3D
19
Q
is the image produced by a TEM 2D or 3D
2.1.1(a)
A
2D
20
Q
is the image produced by a SEM 2D or 3D
2.1.1(a)
A
3D
21
Q
How do you prepare a dry mount slide
2.1.1(b)
A
solid specimens are used whole or cut into very thin slices with a sharp blade or a microtome
a specimen is then placed on a slide
a coverslip may be used to keep the specimen in place
22
Q
what samples are suitable a dry mount slide
2.1.1(b)
A
pollen, hair, feathers and parts of insects
23
Q
How do you prepare a wet mount
2.1.1(b)
A
samples are suspended in liquid eg-water or immersion oil
a coverslip is placed at an angle to prevent air bubbles
living cells or small organisms can be viewed this way as the liquid allows them to live and move
24
Q
how to prepare a squash slide and example
2.1.1(b)
A
a wet mount is prepared then a lens tissue is used to gently press down the coverslip
this flattens out a soft sample
for example a squash at the tip of a garlic root is often used to examine cell division
25
how can you minimise damage to the coverslip on the squash slide
2.1.1(b)
by squashing the sample between two microscope slides
26
what is a transverse section AKA cross-section
2.1.1(b)
where a cut is made perpendicular to the long axis of a structure
27
what is a longitudinal section
2.1.1(b)
where a cut is made parallel to the long axis of a structure
28
What is an eyepiece graticule
2.1.1(b)
a scale embedded in the eyepiece that does not have any measurements on it
29
what is a stage micrometer
2.1.1(b)
a stage micrometer is used to calibrate the eyepiece graticule
30
how do you calibrate the eyepiece graticule
2.1.1(b)
1. Focus on stage micrometer using the desired objective lens
2. move the eyepiece graticule and the stage micrometer until they line up
3. count how many stage micrometer divisions fit inside a certain number of eyepiece graticule divisions
31
What is differential staining and when is it useful
2.1.1(c)
staining process that uses more than one stain
its useful when looking at blood smears-its useful to have WBC and RBC different colours to make it easier to see and identify them
32
what does methylene blue bind to
2.1.1(c)
DNA stains it blue
33
what does crystal violet bind to
2.1.1(c)
pedtidoglycan
34
what is gram staining
2.1.1(c)
staining procedure used to classify bacterial species
gram + and gram - bacteria have different cell wall structures so different antibiotics are effective for each group
we can therefore see which bacteria a patient is effected with
35
describe or draw the structure of gram positive bacteria
2.1.1(c)
-thick peptidoglycan layer
-with NO outer lipopolysaccharide membrane
-they have a cytoplasmic membrane at the bottom
36
describe or draw the structure of gram negative bacteria
2.1.1(c)
-DOES have an outer lipopolysaccharide layer
-has a THIN peptidoglycan layer
-also has a cytoplasmic membrane
37
describe the steps involved in staining bacterial colonies
2.1.1(c)
1. cells are stained with crystal violet which binds to peptidoglycan so all cells turn purple
2.iodine solution is added which forms a complex with the crystal violet stain and traps it within the cell
3.the cells are washed with ethanol which decolourises the gram - bacteria as it dissolves the outer lipopolysaccharide membrane so the crystal violet washes out
4.gram - cells are visualised by applying a pink coloured counterstain called safranin. Both cells retain the counterstain BUT the pink colour cannot be distinguished in the purple stained gram + cells
38
what is a cell drawing
2.1.1(d)
Show components of individual cells observed using a light microscope
39
what is a tisssue map AKA a plan view
2.1.1(d)
Drawing that shows a plan view of tissues in an organ or organism
40
what is the magnification equation
2.1.1(e)
magnification=image/actual
41
how do you get from m to nm and backwards
2.1.1(e)
in booklet
42
what is magnification
2.1.1(f)
how many times larger an image is than the actual object
43
what is resolution
2.1.1(f)
the smallest distance between two points where the points can be distinguished as separate
44
what is a smear slide
2.1.1(b)
a drop of liquid eg-blood or saliva is placed at one end of the microscope slide. The edge of another microscope slide is used to smear the liquid creating an even coating
this separates out the cells in the sample allowing them to be seen as a single layer
45
what is the structure of the nuclear envelope
2.1.1(g)
double layer of membrane with nuclear pores
46
what is the function of the nuclear envelope
2.1.1(g)
separates the contents of the nucleus from the rest of the cell
nuclear pores allow small substances eg-mRNA to leave the cell and some substances like steriod hormones to enter
47
what is the structure of the nucleolus
2.1.1(g)
spherical structure inside the nucleus made of RNA DNA and proteins
48
what is the function of the nucleolus
2.1.1(g)
site of ribosome syntheisis
49
what is the structure of the nucleoplasm
2.1.1(g)
contains chromatin
chromatin is the genetic information, consisting of DNA wound around histone proteins
when the cell is preparing for mitosis the chromain condenses into tightly coiled chromosomes
50
what is the function of the nucleoplasm
2.1.1(g)
chromatin contains the DNA of the cell which provides instruction for protein synthesis
51
what is the structure of the RER
2.1.1(g)
a system of connected flattened membrane bound sacs called cisterna continuous with a nuclear membrane
coated with ribosomes
52
what is the function of the RER
2.1.1(g)
vesicles can bud off from the RER and the contents transported elsewhere in the cell
provides a site for polypeptide synthesis
the polypeptide enters the RER and are folded into their 3D shape
53
what is the structure of the SER
2.1.1(g)
a system of connected flattened membrane bound sacs called cisterna continuous with a nuclear membrane
no ribosomes
54
what is the function of the SER
2.1.1(g)
the SER cisterna contains enzymes which catalyse reactions involved with lipid metabolism
-synthesis of cholesterol
-synthesis of lipids and phospholipids
-synthesis of steroid hormones
55
what is the structure of the golgi apparatus
2.1.1(g)
a stack of membrane bound flattened sacs
transport vesicles fuse to one side of the golgi and secretory vesicles bud off from the other
56
what is the function of the golgi apparatus
2.1.1(g)
modification of proteins
-add carbohydrate group to make glycoproteins
-add lipid molecule to make lipoproteins
proteins are then packaged into vesicles
-transport vesicles move the protein elsewhere in the cell
-secretor vesicles move the protein to the plasma membrane where it can be incorporated or exocytosed to the outside of the cell
57
what is the structure of the ribosomes
2.1.1(g)
made of protein and Rrna made in the nucleolus
20-30nm in diameter
Eukaryotic ribosomes are larger than prokaryotic
eukaryotic ribosomes are 80S
58
what is the function of the ribosomes
2.1.1(g)
site of polypeptide synthesis (amino acids are joined together by peptide bonds to make a polypeptide)-this polypeptide later becomes a protein
59
what is the structure of the mitochondria
2.1.1(g)
may be spherical, rod-shaped or branched
are 2-5 micrometres
have a double membrane the inner membrane is highly folded into cristae
inner part of the mitochondrion is a fluid-filled matrix
contains circular DNA and small ribosomes (different from 80S ribosomes)
60
what is the function of the mitochondria
2.1.1(g)
site of ATP production during aerobic respiration
cristae provides large surface area for respiration reactions that take place on the inner membrane
double membrane allows compartmentalisation to create conditions in the inter-membrane space that are needed for respiration reactions
matrix contains enzymes for the respiration reactions that take place there
61
what is the structure of vesicles
2.1.1(g)
vesicles are membrane bound sacs. They consist of a single membrane with fluid inside
62
what is the function of vesicles
2.1.1(g)
storage and transport
63
what is the structure of the lysosomes
2.1.1(g)
lysosomes are specialised vesicles. They are a membrane bound sac but the fluid inside contains hydrolytic (digestive) enzyme like lysosome
64
what is the function of the lysosomes
2.1.1(g)
breakdown of waste material in the cell,
including old organelles
breakdown of pathogens engulfed by phagocytes
programmed cell death-apoptosis
65
what is the structure of chloroplasts
2.1.1(g)
surrounded by a double membrane
4-10 micrometers long
found only in plant cells and some protists
contain thylakoid which are flattened membrane-bound sacs. These can be stacked into grana, which are connected by elongated thylakoid called intergranal lamellae.
Contain fluid called stroma, which contains:
starch grains
DNA and small ribosomes (not the same as 80S ribosomes found in the cytoplasm of the cell)
enzymes for photosynthesis reactions.
66
what is the function of chroloplasts
2.1.1(g)
Thylakoid membranes contain photosynthetic pigments including chlorophyll, which absorb light needed for photosynthesis. Internal membrane provides large surface area for photosynthesis reactions
Enzymes allow photosynthesis reactions to take place in the stroma
67
what is the structure of plasma membrane
2.1.1(g)
Phospholipid bilayer – two layers of molecules called phospholipids
Contains embedded proteins
68
what is the function of plasma membrane
2.1.1(g)
Separate inside of cell from outside
Act as:
· Receptors for cell signalling
· Channels / carrier proteins to allow molecules in and out of cell · Enzymes
69
what is the structure of centrioles
2.1.1(g)
Composed of microtubules, long polymers of tubulin protein
70
what is the function of centrioles
2.1.1(g)
Forms spindle fibres, which are microtubules that pull chromosomes apart during cell division
Involved in the formation and positioning of cilia and flagella
71
what is the structure of the cell wall
2.1.1(g)
Found around the outside of the plasma membrane.
Made of bundles of cellulose fibres in plants. In fungi it is made of chitin. Cellulose and chitin are both carbohydrates.
72
what is the function of the cell wall
2.1.1(g)
Provide strength, support and shape to the cell and to the whole plant / fungus
Prevent cells from bursting when they are turgid
73
what is the structure of the flagella and cilia
2.1.1(g)
Extensions that protrude from some cell types.
Flagella are longer than cilia but cilia are usually present in greater numbers.
Cilia can be stationary or mobile.
Cilia and flagella both contain microtubules. The microtubules have a characteristic 9+2 arrangement, with 9 fused pairs of
microtubules surrounding a central unfused pair (“2”).
74
what is the function of the flagella and cilia
2.1.1(g)
Flagella provide motility. They can also be a sensory organelle.
Mobile cilia beat in a rhythmic manner causing fluids or objects adjacent to the cell to move, e.g. ciliated cells in trachea move mucus, ciliated cells in oviduct move the ovum.
Stationary cilia have a sensory function
75
2.1.1(h)
in worbook
76
what is a gene
2.1.1(i)
section of DNA that contains instructions for an amino acid sequence
77
what is transcription
2.1.1(i)
First, transcription occurs. The gene is transcribed into a length mRNA.
mRNA is small, so it is able to pass through nuclear pores and move to the ribosomes.
78
where does translation take place
2.1.1(i)
ribosomes
79
what is translation
2.1.1(i)
where the mRNA sequence is used to assemble a sequence of amino acids, which are joined by chemical bonds. This forms a polypeptide.
The polypeptide enters a cisterna of the rough endoplasmic reticulum. Inside the RER, the polypeptide is folded into its 3D shape.
A transport vesicle containing the folded polypeptide buds off from the RER and is transported by microtubules to the Golgi apparatus. The transport vesicle fuses with the Golgi apparatus.
Inside the Golgi, the polypeptide is modified, for example by adding carbohydrate or lipid groups. It is now a complete protein.
A secretory or transport vesicle containing the finished protein buds off from the Golgi. Microtubules move secretory vesicles to the plasma membrane, and move transport vesicles to the correct location inside the cell.
80
where is the cytoskeleton present
2.1.1(j)
The cytoskeleton is present throughout the cytoplasm of all eukaryotic cell
81
what is a cytoskeleton a network of
2.1.1(j)
It is a network of protein fibres necessary for the shape, stability and movement or contraction of a cell
82
what does the cytoskeleton control
2.1.1(j)
controls cell movement and the movement of organelles within cells.
83
what are the 3 components of the cytoskeleton
2.1.1(j)
microfilaments
microtubules
intermediate fibres
84
what do microfilaments do
2.1.1(j)
fibres made of the protein actin
responsible for cell movement
and the splitting of a cell during cell division
85
what do microtubules do
2.1.1(j)
Polymers of tubulin protein.
They act as tracks for the movement of organelles, including vesicles, around the cell.
Small motor proteins attach to the components to be moved, and “walk” along the microtubules to move the component from one place to another.
The spindle fibres, important in movement of chromosomes during cell division, are composed of microtubules.
86
what are intermediate fibres
2.1.1(j)
give mechanical strength to cells
87
what is a prokaryote
2.1.1(k)
single celled organism that lacks a
nucleus
other membrane bound organelles
88
what are the two domains of prokaryotes
2.1.1(k)
bacteria and archea
89
similarities between prokaryotic cells and eukaryotic
2.1.1(k)
• Both have a plasma membrane
• Both have cytoplasm
• Both have ribosomes (but not the same type)
• Both contain DNA and RNA
• Cell walls are found in both
90
Differences between prokaryotic cells and eukaryotic
2.1.1(k)
• Prokaryotic cells are smaller (~2μm) than eukaryotic cells (~100 μm)
• Prokaryotic cells have a nucleoid with no outer membrane where the circular DNA is found, whereas eukaryotic cells have a nucleus with a double membrane containing chromatin
• Prokaryotic cells do not contain any membrane-bound organelles whereas eukaryotes do, e.g. mitochondria, endoplasmic reticulum etc.
• Prokaryotic cells have 70S ribosomes whereas eukaryotic cells have 80S ribosomes
• Prokaryotic cells sometimes contain additional plasmids of circular DNA which are not found in eukaryotes
• Prokaryotic flagella have a different structure to the eukaryotic flagella/cilia
• Prokaryotic cell wall is made of peptidoglycan whereas in eukaryotes it is made of cellulose or chitin
• Prokaryotic cells have pili (singular pilus) which allow them to adhere to host cells or other bacteria, to allow the passage of DNA from one bacterium to another. These are not found in eukaryotes
• Prokaryotic cells divide by binary fission, whereas eukaryotic cells divide by mitosis
91
what is the endosymbiotic theory
2.1.1(k)
the idea that an ancient eukaryote-like cell engulfed prokaryotic cells that were capable of photosynthesis / respiration, and formed a symbiotic relationship with them.
92
what is the evidence for endosymbiotic theory
2.1.1(k)
1. Mitochondria and chloroplasts contain ribosomes that are smaller than those found in the cell cytoplasm
2. Mitochondria and chloroplasts are a similar size to bacteria
3. Mitochondria and chloroplasts have their own circular DNA
4. Mitochondria and chloroplasts can reproduce by binary fission
93
