3.2.1 Cell Structure Flashcards
3.2.1.1 Structure of Eukaryotic Cells, 3.2.1.2 Structure of Prokaryotic Cells and of Viruses & 3.2.1.3 Methods of Studying Cells
1
Q
(Cell Structure & Microscopy) What are stem cells?
A
Undifferentiated cells - cell cycle
2
Q
(Cell Structure & Microscopy) What are specialised cells?
A
Differentiated cells - certain genes on/off
3
Q
(Cell Structure & Microscopy) What are tissues?
A
Group of different cells working together to perform a specific function.
4
Q
(Cell Structure & Microscopy) What is an organ?
A
Groups of tissues aggregated together to perform a function.
5
Q
(Cell Structure & Microscopy) What is an organ system?
A
Organs working together as a single unit to perform a function.
6
Q
(Cell Structure & Microscopy) Prokaryotic Cells: No ____ nucleus, only a diffuse area of _______ ________ with no nuclear ________.
A
true
nuclear material
envelope
7
Q
(Cell Structure & Microscopy) Prokaryotic Cells: DNA is _____ (not associated with ________).
A
naked
histones
8
Q
(Cell Structure & Microscopy) Prokaryotic Cells: ________ strands of DNA but no ___________.
A
Circular
chromosomes
9
Q
(Cell Structure & Microscopy) Prokaryotic Cells: No ________ _______ organelles.
A
membrane bounded
10
Q
(Cell Structure & Microscopy) Prokaryotic Cells: No ____________, only ______________ regions in some bacteria.
A
Chloroplasts
photosynthetic
11
Q
(Cell Structure & Microscopy) Prokaryotic Cells: Ribosomes are _______ (__S type)
A
smaller
70
12
Q
(Cell Structure & Microscopy) Prokaryotic Cells: No __, _____ _________ and _________.
A
ER
Golgi apparatus
lysosomes
13
Q
(Cell Structure & Microscopy) Prokaryotic Cells: Cell wall made of ______.
A
Murein
14
Q
(Cell Structure & Microscopy) Eukaryotic Cells: ________ nucleus, with a nuclear ________.
A
Distinct
envelope
15
Q
(Cell Structure & Microscopy) Eukaryotic Cells: Chromosomes _______, in which DNA is located.
A
Present
16
Q
(Cell Structure & Microscopy) Eukaryotic Cells: Membrane bound organelles are _______.
A
Present
17
Q
(Cell Structure & Microscopy) Eukaryotic Cells: ___________ present in ____ and _____.
A
Chloroplast
plants
algae
18
Q
(Cell Structure & Microscopy) Eukaryotic Cells: Ribosomes are ______ (__S).
A
Larger
80
19
Q
(Cell Structure & Microscopy) Eukaryotic Cells: __, _____ _________ and _________ present.
A
ER
Golgi apparatus
lysosomes
20
Q
(Cell Structure & Microscopy) Eukaryotic Cells: Where present cell wall is made mostly of _________ (or chitin in _____)
A
Cellulose
fungi
21
Q
(Cell Structure & Microscopy) What additional features may some prokaryotic cells have?
A
Cell wall made from muerin
External capsule
Plasmids
Flagella
Pili
22
Q
(Cell Structure & Microscopy) What does the muerin cell wall do?
A
Protect against osmotic lysis.
23
Q
(Cell Structure & Microscopy) What does an external capsule do?
A
Protection and helps bacteria to stick together.
24
Q
(Cell Structure & Microscopy) What are plasmids?
A
Small circular pieces of DNA which have additional genes e.g. antibiotic resistance.
25
(Cell Structure & Microscopy) What is the flagella?
Motile "tail(s)"
26
(Cell Structure & Microscopy) Describe the structure of the nucleus.
Largest cell organelle, usually spherical and about 10-20 micrometres in diameter.
27
(Cell Structure & Microscopy) Describe the functions of the nucleus.
- Acts as the control centre of the cell - controls cell's activities.
- Controls synthesis of proteins
- Contains the organism's genetic material (in the form of DNA)
- Manufactures ribosomes from ribosomal RNA
28
(Cell Structure & Microscopy) What are the features of a nucleus? (5)
Nuclear envelope, nuclear pores, nucleoplasm, chromatin, and nucleolus.
29
(Cell Structure & Microscopy) Describe the nuclear envelope in the nucleus.
A double membrane that surrounds the nucleus.
The outer membrane can connect to the endoplasmic reticulum (rough).
It controls entry and exit of materials in and out of the nucleus.
30
(Cell Structure & Microscopy) Describe the nuclear pores in the nucleus.
Allows the movement of large molecules out of the nucleus.
Are usually around 3000 pores.
31
(Cell Structure & Microscopy) Describe the nucleoplasm in the nucleus.
The jelly like material that makes up most of the nucleus.
32
(Cell Structure & Microscopy) Describe the chromatin in the nucleus.
DNA exists as chromatin in the nucleus, this condenses into chromosomes during cell division.
33
(Cell Structure & Microscopy) Describe the nucleolus in the nucleus.
A small sphere in the nucleoplasm.
There may be more than one.
34
(Cell Structure & Microscopy) Describe the structure of mitochondria.
Usually rod shaped and around 1-10 µm long.
35
(Cell Structure & Microscopy) Describe the functions of mitochondria.
- Site of aerobic respiration
- Produce ATP during respiration
- Cells with a high level of metabolic activity that require a lot of ATP have lots of large mitochondria with many cristae
36
(Cell Structure & Microscopy) What are the features of mitochondria? (2)
Double membrane and the matrix
37
(Cell Structure & Microscopy) Describe the double membrane in mitochondria.
Controls the entry and exit of material. In a membrane is highly folded to form cristae (this takes place where respiration takes place, and the folds provide a large surface area for increased respiration).
38
(Cell Structure & Microscopy) Describe the matrix in mitochondria.
The remainder of the mitochondrion.
It contains protein, lipids, ribosomes, and circular DNA – allowing it to control the production of some of its own proteins.
Many enzymes involved in respiration are found in the matrix.
39
(Cell Structure & Microscopy) Describe the structure of chloroplasts.
Typically, disc shaped, but very in shape and size.
Contains DNA and ribosomes, so they can easily manufacture some of the proteins needed for photosynthesis.
40
(Cell Structure & Microscopy) Describe the function of chloroplasts.
Carries out photosynthesis – converts light energy to chemical energy.
41
(Cell Structure & Microscopy) What are the features of chloroplasts? (5)
Chloroplast envelope, grana, thylakoids, lamella and stroma.
42
(Cell Structure & Microscopy) Describe the chloroplast envelope in chloroplasts.
A double plasma membrane – highly selective in what it allows to enter and leave the chloroplast.
43
(Cell Structure & Microscopy) Describe the grana in chloroplasts.
Stacks of disc-like structures called thylakoids.
44
(Cell Structure & Microscopy) Describe the thylakoids in chloroplasts.
Contains chlorophyll - so where the first stage of photosynthesis takes place (light absorption) - in the membrane.
The stacks of discs provide a large surface area for the first stage of photosynthesis to occur on.
45
(Cell Structure & Microscopy) Describe the lamella in chloroplasts.
Joins thyroids in adjacent grana (acts like a skeleton).
46
(Cell Structure & Microscopy) Describe the stroma in chloroplasts.
Fluid filled space, filling the rest of the chloroplast where the second stage of photosynthesis occurs (synthesis of sugars).
- Starch grains found in the stroma – energy store
- Possesses all the enzymes needed for the second stage of photosynthesis.
47
(Cell Structure & Microscopy) Describe the structure of endoplasmic reticulum.
- 3-D system of membranes that spreads throughout the cytoplasm of the cell
- The membranes for a network of tubules and flattened sacks, called cisternae
- It is continuous (attached to) the outer nuclear membrane
The two types of ER are rough and smooth .
48
(Cell Structure & Microscopy) Describe the rough ER.
Has ribosomes on its surface.
Provide a large surface area for the synthesis of proteins.
Provide a pathway for the transport of proteins throughout the cell.
49
(Cell Structure & Microscopy) Describe the smooth ER.
Lacks ribosomes on its surface.
Often more tubular in appearance, rather than flattened sacks.
Synthesises, stores and transports, lipids, and carbohydrates.
50
(Cell Structure & Microscopy) What type of cells have very expensive ER?
Cells that need to synthesise and store, large quantities of proteins, lipids and carbohydrates.
51
(Cell Structure & Microscopy) Describe the purpose of the Golgi apparatus regarding protein modication.
- Collect, modifies and transports molecules around/out of the cell.
- Proteins, lipids and a carbohydrates produced in the ER enter, and a passed through the Golgi apparatus.
- Proteins are modified.
- The proteins are also labelled, allowing them to be sorted and then sent to their correct destination.
- Once sorted, the modified proteins and lipids are transported in Golgi vesicles to their destination.
52
(Cell Structure & Microscopy) What is the cis face in the Golgi apparatus?
Where vesicles from the ER fuse.
53
(Cell Structure & Microscopy) What is the trans face in the Golgi apparatus?
Where Golgi vesicles pinch off regularly from the cisternae.
54
(Cell Structure & Microscopy) Describe what cisternae is regarding the Golgi apparatus.
A stack of membranes that form flattened sacks.
55
(Cell Structure & Microscopy) The Golgi ________ may travel to and fuse with the cell membrane to insert the ________/lipids into the ________ or release their contents to the _______.
Vesicles, proteins, membrane, outside
56
(Cell Structure & Microscopy) Describe the functions of the Golgi apparatus. (5)
- Carbohydrates are added to proteins to form glycoproteins
- Production of secretory enzymes (to be secreted from the cell)
- Production of secreted carbohydrates
- Transport, modification and storage of lipids
- Formation of lysosomes
57
(Cell Structure & Microscopy) When do lysosomes form?
Form when vesicles that bud off the Golgi apparatus contain hydrolytic enzymes for breaking things down.
58
(Cell Structure & Microscopy) Describe the functions of lysosomes.
- Hydrolysis material taken up by cell (phagocytic cells)
- Release enzymes to the outside of the cell (exocytosis) in order to destroy external material
- Digest, old, worn out organelles for recycling
- Breakdown of cells that have died
59
(Cell Structure & Microscopy) Why are lysosomes, especially numerous in secretory cells and phagocytic cells?
Because of the roles they perform.
60
(Cell Structure & Microscopy) Describe the structure of ribosomes.
Small granules found in all cells.
Occur in large numbers.
They may either be found in the cytoplasm or attached to the rough ER.
There are two types: 80S (found in eukaryotic cells and larger) and 70S (found in prokaryotic cells, mitochondria and chloroplasts, and are smaller)
61
(Cell Structure & Microscopy) Describe the function of ribosomes.
The site of protein synthesis.
62
(Cell Structure & Microscopy) Describe the features of ribosomes.
They have two sub units – a large and small.
Made of ribosomal RNA and protein.
63
(Cell Structure & Microscopy) Describe the structure of the vacuole.
A fluid filled sack with a single membrane.
Usually a single large vacuole in plant cells.
Contains a solution of minerals, sugars, amino acids, wastes, and sometimes pigments.
64
(Cell Structure & Microscopy) Describe the functions of the vacuole.
They support herbaceous plants or herbaceous parts of woody plants by making cells turgid/rigid.
Storage of substances.
Sugars and amino acids – temporary food stores.
Pigments – give colour in petals to attract pollinating insects.
65
(Cell Structure & Microscopy) What does the vacuole consist of?
Its membrane called the tonoplast.
66
(Cell Structure & Microscopy) Describe the structure of centrioles.
Small, hollow cylinders
A centrosome = 2 centrioles (oriented at right angles to each other)
Form a network of fine fibres in the cytoplasm called the cytoskeleton made out of microtubules and filaments.
67
(Cell Structure & Microscopy) Describe the functions of centrioles.
- Supports the cell’s shape
- Organises and moves organelles
- During cell division, the pair separate to opposite ends of the cell and form the spindle
68
(Cell Structure & Microscopy) Finish the sentence regarding centrioles: each centriole is a cylindrical array of…
Nine microtubules
69
(Cell Structure & Microscopy) Describe the structure of the cell wall.
Found in plant cells.
Made of cellulose microfibrils – very strong
70
(Cell Structure & Microscopy) What are the functions of the cell wall?
Providing the cell with strength to prevent it bursting due to osmosis.
Providing strength and support to the whole plant.
Fungi also have cell walls (chitin).
Algae have cell walls (cellulose or glycoproteins or both).
71
(Cell Structure & Microscopy) What is a feature of the cell wall and what is its function?
Middle lamella which marks the boundary between adjacent cell walls.
72
(Cell Structure & Microscopy) Bacterial cell structure: Describe the function of the large circular DNA strand.
Primary DNA structure.
73
(Cell Structure & Microscopy) Bacterial cell structure: Describe the function of plasmids.
Smaller, secondary DNA storage.
74
(Cell Structure & Microscopy) Bacterial cell structure: Describe the function of the capsule.
Prevent desiccation and chemical attack.
75
(Cell Structure & Microscopy) Bacterial cell structure: Describe the function of the cell wall.
Cell structure, made of murein.
76
(Cell Structure & Microscopy) Bacterial cell structure: Describe the function of pilus.
Transfer material between bacteria.
77
(Cell Structure & Microscopy) Bacterial cell structure: Describe the function of flagella.
Locomotion
78
(Cell Structure & Microscopy) Bacterial cell structure: Describe the function of plasma membrane.
Exchange of substances with environment.
79
(Cell Structure & Microscopy) Bacterial cell structure: Describe the function of ribosomes.
Protein synthesis, smaller than eukaryotes.
80
(Cell Structure & Microscopy) Bacterial cell structure: Describe the function of cytoplasm.
Contains enzymes, site of many reactions.
81
(Cell Fractionation and Ultracentrifugation) Fill in the blanks:
Step 1: Homogenisation: This _____ open the cell. Usually done by _________ the cells, or ________ them up in a blender. It is done with a ____, _______ ______.
Breaks, vibrating, grinding, cold, isotonic buffer
82
(Cell Fractionation and Ultracentrifugation) What is the name of step one?
Homogenisation
83
(Cell Fractionation and Ultracentrifugation) What is the purpose of the cold isotonic buffer being cold?
To slow down and stop organelle activity, particularly in the hydrolytic enzymes in lysosomes.
84
(Cell Fractionation and Ultracentrifugation) why is the cold, isotonic buffer isotonic?
To prevent the movement of water in and out of organelles by osmosis.
85
(Cell Fractionation and Ultracentrifugation) Why is a buffer solution used?
To prevent changes in pH levels and therefore denaturation of proteins.
86
(Cell Fractionation and Ultracentrifugation) What is step two called?
Filtration
87
(Cell Fractionation and Ultracentrifugation) What happens during filtration?
The solution is filtered through a gauze to remove debris, e.g. large cell, debris or tissue debris.
88
(Cell Fractionation and Ultracentrifugation) What is step three called?
Ultracentrifugation
89
(Cell Fractionation and Ultracentrifugation) Fill in the blanks:
Step 3: Ultracentrifugation: Spin the solution in a __________ at a ___ speed. The heaviest organelles (______, ____________) full to the bottom. The rest of the organelles suspended in the fluid above this ________. This is the ___________. The supernatant is drained off, poured into another tube and spun again at a ______ speed. This time organelles like ____________ and _________ fall to the bottom. Again, the supernatant is drained off, pulled into another tube and spun at a higher speed. Finally, the ________ organelles remain.
Centrifuge, low, nuclei, chloroplasts, sediment, supernatant, higher, mitochondria, lysosomes, lightest.
90
(Methods of Studying Cells) What is the equation for magnification?
Magnification = size of image ÷ actual size of object
91
(Methods of Studying Cells) What is the resolving power of a light microscope?
Limited to 0.2µm / 200nm
92
(Methods of Studying Cells) What are the advantages of a light microscope? (3)
Can see living specimens.
Easier specimen preparation.
Variety of coloured stains.
93
(Methods of Studying Cells) What is a disadvantage of a light microscope?
Low resolution so organelle detail / smaller components not visible.
94
(Methods of Studying Cells) What is the resolving power of a TEM (transmission) microscope?
0.1 nm but not always achieved as difficult specimen prep. / high energy beam can destroy specimen.
95
(Methods of Studying Cells) What are the advantages of a TEM (transmission) microscope? (2)
Very high resolution at high magnification.
Detailed organelle / sub-organelle structure.
96
(Methods of Studying Cells) What are the disadvantages of a TEM (transmission) microscope? (4)
Specimens are not alive I.e. in a vacuum.
Difficult prep. E.g. very thin specimens / complex staining.
Black and white image.
Artefacts can spoil image.
97
(Methods of Studying Cells) What is the resolving power of a SEM (scanning) microscope?
20nm
98
(Methods of Studying Cells) What are the advantages of a SEM (scanning) microscope? (2)
3D images show structural formation.
Totally sic pics.
99
(Methods of Studying Cells) What are the disadvantages of a SEM (scanning) microscope? (4)
Specimens are not alive.
Difficult prep.
Vacuum.
Black and white image.
100
(Cell Structure) What are the 7 key features of viruses?
- Acellular, non-living (NOT cells!)
- 20-300 nm
- Contain DNA or RNA nucleic acids (genome)
- Enclosed within a protein coat - capsid
- Surface attachment proteins
- Sometimes enveloped (e.g. HIV)
- Require a specific host cell to enter and replicate
101
(Methods of Studying Cells) What is the equation for magnification?
Magnification = size of image / actual size of image
102
(Methods of Studying Cells) Define magnification.
How many times bigger the image is compared to the actual size of the object.
103
(Methods of Studying Cells) Define resolution.
The smallest distance 2 points can be separated and still be seen as separated items. Seeing an image in more detail is dependent on a microscope's resolving power.
104
(Cell Structure) State the 6 structural features of viruses.
- Genetic material (DNA/RNA)
- Attachment proteins
- Capsid
- Lipid envelope
- Matrix
- Reverse transcriptase (enzyme)
105
(Methods of Studying Cells) What is the equation for magnification?
Magnification = size of image / size of real object
