3.1.3 Movement Of Cells Flashcards
(90 cards)
1
Q
What are triglycerides made of?
A
Glycerol and Fatty Acids
2
Q
What is Glycerol?
A
A small 3 carbon molecule with 3 alcohol (OH) groups
3
Q
What are fatty acids?
A
Long molecules made of a non polar hydrocarbon chain with a polar carboxyl acid group at one end
4
Q
How long can the hydrocarbon chain of a fatty acid be?
A
Between 14 and 22 CH2 units long.
5
Q
What is a simplified way of writing the formula for a fatty acid?
A
R-COOH
6
Q
How are triglycerides formed?
A
One glycerol molecule joins 3 fatty acid molecules by ester bonds in a condensation polymerisation reaction
7
Q
How many water molecules are produced per Triglyceride molecule in a condensation reaction?
A
3, because 3 bonds are made.
8
Q
Are fats soluble or insoluble in water?
A
Insoluble in water.
9
Q
What are fats/triglycerides used for?
A
Storage, insulation and protection.
10
Q
Why are fats not used for quick energy requirements in the body if they yield more energy per unit mass than other compounds?
A
Their insolubility means they can’t be mobilised quickly.
11
Q
What makes a fatty acid saturated, in terms of its molecular structure?
A
If it has no C=C bonds.
12
Q
What is the key characteristic of a saturated fat?
A
High melting point; solid at room temperature
13
Q
What makes a fatty acid unsaturated?
A
The presence of C=C bonds in the fatty acid chains.
14
Q
What is the key characteristic of unsaturated fat?
A
Low melting point; liquid at room temperature
15
Q
What is used to denote the position of a double bond in an unsaturated fatty acid?
A
Omega Numbers (omega-3, e.g.)
16
Q
What are the two most common lipids?
A
Triglycerides and Phospholipids
17
Q
What is a phospholipid and how does it differ from a triglyceride?
A
Have the same structure as a triglyceride but with a phosphate group in place of one fatty acid
18
Q
What is a key characteristic of phospholipids?
A
They have polar hydrophilic heads (phosphate) and non-polar hydrophobic tails (fatty acid)
19
Q
What are phospholipids the key component of?
A
Cell membranes
20
Q
What occurs when phospholipids are mixed with water?
A
A liposome is created; droplet spheres with a phospholipid bilayer, where the heads face the water and the tails face each other. A compartment of water is trapped in the centre.
21
Q
Biochemical test for lipids
A
Vigorously shake test sample with 4 ml of ethanol, decant liquid into second tube of water. If lipids are present, they will precipitate in the water and form a cloudy white emulsion
22
Q
What is a prokaryotic cell?
A
Cells without a nucleus. Often bacteria cells.
23
Q
What is a eukaryotic cell?
A
A cell with a nucleus. Animal, plant, fungal and protictista cells
24
Q
What is cytoplasm/cytosol?
A
The solution within the cell membrane which contains enzymes for glycolysis and other metabolic reactions
25
What is a Nucleus?
The largest organelle. Surrounded by a nuclear envelope. The interior is called the nucleoplasm which is full of chromatin, which becomes condensed into discrete observable chromosomes during cell division.
26
What is a nucleolus?
A dark region of chromatin involved in the making of ribosomes
27
What is chromatin?
The DNA Protein Complex?
28
What are mitochondria?
An organelle where aerobic respiration takes place in all eukaryotic cells.
29
In what form do mitochondria release energy?
ATP
30
Why do muscle cells have a lot of mitochondria?
They require more energy than other cells
31
Explain the structure of a mitochondrion
A permeable outer membrane and an inner membrane which is folded into 'cristae' to give it large surface area. The area within the inner membrane is the mitochondrial matrix and contains small circular strands of DNA. Inner membrane is studded with stalked particles which are enzymes which make ATP
32
What are ribosomes?
They are the site of protein synthesis and are either found free in the cytoplasm making proteins for the cells own use or are found attached to the Endoplasmic Reticulum where they make proteins for export from the cell
33
What is the Endoplasmic reticulum?
A series of membrane channels involved in synthesising and transporting materials
34
What is a Rough Endoplasmic reticulum?
An ER which is studded with ribosomes which synthesises and processes proteins for export from the cell via the Golgi Apparatus
35
What is a Smooth Endoplasmic Reticulum?
An ER without ribosomes which is used to process materials like lipids which are needed by the cell
36
What is the Golgi Body?
A series of flat membrane vesicles formed by the ER to transport proteins from the RER to the cell membrane.
37
What is a Lysosome?
Small membrane bound vesicles formed from the RER that contain a cocktail of digestive enzymes used to break down unwanted substances that can be recycled. They can also fuse with a feeding vacuole to digest its contents
38
What is a cytoskeleton?
A network of protein fibres extending throughout all eukaryotic cells, used for support, transport and motility. It is attached to the membrane to give the cell its shape. It also is responsible for cell movements
39
What is an Undulipodium?
A long flexible tail present in some cells used for motility. It is an extension of the membrane full of micro tubules and motor proteins so is capable of complex swimming movements. Cilia are short and numerous. Flagella are longer and usually only one or two (e.g. Sperm)
40
What are MicroVilli?
Small finger like extensions of the cell membrane found in certain cells such as the epithelial cells of the intestine and kidney where they increase surface area for absorption. They are visible under light microscope as a brush border
41
What is cell membrane?
A thin flexible layer surrounding the outside of cells made of phospholipids and proteins. It separates the contents of the cell from the outside environment and controls entry and exit of materials.
42
What organelles are not found in Fungi?
Chloroplasts and Undulipodia
43
What organelles are not found in plants?
Undulipodia
44
What organelles are not found in Animals?
Chloroplasts, Vacuoles and Cell Walls
45
What are the main features of prokaryotic cells?
- Cytoplasm
- Ribosomes
- Nucleoid
- DNA
- Plasmid
- Plasma Membrane
- Cell wall
- Capsule
- Flagellum
46
Where are ribosomes found in prokaryotic cells?
Freely in the cytoplasm
47
What is the Nuclear Zone/Nucleoid?
The area in a prokaryotic cell where DNA is found but not enclosed by nuclear membrane
48
How is DNA found in Prokaryotic Cells?
Always circular and not associated with any proteins to form chromatin.
49
What is a plasmid?
Small circles of DNA found in a Prokaryotic cell, different from the main DNA loop used to exchange data between bacterial cells
50
What type of cells are Prokaryotes?
Bacteria
51
What is a cell wall?
Structural wall around the cell made of murein, A glycoprotein (a protein carbohydrate complex that is also called Peptidoglycan)
52
In terms of prokaryotic cells, what is a 'Capsule'?
A thick polysaccharide layer outside the cell wall, used for sticking things together, food reserve, protection against desiccation and chemicals and phagocytosis.
53
What is a biofilm?
A mass of sticky cells created when the capsules of many prokaryotes fuse together.
54
What is a prokaryotic flagellum?
A rigid rotating helical shaped tail used for propulsion.
55
Prokaryotic vs. Eukaryotic. State differences
- Prokaryotes have no nucleus or other membrane bound organelles. Eukaryotes do.
- prokaryotes have no cytoskeleton. Eukaryotes do.
- Prokaryotes have smaller ribosomes than Eukaryotes.
- Prokaryotes divide by binary fission. Eukaryotes divide by mitosis or meiosis.
56
What is a fluid mosaic structure?
The structure in the cell membrane where the proteins and the attached carbohydrates float around the the phospholipid bilayer
57
How are phospholipids arranged in the cell membrane?
In a bilayer with their polar hydrophilic heads facing out. the non polar hydrophobic tails face each other, which acts as a barrier to most molecules, the strength of which varies based on the type of phospholipid in the membrane.
58
What are the two sizes of proteins in the cell membrane?
Integral proteins, which span both sides of the bilayer, and peripheral proteins which only sit on one of the surfaces.
59
What kinds of proteins are found in cell membranes?
- Transport proteins
- Receptor Proteins
- Enzymes
- Recognition Proteins
- Structural Proteins
60
What is the function of transport proteins in the cell membrane?
Facilitates the transport of most molecules across the membrane. Transport proteins are integral proteins.
61
What is the function of receptor proteins in a cell membrane?
Receptor proteins are peripheral proteins which have a binding site where hormones or other chemicals can bind to form a hormone receptor-complex, which triggers other events inside the cell or membrane
62
Explain the function of enzymes in the cell membrane
They catalyse reactions in the cytoplasm or outside the cell
63
What is the function of recognition proteins in the cell membrane?
Recognition of cells
64
What is the role of Structural Protein in the cell membrane?
They are involved in maintaining the cells shape and are attached to the cytoskeleton. If they are on the outside layer of the membrane they can be used in cell adhesion.
65
How do substances move around inside cells?
Diffusion.
66
What is diffusion?
The random movement of particles due to thermal motion. It does not require energy other than surrounding thermal energy so it is a passive process. If a difference in concentration between two places occurs, the substance will have a net diffusion from high to low concentration.
67
What are the four methods by which substances can move across a cell membrane
- Lipid Diffusion
- Osmosis
- Facilitated Diffusion
- Active Transport
68
Explain Lipid Diffusion
Diffusion directly through the bilayer. The only substances which can do this are hydrophobic or extremely small hydrophilic molecules. Lipid diffusion cannot be controlled as it is a passive process.
69
What are the three concentrations of solutions in relation to cell water potential?
- Isotonic - Same water potential as cells
- Hypertonic - Lower water potential than cells
- Hypotonic - Higher water potential than cells
70
What is the effect of surrounding a cell with hypotonic solution?
In an animal cell, there is net diffusion into the cell, Causing it to Burst.
In a plant cell, it swells and becomes turgid, but does not Burst due to cell wall
71
What happens to a cell surrounded by isotonic solution?
No net diffusion, so cells remain unchanged
72
What happens to cells surrounded by hypertonic solution?
Animal cells shrink and crenate due to net diffusion out of cell
Plant cells cytoplasm shrinks from cell wall and plasmolyses
73
Explain facilitated diffusion
The diffusion of a substance across a trans-membrane protein molecule, that is specifically intended for certain molecules.
74
What are the two types of transport proteins?
Channel proteins and Carrier Proteins.
75
Explain Channel Proteins
A water filled pore which allows charges substances to diffuse across. Most channels are gated and can control the movement of ions
76
What are carrier protein
They have a binding site for a specific solute and constantly flip between opposite sides of the membrane. The substance will bind at high concentration and release at low concentration.
77
What is active transport?
The pumping of substances across a membrane by a trans-membrane protein pump molecule, using energy.
78
How does Active Transport work?
The protein binds to a molecule of the substance on one side of the membrane, changes shape, and releases it on the other side. This is the only process that can move substances up a concentration gradient
79
What does Active TransPort use as fuel/energy?
ATP
80
What is ATP synthesised from?
ADP and Pi (Phosphate)
81
How is ATP used in active transport?
Active transport pumps hydrolyse ATP into ADP + Pi and use the energy to change shape.
82
What is another way of referring to a protein pump molecule in terms of enzymes?
ATPase, as it has an active site which catalyses the hydrolysis of ATP
83
What is the effect of concentration on lipid diffusion?
There is a linear relationship between lipid diffusion and concentration.
84
What is the relationship between Facilitated diffusion and Concentration?
There is a curved relationship with a maximum rate. At high concentrations the rate is limited by the number of transport proteins.
85
What is the relationship between active transport and concentration?
Active transport has a high rate regardless of concentration difference across membranes
86
How can different organelles be studied in detail?
Cell fractionation
87
What is the most common method of fractioning cells?
Differential fractionation
88
How does differential fractionation work?
Cut tissue is put into an ice cold isotonic buffer, then ground down to break open cells and filtered to remove insoluble tissue. It is then centrifugated at increasing speeds to remove different organelles at different speeds.
89
What is the relationship between organelles and the speed required to remove them from a cell free extract during differential centrifugation?
In order of low speed to high speed required to pellet from extract:
- Nucleus (1,000xG)
- Mitochondria and Chloroplasts (10,000xG)
- ER, Golgi and other membrane fragments (100,000xG)
- Ribosomes (300,000xG)
90
What is left after the process of differential centrifugation in cell fractionation?
Organelle free cytoplasm
