BY01 Cells and Foundation Biology Flashcards
1
Q
What is the monomer of carbohydrates?
A
Monosaccharides.
2
Q
What is the general formula for a monosaccharide?
A
(CH₂O)ₙ,
3
Q
Name two examples of monosaccharides.
A
Glucose, fructose, Galactose
4
Q
What is the difference between alpha-glucose and beta-glucose?
A
In alpha-glucose, the hydroxyl group on carbon 1 is below the ring; in beta-glucose, it is above the ring.
5
Q
What reaction joins two monosaccharides together?
A
Condensation reaction.
6
Q
What bond is formed between two monosaccharides?
A
Glycosidic bond.
7
Q
Name the disaccharide formed from glucose and fructose
A
Sucrose
8
Q
How is glycogen structurally different from starch?
A
Glycogen has more branches, making it more compact and readily hydrolysed.
9
Q
What is the primary structural carbohydrate in plant cell walls?
A
Cellulose.
10
Q
How do the beta-glucose molecules in cellulose form strong fibres?
A
They form straight chains that hydrogen bond to form cross links with adjacent chains, forming microfibrils.
11
Q
What is the biochemical test for starch?
A
Iodine solution turns blue-black in the presence of starch.
12
Q
What enzyme breaks down starch into maltose?
A
Amylase.
13
Q
What is the reducing sugars test?
A
Heat with Benedict’s solution, which turns from blue to red in the presence of reducing sugars.
14
Q
How is the non-reducing sugar test carried out?
A
Heat with Benedict’s to confirm negative result/blue colour.
Test again by first heating with acid and then neutralising, then heat with Benedict’s to give red precipitate/colour
15
Q
What is the primary structure of a triglyceride?
A
One glycerol molecule and three fatty acids.
16
Q
What bond forms between glycerol and fatty acids?
A
Ester bond.
17
Q
What is the difference between saturated and unsaturated fatty acids?
A
Saturated fatty acids have no double bonds between carbon atoms in hydrocarbon chain.
Whereas unsaturated fatty acids have one or more double bonds.
18
Q
What is the structure of a phospholipid?
A
A glycerol backbone, two fatty acids, and a phosphate group.
19
Q
Why are phospholipids important in cell membranes?
A
They form a bilayer with hydrophobic tails facing inward and hydrophilic heads facing outward, creating a barrier to water-soluble substances.
20
Q
What is the biochemical test for lipids?
A
The emulsion test, which forms a cloudy emulsion if lipids are present.
21
Q
What role do lipids play in organisms besides energy storage?
A
Insulation, protection, and formation of cell membranes.
22
Q
What is the monomer of proteins?
A
Amino acids.
23
Q
What are the four components attached to the central carbon in an amino acid?
A
Amino group (-NH₂), carboxyl group (-COOH), hydrogen atom (H), and R group (side chain).
24
Q
What type of bond forms between two amino acids?
A
Peptide bond.
25
What is the primary structure of a protein?
The sequence of amino acids in a polypeptide chain.
26
What is the secondary structure of a protein?
Alpha-helices and beta-pleated sheets formed by hydrogen bonding
27
What is the tertiary structure of a protein?
The 3D folding of a polypeptide chain, stabilized by interactions between R groups (ionic bonds, hydrogen bonds, disulfide bridges).
28
What is the quaternary structure of a protein?
The association of multiple polypeptide chains into a functional protein.
29
What is the biochemical test for proteins?
Biuret test, which turns purple/violet in the presence of proteins.
30
What causes a protein to denature?
Changes in temperature (above optimum) or pH (above and below optimum)
31
What is the role of enzymes in biological systems?
Enzymes are biological catalysts that increase the rate of chemical reactions by reducing activation energy without being used up.
32
What is the active site of an enzyme?
The region with a specific shape where the complementary substrate binds and the reaction occurs.
33
Other than Lock and Key, What model explains how enzymes work?
The induced fit model, where the enzyme changes shape to fit the substrate.
34
What is the effect of temperature on enzyme activity?
Increased temperature increases activity as more kinetic energy means higher rate of successful collisions, until the enzyme denatures and activity decreases.
35
What factors affect enzyme activity?
Temperature, pH, substrate concentration, and enzyme concentration.
36
How does pH affect enzyme activity?
Deviations (increases/decreases) from the enzyme's optimum pH can reduce its activity by altering the charge of amino acids in the active site, affecting the bonding between R groups.
37
What is enzyme inhibition?
The process by which a molecule decreases or stops the activity of an enzyme.
38
What is the difference between competitive and non-competitive inhibition?
Competitive inhibitors bind to the active site, while non-competitive inhibitors bind to another part of the enzyme (allosteric site), altering its shape.
39
What is the function of the nucleus in a cell?
The nucleus controls cell activities and contains the cell's genetic material (DNA) in the form of chromatin.
40
What is the function of the nuclear envelope?
The nuclear envelope is a double membrane that surrounds the nucleus and controls the entry and exit of materials, including RNA and ribosomal subunits.
41
What are nucleoli?
Nucleoli are dense regions within the nucleus where ribosomal RNA (rRNA) is synthesized and ribosome subunits are assembled.
42
What is the function of ribosomes?
Ribosomes are responsible for protein synthesis by translating messenger RNA (mRNA) into amino acid sequences.
43
What is the function of the endoplasmic reticulum (ER)?
The ER is involved in the synthesis, folding, modification, and transport of proteins (rough ER) and lipids (smooth ER).
44
What is the difference between smooth ER and rough ER?
The rough ER has ribosomes on its surface and is involved in protein synthesis, while the smooth ER lacks ribosomes and is involved in lipid synthesis
45
What is the function of the Golgi apparatus?
The Golgi apparatus modifies, sorts, and packages proteins and lipids for transport either within or outside the cell.
46
What is a vesicle and what is its function?
A vesicle is a small, membrane-bound sac that transports substances within the cell or to the cell membrane for secretion.
47
What is the function of mitochondria?
Mitochondria are the sites of aerobic respiration, producing ATP (energy) through the breakdown of glucose and other molecules.
48
What is the structure of a mitochondrion?
A mitochondrion has a double membrane; the inner membrane is folded into cristae and contains enzymes for respiration. The inner space is called the matrix.
49
What is the function of chloroplasts?
Chloroplasts are the sites of photosynthesis, where light energy is converted into chemical energy in the form of glucose.
50
What is the structure of a chloroplast?
Chloroplasts have a double membrane, with an internal system of membranes called thylakoids that contain chlorophyll for light absorption. The surrounding fluid is called the stroma.
51
What are lysosomes and what is their function?
Lysosomes are membrane-bound organelles that contain digestive enzymes to break down waste materials, cellular debris, and foreign substances.
52
What is the function of the plasma membrane?
The plasma membrane controls the movement of substances into and out of the cell and maintains the integrity of the cell by providing a semi-permeable barrier.
53
What is the function of the cell wall in plant cells?
The cell wall provides structural support, protection, and helps maintain cell shape in plant cells.
54
What is the composition of the plant cell wall?
The plant cell wall is mainly composed of cellulose
55
What is the function of vacuoles in plant cells?
Vacuoles store water, nutrients, and waste products, and help maintain turgor pressure in plant cells.
56
What is the difference between prokaryotic and eukaryotic cells?
Prokaryotic cells do not have a nucleus or membrane-bound organelles, whereas eukaryotic cells have a nucleus and various membrane-bound organelles.
57
What structures are found in prokaryotic cells?
Prokaryotic cells typically have a plasma membrane, cytoplasm, ribosomes, DNA (in a nucleoid), and sometimes additional structures like a cell wall, flagella, and pili.
58
What is a plasmid?
A plasmid is a small, circular piece of DNA found in prokaryotic cells that is separate from the chromosomal DNA and can carry genes, often for antibiotic resistance.
59
What is the role of the Golgi vesicles?
Golgi vesicles transport proteins and lipids from the Golgi apparatus to their destination, either within the cell or to the cell membrane for secretion.
60
What is passive transport?
Passive transport is the movement of substances across the cell membrane without using energy/ATP, following concentration gradients (higher to lower concentration).
61
What is diffusion?
Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration until equilibrium is reached.
62
What is facilitated diffusion?
Facilitated diffusion is the passive movement of molecules across the membrane through protein channels or carriers, without the need for energy/ATP.
63
What type of molecules are transported by facilitated diffusion?
Facilitated diffusion typically transports larger, polar, or charged molecules such as glucose, amino acids, and ions.
64
What is osmosis?
Osmosis is the passive movement of water molecules through a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
65
What is active transport?
Active transport is the movement of molecules or ions across a cell membrane against their concentration gradient, requiring energy (usually ATP).
66
What is the role of carrier proteins in active transport?
Carrier proteins change shape to transport molecules across the membrane against their concentration gradient, requiring energy input from ATP.
67
What is endocytosis?
Endocytosis is the process by which cells engulf large particles or liquids into vesicles by infolding the plasma membrane.
68
What is exocytosis?
Exocytosis is the process by which cells expel substances by vesicles fusing with the plasma membrane and releasing their contents outside the cell.
69
What is the effect of a hypotonic solution on a cell?
In a hypotonic solution (lower solute concentration/Higher Water Potential outside), water enters the cell, which can cause animal cells to burst (lysis) and plant cells to become turgid.
70
What is the effect of a hypertonic solution on a cell?
In a hypertonic solution (higher solute concentration/Lower Water Potential outside), water leaves the cell, causing it to shrink (plasmolysis in plant cells and crenation in animal cells).
71
What is the difference between a solvent and a solute?
A solvent is a substance that dissolves other substances (e.g., water), and a solute is the substance that is dissolved in the solvent (e.g., salt or sugar).
72
What is the principle of light microscopy?
Light microscopy uses visible light and lenses to magnify objects, allowing the study of living cells and their structures.
73
What is resolution in microscopy?
The resolution of a microscope is the smallest distance at which two points can be distinguished as separate points.
74
What is an electron microscope?
An electron microscope uses electron beams instead of light to achieve much higher useful magnifications and resolutions, allowing the observation of sub-cellular structures.
75
What is the difference between scanning electron microscopy (SEM) and transmission electron microscopy (TEM)?
SEM provides 3D surface images of specimens, while TEM provides 2D images of internal structures at very high resolution.
76
What are the advantages of using an electron microscope over a light microscope?
Electron microscopes offer much higher magnification and resolution, allowing the study of smaller structures such as viruses, organelles, and even molecular structures.
77
Why is staining important in microscopy?
Staining enhances contrast by coloring specific parts of the cell or tissue, making structures such as nuclei, membranes, and organelles more visible.
78
What is differential centrifugation?
Differential centrifugation separates cellular components by their size and density through repeated spins at increasing speeds, isolating different organelles.
79
What are the typical components separated by centrifugation in cell fractionation?
Centrifugation can separate organelles such as the nucleus, mitochondria, ribosomes, and lysosomes based on their size and density.
80
What is pellet and supernatant in centrifugation?
After centrifugation, the denser components form a pellet at the bottom of the tube, while the less dense components remain in the supernatant (the liquid layer above the pellet).
81
Why is a homogeniser used in the cell fractionation process?
A homogeniser is used to break open the cells (homogenisation) to release their contents before centrifugation.
82
What is the role of the buffer solution in the centrifugation process?
The buffer solution maintains the pH and ionic strength during the process, ensuring the organelles remain stable and functional, and preventing enzyme and protein denaturation.
83
Why is it important to carry out centrifugation using an ice cold solution?
Helps prevent enzyme activity, which could break down organelles and other cellular components
84
