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INTEL DEV. CLASS
ND SCIENCE LAB TECH.
Committee of Intellectuals [CoI]
INTELLECTUAL DEVELOPMENT CONFERENCE CENTER [INTEL CENTER]
SCIENCE LABORATORY TECHNOLOGY
COURSE TITLE: CELL BIOLOGY
COURSE CODE: STB 121
a. Define Cell (2 marks)
b. Itemize the four (4) basic characteristic features exhibited by a cell (4marks)
c. Differentiate between prokaryotic and eukaryotic cells (9marks)
d. Draw and label a typical cell (5marks)
a. Classify and explain proteins according to their structures (4marks)
b. Explain two ways by which inhibitors disrupt enzymes activities (10marks)
c. List six (6) properties of an enzyme (6marks)
With reference to glycogen and starch, discuss exhaustively polysaccharides (20marks)
a. Attempt a breakdown of nucleic acid into its monomeric units (5marks)
b. Differentiate between RNA and DNA (3marks)
c. Explain the functions of the followings to the cell
(i) Plastid (ii) Mitochondrion (iii) Rough Endoplasmic Reticulum (12marks)
a. Differentiate between saturated and unsaturated fat (2marks)
b. Itemise five basic importance of fat to the body (4marks)
c. List four functions plasma membrane of a living cell (4marks)
a. List three pH of buffer solutions used for calibration of standardization of pH meter in laboratory (3marks)
b. Explain briefly how to calibrate a pH meter in the laboratory (5marks)
c. What are the precautions to be taken during the calibration? (2marks)
d. Discuss colorimeter method for measuring pH in the laboratory (10marks)
a. Briefly explain eight (8) functions of protein in the cell (12marks)
b. Enumerate the eight (8) importance of
water to a living cell (8marks)
a. Define Cell
1a. A Cell can be defined as the smallest organized unit of any living from which is capable of prolonging independent, existence and replacement of its own substance in a suitable environment.
b. Itemize the four (4) basic characteristic features exhibited by a cell
- They atlize extraneous energy to organize atom and molecule from external environment and synthesize macro molecule that are useful to them.
- They perpetuate information for their own overall synthesis through repeated cycle of multiplication.
- They control their internal environments so as to create the most suitable conditions for their metabolism.
- They regulate their component reaction such that harmony is obtained
c. Differentiate between prokaryotic and eukaryotic cells
c. PROKARYOTIC EUKARYOTIC
- The cells are usually small The cells are usually large
- Lacks nuclear membrane Possess nuclear membrane
- Lacks membrane bond organelle Contain membrane bond organelle
- Possess simple chromosome Possess more than one chromosome
- Chromosome does not contain basic Histone is present in the cell
- No nucleus Nucleus present
- No mitotic apparatus Mitotic apparatus present
- There is no cytoplasm streming Cytoplasm capable of internal movement
- Flagella is not multistranded It is multistranded
d. Draw and label a typical cell
The most important structures of plant and animal cells are shown in the diagrams below, which provide a clear illustration of how much these cells have in common. The significant differences between plant and animal cells are also shown. The diagrams are followed by more in-depth information.
a. Classify and explain proteins according to their structures
2a. Fibrous Proteins and Cobular Protein => Classification
Fibrous Proteins: This has long parallel chain and pleated sheath structure i.e. usually flat. They are cross linked at many points across their length. They are found in many structural material of the body e.g. Keratin found in hair.
Cobular Protein: This has polypeptide chain tightly folded to form spherical shapes. They are relatively soluble and can go into colloidal suspention. They are found as enzymes, hormones and blood protein.
b. Explain two ways by which inhibitors disrupt enzymes activities
b. In Competitive Inhobition: The inhibitor is a substance i.e. similar in shape with substrate but enzymes cannot metabolize it. In this mode of inhibitor, the inhibitor compotes with the substrate at the active site of the enzyme: the inhibitor is characterized by two properties:
(a) It is specific in certain reaction
(b) The effect can be reversed when the inhibitor is removed
It is mostly used in therapeutic purpose
Non Competitive Inhibitor: Of non-competitive inhibitor, it has no resemblance with substrate; therefore do not compete for active site of the enzyme. They exert their effect by binding at the other sites of the protein molecule, this normally leads to alteration of the shape of the enzyme thereby making it inactive. Some non-competitive inhibitor may normally bind to enzyme molecule. The reaction of this inhibitor are not specific. Examples of non-competitive inhibitor are heavy metal such as lead e.t.c
c. List six (6) properties of an enzyme
- They are all proteins
- They are height specific in their reaction
- They are denatured by heat and also by exposure to extreme pH
- They have high molecule weight
- They are not used up in the reaction they catalyse
- They are catalyst
With reference to glycogen and starch, discuss exhaustively polysaccharides
GLYCOGEN: It is found only in animal, it is the storage form of carbohydrate in animal. It is highly branched molecule, contains up to 25,000 glucose units. Some of the glucose residue are linked at carbon atom 1 and t while the branched ones are linked at carbon atoms 1,486 .
The average chain length is about eight glucose unit (i.e. where it does not branch). In the main chain; it branched before 3 to 5 glucose unit. The branching increases the solubility to glycogen therefore, it is water soluble and does not exist in cytoplasm as tiny granules.
Glycogenase are group of enzymes responsible for the conversion of glucose of glycogen
STARCH: It is the storage form of carbohydrate in plant. It is deposited as huge microscopically visible granules in part of plant which are concerned with storage such as tuber of yam. The starch is made up of two types of glucose namely; amylose and amylopectin.
Amylose is unbranched while amylopectin is branched
Starch Amylose + Amylopectin
Both amylose and amylopectin are made up of dextral glucose. The amylose contains between 200 and 250 glucose unit which is linked by alpha (α) 1, 4 glycosidic bond. Amylopectin is highly branched roughly at every 25 glucose residue. It contains between 250 – 5000 of glucose units. The main linkage in alpha (α) 1, 4 bond at the branched point. Alpha (α) 1, 6 linkages also present. Both amylose and amylopectin can further hydrolise to maltose and subsequently to glucose unit.
a. Attempt a breakdown of nucleic acid into its monomeric units
of nucleotide Phosphorus
Mixture of organic base Pentose or deaxpentose sugar
i.e. punne and pynmidize
b. Differentiate between RNA and DNA
DNA (Deoxyribonucleic Acid) carries hereditary information of the cell. Hence it is double stranded molecule made up of two poly nuleolide chain while RNA(Ribonucleic Acid) occur as simple as a poly ribonuleotride strands.
c. Explain the functions of the followings to the cell
(i) Plastid (ii) Mitochondrion (iii) Rough Endoplasmic Reticulum
i. PLASTID: It is also membrane bound organelle found only in plants. It is a bound by two membrane. These are three types of mature plastid leucoplast, chromoplast and chloroplast.
Leucoplast: It mostly store starch but sometimes contains protein and oil. It occurs in large number in storage organ such as root e.g. cassava, tuber e.g. potatoes.
Chromoplast: Contains pigments; these pigments are associated with the brilliant red or yellow colour of the fruits, flower, old leaves and carrots.
Chloroplast: Plastid containing chlorophyll and photosynthesis occur in them. The number of chlorophyll per cell varies from one: in some algae to serveal; in high plants.
ii. Mitochondrion: Is a very large cell organelle: thus is one of the most numerous organelles in the cell. It varies in physical form. It may be filamenteous or granular and it can change from one physical form to another, depends upon the physiological state of the cell. The position of mitochondrion is also varies. It may aggregate to form rings within the cytoplasm as in the muscle cell.
iii. Rough Endoplasmic Reticulum: They have ribosomes attached to them. Rough endoplasmic reticulum is associated with cell producing protein for export (use outside the cell). Sometimes they seems to be continued with the other layer of the nuclear membrane. This rough endoplasmic reticulum often includes; large flattened sac and these are called cisternae. Rough endoplasmic reticulum involves in protein synthesis.
a. Differentiate between saturated and unsaturated fat
5a. Saturated fat contain one double bond WHILE Unsaturated fat has at least two or more double bonds.
b. Itemise five basic importance of fat to the body
- Fat contains a large number of carbon than carbohydrate
- Fat prevents the excess heat loss
- Fat serves as weight for the body
- Fat contains more energy than carbohydrate
- Fat when they are present as phospholipids; they form part of structural component of the cell which is not function as fat.
c. List four functions plasma membrane of a living cell
- To maintain stable pH and ionic concentration within the cell for enzyme activities
- To obtain food supply and energy for synthesis
- To generate the ionic gradient essential for norouns and muscular activities
- To excrete tonic substance or secrete useful substance
d. Diffusion: This is simply defined as a movement of substance from high concentration to a region of low concentration. Assume a cylinder with a cross Section A and contains a solution which decreases in concentration from left to right.
Osmosis: This is the movement of water molecule from region of lower concentration to the region of higher concentration.
Active transport: This is the reverse case of osmosis; where energy is being expended against concentration gradient. In case of osmosis; it is spontaneous, no external force being applied; it is natural.
ENDOCYTOSIS OR EXOCYTOSIS: This is the movement of materials from in and out of the cell respectively.
a. List three pH of buffer solutions used for calibration of standardization of pH meter in laboratory
- pH 4.0
- pH 7.0
- pH 9.0
b. Explain briefly how to calibrate a pH meter in the laboratory
b. To calibrate a pH meter in the laboratory we start with buffer solution of pH 4.0; immerse the glass electrode into the bitter solution and measure the reading. Remove the glass electrode and touch its tie with a blotted paper. Then followed by the second buffer solution of p.H 7.0 and take former process, follow by last buffer solution of pH 9.0 and check the reading, which should read pH 9.0. Having done this; pH meter is said to be standardized or calibrated.
c. What are the precautions to be taken during the calibration?
- Make sure that; the glass electrode does not knock the beaker that contains unknown solution.
- After the determination of your pH, the glass electrode should always be immerse in distilled water distill it is ready to be used.
d. Discuss colorimeter method for measuring pH in the laboratory
d. Colorimeter Method: It depends on the properties of some weak organic acid; to change their degree of dissociation of pH over the limited range e.g.
CH3 COOH CH3 COO + H+
That is the acetic acid at the different pH value will dissociate depending on the pH value. The degree of dissociation of one pH may be more than the solution of another pH. However this is meant to give different colours. The colour produced with solution contains hydrogen ion and hydroxide ion (OH) can be compared with standard colour chat. In the colorimetric method; it is usually advisable to start with wide range colour chare i.e. pH 1 – pH 14
To achieve this, there are two colours methods i.e.
- Comparator method
- pH test paper: This is by immersing the paper into the solution than compare the colour with the colour in the chart.
a. Briefly explain eight (8) functions of protein in the cell
- They function under extreme condition as source of energy
- Function as biological catalyst: that is enzyme
- Function in nutrient storage i.e. storage molecule e.g. oval bumne fonder egg white
- Function in aiding transportation within the cell e.g. Haemoglobin is a protein which transport oxygen in the blood of vertebrates; myoglobin transports oxygen in muscle cell.
- Protein serves as protective molecule e.g. Antibodies which can destroy foreign materials in the body.
- Protein functions as structural material in the cell e.g. they are present in plasma membrane of most cells and coat of viruses
- They function as regulators of cellular metabolism that is as hormones e.g. insulin that regulates glucose metabolism
- They functions as toxic molecules e.g. snake venom and bacteria torun
b. Enumerate the eight (8) importance of water to a living cell
- Water participates either r direct or indirectly in all metabolic reaction
- Water serves as solvent for soluble food substance during digestion
- Water acts as a medium for the biological reaction in the cell e.g. photosynthesis, respiration and synthesis
- Water is the basic part of body tissue; in the cell it makes them turgid
- Water is maintenance of osmotic potential of burning tissue
- Water comprises over 90% of every living organism
- Water aids excretion
- Water acts as a medium of transport for nutrients, hormone also for oxygen as well as carbondioxide