Science · X-Factor Notes
Cell revision notes for UPPCS Prelims.
High-Yield Revision| Concept | What to remember | Asked in UPPCS |
|---|---|---|
| Cell Definition | The basic structural, functional, and biological unit of all known living organisms. It is the smallest unit of life, often called the 'building block' of life. | U.P. R.O./A.R.O. (Mains) 2013 |
| Study of Cells | The study of cells is called cell biology or cellular biology. | |
| Cell Discovery | Cells were discovered by Robert Hooke in 1665. | |
| Cell Theory | First developed in 1839 by Schleiden and Schwann; states that all organisms are made of one or more cells, and all cells originate from pre-existing cells. | |
| Mycoplasma | Smallest Organism capable of autonomous growth and reproduction |
| Concept | What to remember | Asked in UPPCS |
|---|---|---|
| Mitochondrion | Known as the 'Power House' of the cell because it is where the maximum energy (in the form of ATP) is produced during cellular respiration. | U.P. R.O./A.R.O. (Mains) 2013 |
| DNA Location | DNA (genetic material) is found primarily in the nucleus, but also in the Mitochondria and Chloroplast (in plant cells). | |
| Nucleus |
| Concept | What to remember | Asked in UPPCS |
|---|---|---|
| Programmed Cell Death | The cellular and molecular control of programmed cell death is known as Apoptosis (also referred to as PCD). | |
| Programmed Cell Death (Types) | Apoptosis and autophagy are both forms of programmed cell death. |
| Concept | What to remember | Asked in UPPCS |
|---|---|---|
| Gene/Heredity Unit | The gene is the basic physical and functional unit of heredity. Genes consist of DNA. A functional segment of DNA is referred to as a gene. | U.P.P.S.C. (GIC) 2010, UPPCS (Pre) 2024 |
| Genome Mapping | Genome mapping relates to the process of mapping of genes, determining the location of genes and the relative distances between them on a chromosome. | UPPCS (Pre) 2002 |
| Concept | What to remember | Asked in UPPCS |
|---|---|---|
| DNA Double Helix Model | The double helix structure of DNA was proposed by James D. Watson and Francis Crick in 1953. | UPPCS (Pre) 2012, UPPCS (Mains) 2012, U.P. P.C.S. (Pre) 2018 |
| DNA Discovery | DNA was first identified and isolated by Friedrich Miescher in 1869. | |
| Sugar in DNA |
| Concept | What to remember | Asked in UPPCS |
|---|---|---|
| Human Chromosome Count | Each human cell normally contains 46 chromosomes (or 23 pairs). | UPPCS (Pre) 1991, UPPCS (Pre) 1992 |
| Female Chromosome Constituent | Women have two 'X' chromosomes (XX). | |
| Male Chromosome Constituent |
| Discovered by Robert Brown in 1831. It is the controlling and coordinating organ of the cell. It houses the cell’s chromosomes and is the site of almost all DNA replication and RNA synthesis. |
| Ribosome | Functions as a micromachine for making proteins (site of protein synthesis). Related to protein synthesis with ER. |
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| Endoplasmic Reticulum (ER) | A cellular organelle that acts as a transport network. Rough ER (RER), due to ribosomes on its surface, acts as a site for protein synthesis. Smooth ER (SER) synthesizes lipids, phospholipids, and steroids. |
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| Plasma Membrane | Also known as the cell membrane, it is composed of two layers of phospholipids embedded with proteins. It is a semipermeable or selectively permeable membrane. | UPPCS (Mains) 2008 |
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| Eukaryotic Cells | Cells that contain a nucleus and membrane-bound organelles. |
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| Prokaryotic Cells | Cells characterized by the absence of a true nucleus and membrane-bound organelles. Found in bacteria and blue-green algae. |
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| Genetic Code Characteristics |
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| The genetic code is generally described as always universal, triplet of nucleotides bases, non-overlapping, non-ambiguous, commaless, and redundant. It includes 61 sense codons coding for 20 amino acids, plus start and stop codons (AUG, UAA, UAG, UGA). |
| Cell Nucleus Role | The nucleus houses the cell's genetic material (DNA) and co-ordinates the cell's activities. It plays a crucial role in cellular reproduction by housing and replicating DNA. | UPPCS (Pre) 2024 |
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| Chromosomes and Inheritance | Hereditary symptoms are typically transmitted to descendants by chromosomes. Chromosomes are composed of DNA and Protein. | UPPCS (Pre) 2024 |
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| Chromosome Terminology | The term "chromosome" was originally coined by Waldeyer. |
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| Chromosome Number | The number of chromosomes is constant for a particular species and does not change with age or weight. |
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| U.P. P.C.S. (Mains) 2016 |
| DNA Location (Extranuclear) | Besides the nucleus, DNA is also found in the mitochondria and chloroplast (in plant cells). |
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| Human Genome Project (HGP) | A world-level program related to the identification and mapping of human genes and its sequences. | UPPCS (Pre) 2001 |
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| Stem Cells | Undifferentiated biological cells that can differentiate into specialized cells; they are frequently used for medical therapies (e.g., bone marrow transplantation) and for screening new drugs. |
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