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cell is the basic structural and functional unit of life.
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cell -> tissue -> organ -> organ system -> organism (this is how cell is the structural unit)
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cell does metabolic functions, produces glucose, energy(in the form of ATP[adenine triphosphate])
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smallest cell: mitoplasm(0.3 micrometer)
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longest cell: neuron
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largest cell: ostrich egg
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CELLS IN ANIMALS
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smallest cell in males: sperm
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largest cell in males: WBC
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smallest cell in females: RBC
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largest cell in females: ovum
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Control center of the cell.
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common stain used for nucleus: acetocarmine
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exceptions for nucleus: matured RBC of mammals, Platelets, Sieve tubes of phloem.
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Covered by two membranes-> inner and outer membrane(together they are called the nuclear membrane)
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ER is an extension of the outer membrane.
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Nuclear membrane has openings called nuclear pores which contain Amuli.
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Nuclear pore with amuli is called pore complex.
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Nuclear pores allow passage of selective materials in and out of the nucleus.
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nucleus contains a dense part called the nucleolus.
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ribosomal subunits of rRNA are formed in the nucleus.
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nucleolus is also important for protein synthesis.
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nucleus is filled with jelly like substance called nucleoplasm/ karyoplasm/ nuclear sap. It contains all the components of the nucleus like nucleolus, chromatin fibres, enzymes, and nucleotids.
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the nuclear membrane seperates nucleoplasm from cytoplasm.
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nucleus contains thread like structures called chromatin. chromatin condenses during cell division to form chromosomes. chromosomes are strands of DNA wrapped around proteins called histones.
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chromosomes contain genes that contain codes for protein synthesis.
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the process in which a cell divides to form two or four daughter cells.
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cells which do not divide: RBC, WBC, Platelets, Neurons, Sieve cells.
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- why is cell division important-
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1. growth of organism.
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2. to repair damaged tissue of the body.
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3. to recover from injuries.
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4. for production of gametes that help in reproduction.
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1) organelles work together to make the cells work efficiently and properly
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2) organelles who work together form this system. (functions of organelles depend on eachother)
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3) organelles: ER, golgi body, lysosomes, vacuoles, etc.
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1) single membrane structure.
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2) also called suicidal bag.
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3) membrane bound organelle having digestive enzymes.
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4) absent in matured RBC and prokaryotic cells.
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- FUNCTIONS -
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1) cleans the cell by destroying worn out organelles.
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2) destroys pathogens and toxic materials entering the cell.
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3) they carry out autophagy -> destroying its own cell.
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-steps of autophagy-
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when a cell is damaged or infected -> lysosome enzymes gets activated -> lysosomes burst and digestive enzymes are released inside the cell -> the cell is digested completely.
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1) double membrane structure.
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2) present mainly in plant cells and euglena(animal cell)
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3) has its own circular DNA
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4) ribosomes present are 70s
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5) plastids generally have pigments which give them colour
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- types of plastids -
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1) leucoplasts: colourless, no pigment. functions: storage of starch(potato), proteins(pulses), oil(peanuts)
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2) chromoplasts: coloured due to pigment. functions: to attract pollinators, nutritional value.
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3) chloroplasts: green coloured due to chlorophyll. functions: photosynthesis.
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DIFFUSION
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OSMOSIS
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1) movement of substances from high concentration to low concentration.
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1) diffusion through semi-permeable membrane.
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2) movement of substances from an area of higher concentration to an area of lower concentration through a semi-permeable membrane.
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-applications and importance of osmosis-
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1. absorption of water by root hair.
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2. unicellular organisms gain water through osmosis.
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robert hooke: discovered cork cell(which was dead) using a primitive microscope.
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anton von leeuwenhoek; found free living cells in pond water using an improved microscope.
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robert brown: discovered nucleus
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purkinje: coined the term protoplasm.
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schleiden and schwann: made the cell theory.
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rudolph virchow: cell theory.
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PROKARYOTES
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EUKARYOTES
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1. prokaryotes have a nucleoid and nuclear membrane is absent.
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1. has a well defined nucleus with nuclear membrane.
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2. lacks membrane bound organelles.
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2. membrane bound organelles are present.
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3. DNA is circular.
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3. DNA is linear.
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4. ribosomes are small(70s)
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4. ribosomes are large(80s)
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5. single chromosomes are present.
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5. multiple chromosomes are present.
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6. cell wall is peptidoglycan.
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6. cell wall is cellulose(plants) and chitin(animals)
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diploid: two sets of chromosomes, only in vegetative cells.
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haploid/gametal cells: only one set of chromosomes.
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1) The universally accepted model of DNA is the double helical structure proposed by WATSON AND CRICKE.
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2) adenine = thymine
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3_ cytosine ≡ guanine
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4. the functional unit of chromosomes are genes. Genes contain the code for production of proteins and is made of 3 alphabets .
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5. DNA contains all the information necessary for the growth and development of the organism.
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1) found in all plant and animal cells.
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2) absent in mature RBC in mammals and prokaryotic cells.
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3) gives rigid support to cells.
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-ELEMENTS OF ER-
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1) cisternae(RER): flat structures.
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2) vesicles(SER): round and smooth.
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3) tibules(SER): tube like structures.
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- FUNCTIONS OF ER -
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1) helps in the transfer of materials between various regions of the cytoplasm and between the nucleus and the cytoplasm.
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2) RER helps in protein synthesis.
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3) SER helps in lipid(fat) synthesis.
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4) Biogenesis: process of producing lipids and proteins and using them to produce membranes of cells is called Biogenesis.
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5) SER detoxifies drugs and poisons in the cell.
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1) modifying and packaging unit.
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2) absent in prokaryotic cells, matured sperms and matured RBC's.
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3) consists of membrane bound sac-like structures called cisternaes, secretory vesicles.
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4) single membrane structure.
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5) it produces complex sugars from simple sugars.
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6) it packs substances in secretory vesicles.
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7) it gives rise to lysosomes.
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8) it is a site for formation of glyco-lipids and glyco-proteins.
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1) powerhouse of the cell.
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2) absent in matured RBC's, prokaryotic cell.
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3) it produces energy in the form of ATP during cellular respiration.
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4) stain used under microscope: Janus Green.
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5) double membraned organelle.
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6) semi autonomous organelle( does a few functions by itself)
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-why is mitochondria a semi autonomous organelle?-
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1) it has DNA and Ribosomes
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2) it can sustain for 10 to 12 hours without the nucleus
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3) it depends on the nucleus for some proteins.
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4) it can produce certain proteins required for its metabolism.
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1) made of lipids and proteins and some carbohydrates.
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2) structure: sea of lipids in which proteins are present(phospho lipid bylayers)
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3) plasma membrane is a semi permeable/selectively permeable membrane.
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4) it allows certain substances to pass through it.
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- functions of plasma membrane -
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1) movement of substances in and out of the cell. Higher concentration to lower concentration where ATP is not used.
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- ISOTONIC SOLUTION(balanced) -
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- HYPOTONIC SOLUTION (diluted)-
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- HYPERTONIC SOLUTION(concentrated) -
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1. it has exactly the same water concentration as the cell.
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1. it has more concentration of water than the cell.
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1. it has less concentration of water than the cell.
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2. so there is no net water movement across the cell.
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2. water moves in the cell and causes the cell to swell.
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2. water moves out of the cell and causes the cell to shrink.
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1) every organism is made up of cells.
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2) cells are the structural and functional unit.
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3) all cells arise from prexisting cells. (omicellula-e-cellula
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MODERN CELL THEORY ADDITIONS:
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4) all cells contain genetic material.
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5) some organisms can divide again and again and give rise to organs or organisms.
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plant cell
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animal cell
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1. nucleus is in the peripheral area.
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plant cell
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animal cell
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1. nucleus is situated in the peripheral area.
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1. nucleus is in the center of the cell.
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2. cell wall is present.
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2. cell wall is absent.
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3. vacuoles are large and present.
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3. vacuoles are small and temporary.
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4. plastids are present.
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4. plastids are absent.
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5.lysosomes are absent.
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5. lysosomes are present.
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6. centrosomes are absent.
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6. centrosomes are present.
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7. cytoplasmic division happens by cell plate formation.
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7. cytoplasmic division happens by cell furrow formation.
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1. nucleus is in the peripheral area.
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during cell division, chromatin condenses to form chromosomes.
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chromosomes contain DNA along with proteins called Histones which helps in the packing of DNA.
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DNA is made of nucleic acids.
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NUCLEIC ACIDS:
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1) made up of sugar(deoxyribose sugar-> 5 carbon compound)
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2) nitrogenous bases-> adenine, guanine, cytosine, thymine. (thymine is only in DNA, in RNA it is Uracil)
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Adenine = Thymine (double bonding)
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Guanine ≡ Cytosine (triple bonding)
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SER
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RER
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1) ribosomes are present.
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1) ribosomes are absent.
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2) protein synthesis.
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2) lipid synthesis.
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3) mainly has cisternae.
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3) mainly has vesicles and tibules.
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mitosis
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meosis
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1) forms 2 daughter cells.
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1) on cell forms 4 daughter cells.
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2) also known as equational division.
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2) also known as reductional division.
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3) occurs in vegetative cells or somatic cells.
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3) occurs in gametes or germinal cells
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4) daughter cells have same number of chromosomes.
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4) daughter cells will have half the number of total chromosomes.
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5) helps in growth and healing of an injury.
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5) formation of gametes for reproduction.
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1) single membrane bound organelle.
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2) types of vacuoles: food, gas, contracile(only in aquatic animals)
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-functions-
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storage, maintains water balance in the cell, helps in excretion.
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1) found on the surface of ER.
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2) freely found in the cytoplasm.
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3) present in plastids and mitochondria.
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4) sometimes found in the outer membrane of the nucleus also.
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5) produced in the nucleolus of the nucleus.
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6) made of RNA and proteins.
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7) membrane-less organelle.
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8) it has two subunits:- a small unit(70s) and a large unit(80s).
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9) 70s ribosome: present in prokaryotic cells, mitochondria and chloroplast.
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10) 80s ribosome: present in eukaryotic cell, ER, cytoplasm of ER, outer membrane of the nucleus.
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1) present only in animal cells.
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2) form spindle fibres during cell division.
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PASSIVE TRANSPORTATION
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ACTIVE TRANSPORTATION
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1. high concentration to low concentration.
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1. low to high concentration.
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2) no energy is used.
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2. energy used.
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3) eg: diffusion, osmosis.
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3. eg: reabsorption of substances in the kidney, sodium/potassium pump.
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homologous chromosomes : chromosomes which are similar in structure and function.
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crossing over: process of exchange of genetic material between non-sister chromatids of homologous chromosomes.
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Cheatography n. The art of mapping complex subjects into clear, instantly navigable reference guides.
