Mitosis and Meiosis

Cell Cycle and Cell Division

• The cell cycle is the sequence of events from one cell division to the next.
• It involves two main phases: interphase and the mitotic (M) phase.

Interphase

• Interphase lasts about 6-8 hours.
• It consists of three phases: G1, S, and G2.
• The G1 phase lasts for 8-10 hours.
• During G1 the cell is metabolically active
• Organelles and cytosolic components are duplicated.
• Centrosomes start replicating.
• The S phase lasts for 6-8 hours.
• DNA is replicated in the S phase.
• The G2 phase lasts for 4-6 hours.
• Cell growth continues during G2.
• Enzymes and other proteins are synthesized.
• Replication of centrosomes is completed.
• Some cells exit the cell cycle to become nondividing cells in the G0 phase.

Mitotic (M) Phase

• Includes Prophase, metaphase anaphase, telophase.

Important Definitions: Cell Division

• Sex cells or reproductive cells are also known as gametes.
• Gametes are formed in the reproductive organs of higher organisms for sexual reproduction.
• Somatic cells are any cells of the body of a living organism other than reproductive cells.
• A diploid cell contains two complete sets of chromosomes (2n).
• A haploid cell contains one complete set of chromosomes (n).
• Cell division is the process by which a parent cell divides into two or more daughter cells.
• Mitosis results in the formation of two daughter cells with the same number and kind of chromosomes as the parent cell.
• Mitosis is a type of somatic cell division.
• Prophase is the first stage of cell division before metaphase when chromosomes become visible as paired chromatids.
• During prophase the nuclear envelope and nucleolus disappear.
• Before anaphase the metaphase chromosomes become attached to the spindle fibers and align on the equatorial plate.
• Anaphase is the third stage of cell division.
• Duirng the anaphase, the centromere of each chromosome splits, and the daughter chromosomes move to opposite poles of the spindle.
• Telophase is the fourth stage of cell division.
• During telophase, chromatids or daughter chromosomes reach opposite ends of the cell, and two daughter nuclei are formed.
• Cytokinesis is the cytoplasmic division of a cell at the end of mitosis.
• During Cytokinesis, the parent cell separates into two daughter cells.
• Meiosis is a type of reductional cell division which produces four daughter cells.
• Each daughter cell produced by Meiosis contains half the number of chromosomes as the parent cell.
• Homologous chromosomes are the two identical chromosomes of a diploid cell.
• Each homologous pair contains one maternal chromosome and one paternal chromosome.
• The pairs will be identical by the shape, size, the position of the centromere and location of the gene.
• Crossing over is the exchange of genetic material between two non-sister chromatids of homologous chromosomes during meiosis.
• Crossing over occurs at chiasmata, resulting in recombination of genes in the chromosomes.
• Variations are defined as the differences among individuals of the same species.

Crossing Over

• Crossing over occurs during meiosis, when non-sister chromatids of homologous chromosomes exchange genetic material at points called chiasmata.
• Homologous chromosomes pair up in synapsis, allowing non-sister chromatids to overlap.
• Fusion and exchange of genetic material takes place at the chiasma.
• Crossing over results in genetic recombination in the chromosomes.
• Crossing over leads to homologous chromosomes exchanging genes.
• Genetic information from both paternal and maternal chromatids are exchanged.
• This is a recombination of paternal and maternal genes.

Chromosome Structure

• The chromosome structure includes chromatin, chromatids, gene structure of DNA, and centromeres.

DNA Structure

• DNA stands for Deoxyribonucleic Acid.
• It contains a sugar-phosphate backbone, and base pairs connected by hydrogen bonds (A with T, G with C).
• Adenine (A), Thymine (T), Cytosine (C), and Guanine (G) are the primary bases in DNA.
• Nucleotides form the basic building blocks of DNA, each containing sugar, a phosphate group, and a nitrogenous base.

Mendel's Laws of Inheritance

• These include the Law of Dominance, the Law of Segregation, and the Law of Independent Assortment.
• Law of Dominance: In a pair of contrasting characters, one expresses itself (dominant) while the other remains masked (recessive).
• Law of Segregation: When a pair of contrasting characters is brought together in a heterozygote, the alleles remain together without blending and separate during meiosis.
• Law of Independent Assortment: during simultaneous inheritance of two or more pairs of contrasting characters, the distribution is independent.
• A monohybrid cross involves a genetic cross between homozygous individuals with different alleles for a single gene locus of interest. One character is considered and studied.
• In monohybrid cross single pairs of genes are involved, and the predicted phenotypic ratio is 3:1; it is important for determining the dominance relationship of the alleles.
• A test cross is used to determine if an individual is homozygous or heterozygous dominant.
• A dihybrid cross is a genetic cross between individuals with different alleles for two gene loci of interest. Two independent characters are considered and studied.
• Is involves two pairs of genes are involved, and the predicted phenotypic ratio is 9:3:3:1; it's used to assess the independent assortment of alleles.

Plant Physiology - Absorption by Roots

• Absorption involves imbibition, diffusion, osmosis, osmotic pressure, and root pressure.
• Turgidity and flaccidity, plasmolysis, and deplasmolysis.
• It is important for the absorption of water and minerals; active and passive transport.
• The rise of water up to the xylem depends on forces responsible for ascent of sap including the understanding of the processes related to absorption of water by the roots
• Factors that help plant physiology include characteristics of roots, structure of a full-grown root hair and idea of Cohesive, Adhesive forces and transpirational pull
• We can also carryout Experiments to show the conduction of water through the xylem
• A root hair cell is a type of cell found in the roots of plants.
• Its structure includes the nucleus, cytoplasm, vacuole, cell membrane, and cell wall.
• Endosmosis is the inward diffusion of water into a cell through a semi-permeable membrane when the surrounding solution is less concentrated.
• Endosmosis causes the swelling of cells.
• Exosmosis is defined as the outward diffusion or flow of water from a cell through a semi-permeable membrane when the surrounding solution is more concentrated.
• Exosmosis causes shrinkage of cells.
• Plasmolysis is the movement of water particles out of the cell and shrinking of the cell membrane away from the cell wall when the hypertonic solution..
• Plasmolysis occurs when a tissue is placed in a hypertonic solution.
• It also involves shrinkage of protoplast from the cell wall..
• De-plasmolysis is the entry of water into a plasmolysed cell, bringing back the cell membrane and other organelles to normal condition.
• Deplasmolysis occurs when freshly plasmolysed cells are kept in hypotonic solutions or pure solvents.
• Deplasmolysis involves swelling of shrunken protoplasts until they come in contact with the cell wall.
• Plasmolysis is not reversible after a long interval, deplasmolysis is.

Transpiration

• Transpiration involves the the process and its significance and factors affecting transpiration.
• This can demonstrated using Ganong's potometer and its limitations a brief idea of guttation and bleeding.
• The concept includes the process and its importance to plants and experiments related to transpiration:
• We can weigh a potted plants or take the weight of a leafy shoot in a test tube as a result of transpiration.
• We can Use cobalt chloride paper to demonstrate unequal rate of transpiration in a dorsiventral leaf.
• Transpiration involves the stomata, which can be explained by the potassium ion exchange theory.
• Aditionally adaptations in plants to reduce transpiration, guttation and bleeding
• Plants open and closes stomata using the potassium ion exchange theory.
• High concentration of K and malate ions in the guard cells causes endosmosis, and water is absorbed.
• Leads to increase in turgor pressure, which causes bulging outwards, and their inner walls curve apart, opening the stomata
• During the dark phase, the CO2 concentration increases. And the pH in the guard cells decrease.
• ABA is released to stop the K+ exchangeMalate ions combine with the the acid again and they are eventually taken out of the guard calls resulting in a closure
• Ganong's potometer measures the rate of water uptake by plants and approximates it to the water transpired.
• Some limitations of Ganong's Potometer include trouble introducing the air bubble.
• The twig may not remain alive for a long time and Any change might effect the position of the level in the tube

Photosynthesis

• This is defined as the process and its importance to life in general, the necessity of light and dioxide, the process for the formation of starch production and overall carboncycle.
• In photosynthesis the internal structure of chloroplast gives us light into dark reaction. And potasisum opening helps with the exchange.
• There will be "photochemical" terms for "light" which includes: Photolyisis, water and oxygen(O2), formation of ATP and NADP2
• In the "biosynthetic" phases there is reactions that occur during the dark which included NADP with CO2 combining to form glucose, for what has to happen the next step is for Adaptations to occur this are essential in order for photosynthesis to emphasis on the plant.
• The dark reactions is bio synthesis which is called the "Calvin Cycle" This dark reaction takes place inside the stroma of the chloroplast where the carbon reacts in sugar by using ATP which is formed during the reaction

Light Reaction

• Occurs in Thylakoids (Grana) in the chloroplast
• Depends of light
• Involves activation Chlorophyll,photolysis of water

Dark reaction

• Occurs with no pigment needed
• It occurs in an idenpedent light reaction when light is not dependent
• It forms reduction of carbon dioxide by enzymes

Chemical Coordination in Plants

• The study includes plant growth; Tropic movements in plants like Auxins, Cytokinins, Ethylene in regulating the growth of plants.
• Tropic movements in plants - Phototropism, Geotropism, Hydrotropism, Thigmotropism and Chemotropism
• Phototropism occurs when the plant response in light
• Geotropism occurs when the plant response in gravity
• Hydrotropism occurs when the plant response in water
• Thigmotropism occurs when the plant response in touch
• Auxins can influence cell division, elongation, differentiation, and flowering by speeding up tropisms, abscission and senescense.
• Gibberellins increase cell elongation and makes plant tall
• Ethylene will ripening fruits also absicission
• Cytokinins helps to have cell division
• Abscisic acid inhibit other hormones promoting dormancy

Human Anatomy and Physiology: Circulatory System

• The structure of rbc, wbc with platelets along with blood pressure
• Structures are leaving and entering, with working of the kidney
• The concept is called systole and diastole.
• The structure includes the relationship between the function
• ABlood group.
• Blood is composed primarily of plasma and blood cells.
• Plasma contains 90% water, 7-8% proteins, and 1% inorganic salts.
• Cellular components include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).
• The function of blood is oxygen and nutrient transport, immune response, and blood clotting.
• Blood clotting involves a series of steps.
• Prothromboplastin converts Thomboplastinto Thrombin.
• Prothrombin converts Fibrinogen to Fibrin.
• Fibrin polymers form a clot with red blood cells, white blood cells, and platelets.
• Arteries carry oxygenated blood away from the heart (except for the pulmonary artery).
• Veins carry deoxygenated blood back to the heart (except for pulmonary veins).
• Arteries have thicker walls than veins, deeper and have no values unlike veins
• The heart valves include the mitral valve, tricuspid valve, aortic valve, and pulmonary valve
• : at the aperture between left auricle and ventricle. Functions to Prevents flow from left ventricle to left auricle.
• : at the aperture between right auricle and ventricle Function that prevents backflow from right ventricle to left auricle.
• : Guards the opening left ventricle into aorta Function that prevents backflow from right ventricle to left auricle. Chordae tendineae are the strands of fiber from the heart. Papillary makes up chordase of these chords. and they are on the ventricles of the heart!
• Semi-lunarValves:Guards the opening left ventricle into aorta. Function: prevents backflow of blood from right ventricle to right auricle.
• • Double circulation flows through
• The pulmonary artery is transported inbetween the lungs whereas arteries carry them to other parts.
• The Hepatic vein consists of having the highest concentration of urea
• The diagram consist the outline of pulmary vein, the Aorta the Arter. Hepatic arter Pulmonary arteries to kidney blood etc

Human Anatomy and Physiology: Excretory System

• The kidneys play a vital role in excretion.
• The excretory system includes the veins or artery's with the parts and its external structure.
• The tubules in the kidneys are to filter the excess in the body and are then labelled in the form of labels.
• The system ultra-filtration the capsule, se-selective in the blood.
• Afferent arteriole brings blood to the renal corpuscle; the efferent arteriole carries blood away.
• In urine formation includes glomerular filtration, tubular reabsorption, and tubular secretion.

Human Anatomy and Physiology: Nervous System

• The nervous system consists of two parts,the central nervous system (CNS), brain, and spinal cord, the PNS (all of sensory parts that is outside.
• Somatic- controls the body parts with volontry contro
• Autonmic which has both involuntery
• **Reflex Arc
• Sensory receptors are a part of pain
• It signals in the "Sensory Neuron" with the nerve to the brain
• It passes into the spinal cord ( with and then has a response signal after

Human Anatomy and Physiology: Sense Organs – The Eye

• Cornea. iris
• Pupil
• Sclera
• Conjunctiva
• . lens Myopic eye- is form at the front of the eye
• Retina Hyeropiciyes-the image is behind the retina

Endocrine system

• The system consist of a study involving the "adernal. and thryoid to pituitary!"
• Exact locations of the glands.
• Thyroid and pancreas (glucose
• Pituitary growth, oxytocin Some affects could hyper or hypo during secretion if the hormone, these occur during t
• *Pituraty gland:
• Oxytocin is protein and peptide are stimulated as it ejection that stimulates growth and reproduction.

Human Reproduction

• During extraembronic it is very important when enclosing the uterus
• The four stages being:
• The yolk
• The fluid
• The chorion
• The Amnitoic

Human Reproduction: Female and Menstrual Cycle

• This stage involves the menstruation and pregnancy. Divided into the ovulation , fallopian where this divides before the egg enters the uterus for preganancy! The cycle consists of four stages,
• INITATION
• FERTILIZATION
• Implantation in the body

Human Reproduction: Population and Control

• Vasectomy with Males
• For prevention
• Tubectomy in females
• In order for no growth to happen

Human Evolution:

• Basic introduction to Human evolution and Theories of evolution: Lamarck's theory of inheritance; Darwin's theory of evolution by natural selection. • A brief idea of human ancestors - Australopithecus, Homo habilis, Homo erectus, Neanderthals, Cro-Magnon and Homo sapiens sapiens (Modern Man) with reference to the following characteristics:
• Bipedalism is the most important and is part of "australthicus"
• Lamarck’s theory of inheritance of acquired characteristics - with reference to use of organs (e.g.: neck and forelimbs of giraffe)and disuse of organs (e.g.: vestigial organs in humans like wisdom teeth, vermiform appendix, pinnae).
• Darwin's theory of Natural selection: Survival of the fittest - e.g. adaptation of peppered mot

Pollution

• Types and sources of pollution includes -air is the most important! -water,oil and thermal -chemical fertilisers -X ray

Tips To Remember and Implement

• One must follow the rules of class 10 and know all answers. and be precise in the answer if there is two of blanks on the answer
• If a number of tick mark needs to "match" be prepared because some questions will ask multiple
• Follow the instruction and permit diagrams when they can. If there the diagram doesn't need to be there, then don't put it
• Also practice on stroma stoma to test for similar questions , always differentiate.

Explore the intricate processes of mitosis and meiosis, highlighting key differences and the significance of chromosome behavior. Understand the mechanics of cell division, genetic variation, and the unique features of each process. Learn about stomata opening and closing.