Science Module 4: Cycles & Patterns (PDF)

MODULE 4: CYCLES AND PATTERNS Cells - Basic unit of life Cell division - The ability of organisms to produce more of their own kind Unicellular organism - division of one cells Multicellular organism - development from a fertilized cell DNA (deoxyribonucleic acid) - carrier of genetic...

MODULE 4: CYCLES AND PATTERNS Cells - Basic unit of life Cell division - The ability of organisms to produce more of their own kind Unicellular organism - division of one cells Multicellular organism - development from a fertilized cell DNA (deoxyribonucleic acid) - carrier of genetic information Gene - Basic unit of inheritance Chromosomes - structures that look like thread, living in the nucleus of cells Sister chromatids - attached together at the centromere being exact copies of each other ○ Kinetochore - a protein that is found on the center of each of the sister chromatids Centrosome Microtubules - forms a spindle to allow us equally divide chromosomes Centrioles - organizes microtubules and spindles Diploid - Two sets of chromosomes Haploid - One set of chromosome CELL CYCLE - how a cell duplicates itself (IPPMATC) 1. Interphase - DNA is copied - Centrosomes duplicate and moves to the opposite ends of the cell a. G1 phase (first gap) - growing b. S phase (synthesis) - duplicate dna c. G2 phase (second gap) - cell continues to grow i. G0 phase - never divides MITOSIS - to duplicate cells 2. Prophase - chromosomes condense - Mitotic spindle forms 3. Prometaphase - nuclear envelope fragments - Microtubules attach to kinetochore 4. Metaphase (meet in the middle) - metaphase plate 5. Anaphase (apart) - chromatids separate 6. Telophase and cytokinesis - cell elongation - Cleavage furrow - Daughter nuclei form MEIOSIS - to make four genetically different cells - Requires a production of egg and sperm cells Homologous chromosome - 1 chromosome from each parent 1. Interphase - centrosomes duplicate 2. Prophase I - synapsis/crossing over - Exchange of DNA segments - Chromosomes come together - Swapping parts of their chromosomes - Giving variation 3. Metaphase I - independent orientation - 2^23 = 8,388,608 possible ways chromosomes can orient themselves - Spindles attaches to the centromere of each of the homologous chromosomes 4. Anaphase I - pulls them apart 5. Telophase I - forms a new nuclei at each side 6. Cytokinesis - divides the rest of the cell 7. Prophase II - no more crossing over, but chromosomes line up 8. Metaphase II - spindles attach to the centromere 9. Anaphase II - chromosomes are pulled apart 10. Telophase II and cytokinesis - creation of four cells Cell Cycle Checkpoints - Ensures that the incomplete or damaged DNA is not passed to the daughter cells - Prevents certain diseases such as cancer G1/S checkpoint ○ Sufficient number of organelles ○ Growth factors activation G2/M checkpoint ○ Completely replicated genome ○ Large cell volume M/G1 checkpoint ○ Equal distribution of chromosomes between new daughter cells Loss of Cell Cycle Controls in Cancer Cells Transformation - a process where normal cell is converted to a cancerous cell Benign tumor - Lump of abnormal cells that remain at the original site  Malignant tumor - invade surrounding tissues ○ Metastasize - export cancer cells to other parts of the body Characteristics of cancerous cells ○ Many cells that continue to grow and divide ○ Variations in sizes and shapes of cells ○ Nucleus that is larger and darker than normal ○ Abnormal number of chromosomes ○ Cluster of cells without a boundary Cases of nondisjunction in humans - Occurs when the chromosomes fail to separate properly as cell divides Turner’s syndrome - monosomy for chromosome 23 (XO) - A genetic condition that affects females Klinefelter’s syndrome - trisomy for chromosome 23 (XXY) - A genetic condition that affects males Down’s syndrome - trisomy for chromosome 21 (XXY) - Delay in the development of physical and intellectual disabilities Monoploidy and Polyploidy Monoploidy - an organism has only one set of chromosomes Polyploidy - an organism has more than two sets of chromosomes - Results in bigger animals - Lethal for humans (99% die before birth; newborns die soon after birth) 1. Autopolyploidy - extra sets of chromosomes come from the same species 2. Allopolyploidy - extra sets of chromosomes come from different species REPRODUCTIVE LIFE CYCLES - stages that organisms go through to reproduce and pass on their genetic material to the next generation. a. Haplontic life cycle - haploid stage is the dominant and longest stage Gametophyte - can grow and develop into various structures (leaves/stems) but remains haploid. - Produces gametes through mitosis forming diploid zygote - Undergoes meiosis, which reduces the chromosome number back to haploid, growing into new gametophytes b. Diplohaplontic life cycle - alternates between two distinct stages - Also known as alternation of generations - Common in plants, algae, fungi Diploid sporophyte - has two sets of chromosomes - Can grow and develop into a mature plant or algae - Produces haploid spores through meiosis  Haploid gametophyte - only has one set of chromosomes produces gametes through mitosis - When the sperm and egg from the gametophytes meet, they fuse during fertilization, forming a diploid zygote, developing into a new diploid sporophyte. c. Diplontic life cycle - diploid stage is the dominant and longest stage - The organism grows, develops, and performs normal functions - Produces haploid gametes through meiosis - A sperm and an egg meet during fertilization forms a diploid zygote - The diploid zygote (fertilized egg) grows and develops into a new organism - Common in most animals Haplontic Diplontic Diplohaplontic Dominant stage Haploid (1n) Diploid (2n) Both haploid and Diploid Main organism Gametophyte Sporophyte Gametophyte and Sporophyte Gamete formation Produced by mitosis Produced by meiosis Produced by mitosis from haploid cells by diploid cells in the gametophyte and by meiosis in the sporophyte Diploid stage Short-lived, only as a Long-lived, Short-lived zygote zygote throughout most of its formed during life fertilization Haploid stage Main life stage, Brief stage only Multicellular growing and during gamete gametophyte that reproducing formation produces gametes examples Chlamydomonas (a Humans Ferns green algae) Reproductive Primarily sexual Sexual reproduction Alternates between strategy reproduction sexual reproduction phases ANGIOSPERMS LIFE CYCLES - plants that bear flowers Parts of a flowers Non-fertile parts ○ Sepals - green, leafy structures ○ Petals - help attract pollinators ○ Receptacle - axis (stem) to which the floral organs are attached Fertile parts ○ Stamen (male reproductive part)  Anther - contains microsporangia that produces microspores which develops into male gametophytes (pollen) Filaments - structure that supports that anthers ○ Carpel (female reproductive part) Ovary - contains megasporangia that produces megaspores which develops into female gametophytes (embryo sac) Ovule - forms within the ovary Stigma - location where pollen is deposited by wind or by pollinators Style - structure that connects the stigma to the ovary PATTERNS IN LIVING SYSTEMS Reproductive Patterns Reproduction - process by which every kind of living thing produces new individuals of its own kind. Asexual reproduction - produced from one organism ○ Budding - duplicate plant or animal begins to form at the side of the parent and enlarges until an individual is created ○ Regeneration - ability to restore lost or damaged limbs. - Organism breaks into several pieces and each piece may regenerate missing parts ○ Binary fission - one organism becomes 2 complete organisms ○ Parthenogenesis - an unfertilized egg develops into an adult animal - Can store sperms Busy as a bee ○ Reproductive females (virgin queens) - where all future queens come from ○ Workers - sterile females ○ Drones - fertile males ○ Spore formation - parent plant produces hundreds of tiny spores which can grow into new organisms ○ Vegetative propagation - produce new plants from vegetative parts of the original plant Grafting - inserting a part to another and locking them in Cutting - cutting a part and planting it afterwards Layering - planting another part without cutting Tissue culture - combining cells Sexual reproduction - produced from two organisms - Maintains organism’s diploid condition providing advantages in survival ○ Monoecious - common among invertebrates Hermaphroditic - both male and female gonads can be found in only one organism - Paunahan magplant ○ Dioecious - evolved from hermaphroditism - Sexes are separate; division of labor among the two sexes Internal fertilization - union of egg and sperm occurs within the body of the female External fertilization - gametes meet outside the parent’s body with or without physical contact. Gametes are released into the water ○ Sequential hermaphroditism (gender bending) - protandrous species develop first as males but could become females