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Cell Division

Learn about the processes of cell division, mitosis and meiosis. Explore the steps of mitosis and meiosis, and understand the role of genetics and DNA in inheritance. Discover the different types of cells and their characteristics.

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Cell Division

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  1. Cell Division • Mitosis • Growth and Repair • Somatic (body) cells • Daughter cells: • Two produced • Diploid (2n) • Identical to the parent

  2. Cell Division Interphase Prophase Metaphase Anaphase Telophase

  3. Steps of Mitosis • Prophase • Chromatin coiled to form discrete chromosomes • Nucleoli disappear • Form mitotic spindle, lengthen microtubules • Nuclear membrane breaks down • Microtubules attach to chromosomes

  4. Steps of Mitosis • Metaphase • Chromosomes line up at middle of cell

  5. Steps of Mitosis • Anaphase • Microtubules shorten • Chromatids separate, are pulled toward opposite sides of the cell

  6. Steps of Mitosis Telophase • Daughter nuclei form at either side • Chromatin becomes less tightly coiled • Cytokinesis (division of cytoplasm) occurs during telophase.

  7. Meiosis • Sexual reproduction (Why is meiosis required for sexual reproduction?) • Form gametes (sperm and egg) • Daughter cells • Four produced (two nuclear divisions) • Haploid (n, cuts the number of chromosomes in half) • Different from parent and unique from each other

  8. Meiosis • Steps: • Prophase I • Metaphase I • Anaphase I • Telophase I • Prophase II • Metaphase II • Anaphase II • Telophase II

  9. Meiosis

  10. Comparing Mitosis and Meiosis:

  11. Comparing Mitosis and Meiosis:

  12. Genetics/ DNA • Heredity and Mendelian Genetics • Genetics: The study of heredity (the passing of traits from parents to offspring) • Gregor Mendel: The father of genetics. • DNA: Consists of many genes • Gene: Stretch of DNA that codes for a given trait. • Allele: Alternate version of a gene

  13. Body Cells: Make up most of the body’s tissues and organs 2 of each chromosome for a total of 46 Sex Cells: Sperm cell (male) or egg cell (female) Only 1 kind of each chromosome; Half # chromosomes in body cells (23) CHROMOSOMES: Located in nucleus;Split and produce new cells; contain genes

  14. Genetics/ DNA Dominant and Recessive Traits • Dominant Allele • Gene that is fully expressed. • Masks/ “speaks louder than” a recessive allele. • Recessive Allele • Masked/not expressed if dominant allele is present. • Only expressed if dominant allele is absent.

  15. Genetics/ DNA Genotype • The genetic makeup of an organism • Homozygous: having two of the same allele BB bb • Heterozygous: having two different alleles. Bb • Homozygous Dominant: having two dominant alleles BB • Homozygous Recessive: having two recessive alleles bb • Heterozygous: having one of each allele Bb

  16. Genetics/ DNA Phenotype • The physical and physiological traits of an organism • How the genes are expressed • What you would see in a photograph

  17. Example: • In peas, Y is a dominant allele that instructs for yellow seeds; y is a recessive allele that produces green seeds. Given the following genotypes, fill in the term that best describes each, and then indicate what the phenotype of the organism will be.

  18. DNA/ Genetics • A Punnett Square can be used to predict the genotypes and phenotypes of the offspring produced by a given genetic cross. • Generations • Parental (P): The organisms involved in the initial cross • First Filial (F1): The offspring of the Parental Generation • Second Filial (F2): The offspring of the First Filial Generation

  19. Example: • A chicken and a rooster mate. The chicken has white feathers and the rooster has brown feathers. Brown is dominant, and white is recessive. Assuming the rooster is heterozygous, predict the frequency of each genotype and phenotype in their offspring. What is the cellular process that determines which alleles an offspring will receive from their parents? Meiosis

  20. Practice: • 1. A plant that is homozygous dominant for height is crossed with a plant that is homozygous recessive. (T = tall; t = short). Use a Punnett Square to predict the genotypic and phenotypic ratios of the F1 generation.

  21. Practice: • 2. Using question number 1, what would be the genotypic and phenotypic ratios of a cross of two F1 individuals?

  22. Determining Sex Human male: XY Human female: XX Which parent determines the sex of a human offspring? Father What is the probability of having a boy? A girl? 50%/50% DNA/ Genetics

  23. Sex linked traits Carried on the X chromosome Example: hemophilia, color blindness. Disorders occur more often in males than females. Why? Males have one X chromosome, so if one is defective, they do not have a backup copy as do females. DNA/ Genetics

  24. DNA/ Genetics Mutation • A change in the base sequence of DNA. • A change in DNA can lead to a change in the protein coded for by that gene. • A change in the protein structure can lead to certain disorders, for example, sickle cell anemia.

  25. The 6 Kingdoms Bacteria and Archaea • Single Celled, prokaryote • Cell wall • Live in damp places or in water • Asexual reproduction—binary fission • Decomposers (breaks down organic material) • Nitrogen fixation (rhizobium) • Parasites (tuberculosis, cholera, strep-throat) • Symbiotic relationships (humans)

  26. The 6 Kingdoms Complete the chart comparing bacteria and viruses:

  27. Protista Eukaryotes (has a nucleus) Single Celled Euglena Diatoms Dinoflagellates Ciliates Flagellates Sacrodina (amoeba) Sporozoa (malaria) Multi-celled Kelp  Seaweed The 6 Kingdoms

  28. The 6 Kingdoms Plants • Multicellular, eukaryotic • Examples:

  29. Animals Multicelled, eukaryotic Examples: The 6 Kingdoms

  30. The 6 Kingdoms Fungi • Multicelled or single celled; eukaryotic • Examples:

  31. Plants Photosynthetic Autotrophs How are plant cells different from animal cells? Plant cells have a cell wall and vacuole; Plant cells do not have centrioles and lysosomes. The 6 Kingdoms

  32. The 6 Kingdoms • Major parts of a plant: • Roots • absorb water and nutrients from the soil. • Store excess sugars (in the form of starch) • Stem • connects roots to the rest of the plant • Leaves • site of photosynthesis

  33. The 6 Kingdoms Plants • Transport in a plant • Xylem: transports water and nutrients from the roots to the rest of the plant • Phloem: transports products of photosynthesis to the rest of the plant. • What environmental factors might affect a plant? • Water supply, light, pH, acid rain, pollutants

  34. Ecology Biome • A major biological community that occurs over a largearea of land. • Determined primarily by precipitation • Affected by elevation, latitude, soil type, geographical features.

  35. Terrestrial Biomes

  36. Terrestrial Biomes Tropical Rain Forest • Rain: 200-450 cm (80-180 in) per year (A lot of rain) • Rich in number of species (many different types of organisms) • Central America, South America, Africa, Asia • Examples of Animals and Plants:tree frog, monkeys, birds, green canopy

  37. Desert Rain: fewer than 25 cm (10 in) per year (Very little rain) Sparse vegetation May be warm or cold Examples of Animals and Plants: Cactus, snakes, lizards, nocturnal animals Terrestrial Biomes

  38. Savanna Rain: 90-150 cm (35-60 in) per year Prevalent in Africa. Dry grassland Widely spaced trees; animals active during rainy season Examples of Animals and Plants: giraffes, zebras, grasses Terrestrial Biomes

  39. Temperate Deciduous Forest Rain: 75-250 cm (30-100 in) Mild Climate, plentiful rain Deciduous trees shed leaves in fall Warm summer, cold winter Mammals hibernate in winter, birds migrate Eastern US, Southeastern Canada, Europe, Asia Examples of Animals and Plants: Bears, Deer, Oak Trees Terrestrial Biomes

  40. Temperate Grasslands Halfway between equator and poles Interior of North America, Eurasia, South America Fertile soil, used for agriculture Examples of Animals and Plants: Grazing animals (Bison), grasses, field mice Terrestrial Biomes

  41. Terrestrial Biomes Coniferous Forest • Cone bearing trees: pine, spruce, fir, hemlock • Pacific Northwest (temperate rain forests) • Northern Coniferous Forest (Taiga) • Cold and wet • Winters long and cold; precipitation in summer • Coniferous forests (spruce and fir) • Large mammals: elk, moose, deer, wolves, bears, lynx, wolverines

  42. Terrestrial Biomes Tundra • Between taiga and poles • 20% of Earth’s surface • Rain: less than 25 cm (10 in) • Permafrost 1m deep (3ft) • Examples of animals: foxes, lemmings, owls, caribou • Alpine Tundra • Found at high latitudes • High winds and cold temperatures

  43. Aquatic Biomes Freshwater Communities • Standing bodies of water • lakes, ponds • Moving bodies of water • streams, rivers • Wetlands • Swamp, marsh, bog • ~2% of Earth’s surface • Plants, fishes, arthropods, mollusks, microscopic organisms

  44. Aquatic Biomes Marine Communities (salt water) • 75% Earth’s surface covered by ocean • Average depth 3km (1.9mi) • Mostly dark, cold • Photosynthetic organisms mostly towards surface • Heterotrophic organisms throughout • Fish, plankton (algae, diatoms, bacteria).

  45. Flow of Energy Through an Ecosystem • In order to live, organisms must obtain energy and nutrients • Heterotrophs • Obtain energy and nutrients from the food they eat • Autotrophs • Obtain energy from the sun • Obtain nutrients from the soil.

  46. Flow of Energy Through an Ecosystem • Producer • Uses energy from the sun and carbon from the environment to make its own food. • “Bottom of the food chain” • Why are producers necessary in any ecosystem? Make energy from the sun available/usable for heterotrophs.

  47. Flow of Energy Through an Ecosystem • Consumer • Obtains energy through eating other organisms • Herbivore: eats only plants • Carnivore: eats only animals • Omnivore: eats both plants and animals • Primary consumer: eats producers • Secondary consumer: eats the consumers that eat the producers

  48. Flow of Energy Through an Ecosystem • Consumer • Means of obtaining nutrition • Predation • Ecological interaction in which one organism (predator) feeds on another living organism(prey). • Predator may or may not kill the prey. • Scavenging • An animal ingests dead plants, animals, or both. • Vultures, termites, beetles

  49. Flow of Energy Through an Ecosystem • Consumer • Means of obtaining nutrition • Decomposer (Saprophytes) • Breakdown (absorb nutrients from) non-living • Organic material—corpses, plants, waste of living organisms—and convert them to inorganic forms. • Bacteria, fungi • Why are decomposers necessary in any ecosystem? • Recycle nutrients.

  50. Flow of Energy Through an Ecosystem Food Chain • Linear pathway of energy transport through an ecosystem • algaekrillcodsealkiller whalebacteria • Producers always come first in the food chain. • Decomposers always come last in the food chain; they will break down dead organisms and allow nutrients to be recycled. • Arrows indicate the direction in which energy flows through the ecosystem.

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