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Do Now

Do Now. WOD: INUNDATE (IN un dayt ) v. to overwhelm with abundance or excess; flood After the rains, the fields were INUNDATED with water. During final exams, we are so INUNDATED with school work that we have no time for fun.

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Do Now

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  1. Do Now • WOD: INUNDATE(IN un dayt) v. • to overwhelm with abundance or excess; flood • After the rains, the fields were INUNDATED with water. • During final exams, we are so INUNDATED with school work that we have no time for fun. • Jack’s father used to INUNDATE the front yard in the winter so all his friends could ice skate. • Please finish preparing your INBs for your notebook check

  2. INB Check #4 What is the width of the CSM? Lipid bilayer has fluidity we associate with ________. Longer tail = __________fluid membrane Glycolipids and glycoproteins form sugary coating on membrane called _____ Write your answer (complete) to question #2 from the homework on page 32 Write your answer (complete) to questions #4 from the h/w on page 32 Phospholipid bilayer creates effective barrier against ______ and ________ What 4 properties can affect rates of diffusion across the CSM? Water potential is measured by the Greek symbol _______ Difference in charges between inside membrane and outside creates a ________ ______________ is referred to as “cell drinking” Write your answer (complete) to question #5b from the h/won page 34 Write your answer (complete) to question #6b from the h/w on page 34 Write your answer (complete) to question #6c from the h/w on page 34 Copy the complete table from question #7 from the h/w on page 34 Write the word of the day, with definitions, from 1/8, 1/16, and 1/21.

  3. Chapter 5-1: Nuclear division INB pg 35

  4. Cell & nuclear division • Cells reproduce by dividing and passing on their genes to daughter cells • Nucleus always divides before cell divides • Each daughter cell contains its own nucleus

  5. Cell & nuclear division Nuclear division combined with cell division allows cells (and whole organisms) to reproduce themselves, and to grow All cells in your body are all genetically identical (except for gametes – reproductive cells) All cells derived from one cell - zygote

  6. Chromosomes • Before division in eukaryotic cells, thread-like structures called chromosomes become visible • # chromosomes depends on species • Ex: Humans = 46, Flies = 8

  7. Chromosomes Stain very intensely Prepared photograph of chromosomes called a karyogram

  8. Chromosomes • Matching pairs are called homologous pairs. • In humans, there are two sets of 23 paired chromosomes. One set from the mother and one from the father

  9. Chromosomes • Autosomes are numbered 1-22 • Sex chromosomes are not numbered and determine the sex of an individual • XY = male, XX=female

  10. Chromosomes Each chromosome has a characteristic set of genes which code for different features

  11. Haploid and diploid cells • Cells that contain 2 sets of chromosomes are described as diploid, as represented by 2n • n= number of chromosomes in one set • A cell which contains only one set of chromosomes is described as haploid, as represented by n • Ex“: gametes

  12. Chromosomes • Double structure made of two identical structures called chromatids that are joined together • During interphase (period between nuclear divisions) each DNA molecule makes an identical copy of itself (chromatid) and joins them at the centromere

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  14. Chromatids • Each chromatid contains one molecule of DNA • DNA is the molecule of inheritance made up of a series of genes, which is one unit of inheritance. • One genes codes for one polypeptide involved in a specific aspect of the functioning of an organism

  15. Chromatids The gene for a particular characteristic is always found at the same position, or locus (pl. loci) Total number of different genes in humans is thought to be ~20,000-25,000

  16. Homologous chromosomes • Each member of homologous chromosomes comes from one of the parents • 23 maternal + 23 paternal = 23 homologous pairs • Each member of a homologous pair possesses genes controlling the same characteristics • A gene for a different characteristic may exist in different forms (alleles) which are expressed differently

  17. Cystic Fibrosis • Condition caused by a faulty allele (mutation) of a gene that codes for a chloride channel protein needed to produce normal mucus. Faulty allele causes very thick mucus. • Both homologous chromosomes have faulty allele = CF • Only one faulty copy is present = no CF • One faulty copy person is called a carrier

  18. Nuclear division • Growth: as a zygote matures into adult with trillions of cells, each cell must be genetically identical • This type of nuclear division is called mitosis

  19. Nuclear division • Sexual reproduction: point before fertilization where chromosomes must be halved to create haploid cells • this type of nuclear division is called meiosis, or reduction division

  20. The cell cycle Regular sequence of events that takes place between one cell division and the next Three distinct phases: interphase, nuclear division, cell division

  21. Interphase G1 phase: Cell grows to normal size after cell division S phase: Cell receives signal to start dividing and begins synthesizing DNA G2 phase: DNA is checked and repaired, cell continues to grow and replicate organelles

  22. Mitosis and cytokinesis M phase (mitosis): growth stops temporarily. Nucleus divides into daughter nuclei Cytokinesis: Whole cell division. Involved constriction of the cytoplasm between two nuclei

  23. Mitosis Early prophase: chromosomes start to coil up and become visible when stained. Centriole replicate Late prophase: centrioles move to opposite side of nucleus. Nuclear envelope breaks up into vesicle (not visible) Chromosomes are seen as identical chromatids

  24. Mitosis Metaphase: Centrioles reach opposite ends (poles) and organize spindle microtubules. Chromosomes align at the equator of the spindle. MTs attach to centromeres

  25. Mitosis Anaphase: chromatids move to opposite poles, pulled by the centromeres Telophase: chromatids have reached spindle and begin uncoiling. Nuclear envelope reforms.

  26. Biological significance of mitosis Growth: Daughter cells have same number of chromosomes as parent cell and are genetic clones. This allows growth of multicellular organisms from unicellular zygotes

  27. Biological significance of mitosis Replacement of cells and repair of tissues: Cells are constantly dying and being replaced by new cells. (ex: skin) Some animals can regenerate entire body parts

  28. Biological significance of mitosis Asexual reproduction: production of new individuals of a species by a single parent organism. Can be from unicellular organisms or multicellular (budding) Budding is particularly common in plants

  29. Biological significance of mitosis Cloningof B-lymphocytes and T-lymphocytes during immune response is dependent on mitosis

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