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BIOLOGY – AS YOU ENTER

Learn about cell reproduction, mitosis, and meiosis in biology with this study guide. Understand the processes of cell division, chromosome replication, and genetic content reduction. Explore topics such as why cells divide, stages of mitosis, and the difference between sexual and asexual reproduction.

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BIOLOGY – AS YOU ENTER

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  1. BIOLOGY – AS YOU ENTER • I need 3 people to return papers from table 1 • If you missed yesterday • Turn in Biotechnology Study Guide • See me to take test • Pick up Exam Review and Summary Sheet

  2. EXAMS: 1ST = FRIDAY 2ND/ 3rd = Monday 4th/5th = Tuesday 6th/ 7th = Wednesday • Bring a parent note and turn in to your teacher of the last exam each day and you can leave after the last exam EXEMPTIONS – You may exempt up to 3 exams each semester, but not the same course both semesters • 90 or higher – up to 5 excused absences • 85 or higher – up to 3 excused absences • 80 or higher – no absences • Le me know if you think you can exempt

  3. CELL REPRODUCTION2nd 9 Weeks ReviewCELL PHONES SHOULD BE TURNED OFF AN PUT AWAYStudy Questions 1-56 on your test review and click through the PPT for a visual review

  4. Why do cells divide? • They get too big • It gets too hard to diffuse nutrients in and wastes out through the cell membrane What does cell division lead to? • Causes organisms to grow • Replaces worn-out or damaged cells • Causes reproduction in unicellular organisms • Binary fission - Bacteria splits & become 2 identical organisms

  5. Cell Division in Prokaryotes Parent cell Binary fission = Asexual reproduction • Chromosome copies • Cell splits • Daughter cells Identical to the parent cell • Occurs quickly Chromosome relicates Cell splits 2 identical daughter cells

  6. Cell Division in Eukaryotes The Cell Cycle

  7. chromatid telomere centromere telomere Condensed, duplicated chromosome

  8. STAGES OF MITOSIS – cell division to make organisms grow & repair themselves INTERPHASE = PERIOD BETWEEN CELL DIVISIONS PMAT = PROPHASE METAPHASE ANAPHASE TELOPHASE CYTOKINESIS = DIVISION OF CYTOPLASM

  9. MITOSIS – makes 2 identical cells with same DNA – happens in all forms of ASEXUAL REPRODUCTION PARENT CELL WITH 46 CHROMOSOMES 46 46 46 DAUGHTER CELLS HAVE 46 CHROMOSOMES

  10. Cytokinesis – Cell splits to make 2 IDENTICAL daughter cells

  11. Remember • Mitosis is an asexual reproductive process • 1 parent cell forms 2, identical, diploid, somatic cells • Mitosis allows eukaryotic organisms to grow and repair themselves

  12. MEIOSIS = cell division in ovaries & testes to produce gametes (eggs & sperm) Human ovary or testis cell starts with 46 chromosomes. After meiosis, the eggs & sperm only have 23 chromosomes. 23 23 23 46 23 23 23

  13. Crossing-Over Crossing-over multiplies the already huge number of different gamete types produced by independent assortment

  14. SEXUAL REPRODUCTION – involves 2 sex cells (gametes)  offspring will be a combination of the 2 parents HAPLOID HAPLOID EGG (23) + SPERM (23) ZYGOTE (46) DIPLOID

  15. 2n = 6 1n =3

  16. from mom from dad child too much! meiosis reduces genetic content Meiosis Forms Haploid Gametes • Meiosis must reduce the chromosome number by half • Fertilization then restores the 2n number • If this didn’t happen, the chromosome number would double each generation The right number!

  17. CORRECT TESTS a) Open notes/book/study guide b) No talking, sharing answers, cell phones 2) CONTINUE 9 WEEKS/EXAM STUDY GUIDE • Answer all questions on a separate paper • Study #s 1-56 for the 2nd 9 Weeks test (Scheduled for Wednesday) CELL PHONES SHOULD BE TURNED OFF AND PUT AWAY Let me know if you think you can exempt

  18. Remember: • Meiosis is only used to make gametes (Sex cells) • It halves the number of chromosomes and creates diversity through crossing over • In humans, this leads to the creation of gametes with 23 chromosomes each. • In chimpanzees, the diploid number is 48. What is the haploid number produced by meiosis? • 24

  19. Mitosis 2 cells formed Cells are diploid (full set of chromosomes) Cells are identical to “parent” cell Forms all cells besides sex cells Meiosis 4 cells formed Cells are haploid (half set of chromosomes) Cells vary from “parent” cells Forms sex cells (gametes) Comparing Mitosis and Meiosis

  20. Sexual vs Asexual Reproduction • Sexual • Requires 2 parents • Requires haploid gametes made by meiosis • Offspring are different from parents • Process is slower • Asexual • Requires 1 parent • No gametes required • Offspring are identical to parents • Process is faster

  21. 19 20 22 21

  22. DNA, RNA & PROTEIN SYNTHESISAs you enterPlease turn off and put away cell phones

  23. WHAT IS DNA? • Blueprint of Life (has the instructions for making an organism) • GENE = a segment of DNA that codes for a protein, which codes for a trait (skin color, eye color, etc.) • DNA is wrapped around protein to form chromosome

  24. Structure was discovered by James Watson and Francis Crick (1953) Described shape as a double helix (“twisted ladder”)

  25. What is DNA made of? • What organic compound is it? • Nucleic Acid • What are the building blocks of this compound? • NUCLEOTIDES= sugar, phosphate, nitrogen base • DEOXYRIBOSE SUGAR and PHOSPHATES (sides of ladder) • NITROGEN BASES (rungs of ladder)

  26. ADENINE (A) THYMINE (T) GUANINE (G) CYTOSINE (C) Attach to deoxyribose sugar Always follow “base-pair rule” Pair up A - T , C - G Connected by weak HYDROGEN BONDS NITROGEN BASES

  27. DNA REPLICATION – DNA makes a copy of itself • Occurs where? • Nucleus • Occurs when? • S phase • Occurs why? • So the new cells will be identical to the parent cell Semi-conservative

  28. Condensed, duplicated chromosome • Remember, after the chromosomes are replicated, they are now called sister chromatids and are held together by the centromere

  29. DNA, RNA, & PROTEIN SYNTHESIS

  30. DNA is too big to leave the nucleus so RNA (Ribonucleic Acid) must get involved. SIMILARITIES IN DNA & RNABoth have N bases adenine, guanine, cytosineDIFFERENCES DNA Deoxyribose sugar Thymine Double-stranded RNA Ribose sugar Uracil Single-stranded

  31. TYPES OF RNA

  32. AMINO ACIDS mRNAcodonchart • 20 exist • Link together to make proteins during protein synthesis • TRIPLET CODON = 3 NITROGEN BASES  1 AMINO ACID

  33. PROTEIN SYNTHESIS is the making of a protein. To make a protein, a cell needs: • DNA - holds the code in the nucleus • mRNA codons - carries code to ribosome • RIBOSOME - where protein is made • tRNAanticodon - picks up amino acids & brings them to ribosome • AMINO ACIDS - building blocks of proteins

  34. Step #1 - TRANSCRIPTION • mRNA made from DNA code • Occurs in nucleus

  35. HOW DOES mRNA COPY THE DNA CODE? DNA - ATG CCG ATT TGA DNA- TAC GGC TAA ACT mRNA – AUG CCG AUU UGA REMEMBER…RNA has uracilinstead of thymine to bond with adenine!

  36. Step #2 - TRANSLATION • Protein formed from mRNA • Occurs on ribosome • Amino acid sequence determined by codons (groups of 3 mRNA bases) • tRNA picks up correct amino acid and brings it to the ribosome

  37. DNA- TAC GGC TAA ACT mRNA – AUG CCG AUU UGA Amino - met – pro – Ile - stop acid • Remember that tRNA Carries (Transfers) in the Correct amino acid to the ribosome

  38. A = Nucleus B = mRNA C = Ribosome D = tRNA F = Codon THIS SHOWS THE PROCESS OF TRANSLATION (making a protein)

  39. Mutations = Error in the DNA codeMUTATIONS can occur in SOMATICCELLS or GERM (REPRODUCTIVE) CELLS

  40. WHAT’S CAUSING THESE GENE MUTATIONS? SUBSTITUTION • The fat car ate the rat. • The fat cat ate the rat. • The atc ata tet her at. • The fat cat ate the rat. • The fat cat tat eth era t. DELETION INSERTION The last 2 are FRAMESHIFT mutations because everything shifts and the entire sentence (all the amino acid codons) are affected.

  41. POINT – single base is substituted A C G A G G FRAMESHIFT – a base is added or deleted A C GT G C A C GA T G C A C G T G C A C T G C GENE MUTATION – results from changes in a single gene

  42. CONTINUE EXAM REVIEW • 1) The 9 weeks test covers questions 1-56 • 2) Answer all questions on a separate paper • 3) If finished with #s 1-56, study those questions or continue working ahead 9 WEEKS TEST IS TOMORROW CONFERENCE – I WILL CALL YOU UP TO TALK WITH YOU INDIVIDUALLY ABOUT YOUR CURRENT GRADE

  43. CHROMOSOME MUTATIONS: involve changes in entire chromosome • DELETION - a piece of a chromosome breaks off and is lost. • INVERSION - a piece of a chromosome breaks off and reattaches itself in reverse order. • TRANSLOCATION - a broken piece attaches to a nonhomologous chromosome. • NONDISJUNCTION - a pair of chromosomes fail to separate during cell division.

  44. CHROMOSOME MUTATIONS

  45. NONDISJUNCTION – failure of chromosomes to separate during meiosis

  46. Checkpoint: Complete questions 5 and 7 on your notes

  47. HOW TO SET UP A PUNNETT SQUARE TALL X SHORT TT X tt HETEROZYGOUS TALL X HETEROZYGOUS TALL Tt x Tt

  48. Free earlobes (F) is dominant to attached earlobes (f). Indicate the probability that the child will have attached earlobes if: a)One parent is homozygous dominant and the other has attached earlobes Cross = FF x ff 0% attached Both parents are heterozygous for free earlobes Cross = Ff X Ff 25% attached One parent is heterozygous and the other has attached earlobes Cross = Ff x ff 50% attached 26) What type of cross does this represent? (complete, incomplete, codominance)? Complete dominance

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