DNA, RNA, & Meiosis Review

1. DNA, RNA, & Meiosis Review CPBiology Ms. Morrison

2. 3 parts to nucleotide: 5 carbon sugar (deoxyribose) Phosphate group Nitrogenous base (A, T, C, and G) 1. Diagram and label a model of DNA. Include the parts that make up a single nucleotide.

3. 2. Describe in detail how DNA replicates itself. • DNA molecules unzips into two strands • Complementary nucleotides pair with the two strands • DNA polymerase binds the nucleotides together and “proofreads” the DNA • Two new DNA strands – each with one original strand and one new strand (Note: prokaryotes starting replicating at one single point, while eukaryotes start replicating at many points)

4. 3. Differentiate between DNA and RNA.

5. 4. Compare DNA and RNA by checking the appropriate box:

6. 4. Compare DNA and RNA by checking the appropriate box:

7. 4. Compare DNA and RNA by checking the appropriate box:

8. 5. List the main function for each of the following types of RNA: • mRNA – contains instructions for assembling amino acids into proteins from DNA • rRNA – make up ribosomes along with proteins • tRNA – transfers amino acids to ribosome as specified by DNA

9. 6. Summarize the process (steps) of transcription. • RNA polymerase binds to DNA • RNA polymerase separates DNA strands • One strand of the DNA is used as a template to make complementary mRNA strand • mRNA strand edited before leaving nucleus with message to code for proteins

10. 7. Summarize the process (steps) of translation. • The mRNA strand attaches to ribosome. • Start codon on mRNA (AUG) is read and tRNA with anticodon attaches the amino acid (methionine). • The next tRNA with the correct amino acid binds to the 2nd mRNA codon. • The ribosome forms a peptide bond between the two amino acids. • The mRNA strand moves through the ribosome binding amino acids to the growing polypeptide chain. • When the stop codon is reached on the mRNA strand, the mRNA strand and the completed protein is released from the ribosome.

11. 7. Summarize the process (steps) of translation.

12. 7. Summarize the process (steps) of translation.

13. 8. Determine the mRNA, tRNA, and amino acid sequence for the following DNA strand.

14. 9. Contrast gene and chromosome mutations. • Gene mutations affect the DNA sequence which will change the protein that the gene codes for. There are two types: • Point mutations – single base substituted for another so only one amino acid affected • Frameshift mutation – single base added or deleted so all amino acids changed after mutation • Chromosome mutations affect the entire chromsomes and all the genes located on it, examples: • Extra copy of a chromosome • Only one copy of a chromosome instead of two (homologous) • Missing part of chromosome or have extra genes attached

15. 10. Explain why some changes in DNA structure are inherited and some are not. Only changes that occur in gametes (egg or sperm cells) can be passed on to offspring (inherited). If the changes occur in body cells, then only that organism is affected.

16. 11. Identify which type of mutation has occurred in the original DNA sequence. Underline all the mutated codons. DNA: TAC TTA CCG TCA ATT • TAC TCTACCGTCAATT frameshift mutation (insertion) • TAC TTA CGTCAATT frameshift mutation (deletion) • TAC TTA CCG ACA ATT point mutation

17. 12. Diagram the phases of meiosis in an animal cell with 4 chromosomes. Explain what happens in each phase. • Meiosis I (with one cell) • Prophase I – homologous chromosomes (replicated during Interphase I) pair up in tetrads while spindle forms and nuclear membrane disappears, crossing over can occur • Metaphase I – homologous chromosomes line up in middle of cell and spindle fibers attach to them • Anaphase I – homologous chromosomes are pulled to opposite sides of cell by spindle fibers • Telophase I – nuclear membrane reforms around the separated homologous chromosomes, spindle breaks down, cell divides into two haploid cells

18. 12. Diagram the phases of meiosis in an animal cell with 4 chromosomes. Explain what happens in each phase.

19. 12. Diagram the phases of meiosis in an animal cell with 4 chromosomes. Explain what happens in each phase. • Meiosis II (with two cells) • Prophase II – nuclear membranes disappear and spindle forms (no DNA replication occurs during Interphase II) • Metaphase II – sister chromatids (chromosomes) line up along center of cell and are attached to spindle fibers • Anaphase II – sister chromatids are separated and pulled towards opposite sides of the cell • Telophase II – nuclear membranes reform around the chromatids and the spindle breaks down, the two cells divide into four haploid cells

20. 12. Diagram the phases of meiosis in an animal cell with 4 chromosomes. Explain what happens in each phase.

21. 13. How do the results of meiosis differ in female organisms from male organisms? • Males – one gamete forms four sperm cells in even meiotic divisions • Females – one gamete forms one egg cell with most of the cytoplasm and three polar bodies which are NOT used in reproduction, this occurs because of uneven meiotic divisions

22. 14. Differentiate between haploid and diploid cells. Using a human cell, explain how the number in each are different. • Diploid means having two homologous chromosomes – similar chromosomes where one is from the male parent and the other is from the female parent • Haploid means having a single chromosome (only from one parent) • Humans have 23 pairs of chromsomes for a total of 46 chromosomes – this is diploid • Human gametes (eggs, sperm) have 23 chromosomes (therefore when egg and sperm combine – a cell is produced with 46 chromosomes or 23 pairs of chromosomes)

23. 15. Compare mitosis to meiosis.

24. 15. Compare mitosis to meiosis.

25. 15. Compare mitosis to meiosis:

26. 15. Compare mitosis to meiosis: