MEIOSIS MUTATIONS 1 What is meiosis Mitosis Meiosis

MEIOSIS / MUTATIONS

1. ) What is meiosis? Mitosis? • Meiosis – Cell division that results in gametes (sex cells) that are haploid (reduction/division) • Mitosis – cell division that results in somatic cells (body cells) that are diploid

2. ) Define a haploid cell? Diploid cell? • Haploid – half set of chromosomes – sex cell (gamete) – 23 – humans – non-functional • Diploid – full set of chromosomes – somatic cells (body) – 46 – humans – functional

3. ) What is a gamete? What is a somatic cell? • Gamete – sex cell – haploid • Somatic cell – body cell – diploid

4. ) What is crossing over? When does it occur? • Crossing over – when homologous chromosomes exchange genetic information during prophase I – homologous chromosomes form a tetrad

5. ) What separates during Anaphase I? Anaphase II? • Anaphase I – homologous chromosomes separate • Anaphase II – sister chromatids separate – the same as anaphase of mitosis

6. ) What is a chromosome? • Structure on which DNA (genes) are found • they are involved in heredity

7. ) What are the main differences between meiosis and mitosis? • • MITOSIS MEIOSIS involves body cells • involves gametes results in 2 identical • results in 4 daughter cells genetically different haploid cells 1 division asexual reproduction • 2 divisions (meiosis I and II) • sexual reproduction

8. ) What is interphase? What are the 3 sub phases? • Cell grows and functions • Period of rest before it undergoes cell division • G 1 – Cell growth – Preparing for cell division • S – phase – DNA replication • G 2 – Final preparation for Mitosis

9. ) What is cytokinesis? How is it different in animal and plant cells? • Cytokinesis – Process when the cytoplasm divides between the new cells • Animals – Membrane pinches inward creating a cleavage furrow • Plants – Vesicles fuse to form a cell plate which in turn becomes the cell wall.

10. ) What is cytokinesis? How is it different between plants and animals? • Cytokinesis – Process when the cytoplasm divides between the new cells • Animals – Membrane pinches inward creating a cleavage furrow • Plants – Vesicles fuse to form a cell plate which in turn becomes the cell wall.

11. ) What are the stages of Meiosis and what happens during each? • Prophase I – Nuclear membrane disappears – Chromosomes become visible – Homologous chromosomes pair up – Crossing over occurs – Centrioles move to the equator

• Metaphase I – Spindle fibers attach – Homologous chromosomes align along the equator • Anaphase I – Homologous chromosomes separate • Telophase I – Cytokinesis occurs – Nucleus reforms – Chromosomes disappear – End up with 2 daughter cells

• Prophase II – Nuclear membrane disappears – Chromosomes become visible – Centrioles move to the equator • Metaphase II – Spindle fibers attach to the centromere – Chromosomes align along the equator • Anaphase II – Sister chromatids separate

• Telophase II – – Cytokinesis occurs Nucleus reforms Chromosomes disappear Four haploid cells form • Genetically different

12. ) What is an allele? • A characteristic or gene found on a chromosome • Use letters to symbolize • eye color B – brown, b – blue

13. ) What is a dominant allele? How do you recognize a dominant allele? • it is the trait that is shown • capital letter

14. ) What is a recessive allele? How do you recognize a recessive allele? • hidden in a hybrid (heterozygous) • can only be seen if paired with another recessive • lower case letter

15. ) Define the following terms Homozygous (purebred), heterozygous (hybrid), phenotype, genotype • Homozygous – alleles are the same – ex. ) BB, CC, HH • Heterozygous – alleles are different – ex. ) Bb, Cc, Hh

• Phenotype – physical appearance, what it looks like • Genotype – genes (alleles) that make up the trait

16. ) Explain what a karyotype is? (know how to read one) • a chart that displays your chromosomes • chromosomes 1 – 22 are autosomal, • chromosome 23 are sex – chromosomes – XX (female) – XY (male)

17. ) What is a mutation? • Inheritable change in genetic information

18. ) What does a gene mutation involve? • Chemical change (change in base (A, C, T, G) sequence) that affects the DNA molecule

19. ) Explain the difference between a point mutation and a frame shift mutation. • Point mutation – substitution of one nucleotide for another – only changes 1 amino acid • Frameshift mutation (insertion or deletion) – nucleotide is inserted or deleted – reading frame changes – all the amino acids from that point on change

19. ) What does a chromosome mutation involve? • change in the structure of the chromosome

20. ) Explain the difference between a missense, silent and nonsense mutation. • Missense – part of the chromosome is lost • Silent – gene sequence repeated or copied within the chromosome • Nonsense – linear stretch of DNA on a chromosome is reversed

21. ) What does a chromosome mutation involve? • chromosomes

22. ) What is nondisjunction? • Nondisjunction – failure of chromosomes to separate properly during meiosis (anaphase I or anaphase II) – An example of a chromosomal mutation

22. ) Know examples associated with chromosomal mutations. • • • Klienfelters (sex) Turners syndrome (sex) Downs syndrome (autosomal) trisomy 21 Edwards syndrome (autosomal) trisomy 18 Pateau syndrome (autosomal) trisomy 13