Genetics Test Reveiw

1. Genetics Test Reveiw

2. Sexual –v- Asexual Reproduction • Sexual Reproduction • Two parents • Each parent gives 1 copy of each chromosome • Offspring are a genetic combination of both parents DNA • Asexual reproduction • One parent • Parent gives exact copy of DNA • Offspring are identical to the parent

3. Mitosis –v- Meiosis Mitosis Meiosis Parent cell – diploid Nucleus divides twice 4 daughter cells produced Daughter cells have half of the number of chromosomes as parent cell (haploid) Used for production of sperm and egg cells (gametes) • Parent cell – diploid • Nucleus divides once • 2 daughter cells produced • Daughter cells have same number of chromosomes as parent cell (diploid) • Used for growth, repair, asexual reproduction

4. What are gametes? • Gametes are reproductive cells (sex cells) • Gametes are haploid (contain only one copy of each chromosome) • Male gametes are called sperm • Female gametes are eggs

5. Compare haploid and diploid cells • Haploid cells only have one copy of each chromosome • Diploid cells have 2 copies of each chromosome Humans have 46 chromosomes total (23 pairs)

6. Alleles… • Alleles are a different forms of a gene • Dominant alleles mask recessive alleles • Represented by a capital letter • Recessive alleles only show when there is no dominant allele present • Represented by a lower case letter

7. Homozygous and Heterozygous… • Homozygous means two of the SAME • Either two dominant (AA) • Or two recessive (aa) • Heterozygous means one of each • Aa • Shows the dominant trait

8. Genotype and phenotype.. • Genotype is the genetic makeup • Represented by letters • Ex/ AA, Aa, aa • Phenotype is the physical trait • What you see, depends on the genotype • Ex/ blonde hair, tall, red flowers

9. Punnett Squares • Ss x ss • Ratios – • Genotype: 50% Ss, 50% ss • Phenotype: 50% long hair, 50% short hair

10. Punnett square • Tt x Tt • Ratios • Genotype: 25% TT, 50% Tt, 25% tt • Phenotype: 75% Spots, 25 % No spots