Patterns and principles of heredity

Question 1

Describe mitosis

Answer 1

2n –> 2n +2n

Question 2

Describe meiosis

Answer 2

Haploid gamete production
2n–> n x4
Divide pairs of chromosomes and divide sister chromatids

Question 3

Describe Meiosis 1

Answer 3

Meioside is preceded by S phase - replicated DNA
Prophase 1 - Chromosomes condense, homologues pair and form synaptonemal complex
Metaphase - pair of homologues line up at equator, centromeres don’t divide, orientation of pairs is random
Anaphase - chromosomes em ove to seperate poles
Telophase - two cells forms, one of each chromosome but 2 chromatids

Question 4

Meiosis II

Answer 4

Metaphase - individual chromosomes line up
Anaphase - centromeres split and chromatids separate to opposite poles
Telophase - each daughter cell contains one chromosome

Question 5

Define Gene, allele, genotype, phenotype, homozygote, heterozygote

Answer 5

Gene=basicunitofbiologicalinformation, specific segment of DNA that encodes a protein
• Allele = alternative forms of a gene
• Genotype = alleles at a locus
Use italics (or underline)
  • Phenotype = observable characteristics (e.g. colour)
• Homozygote = identical (YY) alleles at a locus
• Heterozygote = different (Yy) alleles at a locus