🥦
Diversity, Classification and
Variation
Created @February 15, 2025 4:20 PM
Class Cells to Systems
DNA Passing Down Generations
Gametes form sperm cells and egg cells
Forms zygote during fertilisation and develops into organism
Body cells have two of each chromosome, one from each parent
Haploid number of chromosomes means one copy of each chromosome
Haploid sperm join with haploid egg at fertilisation
Sperm and egg fertilisation is randomised, producing zygotes with varied
chromosomes combinations
Results in species diversity
Gamete Formation from Meiosis
Two copies of each chromosome from DNA replication are called
chromatids. Process starts before meiosis begins
DNA condenses forming chromosomes made from sister chromatids
Four genetically different gametes are produced
Meiosis I
Diversity, Classification and Variation 1
, Chromosomes self arrange into homologous pairs, chromosome pairs
containing different versions of the same genes
Meiosis II
Chromatid pairs are separated
Meiosis I Cross Over
Homologous chromosome pairs pair up
Chromatids twist and some parts overlap and swap
Still contains the same genes but different combination
Meiosis Cell Production
Chromatid Crossing Over
Crossing over in Meiosis I leads to chromatid formation from four
daughter cells containing different alleles
Independent Segregation of Chromosomes
Homologous chromosome pair contains one maternal chromosome
and another paternal
Separation of homologous pairs by chance
Four daughter cells made by meiosis contain different combinations of
mum and dad chromosomes
Process= Independent Segregation
Mixing of chromosomes leads to gene variation
Meiosis vs Mitosis
Mitosis
Diversity, Classification and Variation 2
Diversity, Classification and
Variation
Created @February 15, 2025 4:20 PM
Class Cells to Systems
DNA Passing Down Generations
Gametes form sperm cells and egg cells
Forms zygote during fertilisation and develops into organism
Body cells have two of each chromosome, one from each parent
Haploid number of chromosomes means one copy of each chromosome
Haploid sperm join with haploid egg at fertilisation
Sperm and egg fertilisation is randomised, producing zygotes with varied
chromosomes combinations
Results in species diversity
Gamete Formation from Meiosis
Two copies of each chromosome from DNA replication are called
chromatids. Process starts before meiosis begins
DNA condenses forming chromosomes made from sister chromatids
Four genetically different gametes are produced
Meiosis I
Diversity, Classification and Variation 1
, Chromosomes self arrange into homologous pairs, chromosome pairs
containing different versions of the same genes
Meiosis II
Chromatid pairs are separated
Meiosis I Cross Over
Homologous chromosome pairs pair up
Chromatids twist and some parts overlap and swap
Still contains the same genes but different combination
Meiosis Cell Production
Chromatid Crossing Over
Crossing over in Meiosis I leads to chromatid formation from four
daughter cells containing different alleles
Independent Segregation of Chromosomes
Homologous chromosome pair contains one maternal chromosome
and another paternal
Separation of homologous pairs by chance
Four daughter cells made by meiosis contain different combinations of
mum and dad chromosomes
Process= Independent Segregation
Mixing of chromosomes leads to gene variation
Meiosis vs Mitosis
Mitosis
Diversity, Classification and Variation 2
