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17.2Inheritance

Mitosis Core — Cambridge IGCSE Biology 0610 Revision Notes & Topical Questions

10 min read 21 parts Lesson 3 of 9 1 quiz

📚 Cambridge IGCSE Biology 0610 Hub / Topical Revision
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Lesson summary

17.2 Mitosis — IGCSE BIOLOGY notes: Describe mitosis, its role in growth, repair, replacement and asexual reproduction, and stem cells.Mitosis = nuclear division giving rise to genetically identical cells.Diploid cells — most body cells have two copies of each chromosome.Doubling…

  • Doubling beforehand
  • Chromosome number
  • Daughter cells
  • Embryonic stem cells
  • Differentiation
  • Uncontrolled mitosis

Part 1 of 6What mitosis is

Mitosis
Mitosis nuclear division giving rise to genetically identical cells.
Diploid cells
  • Diploid cells most body cells have two copies of each chromosome.
Doubling beforehand
  • Doubling beforehand chromosomes copy themselves before division so each new cell is still diploid.
Every body cell except the gametes comes from mitosis of the zygote.

Part 2 of 6Process of mitosis

1
Each chromosome in the nucleus copies itself exactly, forming X-shaped chromosomes.
2
The chromosomes line up along the centre of the cell.
3
Cell fibres pull the copies apart.
4
The cell divides into two, each with a copy of every chromosome.
  • Chromosome number
    • maintained in each daughter cell.

Part 3 of 6Uses of mitosis

Growth
  • Growth produces new cells, for example when a zygote divides to form an embryo.
Repair
  • Repair replaces damaged or dead cells.
Replacement
  • Replacement replaces cells such as skin cells and red blood cells.
Asexual reproduction
  • Asexual reproduction produces offspring genetically identical to the parent.

Part 4 of 6Stem cells

Stem cells
  • Stem cells unspecialised cells in many tissues that divide by mitosis.
Daughter cells
  • Daughter cells can become specialised for specific functions.
Embryonic stem cells
  • Embryonic stem cells the zygote divides by mitosis to form a ball of about 150 to 200 unspecialised cells.
Differentiation
  • Differentiation these cells begin to specialise as the foetus develops, forming the tissues of the body.

Part 5 of 6Mitosis summary

FeatureDetail
Parent cellDiploid, for example a human skin cell with 46 chromosomes
Before divisionDNA replicates
Daughter cellsTwo, genetically identical, with 46 chromosomes each
UsesGrowth, repair, replacement, asexual reproduction
  • Uncontrolled mitosis
    • can cause cancer.

Part 6 of 6More from the specification

1
Replication of nuclear genes
  • Replication of nuclear genes precise chromosome replication during interphase ensures identical transmission of genetic genes into daughter cell nuclei.
2
Monohybrid inheritance
  • Inheritance of one gene.
3
Exact Duplicate Nuclear Division
  • Mitosis produces two genetically identical daughter nuclei with the same diploid chromosome number as the mother cell, essential for organismal growth, tissue repair,
    • and asexual propagation.
4
Preservation of Parental Allelic Identity
  • Because DNA replication and mitotic segregation occur without crossing over, all daughter cells inherit identical copies of each allele, maintaining phenotypic fidelity across cellular generations.
5
Chromosome Condensation and Metaphase Alignment
  • Chromatin condenses into distinct visible chromosomes that align symmetrically along the cellular equatorial plate, guided by microtubules attached to kinetochores.
6
Homozygous
  • Having two identical alleles.
7
Sequence
  • The order of bases in DNA or amino acids in a protein.
8
Phenotype
  • The observable characteristic.
9
Heterozygous
  • Having two different alleles.
10
Probability
  • The chance that an offspring has a given genotype or phenotype.
11
Punnett square
  • A grid predicting offspring genotypes.
12
Blood group
  • A phenotype set by alleles I-A, I-B and I-O.
13
Protein synthesis
  • Making proteins from amino acids using the DNA code.
14
Allele
  • A version of a gene.
15
Inheritance
  • Transmission of genetic information from generation to generation.
16
Recessive
  • Expressed only when no dominant allele is present.
17
Dominant
  • Expressed when present in the genotype.
18
Protein
  • A long chain of amino acids containing carbon, hydrogen, oxygen and nitrogen.
19
Meiosis
  • Reduction division giving four genetically different haploid cells.
20
Genotype
  • The alleles an organism has.

Key terms

TermMeaning
MitosisNuclear division giving genetically identical cells.
ReplicationExact copying of chromosomes before division.
Stem cellAn unspecialised cell that divides and can become specialised.
DifferentiationSpecialisation of a cell for a function.
DiploidHaving two sets of chromosomes.

Avoid these mistakes

1
Saying mitosis halves the chromosome number — it keeps it the same.
2
Saying the daughter cells are different — they are genetically identical.
3
Saying mitosis makes gametes — meiosis does.
4
Saying chromosomes are copied after division — they are copied before.

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