knowt logo

Sexual Reproduction v. Asexual Reproduction

Telomeres- Protective caps on chromosomes

  • consists of DNA associated with proteins in chromatins

  • might be involved in both aging and cancer

  • the same sequences of bases repeated over & over

  • Telomere sequence in humans: TTAGGG

Function of telomere

  • help organize 46 chromosome in the nucleus

  • DNA is left undamaged in the chromosome during DNA replication

  • Important DNA would be lost everytime a cell divides without a telomere

    • Leads to the loss of entire genes

Karyotypes and Nondisjunction

Karyotypes: individual’s complete set of choromosomes

Nondisjunction: cell division during which sister chromatids fail to separate properly

  • occurs in any organism in which gametes are produced through meiosis

  • associated with serious human disorders

Outcomes of nondisjunction:

  • it leads to daughter cells with abnormal numbers of chromosomes, known as aneuploidy

Two types of nondisjunction:

  • Mitotic nondisjunction

    • occurs in anaphase when sister chromatids fail to separate

  • Meiotic nondisjunction

    • homologous chromosomes fail to segregate at anaphase I and lead to haploid cells with abnormal number of chromosomes(meiosis I)

    • sister chromatids fail to separate and leads to half of the haploid cells with abnormal chromosomes(meiosis II)

    • loss or gain of one or more chromosomes

  • Having a set of three chromosmes of one kind - Trisomy (2n+1)

  • Having only one of particular type of chromosome - Monosomy(2n-1)

  • The loss of both pairs of homologous chromsomes Nullisomy (2n-2)

  • Chromosomes are inherited from one parent only Disomy (n+1)

Cause of Nondisjunction

Cellular Differentiation and Stem Cells

Cellular differentiation

  • all cells in the body strts at fertilized egg with unique genetic expression

  • It needs to manipulate genes that will be expressed and developed

    • This is done through transcription factors: one of a class of proteins that bind to specific genes on the DNA molecule promoting or inhibiting transcription.

Stem Cells

  • type of cell that can be directed to become a specialized cell.

  • can divide without limit as needed under specific conditions

Two types of stem cells

  1. Embryonic stem cells

  2. Adult stem cells

Sexual Reproduction v. Asexual Reproduction

Telomeres- Protective caps on chromosomes

  • consists of DNA associated with proteins in chromatins

  • might be involved in both aging and cancer

  • the same sequences of bases repeated over & over

  • Telomere sequence in humans: TTAGGG

Function of telomere

  • help organize 46 chromosome in the nucleus

  • DNA is left undamaged in the chromosome during DNA replication

  • Important DNA would be lost everytime a cell divides without a telomere

    • Leads to the loss of entire genes

Karyotypes and Nondisjunction

Karyotypes: individual’s complete set of choromosomes

Nondisjunction: cell division during which sister chromatids fail to separate properly

  • occurs in any organism in which gametes are produced through meiosis

  • associated with serious human disorders

Outcomes of nondisjunction:

  • it leads to daughter cells with abnormal numbers of chromosomes, known as aneuploidy

Two types of nondisjunction:

  • Mitotic nondisjunction

    • occurs in anaphase when sister chromatids fail to separate

  • Meiotic nondisjunction

    • homologous chromosomes fail to segregate at anaphase I and lead to haploid cells with abnormal number of chromosomes(meiosis I)

    • sister chromatids fail to separate and leads to half of the haploid cells with abnormal chromosomes(meiosis II)

    • loss or gain of one or more chromosomes

  • Having a set of three chromosmes of one kind - Trisomy (2n+1)

  • Having only one of particular type of chromosome - Monosomy(2n-1)

  • The loss of both pairs of homologous chromsomes Nullisomy (2n-2)

  • Chromosomes are inherited from one parent only Disomy (n+1)

Cause of Nondisjunction

Cellular Differentiation and Stem Cells

Cellular differentiation

  • all cells in the body strts at fertilized egg with unique genetic expression

  • It needs to manipulate genes that will be expressed and developed

    • This is done through transcription factors: one of a class of proteins that bind to specific genes on the DNA molecule promoting or inhibiting transcription.

Stem Cells

  • type of cell that can be directed to become a specialized cell.

  • can divide without limit as needed under specific conditions

Two types of stem cells

  1. Embryonic stem cells

  2. Adult stem cells

robot