Heredity and Reproduction MYP 2

What is Sexual Reproduction? Sexual Reproduction is a type of reproduction in which the genetic materials from two different cells combine, producing an offspring. It’s a combination of sex cells, an egg and a sperm, that comes from the sex organs. Fertilization is when these cells come together. The new Cell that forms is a zygote

Diploid Cells The zygote goes through mitosis and cell division. Mitosis is cell reproduction that takes place in body cells and makes nearly all of the cells in a multicellular organism aka YOU! Organisms that produce sexually have 2 types of cells: Body Cells and Sex Cells. All cells carry Chromosomes, Body Cells carry all of the Chromosomes, sex cells carry only half

Different Cells Body Cells Sex Cells Diploid: Carry both copies of a chromosome For example Humans have 46 chromosomes Haploid: Carries only one copy of each Chromosome Human Sperm has 23 Chromosomes Human Egg Cells 23 Chromosomes

Body Cells vs Sex Cells Diploid CELLS Haploid Cells

What are Chromosomes? Chromosomes Carry all of your genetic material. Homologous Chromosomes are pairs of chromosomes that have genes for the same traits arranged in the same order. The genes maybe for the same trait but not be exactly the same You get from an Egg and from a sperm (Blue eyes; Brown Eyes) They are located at the same place but code for different variations

Chromosomes

Chromosomes

Mitosis and Meiosis Mitosis takes place in the body cells Meiosis takes place in the sex cells Mitosis has 4 stages: Prophase, Metaphase, Anaphase, and Telophase Then it goes through cytokinesis to split the cell Mitosis leaves you with Identical 2 daughter cells that have a Diploid number of Chromosomes Meiosis has Prophase 1, Metaphase 1, Anaphase 1, Telophase 1, Prophase 2, Metaphase 2, Anaphase 2, Telophase 2 Meiosis leaves you with 4 Non-Identical Cells with A haploid Number of Cells

Mitosis Prophase : Duplicated chromosomes condense and thicken. Homologous Chromosomes come together and form pairs. Metaphase : Chromosome pairs lineup along the middle of the cell. A spindle Fiber attaches to each chromosome. Anaphase : Chromosome Pairs separate and are pulled toward the opposite ends of the cell. Telophase : A nuclear membrane forms around each group of duplicated chromosomes. Cytoplasm divides through Cytokinesis and 2 Identical daughter cells Form.

Mitosis

Meiosis Prophase 1: Duplicated chromosomes condense and thicken. Homologous Chromosomes come together and form pairs. Metaphase 1: Chromosome pairs lineup along the middle of the cell. A spindle Fiber attaches to each chromosome. Anaphase 1: Chromosome Pairs separate and are pulled toward the opposite ends of the cell. Telophase 1: A nuclear membrane forms around each group of duplicated chromosomes. Cytoplasm divides through Cytokinesis and 2 daughter cells Form.

Meiosis Prophase 2: Chromosomes are not copied again. They remain as condensed, thickened sister chromatids. Metaphase 2: The pairs of sister chromatids line up along the middle of the cell in single file. Anaphase 2: The sister Chromatids of each duplicated chromosome are pulled away from each other and move toward opposite ends of the cells. Telophase 2: During the Final phase of meiosis a nuclear membrane forms around each set of chromatids, which are again called chromosomes. The cytoplasm divides through cytokinesis and four non-identical haploid cells.

Meiosis

Mitosis vs Meiosis

Why is Meiosis Important? Without Meiosis There would be no way for us to remain the species that we are Meiosis gives us half of the chromosomes so when sexual reproduction takes place we have the correct number of chromosomes. In some cases Meiosis does not occur properly and it results in genetic defects like Trisomy 21 and 13. This means that an error may occur during anaphase 2.

Advantages of Sexual Reproduction Main advantage is that we inherit half of our DNA from the Sperm and half of the DNA From the Egg. Genetic Variation is what takes place because of this. The inheritance of one trait does not influence the inheritance of another and this is called independent assortment. This can give some organisms and advantage or disadvantage if the environment around them changes. Selective breeding can take place aka artificial Selection

Selective Breeding

Disadvantages of Sexual REproduciton IT takes time and energy Searching for mates can expose them to predators, disease, or harsh environments Reproduciton is limited due to pregnancy Fertilization can’t happen when an animal is pregnant Some mammals are pregnant for 2 years

What is Asexual Reproduction? One parent organism produces offspring without meiosis and fertilization. That means that the parent and the offspring have the exact same genetics.

Types of Asexual Reproduction Fission is one form It’s a cell dvision that takes palce in prokaryotes and causes two genetically identical cells. The DNA is copied and attaches to the cell membrane and then the cell expands until it makes two cells.

Types of Asexual Reproduction Budding is when a new organism grows by mitosis and cell division on the body of its parents.

Types of Asexual Reproduction Animal Regeneration occurs when an offspring grows from a piece of its parent.

Types of Asexual Reproduction Vegetative Reproduction- the offspring grows from a part of the parent plant.

Cloning A type of asexual reproduction performed in a laboratory that produces identical individuals from a cell or from a cluster of cells taken from a multicellual organism. Can be done in plants and Animals Plant clonig is done to get desireable traits for plants and fruits Animal clonig being done to try and save endangered species

Cloning

Asexual Reproduction Advantages Disadvantages Reproduce without a mate Rapidly produce offspring No genetic variation Mutations will be passed on