Cell Division and Types of Reproduction

Cell Division At times, cells need to divide Divide = split and make copies There are actually different types of cell division

Types of Cell Division Binary Fission Only for Prokaryotic cells Binary = two Fission = Split Binary Fission = Split in two Only for Prokaryotic cells

Types of Cell Division 2. Mitosis Only for Eukaryotic Cells Makes 2 identical cells New cell is exactly the same. Has the same DNA, does the same function (job) Used for: Healing Growing Replacing old cells

Stages of Mitosis Mitosis occurs in a series of steps. These steps are: Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

Stages of Mitosis Interphase Interphase is the longest stage This is when the cell functions normally The cell is growing during this time The DNA of the cell with replicate (copy itself) and the DNA will condense into chromosomes during this stage

Stages of Mitosis Prophase The chromosomes condense even more. Chromosomes can now be seen under a microscope Nucleus dissolves and is no longer visible

Stages of Mitosis Metaphase The duplicated chromosomes line up in the middle of the cell Spindle fibers (long proteins) connect to the centre of each chromosome

Stages of Mitosis Anaphase The duplicated chromosomes are pulled apart to opposite sides of the side The chromosomes are identical and the exact same genetic information is being moved to each side of the cell

Stages of Mitosis Telophase The separated chromosomes arrive at opposite ends of the cell The nucleus begins to reform around the chromosomes Chromosomes become less condensed.

Stages of Mitosis Cytokinesis When the cell actually splits into 2 daughter cells Animal Cells – cell membrane pinches in, in the middle to divide the 2 nuclei Plant Cells – new cell wall forms between nuclei

Types of Cell Division Meiosis Only in Eukaryotic Cells Meio = lessen (decrease) osis = action Meiosis = action that lessens Only in Eukaryotic Cells Makes sex cells Sperm and eggs Makes 4 different cells Each cell has different DNA Each cell has half of the original cell’s DNA A human sex cell has 23 chromosomes. No pairs.

Stages of Meiosis Meiosis occurs in a series of steps. These steps are: Interphase Prophase-1 Metaphase-1 Anaphase-1 Telophase-1 Prophase-2 Metaphase-2 Anaphase-2 Telophase-2

Stages of Meiosis Interphase Prophase - 1 Same as Mitosis Chromosomes find their Homologous Pairs Chromosome #1 pairs up with the other Chromsome #1. Chromosome #2 pairs with Chromosome #2.

Stages of Meiosis Metaphase - 1 Anaphase – 1 Homologous pairs line up in the middle of the cell and attach to spindle fibers Anaphase – 1 Homologous pairs pulled to opposite sides of the cell One side has a Chromosome number 1, the other side has the other Chromosome number one Get different combinations of chromosomes every time meiosis occurs

Stages of Meiosis Telophase - 1 Prophase – 2 Cell divides into 2 daughter cells by cytokinesis Nucleus reforms Prophase – 2 Resting period Nucleus dissolves

Stages of Meiosis Metaphase 2 Anaphase 2 Chromosomes line up in the middles of the cells Spindle fibers attach Anaphase 2 Chromosomes pulled apart to opposite sides of the cells

Stages of Mitosis Telophase - 2 The separated chromosomes arrive at opposite ends of the cells The nucleus begins to reform around the chromosomes Chromosomes become less condensed. Creates 4 gametes – cells with ½ the DNA of the original cell Gametes = sex cells, also called sperm and eggs

Types of Reproduction There are 2 mains types of reproduction that living things can use to reproduce Asexual Reproduction Offspring (child) has same DNA as the parent Sexual Reproduction Offspring has a mix of DNA from both the mother and the father.

Asexual Reproduction New organism is produced with DNA from 1 parent Done through Binary Fission or Mitosis

Types of Asexual Reproduction Bacteria Use Binary Fission Single Eukaryotic Cells Use Mitosis Plants New plant starts from old plants leaves, roots, or stems Example – Starting a bamboo plant from a leaf Uses Mitosis Animals Called Budding New living grows off the parent like a ‘bud.’ Eventually develops into a mature, independent living thing.

Sexual Reproduction New living thing produced using DNA from 2 parents Only in Eukaryotic living things Combines sex cells to make new living thing New living thing has half DNA from mother, half DNA from father When sperm and egg combine, it is called Fertilization New formed cell is called a zygote

Types of Sexual Reproduction External Fertilization Egg and sperm combine outside of mother’s body New living things develops outside of body in an egg Examples – fish, coral, octopi, squid, etc. use this method. Most animals that live in water use this method of fertilization

Types of Reproduction Internal Fertilization Egg and sperm combine inside mother’s body New living thing sometimes develops inside mother Example – humans, mammals Mother sometimes will lay egg. Example – chicken, reptiles, Most land animals use internal fertilization

Questions A human embryo (developing baby) starts as one cell. It divides to grow. Would it use binary fission, mitosis, or meiosis? An E.coli bacteria is dividing. What process would it use? A jellyfish can make an exact copy of itself by budding off copies instead of using sexual reproduction. Would a jellyfish need to undergo meiosis? Explain why or why not. (3 marks) What are the differences between mitosis and meiosis? Create an expression to help you remember the phases of Mitosis. Example of an expression – remember the order of the planets by saying: My Very Educated Mother Just Saw Uncle Nick 

Questions What are the differences between sexual and asexual reproduction? What are the similarities between sexual and asexual reproduction? A trembling aspen is reproducing using asexual reproduction. What differences would there be between its DNA and its offspring’s DNA? Explain. Which would create more genetic diversity (differences in the offspring's genetic material) amongst species? Asexual or sexual reproduction? Explain.