Cell Replication and Genetics

Cell Replication

What is cell replication? The process of duplicating or making a copy of itself. The process of duplicating or making a copy of itself. Also called cell reproduction or mitosis Also called cell reproduction or mitosis

Why do cells go through cell replication? Organism growth Organism growth Repair Repair To copy DNA information to other cells To copy DNA information to other cells Creating offspring Creating offspring

Chromosome Structures in the nucleus that contain the hereditary material (DNA) of all cells. Structures in the nucleus that contain the hereditary material (DNA) of all cells. Most “normal” humans have 23 pairs of chromosomes Most “normal” humans have 23 pairs of chromosomes The 23 rd pair determines the gender of the person The 23 rd pair determines the gender of the person How many total chromosomes does each cell contain? How many total chromosomes does each cell contain?

Cell Cycle A series of events that takes place from one cell division to the next A series of events that takes place from one cell division to the next Varies from cell to cell (20 minutes in growing animal embryos – 19 hours in some plants) Varies from cell to cell (20 minutes in growing animal embryos – 19 hours in some plants) What else has cycles? What else has cycles?

7 - Cell Division The Cell Cycle 7

Mitosis Process in which the nucleus of a cell divides to form two identical cells. Process in which the nucleus of a cell divides to form two identical cells. During Mitosis the cell will go through 5 phases (or steps) During Mitosis the cell will go through 5 phases (or steps)

Phase of Mitosis Interphase Prophase Metaphase Anaphase Telophase & Cytokinesis

Interphase occurs before mitosis begins Chromosomes are copied (# doubles) Chromosomes are copied (# doubles) Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase CELL MEMBRANE Nucleus Cytoplasm

Interphase Animal Cell Plant Cell Photographs from:

Prophase 1 st step in Mitosis Mitosis begins (cell begins to divide) Mitosis begins (cell begins to divide) Centrioles (or poles) appear and begin to move to opposite end of the cell. Centrioles (or poles) appear and begin to move to opposite end of the cell. Spindle fibers form between the poles. Spindle fibers form between the poles. Centrioles Sister chromatids Spindle fibers

Prophase Animal Cell Plant Cell Photographs from: Spindle fibers Centrioles

Metaphase 2 nd step in Mitosis Chromatids (or pairs of chromosomes) attach to the spindle fibers. Chromatids (or pairs of chromosomes) attach to the spindle fibers. Centrioles Spindle fibers

Metaphase Animal Cell Plant Cell Photographs from:

Anaphase 3 rd step in Mitosis Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Centrioles Spindle fibers

Anaphase Animal Cell Plant Cell Photographs from:

Telophase 4th s tep in Mitosis Two new nuclei form. Two new nuclei form. Chromosomes appear as chromatin (threads rather than rods). Chromosomes appear as chromatin (threads rather than rods). Mitosis ends. Mitosis ends. Nuclei Chromatin

Telophase Animal Cell Plant Cell Photographs from:

Cytokinesis occurs after mitosis Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes. Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

REMEMBER! Prophase Metaphase Anaphase Telophase Cytokinesis IPMATC I Pray M ore At T he Church

Chapter 4 : Section 2 Sexual Reproduction & Meiosis P. 98

Types of Reproduction Sexual Sexual –Requires two organisms (or cells) to create an offspring –Ex. Humans, mitosis Asexual Asexual -Requires only one organism (or cell) to create an offspring -Ex. Bacteria, starfish, potatoes, hydra, meiosis

Types of Asexual Reproduction Budding Budding –Offspring growing from a parent organism –Ex. hydra Regeneration Regeneration –The ability of an organism to regrow damaged or lost body parts. –Ex. Starfish

Sexual Reproduction When two gamete cells join to make another cell When two gamete cells join to make another cell

Gametes Males = Sperm Males = Sperm Females = Egg Females = Egg The joining of an egg and a sperm to create a single-celled zygote. Fertilization = The joining of an egg and a sperm to create a single-celled zygote.

Haploid vs. Diploid cells Diploid When cells have pairs of chromosomes When cells have pairs of chromosomes Ex. Most typical human body cells Ex. Most typical human body cells (23 pairs = 46 total) (23 pairs = 46 total)Haploid Means “single-form” Means “single-form” When cells have one set of chromosomes When cells have one set of chromosomes Ex. Human gametes (sperm & egg) each have 23 chromosomes Ex. Human gametes (sperm & egg) each have 23 chromosomes

Blastula A zygote replicates to become a groups of cells called a blastula. The blastula eventually becomes an organism. A zygote replicates to become a groups of cells called a blastula. The blastula eventually becomes an organism.

Why are gametes haploid?

Meiosis Haploid cell Replication Haploid cell Replication 1 parent cell creates 4 daughter cells 1 parent cell creates 4 daughter cells Each daughter cell has 23 chromosomes Each daughter cell has 23 chromosomes

Why Meiosis? Recombination of chromosomes to pass on to offspring Recombination of chromosomes to pass on to offspring Each gamete cell has to go through the division process twice in order for the cell to end up with half the number of chromosomes. The cells pass on genetic information to the offspring. Each gamete cell has to go through the division process twice in order for the cell to end up with half the number of chromosomes. The cells pass on genetic information to the offspring.

Phases of Meiosis Using p. 100, identify each phase of Meiosis Using p. 100, identify each phase of Meiosis

Compare and Contrast MitosisMeiosis