BIOLOGY 111. CHAPTER 9: The Links in Life s Chain Genetics and Cell Division

BIOLOGY 111 CHAPTER 9: The Links in Life s Chain Genetics and Cell Division

The Links in Life s Chain: Genetics and Cell Division 9.1 An Introduction to Genetics 9.2 An Introduction to Cell Division 9.3 DNA in Chromosomes 9.4 Mitosis and Cytokinesis 9.5 Cell Division in Plants and Bacteria

Genetics and Cell Division: An introduction to Genetics DNA contains what is known as an organism's genome: the complete collection of that organism's genetic information. An organism s genome exists as long polymers of DNA and protein that exist as a set of chromosomes. Packaging huge amounts of DNA as separate chromosomes makes the copying and sorting of DNA much easier Different species have different numbers of chromosomes.

Genetics and Cell Division: An introduction to Genetics Chromosomes are structures made of DNA and protein (chromatin) that compact DNA into manageable sized pieces.

Genetics and Cell Division: An introduction to Genetics Chromosomes break up huge lengths of DNA into shorter more manageable lengths Humans have 23 different chromosomes Humans are diploid, meaning they have 2 versions of each chromosome one from mom, and one from dad

DNA: A Review The DNA Double Helix is simply the way in which double stranded DNA is arranged. There are two strands of DNA that are held together by hydrogen bonds. Each strand of DNA is made up of 4 different nucleotides that are joined together by phosphate molecules

Genes and Protein Synthesis: A Review Genetic information exists in units called genes that lie along DNA's double helix.

Genes and Protein Synthesis: A Review Genetic information exists in units called genes that lie along DNA's double helix. Genes carry the code to make proteins. A human genome may have as many as 23,000 different genes.

An Introduction to Cell Division Cells reproduce by dividing in to 2 new cells. (cells come from cells) Why do cells need to divide (reproduce)? Organisms grow by adding more cells, not by making cells larger Some cells eventually die and need to be replaced Sometimes new types of cells are needed

An Introduction to Cell Division If 1 cell divides into 2 cells, do they eventually run out of organelles, DNA and other cellular components? No Before a cell divides, it copies everything inside first. Then it can divided into two identical cells This chapter focuses on how chromosomes are copied and then separated into two new cells

How Do Chromosomes Get Copied? Each of the chromosomes is replicated into an identical copy. These two identical copies are joined in the center and are called Sister Chromatids

How Do Chromosomes Get Copied? DNA must be copied accurately before the cell can divide! The copying of DNA is called DNA Replication. DNA Replication is Semiconservative - Half of the two new chromosomes is from the original strand, and half is newly synthesized

How Do Chromosomes Get Copied? DNA must be copied accurately before the cell can divide! The copying of DNA is called DNA Replication. The enzyme that joins nucleotides together is called DNA Polymerase

DNA Replication

DNA in Chromosomes Chromosomes must be copied before a cell divides When Chromosomes are copied they form.

DNA in Chromosomes Chromosomes must be copied before a cell divides When Chromosomes are copied they form Sister Chromatids Chromosomes are often depicted in this form

DNA in Chromosomes Humans are, meaning we have two homologous pairs of chromosomes.

DNA in Chromosomes Humans are diploid, meaning we have two homologous pairs of chromosomes. Each parent donates one of the homologues in the pair. The homologous pairs are not identical, but are very similar they carry the same genes

DNA in Chromosomes The 23 rd pair are not very homologous These are the, sex Chromosomes

DNA in Chromosomes The 23 rd pair are not very homologous These are the X and Y, sex Chromosomes The other 22 pairs are called

DNA in Chromosomes The 23 rd pair are not very homologous These are the X and Y sex Chromosomes The other 22 pairs are called Autosomes

The Links in Life s Chain: Genetics and Cell Division 9.1 An Introduction to Genetics 9.2 An Introduction to Cell Division 9.3 DNA in Chromosomes 9.4 Mitosis and Cytokinesis (The Cell Cycle) 9.5 Cell Division in Plants and Bacteria

The Cell Cycle: Interphase (3 steps) Mitosis (4 steps) Normal Operations Preparing to Divide Copying Chromosomes Cytokinesis Separating Chromosomes Cell Division

The Cell Cycle: Interphase (3 steps) Mitosis Cytokinesis Mitosis (4 steps) Cytokinesis Interphase

The Cell Cycle: INTERPHASE (3 steps) G1 = Normal cell operations S = Chromosomes replicated (synthesis) G 2 G2 = Preparing for Mitosis S G 1 Interphase

The Cell Cycle: Mitosis: The 4 steps of Mitosis separate the sister chromatids Mitosis Cytokinesis Interphase

The Cell Cycle: CYTOKINESIS: Mitosis is followed by cytokinesis. Mitosis Cytokinesis This finally separates the dividing cell into 2 identical cells. Interphase

Mitosis and Cytokinesis: MITOSIS Mitosis (4 steps) Prophase = Chromosomes condense, Nuclear Envelope breaks down, and the Spindle starts to form. Metaphase = Spindle aligns Sister Chromatids at Metaphase Plate Anaphase = Sister Chromatids are pulled apart one to each side Telophase = Chromosomes unpack, Nuclear envelopes reform and the Spindle breaks down

Mitosis and Cytokinesis: MITOSIS

The Cell Cycle: Mitosis Beads Mitosis and Meiosis: http://youtu.be/zgvbahasjjm Comparing Mitosis and Meiosis: http://www.youtube.com/watch?v=ba9lxkh2ztu&sns=em

Cell Division in Plants and Bacteria Eukaryotic cells have numerous chromosomes and need Mitosis to sort out chromosomes that duplicate when cells divide Bacteria are very simple, and only have one chromosome. So They don t need mitosis to sort out chromosomes. This means they can reproduce very rapidly! Bacterial Cell Division: Link