Both Versions, Part 3 › Don’t worry about the start codon! Quiz A, part 2 # 1 = just the bottom (ACG) # 2 = only 1! # 3 = whole thing #4 = many! Quiz B, part 2 # 1 = many! # 2 = whole thing # 3 = only 1! #4 = just the bottom (ACG)

 What are the two main types of mutations we discussed?  How are these mutations different?  What are examples of each? April 14, 2010 Bellringers

 What are the two main types of mutations we discussed? › Frameshift › Point/Substitution  How are these mutations different? › Frameshift – changes reading frame for amino acids › Point- changes only one base, may or may not change amino acids

 What are examples of each? › Frameshift – insertion/deletion of base › Point – nonsense (makes an early stop codon), missense (changes 1 amino acid)

How do little elephants grow up to be BIG elephants?

The process of asexual cell reproduction (called mitosis) begins after a sperm fertilizes an egg. Body cells are DIPLOID They have 2 copies of each chromosome, one from mom and one from dad

All the cells DNA is found in the cell nucleus in structures called chromosomes Cell Division

When cells divide, the chromosomes appear, divide and separate

Cell Division Two new cells form with identical chromosomes to the original cell

Somatic cells: body cells (non-reproductive cells) Every one of the billions of cells that make up the human body have 46 chromosomes (23 pairs) in their nuclei. 46

Cell Division 46 What will be the result of this cell dividing by MITOSIS ? ? The cell divides ONCE TWO identical cells form Daughter cells have SAME number of chromosomes as parent

Cells that are not somatic cells are called Sex Cells (Gametes)  These are HAPLOID, they only have one copy of each chromosome › Each gamete will meet with another gamete to make a new diploid organism  They do NOT go through the process of mitosis to divide.  Exs: Sperm and egg cells!

More about chromosomes Chromosomes consist of a chromatid and centromere chromatid centromere

These are called SISTER CHROMATIDS. They are EXACTLY alike. centromere chromatid chromatid More about chromosomes When cells divide, chromosomes appear as 2 chromatids and a centromere holding them together.

3 main stages 1. INTERPHASE 2. MITOSIS 3. CYTOKINESIS Enzymes control the cell cycle and check the cell as it goes thru each stage. If there is a problem, the cell will not be allowed to continue in the cycle until the problem is fixed. Sometimes these enzymes get messed up and cell division becomes uncontrollable. This is called cancer.

 Occurs before mitosis (cell division)  3 parts › G 1 = Gap 1 = GROWTH  Normal cell functions (protein being made!)  Organelles multiply › S = Synthesis = DNA replicates  This creates the SISTER CHROMATIDS (exact copies of DNA strand) › G 2 = Gap 2 = final preparations for mitosis

Animal Cell Plant Cell Photographs from:

Animated Mitosis Cycle Prophase Metaphase Anaphase Telophase & Cytokinesis

Chromatin (DNA) coils and chromosomes become visible Easier to move DNA if it is condensed! Sister Chromatids form X shape Centrioles appear and begin to move to opposite ends (poles) of the cell. Animal cells only! Spindle fibers appear from centrioles Nuclear envelope and nucleolus disappear by end of this phase.

Animal Cell Plant Cell Photographs from: Spindle fibers

Chromosomes line up in center Spindle fibers attach to centromeres Centrioles Spindle fibers

Animal Cell Plant Cell Photographs from:

Centromeres split Chromatids separate and begin to move to opposite ends of the cell. Cell membrane pinches in SLIGHTLY Centrioles Spindle fibers

Animal Cell Plant Cell Photographs from:

Spindle fibers break down Nuclear membrane forms around two new nuclei. Chromosomes unwind (now called chromatin) One copy of each chromatid in each daughter cell Nuclei Chromatin

Animal Cell Plant Cell Photographs from:

Cytoplasm and organelles are separated Cell membrane pinches in center to create two daughter cells – each with its own nucleus with identical chromosomes. In plants a “cell plate” forms between the cells, this becomes the cell wall Daughter cells: genetically identical to parent cell!

MITOSIS MITOSIS Original Cell Divides to form TWO new cells with the SAME number of chromosomes. These daughter cells are genetically identical to the parent and each other.

Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

I I nterphase P P rophase M M etaphase A A naphase T T elophase C C ytokinesis IPMATC I Pray M ore At T he Church

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Where does it happen? - All cells -Eukaryotes: nucleus -Prokaryotes: cytoplasm

Why and when does it happen? -to prepare the cell for mitosis - to make daughter cells with the exact same DNA as old cells - happens during Interphase (S = synthesis)

How does it happen? 1.enzymes help DNA unwind and unzip 2. other enzymes help free nucleotides attach to the appropriate bases (A-T, C-G) 3. Two identical DNA strands are made DNA replication #1 DNA replication #2

You are creating a flip book to show mitosis is a CONTINUOUS process as opposed to separate steps with no in between. 1.Start by drawing the END of each phase 2.Then, draw inside the cells to show how the cell gets from interphase to the end of prophase, from prophase to the end of metaphase, etc. 3.You MUST include the following in your diagrams (in appropriate phases) 2 sets of chromosomes (each a different color) Total of 4 chromosomes, each daughter cell should have 2 of each color! Nuclear membrane Centrioles Spindle fibers Cell membrane Nucleolus At least 1 other organelle (mitochondria, ER, etc) 4.Lastly, on the back of your drawings, write a couple notes describing what your picture is showing! 5.Cut out each page, put them in order, and staple one side. Flip through it to see mitosis!