Cell Reproduction

Cell Reproduction

CELL REPRODUCTION ??? What is the first thing that would need to replicate before a cell could make an identical copy of itself? DNA!!! DNA must replicate in order for new cells to be made

DNA Chromosomes What is a Chromosome? Tightly coiled units of Chromatin Humans have 46 Chromosomes (23 pairs) What is Chromatin? Tightly packaged DNA Includes proteins to stabilize DNA

Karyotype Map of chromosomes in a cell Humans have 23 pairs (46 total) # of chromosomes does not relate to

complexity Pineapple 25 pairs Carp 52 pairs Chromosome Structure 2 Sister Chromatids joined at the centromere Replication of Chromosomes Occurs when cells multiply

Copies the entire DNA strand Partial or complete replication? Replication of a portion of DNA= protein Synthesis Replication of an entire strand of DNA= replication of Chromosomes DNA Replication Steps

DNA unzips like in the first step of transcription As the DNA unzips, the nucleotides are exposed Free nucleotides base pair with the exposed nucleotides Replication Continued Results in two molecules of DNA. New DNA consists of: One original strand

One new strand http://youtu.be/hfZ8o9D1tus DNA REPLICATION Cell Replication What kind of cells would need to be produced for YOU to survive AND reproduce?

-Diploid cells (complete set of chromosomes) -Haploid cells (half of a set of chromosomes) -Why only half?! For sex cells (1/2 from each parent = 1 whole set) The Cell Cycle Gap Phase 1 (G1) Synthesis Phase (S)

Gap Phase 2 (G2) Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis Interphase

Interphase Overview G1 (Gap 1): Cell grows & functions normally CHECKPOINT S (Synthesis): DNA replication occurs G2 (Gap 2): Cell grows some more CHECKPOINT Checkpoints make sure that the cells are OK (prevents cancer and other mutations)

Cells spend 90% of their time in this phase! Interphase G1 Rapid cell growth Normal cell functions are on going DNA is in the form of chromatin

Interphase S Phase DNA is copied Interphase G2 Phase Increased growth

Preparations are made for the nucleus to divide MITOSIS (Cell Replication) Prophase Metaphase Anaphase

Telophase CELLS SPEND ONLY 10% OF THEIR TIME IN THIS PHASE Mitosis has two basic functions Duplicate the cell Ensure that each daughter cell (identical new cell) has a complete copy of the DNA

The basic steps of Mitosis are: Divide the chromosomes into two complete sets Divide the cell into two daughter cells Stages of Mitosis 1) PROPHASE

Chromatin condenses into Chromosomes (visible under microscope) Centrioles (organelles that makes spindle fibers) move towards opposite ends of the cell

Stages of Mitosis 2) METAPHASE Chromosomes move to the center of the cell and align on the metaphase plate (ensures daughter cells receive one copy of each chromosome) Spindle Fibers attach the

centrioles to the centromere of the chromosome (aligns chromosomes on the metaphase plate) Stages of Mitosis 3) ANAPHASE Sister chromatids (identical half

chromosomes) are pulled apart via the spindle fibers attached to the centrioles and moved to the opposite ends of the cell Stages of Mitosis 4) TELOPHASE

Sister chromatids arrive at opposite ends of the cell Chromatids uncoil back into chromatin (no longer visible) Nuclear membrane reforms

Cytokinesis FINAL STEP IN MITOSIS Cytoplasm divides, creating 2 cells In animals the cell membrane creates a cleavage furrow (extending cell membrane that pinches the cells in two)

In plants a cell plate grows (part of a cell wall that divides the two cells) What happens when Mitosis screws up? Cells may divide uncontrollably and live forever A normal cell goes through Mitosis

about 50 times, then dies CAN RESULT IN CANCER OR A TUMOR Cancer Cancer is a group of more than 100 diseases It can occur in almost every area of the body, including the lungs, breast, skin,

stomach, pancreas, colon, and even (very rarely) the heart Cancer Cancer: Uncontrollable cell division When these faulty cells keep producing they clump together and form a tumor. A benign tumor is abnormal but doesn't invade healthy tissue. A malignant tumor is abnormal and

invades and destroys healthy tissue. Cancer Cancer cells harm healthy tissue, strangle blood vessels, and steal nutrients from healthy cells. Cancer cells also travel. This process is known as metastasis. New tumors grow in these locations as well.

Cancer in Men Cancer in Women Cancer Causes 90% of cancers develop because of complex interactions between our bodies, our lifestyles, our genetic makeup and our environment.

Scientists have discovered different factors that cause cancer. Research shows that tobacco is estimated to cause 30% of all cancer deaths poor diet 35% reproductive and sexual behavior 7% work-related causes 4% environmental causes 3%

Cancer Causes There are about 200 different types of cancer affecting the different body tissues. What affects one body tissue may not affect another. For example, tobacco smoke that you breathe in may help to cause lung cancer. Over exposing your skin to the sun could give you a melanoma on your leg.

But the sun won't give you lung cancer and smoking won't give you melanoma. Carcinogens A carcinogen is something that can help to cause cancer. Tobacco smoke is a powerful carcinogen. Age

Most types of cancer become more common as we get older. Why? The longer we live more chance there are for mistakes in mitosis. There has to be a lot of changes to the genes within a cell before it turns into a cancer cell. The changes can be accidental when the cell is dividing. Or they can happen because the cell

has been damaged by carcinogens and the damage then passes on to future 'daughter' cells. Genetic make up Sometimes we are born with a genetic mutation. This does not mean we WILL get cancer, but the one mutation makes it more likely that we will.

The BRCA1 and BRCA2 breast cancer genes are examples of a mutation. Women who carry one of these faulty genes have a higher chance of developing breast cancer than women who do not. Less than 5% of all breast cancer is due to these genes. Immune System

People who have problems with their immune systems are more likely to get some forms of cancer. This group includes people who: Have had an organ transplant Have AIDS Are born with rare medical syndromes which affect their immunity

Diet Too many animal fats and not enough fresh fruit and vegetables increases your risk of cancer. But how exactly we should alter our diets is not clear. Sometimes foods or food additives are blamed for directly causing cancer but they are in such small amounts that we could never eat enough of it to do any harm. And some additives may actually protect us.

Day-to-day environment This is what is around you each day that may help to cause cancer. This could include: Tobacco smoke The sun Natural and man-made radiation Work place hazards

Such as asbestos Incidence of Lung Cancer (per 100,000/ 2004) Incidence of Ovarian Cancer (per 100,000/ 2004) Viruses

These cancers and viruses are linked: Cervical cancer and HPV Primary liver cancer and the Hepatitis B virus T cell leukemia in adults and the Human T cell leukemia virus Cancer Treatments Effectiveness of any kind of cancer treatment depends on the type of cancer, the location, and the extent that the cancer has spread to other areas of the body.

Surgery and radiation work best when the cancer cells have not spread too much within the body. Chemotherapy uses a variety of anti-cancer drugs that keep the malignant cells from multiplying. Immunotherapy, involves different types of treatments that rely on manipulating a patient's immune system. A relatively new approach to cancer treatment, immunotherapy procedures increase the body's natural ability to destroy malignant cells.

MEIOSIS For creating reproductive cells (sperm, eggs) Halves the number of chromosomes each cell contains of the genetic information required to make an organism When reproductive cells combine during fertilization, a complete set of chromosomes is produced ( + = 1 whole)

MEIOSIS PHASES MEIOSIS 1 Prophase 1 Metaphase 1 Anaphase 1 Telophase 1

MEIOSIS 2 Prophase 2 Metaphase 2 Anaphase 2 Telophase 2 FINAL PRODUCT= GAMETES (eggs or sperm)

Meiosis 1 Prophase 1 Chromosomes condense Synapsis occurs Chromosomes pair up

Crossing over occurs Paired chromosomes swap genes Metaphase 1 Chromosomes align at

the metaphase plate Meiosis 1 Continued. Anaphase 1 Chromosomes move to the opposite cell poles

(sister chromatids remain together) Telophase 1 Each pole has a haploid number of chromosomes Cytokinesis occurs

MEIOSIS 2 Prophase 2 Chromosomes do NOT replicate Chromosomes begin movement towards metaphase 2 plate

Metaphase 2 Chromosomes line up at metaphase 2 plate Meiosis 2 Continued. Anaphase 2 Sister

chromatids separate Telophase 2 Cytokinesis occurs resulting in 4 haploid cells

What happens when Meiosis gets messed up? Genetic diseases may occur Crossing Over Occurs during Prophase 1 of Meiosis Homologous chromosomes (identical chromosomes) line up to form a tetrad and trade pieces of DNA (called crossing over) Allows for independent assortment of genes

Genes are inherited independently of each other Why is crossing over important? Allows for genetic variation among organisms This is why you may look like both your mother and your father, or more like one than the other. This is also why brothers and sisters may look different even though they have the same parents.

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