CELL CYCLE & MITOSIS

CELL CYCLE & MITOSIS Chapter 5.1-5.2

INTERPHASE Division of the cell nucleus and its contents Gap 1 (G1) Cell grows, carry out normal functions, replicate organelles Cytokinesis Telophase Mitosis (M) Anaphase Metaphase Synthesis (S) Prophase DNA is copied in the nucleus Gap 2 (G2) MITOSIS Cells carry out normal functions and grow more

DNA condenses tightly during the early stages of mitosis

One half of a duplicated chromosome Ends of DNA molecules that are made of repeating nucleotides that do not form genes. They help prevent the loss of genes during replication Holds together the sister chromatids

E Interphase Cell Membrane Nucleolus Centrioles Chromatin • The cell copies its DNA and grows in preparation for cell division • The DNA is loosely organized

A Prophase Centriole (aster) Nuclear membrane Chromosome • DNA condenses into chromosomes • Nuclear envelope breaks down • Centrioles begin to move to opposite poles and asters form from them • Spindle fibers grow from the centriole asters

B Metaphase Spindle fibers • Spindle fibers attach to each chromosome • Spindle fibers align the chromosomes along the center of the cell

C Anaphase Chromatids • Chromatids separate and are pulled to opposite sides of the cell by shortening spindle fibers

D Telophase/ Cytokinesis Daughter cells • Nuclear membranes start to form • Chromosomes begin to uncoil • Spindle fibers begin to fall apart • CYTOKINESIS: Divides the cytoplasm into 2 daughter cells, each with a genetically-identical nucleus

REGULATION OF THE CELL CYCLE Chapter 5.3

Regulation of the Cell Cycle • External Factors (outside of the cell) • Physical: cell-to-cell contact • Chemical • Growth factors – proteins that tell a cell when to grow • Internal Factors (inside of the cell) • Cyclins & kinases • Proteins inside of the cell that regulate cell division • Apoptosis • Programmed cell death

Cancer • Class of diseases that are characterized by uncontrolled cell division • Can occur in any type of cell (liver, blood, bone, skin, lymph) • Results in the formation of a tumor: • Cluster of cells undergoing uncontrolled growth

Cancer • Tumor categories: • Benign – non-cancerous cluster of cells • Malignant – cancerous cluster of cells • Can metastasize (SPREAD) to other areas of the body

Causes of Cancer • Cancer cells develop from normal cells that have suffered damage to the genes that make proteins to control cell growth • Mutations = errors • Carcinogens • Substances that promote the development of cancer • UV radiation, cigarette smoke, air pollution

Cancer – Why is it so deadly? • Cells require food, oxygen and space to grow • Space and nutrients are limited so cell growth is regulated. • Cancer cells don’t follow the rules • Consume all the food and oxygen • Take up all the space • Don’t perform the function that they were supposed to perform if they were a normal cell • If left alone, they will keep growing until they kill the organism.

ASEXUAL REPRODUCTION Chapter 5.4

Asexual Reproduction • The creation of an offspring from a single parent that does not involve the joining of gametes (sex cells – sperm & egg) • Mitosis is a type of asexual reproduction • A single cell divides and creates 2 daughter cells with identical genes (same number of chromosomes) • Some eukaryotic cells reproduce through mitosis • Simple plants & animals (sea stars, flatworms, yeast)

Binary Fission • Most prokaryotic cells (bacteria) reproduce through binary fission • Differences from mitosis: • Bacteria have no nucleus • Bacteria have less DNA • Bacteria do not have centrioles or spindle fibers

PATHOGENS & HUMAN ILLNESS Chapter 31.1

Types of Pathogens • Viruses – non-living • Bacteria – prokaryotic, single-celled • Fungi – eukaryotic, single/multi-celled • Protozoa – eukaryotic, single-celled • Parasites – eukaryotic, multi-celled • All cause disease by attacking healthy cells • Method of attack can be very different

Bacteria • 1 billion types of bacteria • 1030 bacterial cells on Earth • Live everywhere – in rocks, deserts, polar ice caps • Single-celled, prokaryotic organisms • Do not have organelles • NO nucleus • DNA sits in the cytoplasm

Bacterial Structure Cocci = spheres Bacilli = rods Move with flagella: Whip-like tail Pili: – short spikes that help bacteria stick to surfaces and to other prokaryotic cells

Germ Theory • The theory that specific microbes cause disease • Four Conditions (Koch’s Postulates) • Pathogen thought to cause disease must be present in every case where the disease is found. • Pathogen must be isolated and grown outside of the body in pure uncontaminated culture • Healthy animals infected with pure culture must get the disease • The pathogen must be re-isolated and cultured from the newly sick animal and it must be identical to the original pathogen.

MULTICELLULAR LIFE &HUMAN IMMUNE SYSTEM Chapter 5.5 Chapter 32.2-32.4

Multicellular Life -- Levels of Organization Molecules And Compounds Macromolecules (carbohydrates, proteins, lipids, nucleic acids) Atoms Organism Organ Systems Organelles Cells Tissues Organs

Immune System • Body system that fights off infection and pathogens • First line of defense = Barriers (skin) • Second line • White blood cells • Phagocyte: eat pathogens • T Cells: destroy infected body cells • B Cells: produce proteins to attack the pathogens • Antibodies- proteinsmade by B cells • Bind to pathogens and “mark” them for destruction • Very specific

Immune Responses • NONSPECIFIC – Same for every pathogen • Inflammation • Swelling, redness, pain, itching & increased warmth at the affected site • Allows white blood cells to reach infection site • Fever • Increase in body temperature • Speeds up pathogen destruction

Immune Responses • SPECIFIC – Slightly different for each pathogen • Body must be able to distinguish between its own cells and foreign cells • Antigens: Protein markers on the surface of cells and viruses that help the immune system identify foreign invaders • Detection of the pathogen triggers a specific immune response depending on the pathogen: • Cellular Immunity: T Cells destroy the infected body cells • Humoral Immunity: B Cells produce antibodies that help to destroy pathogens

Antibiotics • Chemicals that kill or slow the growth of bacteria. • ONLY WORK AGAINST BACTERIA • Resistance • Occurs by natural selection: bacteria that are resistant to the antibiotic survive and reproduce • HOW CAN THIS HAPPEN? • Overuse: using antibiotics when NOT needed (cold/flu) • Underuse: not taking all of the drug as prescribed • Misuse: using livestock antibiotics to increase growth rate

Vaccines • Substance that contains the antigen of the pathogen • Produces acquired immunity without harming the body • The immune system creates memory cells that will recognize that invader in the future and it will be prepared to destroy it. • Types: • Dead viruses or bacteria • Weakened (attenuated) viruses or bacteria • “Spare part” vaccines – made of bacteria or viruses pieces • “Toxin” vaccines – made of inactivated bacterial toxins

CELL CYCLE & MITOSIS