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Transcript
Chapter 5 The human organism and the perpetuation of life. Topics: The cell and its functions Cell division (mitosis & meiosis) Tissues, organs and systems The Reproductive System About Cells • The cell is the basic unit of structure and function in living things • Cells are usually microscopic, but range from the size of a bacteria to the size of an unfertilized ostrich egg. • Living things contain one or more cells – Protozoans contain a single cell – Humans contain billions of cells CELL PARTS • The various parts of cells are known collectively as CELL PARTS. • Cell parts are structures inside a cell that are too small to be living, but which together allow a cell to live. • Cell parts include: • • • • • Membranes, that surround the cell and nucleus. Filaments, tubules and fibres that Macromolecules, like the DNA of chromosomes. Fluids, like the cytoplasm. Organelles and other structures inside the cell. Three Main Parts of a Cell • A cell usually has three distinct areas or layers: – The membrane – The Cytoplasm & Organelles – The nucleus & Chromosomes Membrane Cytoplasm (with organelles) Nucleus (with chromosomes) Function of the Cell Membrane • The cell membrane is a flexible barrier that that surrounds the cell and allows the cell to interact with its environment – Forms a protective barrier – Helps absorb nutrients and useful substances – Helps eliminate wastes and other materials produced inside cells Drawing of a cell membrane Copy the “simplified diagram” from the blackboard Part 2: The Cytoplasm & Organelles • Together, the cytoplasm and organelles are sometimes called protoplasm – The cytoplasm is the liquid portion of the cell. • It is a complex mixture of materials: water, gases, wastes, nutrients, raw materials – The Organelles • Suspended in the cytoplasm are many tiny structures called organelles. Each organelle has a specific function. The Organelles • Mitochondria (sing. mitochondrion). • Endoplasmic reticulum – Rough – Smooth • • • • Ribosomes Golgi Apparatus Lysosomes Vacuoles Mitochondria • The mitochondrion is the powerhouse of the cell. Here chemical energy is released by the break down of food particles. • It is a bean-shaped organelle with an internal membrane folded into many “cristae” . I am very energetic! And cute as a bean too! Endoplasmic Reticulum • The “ER” or Endoplasmic Reticulum is a network of tubes and membranes that runs through the cell. Its purpose is to transport materials quickly through the cell • Rough ER – Has ribosomes • Smooth ER – Has no ribosomes ER Transport system at your service! For when it absolutely, positively has to get to the ribosomes quick as possible. Ribosomes • Very tiny, round organelles associated with protein synthesis • They help manufacture the cell’s proteins. We are very small, like beads. Sometimes we hang around the endoplasmic reticulum Golgi Apparatus (A.K.A. Golgi body or Golgi complex) • A network of membranes, similar in appearance to the ER • Its purpose is to modify and “package” proteins that will be secreted. • Also makes digestive enzymes I look like sort of like a stack of pancakes with blobs of syrup falling off! Lysosomes & Vacuoles • These are storage areas within a cell • Lysosomes hold digestive enzymes that help the cell metabolize food. When a cell dies, the digestive enzymes help dissolve the dead cell • Vacuoles store food or water Let’s get together I’ve got the digestive enzymes And I’ve got the food And have a feast! Part 3: The Nucleus • The nucleus consists of: – The nuclear membrane or envelope (with tiny nuclear pores in it) – The nucleoplasm – The chromatin material • AKA chromosomes – The nucleolus Hey! I am, like, in control, man! All the organelles get their instructions from me. Exercise • Colour, label and give the functions of the cell drawing. Typical Human Cell A. Cell Membrane B. Smooth ER C. Cytoplasm D. Mitochondrion E. Ribosome F. Nucleus G. Golgi apparatus H. Lysosome I. Endocytosis / Exocytosis J. Nucleoplasm or “matrix” (containing chromatin) K. Nucleolus L. Nuclear membrane “envelope” (with nuclear pores in it) M. Rough ER DNA a helix is a spiral shape, similar to a spring. DNA is a molecule, shaped like a double helix, usually found inside the cell’s nucleus. • Facts about DNA – Chromosomes are made of DNA – Genetic information is stored on DNA – DNA is the only large molecule that is able to copy itself. A Helix • Trivia: – DNA stands for deoxyribonucleic acid. Carbon atom (gray) Hydrogen atom (white) Phosphorus atom (orange) Oxygen atom (red) Nitrogen Atom (blue) Portion of a Model of a DNA Molecule DNA contains carbon, hydrogen, oxygen, nitrogen and phosphorus Simplified drawing of a DNA Molecule The atoms are arranged into a sugar-phosphate backbone, and four types of nitrogen-containing bases. • Some people compare the structure of DNA to a twisted ladder. • The sugar and phosphate form the sides, and the base pairs make the rungs or steps. Genes • A Gene is a segment of DNA that contains the genetic information to carry out a particular job. • That is, to make a particular protein or to control a particular feature. • A Genome is a complete set of genetic information. • Enough information to make a complete body and all the cells in it. • A genome can contain thousands of genes Genetic Diversity • Genetic Diversity is the differences between individuals, achieved by all possible genetic variations of a particular species. • All organisms have different individuals. • The more the differences, the greater the genetic diversity. Assignments • Textbook: • Read pp. 125 to 127 • You may try questions 1 to 7 on p. 152 • Workbook • Do pages 67 to 70 Mitosis & Meiosis Topics: •Mitosis Overview •Meiosis Overview •Mitosis vs. Meiosis Cell Cycle The life of a cell: • Cell grows – Prepares for division (mitosis), – Divides to daughter cells, – Cycle begins again OR • Cell Dies Overview of Mitosis Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase 2 Main Events of the Cell Cycle • Interphase: Cell grows & prepares for Mitosis (see previous slide for diagram) – Prepares 2 ways • Replicates chromosomes • “Tools” for mitosis are produced • Mitosis: Cell divides to form two genetically identical cells – One copy of chromosomes goes into each new cell Mitosis main points • Starts as diploid – two copies of each chromosome (total=46 in humans) • Ends as diploid – One diploid parent cell makes two identical diploid copies of itself. (total=46 in humans) • Very small portion of cell life spent in mitosis (6%) • All living and growing cells undergo mitosis Meiosis Meiosis main points • Meiosis Enables sexual reproduction • Starts with diploid cells – Two of each chromosome type (46 in humans) • Ends with haploid sperm or egg cells. – Only one copy of each chromosome (23 in humans) • Only cells in testicles and ovaries undergo meiosis. • Meiosis increases genetic diversity due to crossing over of genes, and the mixing of two different sets of genes after fertilization Mitosis in Detail • Remember: – Mitosis is normal cell division – It is part of the cell cycle Cell Division (MITOSIS) Phases in the Cell Cycle I PM AT = INTERPHASE Remember: Preparing for Mitosis = PROPHASE = METAPHASE = ANAPHASE = TELOPHASE (and cytokinesis) Where’s It will help my Pee MAT? you keep Undergoing track of the Mitosis 5 main phases of a cell’s life The Cell Cycle G1 S G2 M1 M2 M3 M4 Cytokinesis: Prophase: Metaphase: Interphase: Anaphase: Telophase: The The The The cell nuclear chromosomes Cell chomatids chromosomes splits grows into envelope split and two line the reach into new disapears upDNA new cells near the and the replicates. chromosomes, poles, middle the centrioles new ofThe nuclei theand cell cell migrate begin the prepares new to toform, to opposite (equatorial divide. chromosome the cellpoles prepares plane) migrate of the and to cell split. to spindle fibres opposite attach poles to them . • Mitosis: Short video Interphase • Interphase: Cell prep for mitosis (G1, S, G2) – Cell spends ~94% of life in interphase Photograph of Interphase Stages of Mitosis Prophase: (Prep Phase) • Chromosomes coil and become visible • Nuclear membrane breaks down • Spindle fibers assemble Photo: Early Prophase Chromosomes Stages of Mitosis • Metaphase (Middle) – Chromosomes line up in the middle of cell – Spindle fibers bind to the centromere Photo: Metaphase Spindle (fibers) Centrosome Chromosomes Equatorial Plane Stages of Mitosis • Anaphase (Apart) – Spindle fibers pull chromosomes to opposite sides of the cell Photo: Anaphase Centrosome Chromosomes Stages of Mitosis • Telophase (Two) – Cell begins to split into two cells – Nuclear membranes reform Photo: Telophase & Cytokinesis Cleavage furrow Nucleus forming Cells Divide Stages of Mitosis • Cytokenisis – Cytoplasm is split in half – Each cell has identical chromosomes Annoying Mitosis Song video • During your lifetime, mitosis has created the billions of cells of cells that make up your body. • Mitosis is simple and nearly flawless (errors in mitosis are extremely rare) • Mitosis gives each cell its own copy of all your genetic information (your DNA) • Simple organisms (like the amoeba) can even reproduce by mitosis. If mitosis works so well, why do we need meiosis? • Sexual reproduction helps a species survive. – It allows traits from two individuals to be mixed, giving greater diversity. – Greater diversity gives a species a better chance of surviving hard times. • In order to have sexual reproduction, there must be a way of reducing chromosome numbers. – You have 46 chromosome, your spouse has 46 chromosomes – If meiosis did not occur, your children would have 92 chromosomes – Your grandchildren would have 184 chromosomes – Your great-grandchildren 368, and so on… – This would soon lead to genetic problems like birth defects or bad mutations. • Meiosis strips away half of the chromosomes – In humans this produces eggs and sperm with only 23 chromosomes (instead of 46) • Fertilization restores the chromosomes – When a human egg is fertilized, it gets 23 chromosomes from the mother and 23 from the father, restoring the normal 46 Meiosis G1 S G2 MEIOSIS st 1st1Interphase: Metaphase: Prophase: The The The chromosomes nuclear Cell grows envelope and line the up disapears near DNA the and replicates. middle the centrioles of the Thecell cell migrate prepares to to (equatorial opposite divide. poles plane)ofand thespindle cell fibres attach to them . Meiosis G1 S G2 MEIOSIS cycle 1 11ststAnaphase: Metaphase: The TheWHOLE chromosomes CHROMOSOMES line up near migrate the middle to opposite of the cell poles. They do (equatorial not split yet! plane) and spindle st attach to them . 1fibres Telophase: The chromosomes reach the poles, new nuclei begin to form, the cell prepares to split. Cytokinesis: The cell splits into two new cells Meiosis G1 S G2 MEIOSIS cycle 2 Prophase & Metaphase Anaphase: Telophase: Cytokinesis: The original chomatids chromosomes cellsplit hasreach line into split upnew the into nearfour the middle chromosomes, poles, new cells new of nuclei the andcell begin the new to form, (equatorial chromosome the cell prepares plane) migrate toand split. tospindle fibres attach opposite poles to them . Assignments on Cell Division • Textbook: • Read pages • Try questions 8 to 15 on page 153 • Workbook: • Do pages 71 to 74 Cell Specialization • As your cells divide they also become different from each other. They specialize. • Some cells become blood cells, some become muscles, some become bone cells, and some become brain cells. • A group of similar cells, with a common function, is called a tissue: Levels of Organization Strings? make up Quarks make up Subatomic Particles Atoms make up Molecules make up Macromolecules (like DNA) Cells make up Tissues make up Organs make up Systems Biosphere of our Planet in our Solar System in our Milky Way Galaxy in the Local Galactic Group in the Virgo Supercluster in theUniverse 4 Main Tissue Groups • Although you may have hundreds of tissue types, they all belong to four main groups of tissues • Epithelial Tissues cover and protect your body and its organs. • Connective Tissues bind and support the organs and the body. They also transport oxygen and nutrients. • Nerve Tissues control and guide the body, and communicate between body parts. • Muscle Tissues make body movement possible Epithelial Tissues • Just a few of the many types of epithelial tissue: • • • • • Skin Stomach lining Intestinal lining Arteries and veins Kidney tubules Connective Tissues • There are also many connective tissues, such as: • • • • • Bone tissue Cartilage Tendons & Ligaments Fatty tissues Blood Nerve Tissues • Nerve tissues make up much of: • The Brain • The Spinal Cord • The Nerves Muscle Tissues • There are 3 main types of muscle tissue • Skeletal Muscle: – The muscles attached to bone. They make movement possible. • Smooth Muscle: – Found inside us, smooth muscle pushes things through our organs (peristalsis). • Cardiac Muscle: – Found in the heart, cardiac muscle is very durable. Organs • An organ is a structure composed of two or more tissue types performing one or more specific actions • In other words: it’s a bunch of tissues working together! • Examples of Organs and their function • • • • • Stomach: Intestine: Lungs: Heart: Skin: grinds up food absorbs nutrients absorb oxygen from the air pumps blood protects our bodies Organ Systems • A system is a group of tissues working together to accomplish a common function • Our body has many systems, for example: • Our cardiovascular system which circulates our blood and transports nutrients to cells. • Our nervous system which controls our movements, thoughts, decisions and responses • Our reproductive system, which enables sexual reproduction Examples of Organ Systems (Similar to table on page 139 of Textbook) System Function Cardiovascular Circulates blood, transports nutrients, transports wastes Digestive Breaks down and absorbs nutrients, eliminates solid waste Endocrine Uses hormones to control organ performance. Excretory (Urinary) Eliminates the body’s liquid wastes Immune Protects us against foreign organisms (bacteria, viruses etc.) Lymphatic Helps the immune system to protect us. Drains and excess fluids from the body and filters the fluids back into the blood. Musculoskeletal Provides the body with support, mobility and protection Nervous Controls the entire organism (thoughts, decisions, memories) and relays information to various body parts and interacts with the environment through the sensory organs Reproductive Enables sexual reproduction. Linked to the endocrine system Respiratory Helps the body absorb oxygen and expel carbon dioxide Exercises on Tissues • Textbook: • Read pages 136 to 139 • Try question 16 to 18 on page 153 • Workbook: • Do pages 75 and 76 Reproductive Systems •Puberty •Female: Menstrual & Ovarian Cycles •Male: Erection & Ejaculation •Hormones Puberty • There are major mental and physical changes that occur during your life stages • Humans life stages: – Before birth: zygoteembryofetus then – Birth: babychildadolescent adult and finally an old person • Puberty occurs between childhood and adolescence Puberty cont. • Three categories of change occur at puberty – Anatomical • Shape of body fat, muscles skeletal – Physiological • Genitals mature (external & internal) • Able to procreate – Psychological • Clash with authority • Identity change • Libido (sex drive) Female Reproductive System (internal organs front view) • Ovaries Connected to the uterus by Fallopian tubes • Uterus Also called the womb. Female Reproductive System (internal organs side view) Fallopian Tubes Ovaries Uterus Endometrium Uterine Cervix Vagina Clitoris Female Reproductive System • You have already learned the different parts – so here’s what they do • There are two cycles – Ovarian Cycle • Egg release – Menstrual • Getting your period • Removes and then renews the lining of the uterus Don’t mix them up! • The two cycles occur at the same time, and are often confused with each other, but… • They each rely on different hormones – Ovarian: FSH and LH – Menstrual: Estrogen and progesterone • The Ovarian cycle has to do with releasing eggs. • The Menstrual cycle has to do with preparing the uterus. Ovarian cycle Menstrual cycle • Ovarian cycle, egg released (around day 14) • Body temperature changes slightly during cycles • Hormone levels in blood change. Menstru. Proliferation Phase Secretory Phase • Menstrual cycle: Thickness of the endometrium (uterus lining) grows. (from about day 6 on) The ovarian cycle • All ova (eggs) are produced before a girl is born • The ovarian cycle is simply the release of these eggs – From the ovaries – Every 28 days (approx.) • When a woman begins to run out of eggs, Menopause may occur. • The ovarian cycle stops. • Then the menstrual cycle will change or stop. • Many hormone changes occur. Oogenesis It’s pronounced oh-oh-genesis, not ewww-genesis! • Egg production begins before a woman is even born! – 15 to 28 weeks in utero/fetus, Oocytes (diploid junior egg cells) are produced. – Then wait until puberty to be released one at a time • Each month an oocyte undergoes meiosis to become one haploid ovum (egg cell). Its three “sister eggs” die. The menstrual Cycle • Directly related to the ovarian cycle • Vaginal bleeding occurs – ~Every 28 days – Endometrium (lining of uterus is discarded) • The endometrium is meant to – attach to fertilized egg – Feed the growing fetus • If no fertilization occurs – Bleeding, caused by loss of endometrium occurs Menstruation Proliferation Phase Secretory Phase See pages 146-147 Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 O 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Menstrual Cycle Ovarian Cycle Bleeding, due to expulsion of endometrium and unfertilized An Ovarian follicle begins to mature. ovum. Progesterone decreases due to deterioration of corpus luteum The Pituitary secretes FSH (Follicle Stimulating Hormone) The growing follicle secretes estrogens, which stimulates the Estrogen is produced by a new pituitary to secrete more FSH and LH ovarian follicle. (Lutenizing Hormone) Endometrium Thickens. Ovulation: Follicle bursts, resulting in a surge in hormones. Endometrium continues to thicken. Ovarian follicle becomes the Corpus Lueteum. Progesterone is secreted by Corpus Luteum secretes progesterone, corpus luteum . stopping the pituitary from releasing any more FSH and LH If the ovum is not fertilized, the corpus luteum begins to deteriorate. It stops producing progesterone, so the Progesterone decreases due to pituitary starts producing FSH again deterioration of corpus luteum Assignments and Exercises • Text book: • Read pages 143 to 148 • Workbook: • Page 77 to 82 Male Reproductive System Reference page 149 Male Reproductive System • You have already learned the different parts – so here’s what they do • Why do we need an erection? – 2 things • penetrate/get into the vagina • Deposit sperm near the uterus – Where the egg is waiting Male Reproductive System • What is ejaculation? – Occurs at sexual climax • (most pleasure) – Involuntary wave of contractions from • epididymis, through the vas deferens, prostate, seminal vesicles and finally out the urethra (know this) • seminal vesicles provide 70% of the fluid in ejaculate which acts as a lunch for sperm among other things What about sperm? • Spermatogenesis occurs in the testicles – The whole process can take up to 72 days! – Starts as diploid cells in seminal tubes of, testicles – After meiosis they work through the middle of the tubes. – All the way the epididymis » 6m long voyage! – There they get their tails and they’re ready for action • Bonus: What is a scrotum good for? – Sperm cooling • Sperm grow optimally a 3 degrees C lower Hormones • Hormones are in control of: – the reproductive system development, cycles etc. – Nearly all growth, and maintenance of your body systems • Similar to your nervous system – They communicate but the messages are slower and last much longer. Hormones • Produced and secreted by glands – Male hormone gland: testicles • Produce testosterone – Female glands: ovaries • Produce estrogen and progesterone • The most influential gland – The “gland daddy” of them all – The pituitary • Because its hormones control sex glands and: – – – – – – – – Growth Blood pressure Some aspects of pregnancy and childbirth Breast milk production Sex organ functions in both women and men Thyroid gland function The conversion of food into energy (metabolism) Water and osmolarity regulation in the body Very Important! Long term accumulation Progesterone isInitiates a feedback Puberty Then helps regulate of estrogen causes to the pituitary,cycles causing In Both to in itaSexes! woman development of breasts, reduce the LH after & FSH puberty enlargement of hips, accumulation of fatty by Effects tissue and certain psychological changes. The “Big 6” Hormones Hormone Name Secreted FSH Pituitary (Follicle Stimulating Hormone) LH In female initiates follicle production Pituitary (Luteinizing Hormone) Progesterone Helps initiate puberty Helps initiate puberty In female releases egg & heals follicle Ovaries Inhibits LH & FSH (corpus luteum) Thickens endometrium Estrogen Ovaries Female Hormone (A.K.A: Oestrogen) (developing follicle) Controls female secondary characteristics, affects endometrium Testosterone Testes Male Hormone Controls male secondary characteristics Kisspeptin Pituitary Helps Initiates Puberty Primary vs. Secondary sex characteristics. • Primary Sex Characteristics Affect the sex organs Genital organs develop and mature (M/F) Menstrual cycle starts (F) • Secondary Sex Characteristics Affect other parts of the body Breasts develop (F) Larynx enlarges (M) Pelvis widens (F) Facial hair appears (M) Fatty tissue accumulates (F) Muscles grow (M) Bone density increases (M) Pubic and underarm hair appears (both) Psychological changes occur (both) Effectiveness of Birth Control Methods “worst case” failure rates • • • • Vasectomy Withdrawal* Withdrawal** Condom 1% 96% 27% 12% * As typically done ** as correctly done The actual failure rates depend on brand and quality and the correct use of the contraceptive product. Actual failure rates may be lower • • • • • • • Oral Contraceptive 2% Contraceptive patch 1% Injections / vaginal ring 2% Tubal ligation 1% Spermicides 21% Female condom 12% Diaphragm & spermicide 18% • Mini-pill • Morning after pill • IUD 6% ??% 6% Assignments on Reproduction • Textbook: • Read pages 149 to 151 • Do questions 19 to 34 on pages 153 and 154 • Workbook • Do pages 82 to 88