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Transcript
Life Science Review Chloroplast- The cell organelle in which photosynthesis takes place. In this organelle the light energy of the sun is converted into chemical energy. Chloroplasts are found only in plant cells not animal cells. The chemical energy that is produced by chloroplasts is finally used to make carbohydrates like starch, that get stored in the plant. Chloroplasts contain tiny pigments called chlorophylls. Chlorophylls are responsible for trapping the light energy from the sun. Differences between Prokaryotic & Eukaryotic cells Bacterial cells also contain flagellum, plasmid and capsule. Feature Size Genetic material Organelles Cell walls Ribosome’s Prokaryote Eukaryote Small about 0.5 micrometers Up to 40 micrometers Circular DNA (in cytoplasm) DNA in form of linear chromosomes ( in nucleus) Few present, none membrane bound Rigid formed from glycoproteins (mainly murein) 70s Many organelles: •Double membranes e.g.: nucleus, mitochondria & chloroplasts •Single membrane e.g.: GA, ER & lysosomes •Fungi: rigid, formed from polysaccharide, chitin. •Plant: rigid, formed from polysaccharides. E.g.: cellulose. •Animals no cell wall 80s Definitions and plant cell parts. Cytoplasm-gel like substance found in a cell Chloroplasts-a green structure in a plant Cell Wall-a stiff covering that protects plant cells Nucleus-control center of the cell Chromosomes-provides direction for cell to follow Endoplasmic Reticulum-transportation network Mitchondrion-produces energy in the cell Vacuole-cell storage sac for food, waste and water Parts of the animal cell and definition. Vacuole-cell storage sac for food,waste, and water Mitochondrion –produces energy in a cell Chromosomes-provides direction for cells to follow Nucleus-control center of a cell Endoplasmic Reticulum--transporation system Cytoplasm-gel like substance found in a cell Cell Membrane-surrounds cell material Cells also carry out diffusion,passive transport active transport and osmosis. Diffusion-movement of gases from higher concentrations to lower concentrations Passive Transport-materials do not need energy to move from higher concentration to lower to a lower concentration Active Transport-materials need energy to move from a higher concentration to lower concentration Osmosis-water moving from higher concentration to a lower concentration DNA is a double helix • All DNA Is made up of 3 parts – Phosphate group – 5 sugar deoxyribose – Nitrogen Base What are the four bases? • Pyrimidine: Only one ring – Thymine (T) – Cytosine (C) • Purines; 2 rings – Adenine (A) – Guanine (G) The backbone is connected by covalent bonds. The bases are connected by hydrogen bonds. hydrogen bond covalent bond Replication copies the genetic information. • A single strand of DNA serves as a template for a new strand. • The rules of base pairing direct replication. • DNA is replicated during the S (synthesis) stage of the cell cycle. • Each body cell gets a complete set of identical DNA. A Model used to show the possible ways genes can combine during fertilization. Dominant and recessive alleles are represented by letters. Punnett Squares A capital letter (T) is used for dominant alleles. A lowercase letter (t) is used for recessive alleles. Punnett Squares The letters representing the alleles from one parent are placed along the top of the square. T t Punnett Squares T t xT t T T t t Punnett Squares Squares are filled by writing the letter at the top beside the letter on the side. T T t t TT Tt Tt tt Punnett Squares The letters in each of the squares represents the Genotypes of the offspring that the parents could produce. T T t t TT Tt Tt tt TT Tt Tt tt Punnett Squares The genotype (genetic makeup) can be used to predict the phenotype (physical appearance) of the offspring. Punnett Sqaures Genotype TT Tt Tt tt Phenotype tall tall tall short 1. 2. 3. 4. Chromosomes, Genes, and Genetic Crosses Homologous Chromosomes contain genes (locations) for the same traits Traits are controlled by alleles (alternative forms of a gene). Genotype refers to the alleles an individual receives at fertilization Phenotype refers to the physical appearance of the individual. 5. Homozygous dominant genotypes = two dominant alleles for a trait. (BB) 6. Homozygous recessive genotypes = possess two recessive alleles for a trait (bb) 7. Heterozygous genotypes = one of each allele for a particular trait (Bb) Punnett Squares Probability: the ratio that a particular event could occur. 3 would be tall out of 4 offspring 1 would be short Punnett Squares: •Help you keep track of traits. •Predict genotype and phenotype. •Calculate probability. Cell Cycle • During the cell cycle, a cell grows, prepares for division, and divides to form 2 daughter cells, each with each of which then begins the cycle again. • Interphase – time for growth and regular cell activity. • Most of a cells life is spent in Interphase. Mitosis • The division of somatic or regular cells. • Its divided into 4 phases. • Remember Interphase is NOT part of Mitosis. Prophase • First stage of Mitosis • Chromatin condenses into chromosomes • Centrioles separate and a spindle fiber begins to form. • Nuclear membrane breaks down Metaphase • Second Phase of Mitosis • Chromosomes line up in the middle of the cell. • Each chromosome is connected to a spindle fiber. Anaphase • Third Phase of Mitosis • The sister chromatids separate into individual chromosomes and move apart to opposite ends of the cell. Telophase • Fourth and Final Stage of Mitosis • Chromosomes gather at opposite ends of the cell and lose their distinct shapes • Two new nuclear membranes have formed. Cytokinesis • The cytoplasm pinches in half. • Each daughter cell has an identical set of duplicate chromosomes Regulating the Cycle • A protein call cyclin helps regulate the cell cycle in eukaryotic cells. • They respond to internal and external events. These proteins are regulators. When Things Go Wrong • Cancer cells do not respond to the signals that regulate the growth of most cells. • As a result, they form masses of cells called tumors that can damage surrounding tissues. • Asexual Reproduction – Many single-celled organisms reproduce by splitting, budding, parthenogenesis. – Some multicellular organisms can reproduce asexually, produce clones (offspring genetically identical to parent). Meiosis KM 37 Chromosomes • Karyotype: – ordered display of an individual’s chromosomes. – Collection of chromosomes from mitotic cells. – Staining can reveal visible band patterns, gross anomalies. Meiosis KM 38 In humans … • 23 chromosomes donated by each parent (total = 46 or 23 pairs). • Gametes (sperm/ova): – Contain 22 autosomes and 1 sex chromosome. – Are haploid (haploid number “n” = 23 in humans). • Fertilization/syngamy results in zygote with 2 haploid sets of chromosomes - now diploid. – Diploid cell; 2n = 46. (n=23 in humans) • Most cells in the body produced by mitosis. • Only gametes are produced by meiosis. Meiosis KM 39 Chromosome numbers All are even numbers – diploid (2n) sets of homologous chromosomes! Meiosis KM 40 Ploidy = number of copies of each chromosome. Diploidy Meiosis – key differences from mitosis Meiosis reduces the number of chromosomes by half. • • Daughter cells differ from parent, and each other. • Meiosis involves two divisions, Mitosis only one. • Meiosis I involves: – Synapsis – homologous chromosomes pair up. Chiasmata form (crossing over of non-sister chromatids). – In Metaphase I, homologous pairs line up at metaphase plate. – In Anaphase I, sister chromatids do NOT separate. – Overall, separation of homologous pairs of chromosomes, rather than sister chromatids of individual chromosome. Meiosis KM 41 Meiosis KM 42 Animation Meiosis KM 43 Meiosis 1 First division of meiosis • Prophase 1: Each chromosome dupicates and remains closely associated. These are called sister chromatids. Crossing-over can occur during the latter part of this stage. • Metaphase 1: Homologous chromosomes align at the equatorial plate. • Anaphase 1: Homologous pairs separate with sister chromatids remaining together. • Telophase 1: Two daughter cells are formed with each daughter containing only one chromosome of the homologous pair. Meiosis KM 44 Meiosis II Second division of meiosis: Gamete formation • Prophase 2: DNA does not replicate. • Metaphase 2: Chromosomes align at the equatorial plate. • Anaphase 2: Centromeres divide and sister chromatids migrate separately to each pole. • Telophase 2: Cell division is complete. Four haploid daughter cells are obtained. Meiosis KM 45 Mitosis vs. meiosis Meiosis KM 46 Meiosis KM 47 Meiosis creates genetic variation • During normal cell growth, mitosis produces daughter cells identical to parent cell (2n to 2n) • Meiosis results in genetic variation by shuffling of maternal and paternal chromosomes and crossing over. No daughter cells formed during meiosis are genetically identical to either mother or father During sexual reproduction, fusion of the unique haploid gametes produces truly unique offspring. Meiosis KM 48 In humans e.g. 23 chromosomes in haploid 2n = 46; n = 23 2n = 223 = ~ 8 million possible combinations! Meiosis KM 49 Crossing over Chiasmata – sites of crossing over, occur in synapsis. Exchange of genetic material between non-sister chromatids. Crossing over produces recombinant chromosomes. Meiosis KM 50 Sex is costly! • Large amounts of energy required to find a mate and do the mating: specialized structures and behavior required • Intimate contact provides route for infection by parasites (AIDS, syphillis, etc.) • Genetic costs: in sex, we pass on only half of genes to offspring. • Males are an expensive luxury - in most species they contribute little to rearing offspring. Meiosis KM 51 But … • More genetic diversity: more potential for survival of species when environmental conditions change. – Shuffling of genes in meiosis – Crossing-over in meiosis – Fertilization: combines genes from 2 separate individuals • DNA back-up and repair. – Asexual organisms don't have back-up copies of genes, sexual organisms have 2 sets of chromosomes and one can act as a back-up if the other is damaged. – Sexual mechanisms, especially recombination, are used to repair damaged DNA - the undamaged chromosome acts as a template and eventually both chromosomes end up with the correct gene. Meiosis KM 52 Levels of Organization Remember, the human body is organized in several levels, from the simplest to the most complex. . . Cells – the basic unit of life Tissues – clusters of cells performing a similar function Organs – made of tissues that perform one specific function Organ Systems – groups of organs that perform a specific purpose in the human body ***The purpose of the 11 organ systems is for the human body to maintain homeostasis. The 11 Human Body Systems The 11 human body systems are as follows: -- nervous system -- integumentary system -- respiratory system -- digestive system -- excretory system -- skeletal system -- muscular system -- circulatory system -- endocrine system -- reproductive system -- lymphatic (immune) system The Digestive System Purpose: to convert food particles into simpler micromolecules that can be absorbed into the body bloodstream and used by the Major Organs and their Functions: Mouth – to chew and grind up food -- saliva also begins the chemical breakdown Esophagus – pipe connecting mouth to stomach Stomach – secretes an extraordinarily strong acid (pH = 2) that breakdown of food leads to -- once the food is broken down in the stomach and digestive juices, it is called chyme mixed with Pancreas – produces the hormone insulin that regulates blood sugar levels -- also help neutralize stomach acid Liver – produces bile, which breaks down fats in foods Gallbladder – pouch-like organ that stores bile for future use Small Intestine – after digestion is complete, the chyme enters the small intestine where it is absorbed into the bloodstream -- the chyme is propelled along by folded surfaces called villi, on the intestine Large Intestine – removes water from the chyme and gets the waste ready for excretion The Excretory System Purpose: to rid the body of wastes, including excess water and salts Major Organs and Their Functions Kidneys – the main organs of the excretory system -- waste-laden blood enters the kidney and the kidney filters out urea, excess water and other waste products, which eventually travel out of the kidney as urine -- eventually they travel through the ureter to the urinary bladder Rectum – solid (food) waste travels out of the body through rectum the Skin – sweat glands remove excess water and salts from the Lungs – expel the waste gas carbon dioxide The Excretory System body The Respiratory System Purpose: to provide the body with a fresh supply of oxygen for cellular respiration and remove the waste product carbon dioxide Major Organs and Their Functions Nose – internal entry and exit point for air Pharynx – serves as a passage way for both air and food at throat Larynx – your “voicebox”, as air passes over your vocal speak Trachea – the “windpipe”, or what connects your pharynx to lungs -- a piece of skin, called the epiglottis, covers the swallow, preventing food from entering the back of the chords, you your trachea when you Bronchi – the two large passageways that lead from the trachea to your lungs (one for each lung) -- the bronchi are further subdivided into bronchioles -- eventually, the further subdivisions lead to tiny air sacs called alveoli -- alveoli are in clusters, like grapes -- capillaries surrounding each alveolus is where exchange of gases with the blood occurs The diaphragm is the muscle that causes you to breath -- hiccups are involuntary contractions of the diaphragm the Image of the Respiratory System The Circulatory System Purpose: to deliver oxygenated blood to the various cells and organ systems in your body so they can undergo cellular respiration Major Organs and Their Functions Heart – the major muscle of the circulatory system -- pumps blood through its four chambers (two ventricles and two atria) -- pumps deoxygenated blood into the lungs, where it gets oxygenated, returned to the heart, and then pumped out through the aorta to the rest of the body -- valve regulate the flow of blood between the chambers Arteries – carry blood away from the heart and to the major organs of the body Veins – carry blood back to the heart away from the major organs of the body Capillaries – small blood vessels where gas exchange occurs Blood – the cells that flow through the circulatory system -- red blood cells contain hemoglobin, an iron-rich oxygen -- white blood cells function in the immune system -- platelets help in blood clotting Spleen – helps to filter out toxins in the blood protein that carries Image of the Circulatory System The Nervous System Purpose: to coordinate the body’s response to changes in its internal and external environment Major Organs and Their Functions Brain – control center of the body, where all processes are relayed through -- consists of cerebrum (controls though and senses) (controls motor functions) and cerebellum Spinal Cord – sends instructions from the brain to the rest of the body and vice versa -- any organism with a major nerve cord is classified as Nerves – conduct impulses to muscle cells throughout the body a chordate Diagram of a Nerve Cell The Endocrine System Purpose: to control growth, development, metabolism and reproduction through the production and secretion of hormones Major Organs -- hypothalamus -- pituitary gland -- thyroid -- parathyroid -- adrenal glands -- pancreas -- testes -- ovaries The Skeletal System Purpose: to provide structure and support to the human body Bones are where new blood cells are generated (in the marrow), and require the mineral calcium for strength Major Bones of the Human Body -- femur (thigh bone) -- humerus (upper arm) -- radius and ulna (lower arm) -- cranium (skull) -- sternum (breastbone) -- clavicle (shoulder blade) -- fibula and tibia (calf) -- vertebrae (back) -- scalpula (shoulder) -- pelvic bone -- coccyx (tail bone) -- phalanges (fingers/toes) The Muscular System Purpose: works with the skeletal and nervous system to produce movement, also helps to circulate blood through the human body -- muscle cells are fibrous -- muscle contractions can be voluntary or involuntary Major Muscles in the Human Body -- biceps -- triceps -- glutes -- hamstrings -- deltoids The Immune System Purpose: to remove infectious diseases and other pathogens from the human body Major Organs and Their Functions Skin – also called the integumentary system, the skin is the body’s first line of defense White Blood Cells – recognize disease agents (antigens) and create antibodies to tag and remove these antigens -- phagocytes are the white blood cell type that actually these antigens eats and destroys Lymph Nodes – help restore fluid lost by the blood and return it to the circulatory system Natural Selection & Artificial Selection • Natural variation--differences among individuals of a species • Artificial selection- nature provides the variation among different organisms, and humans select those variations they find useful. Evolution by Natural Selection • The Struggle for Existence-members of each species have to compete for food, shelter, other life necessities • Survival of the Fittest-Some individuals better suited for the environment Struggle For Existence & Survival of The Fittest Natural Selection • Over time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment Descent • Descent with Modification-Each living organism has descended, with changes from other species over time • Common Descent- were derived from common ancestors Evidence of Evolution • The Fossil Record • Geographic Distribution of Living Things • Homologous Body Structures • Similarities in Early Development Evidence for Evolution • The Fossil RecordLayer show change • Geographic Distribution of Living Things • Homologous Body Structures • Similarities in Early Development Evidence of Evolution • The Fossil Record • Geographic Distribution of Living Things-similar environments have similar types of organisms • Homologous Body Structures • Similarities in Early Development Homologous Structures • Homologous Structures-structures that have different mature forms in different organisms, but develop from the same embryonic tissue Evidence for Evolution • Vestigial organs-organs that serve no useful function in an organism • i.e.) appendix, miniature legs, arms Similarities in Early Development Summary of Darwin’s Theory • Individuals in nature differ from one another • Organisms in nature produce more offspring than can survive, and many of those who do not survive do not reproduce. Summary of Darwin’s Theory • Because more organisms are produce than can survive, each species must struggle for resources • Each organism is unique, each has advantages and disadvantages in the struggle for existence Summary (cont.) • Individuals best suited for the environment survive and reproduce most successful • Species change over time Summary (cont.) • Species alive today descended with modification from species that lived in the past • All organisms on earth are united into a single family tree of life by common descent Have you ever wondered how animals are able to survive in the wild? Animals have certain adaptations that help them to survive. Think about the way you dress in the winter. You don’t wear your shorts and bathing suit when it’s snowing outside! You wear warm clothes, and maybe even a hat and mittens to protect yourself from the weather. The way you dress in the winter, as well as the way that you run and hide from someone throwing snow at you are kinds of … Adaptations. We can separate adaptations into two categories: A D Physical A P T AND A T I O N S Behavioral Physical adaptations are body structures that allow an animal to find and consume food, defend itself, and to reproduce its species. Physical adaptations help an animal survive in its environment. © A. Weinberg Physical adaptation Camouflage (use of color in a surrounding) The chameleon can change its color to match its surroundings. Can you do that? Physical adaptation Mimicry (looking or sounding like another living organism) The Viceroy butterfly uses mimicry to look like the Monarch butterfly. Can you tell them apart? I’m the Viceroy! Not poisonous Poisonous I’m the Monarch! Physical adaptation Chemical defenses (like venom, ink, sprays) Physical adaptations Body coverings & parts (claws, beaks, feet, armor plates, skulls, teeth) The elephant’s trunk is a physical adaptation that helps it to clean itself, eat, drink, and to pick things up. Now let’s learn about Behavioral Adaptations… Behavioral Adaptations allow animals to respond to life needs. Behavioral Adaptations are animals’ actions. Remember that Physical Adaptations are body structures. Each organism has unique methods of adapting to its environment by means of different actions. We can divide Behavioral Adaptations into two groups: Instinctive Learned These behaviors happen naturally & don’t have to be learned. These behaviors must be taught. Instinctive behaviors Methods of gathering & storing food Finding shelter happen naturally & don’t need to be learned = Defending oneself Raising young Hibernating Migrating Learned behaviors = Obtained by interacting with the environment and cannot be passed on to the next generation except by teaching. In this lesson, we have learned about animal adaptations. There are 2 ways to describe adaptations: Physical and Behavioral Nevada's Bioregions Western Nevada:Transition zone from Sierra Nevada bioregion to Great Basin cold desert. Dominate plant species: Single Leaf Pinion, Rabbit Brush, Utah Juniper, Sage, Native Grasses. Eastern Nevada: Great Basin bioregion Dominate animal species: Larger Mammals: Feral HorsesDescendants of domestic European horses that have become wild Featured on the Nevada State quarter Herds are “managed” so that they don’t destroy fragile rangeland BearsThis bioregion is home to the American Black Bear Large and adaptable omnivore Mountain LionThe largest predator of the bioregion. Great Basin Bioregion Central / Eastern Nevada Classified as a cold desert Not as dry as the Mojave Desert Tall mountain ranges provide unique local climatesDominate plant species: Utah JuniperBerries are a food source for birds SingleleafPinionUsed by Native Peoples and animals as a major food source Great Basin Bristlecone PineBelieved to be the oldest living organism on earth Core samples of tree rings confirm 2500 years old Two Secrets of Survival: Energy Flow and Matter Recycle • An ecosystem survives by a combination of energy flow and matter recycling. Figure 3-14 Condensation Rain clouds Transpiration Precipitation to land Transpiration from plants Precipitation Runoff Surface runoff (rapid) Evaporation Evaporation from land Precipitation Evaporation from ocean Precipitation to ocean Surface runoff (rapid) Infiltration and Percolation Groundwater movement (slow) Ocean storage Fig. 3-26, p. 72 Fig. 3-27, pp. 72-73 Effects of Human Activities on Carbon Cycle • We alter the carbon cycle by adding excess CO2 to the atmosphere through: – Burning fossil fuels. – Clearing vegetation faster than it is replaced. Figure 3-28