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Transcript
Cells and Tissues What is it that makes you you? What is the biggest organelle? • The nucleus – The control center for the cell – Contains DNA • Contains the message that makes proteins • Proteins run the cell. – Contains the organelle= nucleolus • Nucleolus makes RNA that carries out DNA’s instructions. What surrounds the nucleus? • • • • The Phospholipid membrane Two membranes. Keeps DNA in Only RNA can leave What are the names of DNA? • Chromatin: Unwound DNA • Chromosomes: Tightly wound DNA What surrounds the cell? • The Plasma Membrane. Made out of Phospholipids. • May have cilia or microvilli around the cell. • Microvilli are in the back of your throat (filter air) and in your intestine (absorb food). Pg.389 +419 What is in the cell? • Most of the cell is full of Cytoplasm. – Cytoplasm: Gel like fluid where most of the cells chemical reactions take place. • Organelles: Mini cell organs that carry out specific job functions for the cell. Cells Alive Overview of Cell Parts What are the major organelles? • Ribosomes: rRNA. Where proteins are made. Usually on the rough ER. • Endoplasmic Reticulum: – rough ER close to the nucleus, where proteins are made – Smooth ER makes lipids. No rRNA present. • Golgi Apparatus: Ships proteins and lipids. More organelles… • Lysosomes: SOS. Contain digestive enzymes. Kill invaders and worn out cell parts. • Mitochondria: Power house of the cell. Makes ATP (Body runs on ATP energy.) • Cytoskeleton: Skeleton of the cell. Shape • Centrioles: Move Chromosomes during cell division. Membrane Transport Pg. 46 What kinds of fluids pass through the cell membrane? • Solution: homogeneous mixture of two or more things – Solvent: Bigger word, bigger thing – Solute: Smaller word, smaller thing • Intracellular fluid: fluid in the cell that contains gasses, nutrients, salts, & water • Interstitial fluid: bathes the outside of our cells. Why is the plasma membrane selectively permeable? • Works as a barrier. Only allows certain things in or out of the cell. • Means of protection. • Cells that can not do this are dead or damaged. What are the two forms of cell transport? • Active Transport: uses energy (ATP) to move molecules against the concentration gradient or to move large things. • Passive Transport: uses NO energy to move molecules with the concentration gradient. What types of Passive transport does the body use? • Diffusion: When molecules move from high to low or with the concentration gradient. – Perfume, food coloring, etc. all do this. • Osmosis: a specialized form of diffusion which moves water from high to low across the plasma membrane. What types of Passive transport does the body use? • Facilitated Diffusion: Uses carrier proteins to move substances without energy with the concentration gradient. • Filtration: water and solutes are forced through a plasma membrane. Happens in the Kidneys. What types of Active transport do you use? • Solute Pumping: Require protein carriers and energy to move sugars, Amino Acids, and ions against the concentration gradient. (Sodium Potassium pump used in Nerve cells) More Active Transport… • Bulk Transport: Substances too big to pass through the plasma membrane. – – – – Exocytosis: Large things exit the cells Endocytosis: Large things enter the cell Phagocytosis: Cells that eat- white blood cell Pinocytosis: Cells drink- intestine and kidneys Types of Solutions: Pg 60 • Isotonic Solution: Same tonicity inside and outside the cell. Cell stays the same size. • Hypertonic Solution: Higher tonicity outside the cell. Cell shrinks. • Hypotonic Solution: Lower tonicity outside the cell. Cell swells and “POPS” Chromosomes and Mitosis Pg. 63 Two different Cell Divisions • Meiosis- produces gametes or sex cells. New cells are different from the original cell. • Mitosis- produces new body cells-like your toes. New cells are identical to original cell. DNA in all of its fine forms: • Chromosomes: Tightly wound DNA. Resemble an X because two chromatids are held together.- Supercoiled. • Centromere holds the chromosomes (Two sister Chromatids) together. • Chromatid: A single tightly wound strand of DNA. Homologous Chromosomes And last but not least… • DNA is your genetic information. In the shape of a double helix. The nucleotide pairs are: (Hydrogen bonds) – Adenine= Thymine – Cytosine: Guanine • DNA is broken into segments called genes which code for proteins. • Genes give you your physical characteristics. It DNA the final say? • Epigenetics may play a role. Epigenetic Effect On DNA Epigenetic Movie Before Eukaryotic Cells Divide… • Its chromosomes are replicated. • Happens through the process of DNA Replication. DNA Replication pg.68 • DNA needs enzymes (protein) to copy or replicate itself. • Double helix unwinds using DNA Helicase. • DNA Helicase breaks the hydrogen bonds. • Where the DNA breaks apart is called the replication fork. DNA polymerase (another enzyme) adds nucleotides at this point. How many Chromosomes do humans have? • Each somatic cell or body cell has two copies of 23 chromosomes. • One copy of the chromosomes (sex cells or gametes) have 23 chromosomes and are called haploid or n = 23. • Two copies of the chromosomes (somatic cells) have 2n = 46. There are two types of Chromosomes. • Autosomal Chromosomes: or autosomes are not sex chromosomes. • Sex Chromosomes: determine the sex of the individual. The male of the species determines the sex of the offspring. Women only have one X chromosome. Males have an X or a Y. • XX is a girl • XY is a boy Karyotypes: Pictures of your DNA. • Why do we take pictures? To find mistakes . The 5 stages of the Cell Cycle 6-2 • • • • G1: Cell Growth and Metabolism S: DNA is copied G2: Cell prepares for division. Mitosis: Nucleus divides, cell parts separate. • Cytokinesis: Cytoplasm divides When control of the Cell cycle is lost: Cancer is the outcome. • Cancer: uncontrolled cell division or death. • Read pg 127: Normal cells become cancerous. Hit the Cancer Biology Documentary Link Mitosis The Basic Steps:6:3 • Prophase: DNA forms chromosomes. Nuclear envelope disappears. In Animals spindle fibers form. • Metaphase: Chromosomes move to the center of the cell- pulled by spindle fibers. • Anaphase: Chromosomes are separated into chromatids. Spindles shorten pulling chromatids to opposite ends of the cell. • Telophase: Nucleus reforms. Chromatids turn back into Chromatin. Spindles The Jazzy disappear. Version of Mitosis After Mitosis • Cytokinesis: Cytoplasm divides in half. • Animals: The plasma membrane pinches in half= Furrow. • Plants: A cell wall grows between the two new cells. Cell Plate. Cell Cycle Movie/ Game Meiosis . Meiosis: The making of gametes • • • • One cell eventually creates four cells Each cell is different from the parent cell Haploid Meiosis goes through cell division twice The Stages of Meiosis • Prophase 1: Chromosomes are made and the nucleus membrane disappears. • Homologous Chromosomes pair and attach by centromeres. • Crossing-over occurs. Cross over is the process of homologous chromosomes breaking off and exchanging parts. – This process is responsible for making you unique! Meiosis Continued • Metaphase 1 Homologous chromosomes are pulled by spindle fibers to the middle of the cell. (Two pair of homologous chromosomes are together.) • Anaphase 1 • Pair of Homologous chromosomes separate. Spindle fibers attach to a centromere to guide homologous chromosomes to opposite ends of the cell. Meiosis Continued • Telophase 1 • Two cells have been made. We • Homologous need 4. chromosomes are at opposite ends of the • Here ends the first cell. Cytokinesis cell division. occurs. • Ready for part two? Meiosis- Part 2 • Prophase II • Metaphase II • New spindle fibers • Chromosomes line form around up in the middle (or homologous equator) of the cell. chromosomes. Nucleus disappears. And finally…Meiosis ends • Anaphase II • The spindle fibers pull the homologous chromosomes apart. Chromatids move to opposite ends of the cell. • Telophase II • A new nucleus is formed. Spindle fibers dissolve. • Cytokinesis occurs. • Four cells, genetically different from the parent cell have been made. Why does Meiosis create genetic variation? • Crossing over. Mixes up the traits on each chromosome. • Independent assortment. You have 46 chromatids. ½ go to each new cell in Meiosis 1 and again in Meiosis II. No one knows which chromatids will go to which cell. • Random Fertilization. Which egg and which sperm will meet? = a greater genetic variability. Making Gametes: Different for different sexes. • Sperm Formation • Spermatogenesis • One diploid germ cell makes four haploid sperm cells. • Occurs in the testis throughout the males Third Link adult life • Egg formation: Ovum • Oogenesis • One diploid germ cell makes one egg and three polar bodies. • Egg must provide the food for the zygote (fertilized egg) • Made in ovaries, most before birth Comparison of OOGENESIS & SPERMATOGENISIS Sexual Reproduction: Two parents. • Offspring is genetically different from parents. • Great for environmental change. Easy to evolve. • Meiosis can better repair damaged DNA How Proteins are Made Pgs. 60-61 The Basic Process of Making Protein • DNA (In the Nucleus) is Transcribed into mRNA. (Transcription) • RNA brings the message to the Rough ER where its Translated into a protein. (Translation) The Details: RNA (Ribonucleic Acid) • • • • • • There are three types of RNA mRNA (messenger RNA) rRNA (Ribosomal RNA) tRNA (Transfer RNA) RNA is Single Stranded, sugar is RIBOSE The Nitrogen bases for RNA are… – Adenine bonds to Uracil – Cytosine bonds to Guanine The Story • DNA is stuck in the nucleus. • RNA is made in the nucleolus. • mRNA transcribes or re-writes DNA’s code in RNA and leaves the nucleus through nuclear pores. • mRNA brings the message to the ribosome also known as rRNA. The fairy tale continues Fig 10-5 • Once mRNA is hooked onto the rRNA it needs the right amino acids to make a protein. – Remember 50 or more A.Acids make a Protein! • tRNA carries amino acids to the rRNA and hooks them onto the correct mRNA codon. – A codon is a three nucleotide sequence (AUG) How does the story end? • When the stop codon is reached the Amino Acid chain falls off and rolls into a ball and becomes a protein. • mRNA goes back to the nucleus to be reused. • rRNA stays on the Endoplasmic Reticulum waiting for the next job. • tRNA picks up new Amino Acids for the next job. Overview Movie Start Here