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Transcript
Cells Alive Overview of Cell Parts Cells Chapter 3 Prefixes/Suffixes • • • • • Cyt- cell Endo- in Hyper- above Hypo- below Inter- between • • • • • Iso- equal Mit- thread Phag- eat Pino- drink -som - body Now we are ready to review the cell What is in the cell? • Most of the cell space is Cytoplasm. – Cytosol: 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. 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 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. • Microtubules: Basis for cilia and flagella Mitochondria Ribosome Endoplasmic Reticulum Golgi Apparatus Cytoskeleton Checkpoint • What is the functional difference between cilia and flagella? • What are the structural and functional differences between smooth and rough ER? • Which organelles contribute to synthesizing protein hormones and packaging them into secretory vesicles? Interactive Cell Parts Cell Membrane Fluid-Mosaic Model 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) 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. Checkpoint • List the three main parts of the cell and explain their functions. • Why are membranes said to have selective permeability? Membrane Transport Pg. 47-52 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. Simple Diffusion Diffusion through a gated membrane channel 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. Osmosis • Osmosis: a specialized form of diffusion which moves water from high to low across the plasma membrane. Types of Solutions: Pg 50 • 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” Principles of osmosis applied to red blood cells 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) Sodium-potassium pump 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 Phagocytosis Checkpoint • How would having a fever affect body processes that involve diffusion? • If 0.9% NaCl is isotonic saline solution for red blood cells, would a 2% solution of NaCl cause the red blood cells to expand or shrink? • What is the key difference between active and passive transport? • In what ways are endocytosis and exocytosis similar and different? How Proteins are Made Pgs. 58-62 Overview What are the names of DNA? • Chromatin: Unwound DNA • Chromosomes: Tightly wound DNA 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) Overview of transcription and 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 • 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. Transcription Protein elongation and termination of protein synthesis during translation Checkpoint • If the DNA template had the base sequence AGCT, what be the mRNA base sequence? • What is the difference between transcription and translation? Chromosomes and Mitosis Pg. 62-65 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. 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. Before Eukaryotic Cells Divide… • Its chromosomes are replicated. • Happens through the process of DNA Replication. DNA Replication: • 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 • • • • G1: Cell Growth and Metabolism S: DNA is copied G2: Cell prepares for division. Mitosis: Nucleus divides, cell parts separate. • Cytokinesis: Cytoplasm divides Mitosis: The Basic Steps • 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 disappear. Chromosomes Cell Division and 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. When control of the Cell cycle is lost: Cancer is the outcome. • Cancer: uncontrolled cell division or death. • Read pg 66: Normal cells become cancerous. Abnormal Cell Functioning - Cancer • Malignant – uncontrolled cell division – carried by lymph or blood to other organs to develop secondary tumors (metastasis) –Created by a mutation • Carcinogens, ultraviolet light • Benign – remain localized Mitosis Interaction Checkpoint • In which phase of the cell cycle does DNA replication occur? • Why must DNA replication occur before cytokinesis? • When does cytokinesis begin? 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 Animation 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. • • • • • Egg formation: Ovum Sperm Formation • Oogenesis Spermatogenesis • One diploid germ cell One diploid germ makes one egg and cell makes four three polar bodies. haploid sperm • Egg must provide the cells. food for the zygote Occurs in the testis (fertilized egg) throughout the • Made in ovaries, most males adult life before birth Sexual Reproduction: Two parents. • Offspring is genetically different from parents. • Great for environmental change. Easy to evolve. • Meiosis can better repair damaged DNA Checkpoint • How does crossing-over affect the genetic content of the haploid gametes? • How are haploid and diploid cells different? • What are homologous chromosomes? Sickle-Cell Anemia • Most common genetic disorder among people of African descent • Hemoglobin crystallizes when the oxygen levels are low and the red blood cells deform into sickles, which can clog and rupture capillaries causing internal bleeding • Incurable Chapter Quiz Cell Case Study Stem Cells • Stem • Cell • Differentiation