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Cell Structure and Function Chapter 7
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Characteristics of Living Things Page 16
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Levels of Organization Page 21 Cell Size Cell Size and how we know
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The Diversity of Cellular Life Unicellular - single celled organisms, exhibit all the characteristics of life Can be both Eukaryotic and Prokaryotic
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Multicellular - made up of many cells and all cells are interdependent Each has a specific function that contributes to the whole (specialization of roles)
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The Cell Theory All living things are composed of cells Cells are the basic units of structure and function in living things New cells from existing cells
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Two Categories of Cells Prokaryotes no Nucleus smaller, simpler cells Example: Bacteria
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Eukaryotes Have a Nucleus Have Organelles examples: Plant cells and animal cells (pg 174 fig 7.5)
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Comparing Cells Chart on page 183
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Cell Project
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Cell Membrane The cell membrane regulates what enters and leaves the cell and provides protection and support
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Cell Membrane (pg 184 fig 7-15) Phospholipid bilayer
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Semi-permeable Some substances can cross and others can’t Protein molecules run through the lipid bilayer Carbohydrate molecules attached to outer surfaces of proteins
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Concentration - mass of solute in a give volume of solution Isotonic - same strength Hypertonic - above strength Hypotonic - below strength
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Diffusion Molecules in solution move constantly and spread randomly through space. They naturally move from an area of high concentration to an area of low concentration until equilibrium is reached.
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EquilibriumEquilibrium is reached when the solute is the same throughout Diffusion does not require energy
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Osmosis The diffusion of water molecules through a biological membrane Naturally moves from a higher concentration to a lower concentration
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Will continue until Equilibrium is reachedEquilibrium Does not require energy Osmotic pressure is on the hypertonic side of a selectively permeable membrane Almost all cells are hypertonic to fresh water
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Facilitated Diffusion Diffusion that occurs through protein channels in the cell membrane Each channel is specific and allows only certain molecules into the cell
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Does not require energy MoleculesMolecules must flow from a higher concentration to a lower concentration
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Active Transport Molecules move against the concentration difference and flow from a lower concentration to a higher concentration Requires energy
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Examples: Sodium - Potassium pumppump Endocytosis - the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane to make a vacuole
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PhagocytosisPhagocytosis - taking in large particles by endocytosis
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Exocytosis - the removal of large amounts of material from a vacuole that fuses with the cell membrane forcing it’s contents out of the cell
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Every living cell contains a liquid interior and is surrounded by liquid. Cytosol - a solution of many different substances in water Cytoplasm = cytosol + organelles
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Cytoplasm Cytosol + Organelles Fills the entire cell Made of water, salt and organic substances, also contains enzymes
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Cytoplasm Functions to hold organelles, allows for storage of chemicals, and provides pathways for molecular movement (cytoplasmic streaming)cytoplasmic streaming
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Cell Wall Not found in all cells Outside the cell membrane Made of cellulose – a tough carbohydrate fiber
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Cell Wall Porous enough to allow water, oxygen, carbon dioxide and some other substances through easily Main function is to provide support and protection for the cell
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Nucleus Largest organelle Control Center Contains DNA Instructions for everything that goes on in the cell
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Nucleic acid that stores and transmits genetic information from one generation to another DNA
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Has to be able to carry info from one generation to another Structure of DNA
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That info needs to determine characteristics Needs to be easy to copy Structure of DNA
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A long molecule made of nucleotides 5 carbon sugar (ribose) Phosphate group Nitrogenous base DNA is…
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Adenine Cytosine Guanine Thymine 4 Bases
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Any sequence is possible Base order = the coded genetic information Base order
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The amount of Adenine is always equal to the amount of Thymine and Chargaffs’ rule
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The amount of Cytosine is always equal to the amount of Guanine Chargaffs’ rule
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Adenine will always pair up with Thymine Cytosine will always pair up with Guanine Base Pairing
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Took x-ray defraction photographs of DNA molecules Noticed a spiral shape Wilkins and Franklin
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Looked at Chargaffs research and photos by Wilkins and Franklin Built a 3 dimensional model of DNA Watson and Crick
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Discovered the shape = Double Helix (2 strands wound around each other) Page 294 Watson and Crick
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The DNA Song We love DNA Made of nucleotides Sugar, phosphate and a base Bonded down one side
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Adenine and thymine Make a lovely pair Cyotsine without guanine Would feel very bare
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Sugar and phosphate make sides of the ladder The bases are held together with hydrogen bonds to make the rungs (C=G and A=T) Like a Ladder
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This structure explains how DNA can be copied Each half has the info needed to make the other half (complimentary strands) Replication
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Enzymes unzip the molecule by breaking hydrogen bonds (DNA Polymerase) Replication
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Starts at one point and goes along entire molecule (can go in both directions) Each strand serves as a template for complementary bases Replication
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The result is two DNA molecules identical to each other and to the original molecule Replication
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Coded DNA instructions that control production of proteins Sequence of bases are in the DNA molecule Genes
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Mutations Changes in the DNA sequence that affect the genetic information Changes the kind of protein made
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Proteins are the keys to almost everything that living cells do Enzymes, growth regulators, building materials Proteins
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Nucleolus Makes Ribosomes
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Ribosome Assemble proteinsproteins
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Step 1 – make RNA What is RNA? To make a protein
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Required for protein synthesis Disposable copies of DNA Long chains of nucleotides RNA
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Sugar is ribose instead of deoxyribose Single strand not double Uracil replaces thymine Different from DNA
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Messenger – carries copies of DNA instructions Ribosomal – found in the ribosome Transfer – transfers amino acids to the ribosome 3 Types
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The RNA Song We love RNA Transcribed from DNA Single stands of three kinds M & T & R
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M is the messenger T does the transfer R is in the ribosome For translation to occur
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RNA and DNA Make a lovely pair Synthesizing proteins and
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Copying part of the nucleotide sequence of DNA into a complementary sequence of RNA Transcription
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Proteins are made of chains of Amino Acids Bases are read in groups of three to code for different Amino Acids Transcription
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the three letter “words” are called codons Transcription
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the three letter “words” are called codons There are 64 possible codons that can be made with the 4 bases Transcription
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The decoding of mRNA to form a protein (polypeptide chain) Happens in the Ribosome Translation
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1.mRNA is transcribed from DNA and released into cytoplasm (transcription), then attach to ribosome To Make a Protein
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2.tRNA brings amino acids to the ribosome to match codons 3.Ribosomes form peptide bonds between amino acids and breaks bonds between amino acids and tRNA To Make a Protein
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4. Peptide chain continues to grow until it hits a stop Peptide chain continues to grow until it hits a stop codon that causes it to release from the ribosome and the mRNA molecule To Make a Protein
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Proteins are the keys to almost everything that living cells do Enzymes, grow regulators, building materials To Make a Protein
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Mutations Changes in the DNA sequence that affect the genetic information Changes the kind of protein made
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Changes sunlight into food Changes food into energy Create Energy Chloroplasts & Mitochondria
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Energy The ability to do work All living things depend on Energy
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ATP page 202 Figure 8-2 Adenosine Triphosphate Used to store energy needed for life processes
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ADP page 203 Figure 8-3 Adenosine Diphosphate Similar in structure to ATP but has only 2 phosphates
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Phosphate groups can be added or taken away according to cell supply and need Energy stored in ATP is released when it is converted into ADP and 1 phosphate group
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Uses for ATP in cells Movement within the cell organelles along microtubules Active Transport sodium/potassium pump 1 ATP molecule can move 3 sodiums and 2 potassiums
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Glucose and ATP Cells only keep a small amt of ATP Glucose can store 90x the chemical energy of ATP They keep larger amounts of glucose
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Glucose ATP more value less value less mass more mass
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Where does the cell get the energy it needs? energy Photosynthesis Cellular Respiration
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Where do they get it? Autotrophs Heterotrophs (carnivore, herbivore, omnivore, decomposer, scavenger)
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