Anatomy and Physiology Chapter #4 23 pairs of chromosomes in the human nucleus Genes Chromosome Bases DNA Strand

4.1 Introduction Cells require energy and information to build bodies. Cells carry out many reactions of metabolism. These reactions break down nutrients to release energy. Cells carry genetic info. Enzyme is a special type of protein that controls each reaction of metabolism.

4.2 Metabolic Reactions Metabolic reactions are of two types: in anabolism reactions, larger molecules are constructed from smaller one. The process that provides the biochemicals required for cell growth and repair is anabolism. In catabolism reactions, larger molecules are broken down. The reactions of metabolism are often reversible. Which process requires energy? Anabolism Which releases energy? Catabolism The process of joining two molecules by removing water is called dehydration synthesis. A by-product of dehydration synthesis is water. The process of splitting two molecule by adding water is called hydrolysis. Hydrolysis occurs during digestion.

4.3 Control of Metabolic Reactions Enzymes control the rates of all the metabolic reactions of the cell. Enzymes are complex molecule (PROTEIN) that function to lower the activation energy of a reaction so it may begin and proceed more quickly. Because they do this, enzymes are called catalysis. The substances the enzymes act on are called substrate. Each enzyme is specific. Enzymes recognize the specific shape of the substrate with which they react.

4.3 Control of Metabolic Reactions continued… Enzymes are needed to promote metabolic reactions in the body because the temperature in cells is not high enough to promote the increase in chemical reaction rates. Very small quantities of enzymes are needed because they are not consumed in the metabolic reaction they facilitate. Enzymes can be denatured (destroyed) by heat and radiation, chemicals and extremes of pH, and electricity.

4.4 Energy for Metabolic Reactions The form of energy most often used by the body's metabolic processes is chemical. ATP is Adenosine Triphosphate . It stores the energy for every reaction in the body. Energy can be mechanical, chemical, and thermal. The function of ATP is to store energy in its terminal phosphate bond.

Cellular Respiration Is the process that releases the energy in the chemical bonds of the energy nutrients and stores it in molecules of ATP. It has 3 basic stages, each of which have several steps and are controlled by many enzymes. The first stage does not require oxygen and so is said to be anaerobic. The other two stages require oxygen and therefore are aerobic.

1st Stage of Respiration The first stage of cellular respiration is anaerobic and occurs in the cytosol. The anaerobic respiration is called glycolysis. Where does it take place? cytosol What chemical does it start with? glucose What chemical does it end with? Pyruvic acid Are any ATP’s formed? 2

2nd & 3rd Stages of Respiration The second phase of cellular respiration is aerobic and occurs in the mitochondria. aerobic respiration has two stages. Where do they occur? mitochondria What are the three end products of this process? Oxygen, water, and ENERGY Stage 2 is called citric acid cycle. Stage 3 is called electron transport chain.

Figure 4.5 pg 77

Cellular Respiration

Respiration C6H12O6 + 6O2  6CO2 + 6H2O+ ENERGY

4.5 Metabolic Pathways Metabolic pathways are a sequence of enzyme-controlled reactions. lipids & protein pathways – these two nutrients can be used to make ATP. Where they “plug into” the process is going to depend on how many Carbons are in the piece the cell is working on. How many ATPs formed will also depend on this.

Genetic Info Genetic information must tell cells how to position amino acids correctly in polypeptide chains. The function of DNA is to direct the activities of the cell and to direct the synthesis of protein by the cell. DNA molecules are replicated during what phase of the cell cycle? Interphase

4.6 Nucleic Acids (DNA & RNA) Deoxyribonucleic acid (DNA) contains the genetic code needed for the synthesis of each protein (including enzymes) required by the cell. The "backbone" of DNA is composed of alternating nucleotides joined so that phosphate and sugar portions alternate. The sugar is named deoxyribose. Name the four bases. Adenine, Thymine, Cytosine, Guanine What are the two base complementary pairs of DNA? A-T & C-G DNA is double strands and twists to form a double helix. The sequence of nucleotides in a DNA molecule gives the sequence of amino acids for a given protein.

DNA

4.7 RNA What is the sugar in RNA called? ribose Name the four bases: Adenine, Cytosine, Guanine, Uracil. RNA is single-stranded. There are 3 types of RNA. Ribosomal RNA (rRNA)- make ribosomes. Messenger RNA (mRNA) copy and transfer the genetic information to the cytoplasm where proteins are manufactured. Transfer RNA (tRNA) position amino acids along a stand of mRNA. tRNA join and form a protein molecule.

RNA

4.7 Protein Synthesis Transcription is the transferring of info from the DNA in the nucleus to the mRNA. Translation is the converting from the “language” of nucleic acids to the “language” of amino acids this occurs in the cytoplasm. Transcription = DNA → RNA Translation = RNA → protein

4.7 Protein Synthesis mRNA molecules copy part of the DNA code in the nucleus. They then travel to the ribosome where protein synthesis will occur. They lie across the ribosome and wait for the tRNA to bring in the appropriate amino acids. The correct amino acids will be lined up because the tRNA bases are arranged in anticodon that are complementary to the codons of the bases of the mRNA. The amino acids bond with peptide bonds to each other to form a protein.

RNA Transcription

4.8 DNA Replication Each new cell must be provided with an exact replica of the parent cell's DNA. When does DNA replication occur? Mitosis The DNA molecule splits. Nucleotides form complementary pairs with the original strands. Each new DNA molecule consists of one parental strand and one newly synthesized strand of DNA. What is a mutation? Changes in DNA can be harmful, helpful, or have no effect. The occurrence of mutations may be spontaneous or a result of exposure to ionizing radiation and toxic chemicals DNA of the parent cell must be replicated accurately so that the new cell can maintain life functions, build cell parts and metabolize nutrients.

DNA Replication

Work Cited DNA Replication image. http://www.genelex.com/paternitytesting/paternityslide1.html DNA image. http://www.tokyo-med.ac.jp/genet/picts/dnaL.jpg DNA, gene, chromosome image. http://www.alzheimers.org/unraveling/09.htm RNA image. http://library.thinkquest.org/C0123260/basic%20knowledge/images/basic%20knowledge/RNA/structure%20of%20RNA.jpg RNA transcription image. http://www.accessexcellence.org/AE/AEPC/NIH/gene03.html Cellular respiration image. http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20101/Bio%20101%20Lectures/Cellular%20Respiration/cellul13.gif