BIOL 1333-001 Exam 2 Study Guide
BIOL 1333-001 Exam 2 Study Guide BIOL 1333 - 001
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This 9 page Study Guide was uploaded by Samer Hijjazi on Tuesday October 18, 2016. The Study Guide belongs to BIOL 1333 - 001 at University of Texas at Arlington taught by Melissa Walsh in Fall 2016. Since its upload, it has received 120 views.
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Date Created: 10/18/16
Chapter 5 Notes: What is energy? - it is the capacity to do work - needed for building complex molecules and moving substances in and out of the cell - without a source of energy, all life on earth would stop The types of energy - Chemical energy, thermal energy, light energy, thermal energy The Law of Conservation of Energy - Energy cannot be created or destroyed, but It can change from one form to another - Example: Potential energy Kinetic energy Potential and kinetic energy - Potential energy: The energy stored in chemical bonds - Example: A sandwich has potential energy (in the form of chemical energy) - Kinetic energy: The energy of motion - Example: After eating the sandwich, you go for a run. The potential energy (the chemical energy in the bonds of the sandwich) is converted into kinetic energy (running) - As the conversion of energy occurs, some energy is lost as heat, which is why energy must be supplied continuously How organisms use energy - They use the energy to: - join molecules to form a larger organic molecule (photosynthesis) - break apart organic molecules to release more energy for metabolic reactions (respiration) What is Photosynthesis? - The process in which plants use carbon dioxide, water, and sunlight energy to produce glucose - The equation for photosynthesis: 6CO 2 + 6H 2O + Sunlight C 6H 12O 6 + 6O 2 (carbon dioxide) (water) (glucose) (oxygen) - Photosynthesis only occurs in autotrophs Autotrophs and heterotrophs - Autotrophs: organisms produce their own energy by producing glucose (by photosynthesis), which is used as a source of energy for cellular respiration (example: plants) - Heterotrophs: organisms that obtain their energy by eating other organisms and use that energy for cellular respiration (example: animals) - Autotrophs synthesize their own organic molecules. Heterotrophs ingest organic molecules Where in the plant does photosynthesis occur? - In the chloroplasts of the cells - Chloroplasts: organelles that are green in color which are present in plants and algae - Chloroplasts consist of a pigment known as chlorophyll Sunlight energy: - Light energy: the energy of the electromagnetic spectrum of radiation - Light energy consists of different wavelengths, and wavelengths have different colors - Each wave has a packet of energy known as a photon - Photons of different wavelengths have different amounts of energy - Most wavelengths are absorbed by the chlorophyll, except for the green wavelengths, which is why leaves appear to be green to us. - As the chlorophyll absorbs the photons of light, its electrons become excited because of the energy from light - The excited electrons then produce an energy-carrying molecule known as ATP (used to make sugar) The two steps of photosynthesis 1. Photo: Energy is captured from the sun, which splits the water molecules. As a result, oxygen is released as a by-product 2. Synthesis: The energy from sunlight is used to convert carbon dioxide into glucose Carbon fixation - After light energy is captured, it is converted into chemical energy - This chemical energy is used to convert inorganic molecules (carbon dioxide) into organic molecules (glucose) - Carbon fixation is the main way carbon enters the global energy chain Carbon cycle - Factories, cars, and humans release carbon dioxide into the air, while plants absorb carbon dioxide for photosynthesis. This is a continuous cycle Fossil Fuels - Carbon is present in fossil fuels - Fossil fuels are formed by plants which were buried under water and dirt millions of years ago. The heat and pressure on the buried plants converted them into coal, which is used as an important source of energy (used for cars and buildings). - Fossil fuels are limited. Renewable sources are alternatives for energy - Renewable sources of energy include solar, wind, and hydroelectric energy - Fact: The U.S.A is the largest consumer of fossil fuels Biofuels - They are renewable fuels made from organisms - Come from animal fats and waste, sugar cane, corn, and algae - Many companies use fuel from algae - Algae produce lipids and sugar, which are ideal for making fuel - Plant biofuels are carbon-neutral (net zero carbon emissions) Pros and cons of Algae biofuels - Pros: grown on non-arable land (not competing with food production), small organism, which makes conversion of sun energy into chemical energy efficient - Cons: require lots of water and nutrients (nutrients from fossil fuels) Chapter 6 Notes: The importance of diets - Diets consist of what we eat - The nutrients from food are used for building tissues during growth and development - They’re also used for replacing lost cells - Many foods contain additives and preservatives that cannot be used by the body. Therefore, they are excreted (released as waste) - Unhealthy diets lead to diseases, such as heart disease, high blood pressure, and diabetes - Not everyone has the same diet What determines a person’s diet? 1. Biology - Sex, age, and physical activity - Cravings for high fat and calorie foods 2. Environment - What foods can be grown in the area 3. Culture - Each culture has its own food culture (what to eat and how to eat) 4. Socioeconomic status - Food availability Food energy - Food is a source of energy for heterotrophs - Food contains macromolecules, which are broken down into subunits. They are used to make new molecules, and are also used as a source of energy - Food energy is measure in Calories (C) - Calories: amount of energy needed to raise the temperature of 1g of water by 1 degree Celsius - Men require more calories than women due to their higher muscle mass Storing excess calories - When an excess amount of calories is ingested into our bodies, they are stored short-term as glycogen molecules in both muscle and liver cells. Glycogen is a carbohydrate made up of linked chains of glucose molecules. - Glycogen is used as a quick energy source when food molecules are unavailable - Once glycogen stores are filled, excess calories are stored as triglyceride in fat cells - Triglycerides are lipids found in fat cells that are used for long-term energy storage - Extra calories are burned by performing different activities (swimming, running, playing sports) Steps of extracting energy from food 1. After food is digested, the subunits are delivered to the cells through the bloodstream 2. Enzymes break down the bonds between the subunits 3. Potential chemical energy stored in bonds molecular bonds that make ATP What is ATP? - Known as adenosine triphosphate, is a nucleotide that stores chemical energy. - Energy in food must be converted into ATP to be used by the cell What is aerobic respiration? - It’s a process in which food energy (from lipids, fats, glucose) is converted into ATP - Aerobic respiration requires oxygen - The equation for aerobic respiration: C 6H 12 O 6 + 6O 2 ATP + 6CO 2 + 6H 2O (glucose) (oxygen) (carbon dioxide) (water) - The oxygen comes from the lungs. Travels through the bloodstream - The glucose comes from the intestines. Travels through the bloodstream - Food is broken down into energy. This energy is used to make ATP - Water and carbon dioxide are waste products The three stages of aerobic respiration - Aerobic respiration takes place in different parts of the cell 1. Glycolysis: - Occurs in the cytoplasm (The process of glycolysis occurs with/without the presence of oxygen) - Breaks down each glucose into 2 pyruvate molecules. Pyruvate formula: C3 H3O 3- - Produces 2 ATP 2. Citric Acid Cycle (also known as Krebs Cycle): - Occurs in the mitochondria - Electrons are extracted from pyruvate. NAD+ picks up/transfers electrons, becoming NADH - The transferred electrons are carried to the inner membranes of the mitochondria by NADH - Produces 2 ATP. In addition, carbon dioxide is released 3. Electron Transport Chain (ETC): - Occurs in the mitochondria - NADH releases electrons, which are passed down on molecules, releasing energy - NADH is regenerated into NAD+ so that it can be used again in glycolysis - At the end, oxygen accepts electrons, and combine with hydrogen to form water - Produces 36 ATP Fermentation - This process occurs when oxygen is absent (it replaces citric acid cycle and ETC) - With the absence of oxygen, the electron transport chain cannot receive electrons. Moreover, electrons cannot be transferred from NADH to ETC - The process happens only in the cytoplasm - The process keeps glycolysis going by regenerating NADH - Fermentation produces lactic acid (in humans) or alcohol (in bacteria or yeast) - The products of fermentation leave the cell - Only 2 ATP is produced (from glycolysis) Photosynthesis and aerobic respiration form a cycle: - When a plant respires, it releases carbon dioxide. The carbon dioxide released is then used for the process of photosynthesis, which produces oxygen needed for aerobic respiration. The result is a continuous cycle. Chapter 7 Notes: What is DNA? - Also known as deoxyribonucleic acid - A hereditary molecule passed from parents to offspring - It’s used as an instruction for making proteins (proteins include enzymes, hormones, pigments) Where is it found? - In the nucleus of the eukaryotic cell - They are wound and coiled up tightly into chromosomes - The DNA is coiled up for protection Chromosomes - They come in pairs - Humans have 23 pairs (46 chromosomes) rd - The 23 determines sex (XX: female, XY: male) - Different animals have different amount of pairs - The amount of chromosomes has nothing to do with the complexity of an organism The DNA structure - A DNA has two connected strands, forming a shape called - It’s made up of nucleotides - A nucleotide consists of: 1. Sugar 2. Phosphate 3. One of 4 nitrogenous bases: adenine (A), thymine (T), guanine (G), cytosine (C) - Phosphate and sugar are on the outside of the DNA structure - Hydrogen bonding is what holds the two stands of DNA together, forming a ladder shape - Complementary base pairing: certain bases pair together (A with T, C with G) DNA replication - One of the primary jobs of DNA - A process in which cells make an identical copy of a DNA molecule - Replication is needed for cell division which includes: 1. Growth 2. Replacement of cells (many cells die) 3. Reproduction - Replication takes advantage of complimentary base-pairing rules The steps for DNA replication 1. The hydrogen bonds holding the base pairs are broken down 2. DNA polymerase (an enzyme) reads the DNA 3. Adds complementary nucleotides Semi-conservative mechanism - After DNA replication, two copies of the original DNA molecule are produced - Each molecule has two strands: 1 original strand, 1 new strand The polymerase chain reaction (PCR) - Taking a small sample of DNA and amplifying it into many more DNA molecules - Used in laboratories - Primers are used for showing the DNA polymerase which section of the DNA needs to be copied The steps of PCR 1. Heat the DNA sample to separate the strands 2. Allow it to cool 3. The DNA polymerase binds the strands together, replicating the DNA - Enzymes have a temperature optimum, which is why DNA polymerase functions in cooler temp. DNA profiling - The analysis of DNA samples to identify individuals - No two people have the exact same DNA sequence (genome) - Sequencing an entire sequence is not easy because it has millions of base pairs - Instead, short tandem repeats (STR) are used - Usually used in crime scenes What is STR? - Non-coding sections of DNA (not being used to make proteins) - Located in the same places along chromosomes - The lengths vary from one person to another Steps of DNA profiling 1. Collect cells from crime scene 2. Extract the DNA 3. Amplify multiple STR regions using PTR 4. Separate STRs by using gel electrophoresis - The separated fragments of DNA create a certain pattern of bands - Different STR lengths: 2 bands, Same STR lengths: 1 band 5. Compare the patterns The Innocence Project - Uses DNA as evidence to free wrongfully accused people - It is a reliable source of evidence Chapter 8 Notes: What is a protein? - It’s a macromolecule made of folded chains of amino acids The functions of a protein - Muscle contraction - Facilitates chemical reactions - Used against infections Amino Acids - Bond together to form linear chains, which make up a protein molecule - Amino acids have the same base structure - The sequence of the chain determines the shape and function of the protein - A change in DNA sequence = a change in the corresponding amino acid sequence = a change in the function of a protein Protein Synthesis - Starts with a gene - A gene is a region that carries instructions to make proteins - The process of taking the instructions from the gene to make proteins is called gene expression - Note: protein synthesis does NOT occur in the nucleus Alleles - The different versions of the same gene - There are two alleles in a chromosome - one on each homologous chromosome (one inherited from each the mother and father) - may have a similar nucleotide sequence - different alleles influence the structure and function of the protein - genes have two parts: 1. Regulatory sequences: determine when and how much protein a gene makes 2. Coding sequences: determine the amino acid sequence of the encoded protein What is gene expression? - The process of converting genetic information into protein - It consists of two steps: transcription and translation Transcription - From DNA to mRNA - The process occurs in the nucleus - This process copies the coding sequence of DNA into the complementary messenger (mRNA) sequence Steps of transcription 1. The strand of DNA unwinds 2. RNA polymerase (enzyme) moves along the unwound strand, reading the DNA coding sequence 3. Synthesizes a complimentary mRNA strand - Note, the Adenine (A) pairs with uracil (U) 4. Once mRNA strand is formed, it detaches from DNA sequence - DNA reforms its shape. It can be used again in the future 5. mRNA leaves the nucleus and binds to a ribosome Translation - mRNA to protein - the process takes place on a ribosome - it uses the mRNA sequence to assemble the appropriate amino acid sequence of the protein Steps of translation 1. The ribosome moves along the mRNA to read it - It reads the mRNA sequence in groups of three nucleotide - This group of three is known as a codon, which specifies a particular amino acid 2. The transfer RNA (tRNA) binds the amino acids in the cytoplasm 3. tRNA then delivers them to the ribosome 4. tRNA matches an anticodon with the corresponding codon 5. after the codon and anticodons attach, the protein is formed and leaves the ribosome - The ribosome is used again for future use The Genetic Code - A set of rules that relate certain mRNA codons to certain amino acids - It has 64 codons - It’s used for making proteins - It’s the same for all organisms Antithrombin protein - Helps prevent blood clots (thrombosis) - The antithrombin gene is on chromosome one - The protein is produced in the liver, then released into the bloodstream Antithrombin Deficiency - A disorder. It happens when one or both copies of antithrombin gene defective - This prevents the blood from flowing freely Genetically modified organisms - Also known as transgenic organisms, organisms that have been changed genetically - Genetic engineering: the insertion of genes into an organism - Examples: bananas (for vaccinations), herbicide resistant/pesticide producing crops (to help growth of plants), golden rice (adding vitamin A to it) Genetically modified organisms (in medicine) - First, isolate the gene of interest from human chromosome - Then insert it into bacteria/virus/animal embryo - Example: injecting goats with antithrombin. The protein will be present in the milk - Pharming: using genetically modified animals to make pharmaceutical drugs Steps of antithrombin production 1. Use regulatory sequence of a milk gene 2. Insert coding sequence of human antithrombin gene - Antithrombin is expressed only in the mammary cells 3. Harvest the transgenic milk 4. Purify the protein The Genome Project - A human genome contains 3 billion base pairs - The purpose of the project is to identify genetic diseases and understand gene expression and regulation
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