BIO 102- Exam 2 Study Guide
BIO 102- Exam 2 Study Guide Bio 102
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This 10 page Study Guide was uploaded by George Maxwell Miller on Wednesday October 5, 2016. The Study Guide belongs to Bio 102 at University of Louisville taught by Dr. Rachel Hopp in Fall 2016. Since its upload, it has received 130 views. For similar materials see Intro to Biology in Biology at University of Louisville.
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Date Created: 10/05/16
Exam 2 Study Guide TAY SACHS DISEASE: Recessive genetic disease involving accumulation of ganglioside in the lysosomes -This occurs when beta-hexosaminidase A (Hex A), an enzyme needed to break down ganglioside, is unable to be created due to a genetic mutation. This disease is inherited and destroys the BRAIN and CENTRAL NERVOUS SYSTEM Most commonly affects babies Those suffering from this disease typically become blind, deaf, and paralyzed Few survive past the age of 3-5 years old CHAPTER 3.2: Cell Theory & Cell Structure Cell Theory: 1. All living organisms are composed of one or more cells 2. The cell is the basic unit of structure and function in organisms 3. Cells arise from preexisting cells Exceptions: The first cell did not originate from preexisting cell OR some scientists say viruses are noncellular lifeforms Cytoplasm: Includes cytosol and organelles Organelles: Perform specific jobs required by the cell and work with other organelles Cytosol: Watery matrix with salts and enzymes; houses the organelles Plasma Membrane: Encloses all cells, defines outer boundary of cells, and isolates cell contents from environment. Determines materials to be allowed in or out Semipermeable membrane: Some molecules can cross and some can’t Membrane Structure: Phospholipid Bilayer Hydrophilic heads maximize exposure to water Hydrophilic tails orient inside the membrane, away from water Fluid Mosaic: Lipids and proteins can move about within the membrane Membrane Transport: Substances must travel through the plasma membrane Food Supplements Gases Waste (exits) Plasma Membrane: Phospholipid bilayer is differentially permeable Hydrophobic (water fearing) substances pass more easily through the hydrophobic interior Hydrophilic (water loving) substances use protein channels or carriers ***Be able to label the parts of a cell (both plant and animal) on the test*** can be found on BB slides Subcellular Structures: Cell Wall: Helps protect certain cells (plants, fungi, bacteria) and maintains shape Nucleus: Holds chromatin (DNA and Proteins) in eukaryotic cells Nucleolus: Synthesizes ribosomes; inside nucleus Mitochondrion: Produces energy for the cell through cellular respiration Chloroplast: Produces sugars through photosynthesis in plant cells Lysosome: Contains digestive enzymes to recycle molecules Ribosomes: Assemble proteins; free floating or attached to ER Rough Endoplasmic Reticulum (Rough ER): Membrane network with ribosomes attached for protein synthesis Smooth Endoplasmic Reticulum (Smooth ER): Involved in lipid synthesis; lacks ribosomes Golgi Apparatus: Modifies, sorts, and packages proteins Centrioles: Move chromosomes during animal cell division Cytoskeletal Elements: Form cytoskeleton for maintaining shape and structural support Central Vacuole: Stores water, starch, and pigments in plant cells CHAPTER 6.1 & 6.2: Intro to Cancer Biology, Genes, Chromosomes, and DNA Replication Tumors: Unregulated cell division forming a lump of cells with no function Benign Tumor: Doesn’t affect surrounding tissues Malignant Tumor: Invades surrounding tissues; CANCEROUS Metastasis: Cells break away from a malignant tumor and start new cancers at distant locations How do cancer cells differ from normal cells? Cancer cells invade surrounding tissues, dividing when they shouldn’t be and moving to other locations after invading. Cancer cells: Travel anywhere in the body via the circulatory system or the lymphatic system Differ from normal cells Replicate when they shouldn’t Invade surrounding tissues Move to other locations in the body Risk Factors: Behaviors or conditions that increase the chance of developing a disease Inherited cancer risk: Carried in genes Example: mutated BRCA1 gene related to breast cancer Environmental Exposures: Exposure to carcinogens (cancercausing agents) Exmaple: secondhand smoke from tobacco products Synergistic Risk Factors: Enhance the activity of other carcinogens Tobacco Alcohol When used together, tobacco and alcohol have a greater risk than each activity used alone Decreasing Cancer Risk: Don’t use tobacco Limit consumption of alcohol Eat a lowfat/highfiber diet Exercise Regularly/Maintain a healthy weight ***KNOW THIS LIST*** Describe the cellular basis of cancer: A. Uncontrolled Cell Division: a. Oncogenes (Cancer promoting genes) become activated from protooncogenes (encode harmless growth stimulating proteins) B. Lack of Apoptosis (i.e. cell suicide should occur when a cell is abnormal). BAD CANCER CELLS ACCUMULATE!!! C. Loss of Tumor Suppressors: These proteins usually prevent cancer, but may be mutated or deleted… D. Immortality (cells only divide a finite number of times, but cancer cells become immortal). E. New blood vessels (angiogenesis) grow into tumor to feed the tumor. F. Invasiveness cells usually die when they drift away from their home tissue/organ, but cancer cells METASTASIZE G. Immune Function Disaaray a. Long term inflammation causes growth signals b. Loss of immune system scanning to kill abnormal (cancer) cells Types of Reproduction: Asexual Reproduction Only one parent Offspring are genetically identical to parent Sexual Reproduction Gametes combine from two parents Offspring are genetically different from one another and from the parents Genetic Material: DNA (Deoxyribonucleic acid) carries genes Must be copied before cells divide Genes: section of DNA with instructions for building all cell proteins Chromosomes: Made of DNA wrapped around proteins In uncondensed, stringlike form before cell division Carry hundreds of genes Sister Chromatids: Duplicated chromosomes, attached at the centromere DNA Structure: Doublestranded “twisted ladder” Sides of the ladder: Sugarphosphate backbone “Rungs” of the ladder: Nitrogen bases connected by hydrogen bonds Adenine (A) pairs with thymine (T) Cytosine (C) pairs with guanine (G) DNA Replication: Occurs before cell division Begins by splitting helix in half (up the middle) Semiconservative Replication: Newly formed DNA strand has onehalf new daughter DNA and onehalf conserved parental DNA Key Enzymes of DNA Replication: Helicase: Separates DNA strands of the helix so DNA Polymerase can “read” the template strand to know which nucleotides to add DNA Polymerase: Adds new nucleotides to the growing strand based on template sequence (base pairing rules A:T, G:C) CHAPTER 7: Mendelian and Quantitative Genetics Family Resemblances: Children share similarities with their parents and siblings, but… Each child is unique Children are NOT just an “average” of both parents’ traits The Human Life Cycle: Growth and reproduction of an individual Adults produce gametes by meiosis Gametes (Sperm and Egg) fuse during fertilization to form singlecelled zygotes Continued cell divisions form the embryo The embryo grows to become a fetus A fullterm infant is born and with continued growth, becomes an adult. Genes and Chromosomes Genes: Segments of DNA that code for *proteins Prokaryotes: single, circular chromosomes Eukaryotes: Linear chromosomes Human cells have 46 chromosomes Adders Tongue, and ancient fern, have 1260 chromosomes!!! Genes are analogous to words in an instruction manual for building a human Chromosomes are analogous to pages in the instruction manual Each “page” contains thousands of “words” Different types of cells use different words in different orders Different Alleles: Mistakes in copying DNA (mutations) produce different versions of genes (alleles), with different results. Homologous Pairs: Equivalent chromosomes; pairs contain one chromosome received from each parent Parent cell has two complete copies of the manual 23 page copy from mom 23 page copy from dad 23 homologous pairs of chromosomes Unique Offspring Segregation: in meiosis, homologues separate from each other into different gametes Gamete gets just one copy of each page of the manual Independent Assortment: Homologues move into gametes, randomly and independently of other chromosomes, Due to random alignment of chromosomes during metaphase, each sperm or egg has a unique combination of genetic material from the parent. When the parent genes are known, will we always know the genes of the child? No, this is false. Genetic Diversity: about 8 million different combinations of chromosomes are possible Random Fertilization produces more diversity: 8 million x 8 million = 64 trillion possibilities!!! Twins: No two humans are genetically identical, except for monozygotic twins. Dizygotic twins are 50% identical, just like siblings born at different times. Gregor Mendel: The first genetic scientist; accurately described simple rules of inheritance Controlled mating between pea plants Described patterns of inheritance for traits from single genes with a few alleles Mendelian principles also apply to many genetic diseases in humans Phenotype: Physical traits of an individual Genotype: Genetic composition of an individual; describes alleles Homozygous: Homozygote carries two copies of the same allele Heterozygous: Heterozygote carries two different alleles for a gene Recessive: The phenotype of an allele is seen only when homozygous Dominant: The phenotype is seen when homozygous OR heterozygous Cystic Fibrosis: A recessive genetic diseases Defect in chloride ion transport in the lungs Produces thick mucus and lung deterioration Dramatically shortened lifespans Heterozygotes (carriers) do not show the symptoms Most common recessive disease among Europeans Huntington’s Disease: A dominant human genetic disease (only ONE parent needs to be a carrier of the allele). Progressive and incurable Nervous, mental, and muscular symptoms continue to worsen, resulting in DEATH Symptoms appear in middle age Mutant protein kills nerve cells by forming clumps inside the nuclei Having a normal allele does not compensate Punnett Squares: Table that predicts possible outcomes of a cross (mating between two parents) Consider a cross between two cystic fibrosis carriers “F”=normal allele; “f”=recessive disease allele The cross would be Ff x Ff Therefore, what offspring could result? 25% chance of FF, 50% chance of Ff, and 25% chance of ff Quantitative Traits: Show continuous variation Large range of phenotypes (Height, weight, intelligence, etc.) Variation due to both genetic and environmental differences Epigenetics: When gene expression changes, but not mutation involving the nucleotide (letter) sequence does not change. ENVIRONMENT HAS A ROLE! Mean: Adding all of the values for a trait in the population and dividing by the number of individuals in the population, i.e. average Variance: A measure of how much variability there is in the population Polygenic traits: Traits influenced by many genes Include quantitative traits, with continuous variation Interaction of multiple genes with multiple alleles results in many phenotypes Example: Human eye color Light brown/hazel, medium brown, dark brown Green, greenblue, etc. Environmental Effects Continuous variation may result from environment effects Most traits that show continuous variation are influenced by genes AND the environment Heritability: Proportion of the variation within a population due to genetic differences among individuals Natural Experiments: Overlap of genes and environment is limited Twin Studies Compare monozygotic twins (sharing 100% of alleles) and dizygotic twin (sharing 50%) Heritability of IQ is 52% Monozygotic twins separated at birth and raised in different homes Heritability of IQ is 72% Heritability in Humans -Correlations between human groups are used to estimate the genetic components of a trait -Correlation between parents and children -Heritability of IQ is 42% -Apply this to the sperm bank story at the chapter opening Individual Differences -Heritability does not tell us about individual differences -Heritability is based on variances in populations (think gene pool of diff. alleles) -A high heritability value for a trait does not automatically mean that most of the difference between two individuals is genetic -Genes have a strong influence on even complex traits -BUT independent assortment of multiple genes with multiple alleles produces a large number of phenotypes -Environment can also have a large effect. EPIGENETICS! -For quantitative traits, it is difficult to predict the phenotype of children from the phenotypes of the parents Dihybrid Cross (two genes): Mating crosses that involve two traits Determine the possible gamete -Yellow (Y) is dominant to green (y) -Round (R) is dominant to wrinkled (r) For a cross: YyRr x YyRr -Possible gametes for parent 1: -YR, Yr, yR, yr -Possible gametes for parent 2: -YR, Yr, yR, yr CHAPTER 9: Genetically Modified Organisms (GMOs) Protein Synthesis: The process of using instructions carried by genes to build proteins -Gene: a sequence of DNA that encodes a protein -Protein: A large molecule composed of amino acids (aa) Involves multiple steps: Genome in nucleus Copy of gene as mRNA mRNA on ribosome Amino acids tRNAs Protein DNA- -Double-stranded -Nucleotide subunit -Deoxyribose (sugar) -Phosphate group -Nitrogenous base -Four bases: Guanine, Cytosine, Adenine, Thymine RNA- -Single-stranded -Nucleotide subunit -Ribose (sugar) -Phosphate group -Nitrogenous base -Four bases: Cytosine, Guanine, Adenine, Uracil Protein Synthesis: DNA RNA Protein -The flow of genetic information occurs in 2 steps: -Transcription (DNA RNA) & Translation (RNA Protein) Transcription (DNA RNA): -Occurs in the nucleus -Forms messenger RNA (mRNA) -Transcription factors and RNA polymerase binds to the promoter -RNA polymerase zips down the length of the gene, matching RNA nucleotides with complementary DNA Translation (RNA Protein): -Occurs in the cytoplasm (out of the nucleus) at “free” ribosomes in cytoplasm or ribosomes attached to RER -5 Requirements 1. mRNA (made during transcription) 2. Energy (ATP) 3. Ribosomes (rRNA + Protein; in lg and sm subunits) 4. Transfer RNA (tRNA) 5. Amino Acids Ribsomes: -Composed of ribosomal RNA (rRNA) and protein -A small subunit -A large subunit Transfer RNA (tRNA) -Carries amino acids -Matches it complementary anticodon with codons on mRNA -Codons are 3 nucleotides long mRNA has codons (codes for aa’s) tRNA has anticodons Proteins: -A protein is put together one amino acid at a time -The ribosome attaches to the mRNA at the beginning of the transcript before the first codon -Ribosome facilitates the docking of tRNA anticodons to mRNA codons. Each tRNA carries one aa -Peptide Bonds form between the aa’s of two adjacent tRNAs -Eventually, at the stop codon the full protein is released Genetic Code: Allows a specific codon to code for a specific amino acid -A codon is composed of 3 nucleotides -64 (4^3) possible combinations -61 codons code for amino acids -3 others are stop codons, which end protein synthesis Additional properties of genetic code: -The genetic code is redundant: -Multiple codons code for the same amino acid -ACU, ACC, ACA, and ACG all code for the acid threonine -The genetic code is universal: -All organisms decode the same gene to produce the same protein. This is why bacteria can make human insulin! Mutations: Changes in genetic sequence -May affect the order of amino acids in a protein -Precise order of amino acids is necessary for properly functioning proteins -Possible outcomes of mutation: 1. No change in protein (neutral/silent) 2. Nonfunctional protein 3. Different protein with different function Gene Expression: -Each cell in your body (except sperm and egg cells) has the same DNA -Cells express different genes based one their functions -Every cell has the same “library”, but different books are read in different cells -The different book that develops = Differentiation Regulation of gene expression: Turning a gene or set of genes on or off Regulation of Transcription: -Repressors regulate gene expression -Used by prokaryotic cells -Bind to the promoter and prevent the RNA polymerase from bonding -Activators regulate gene expression -Used by eukaryotic cells -Help the RNA polymerase bind to the promoter RNAi or RNA Interface: -After mRNA is produced it is degraded or prevented from being translated at a ribosome
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